Basic Exam Flashcards

Question

What is the order or potentiating volatile anesthetics for prolonging neuromuscular blockade? Why is this physiologically seen?

Answer 1

**Potentiation from greatest to least for volatile anesthetics is:** ***_desflurane*_ \> _*sevoflurane*_ \> _*isoflurane_*.** **Desflurane** is a volatile anesthetic with a low blood gas partition coefficient of 0.42. - The low blood gas coefficient means that very little desflurane is dissolved in tissues, but that desflurane is able to rapidly equilibrate with tissues resulting in quick onset and termination of effects. - This **rapid equilibration into tissues including muscle** is the reason why desflurane potentiates neuromuscular blockade more than other volatile anesthetics. - The location of potentiation is likely at the neuromuscular junction and occurs in a dose dependent fashion.

Answer 2

**Ventilators need "TLC"** Mechanical ventilation can be categorized by three variables **1. Trigger** - What **initiates** the breath and depends on ventilatory drive **2. Limit** - **Governor of PPV** and depends on ventilatory requirements related to how much *_flow*_ and _*volume_* are required to satisfy metabolic demands 3. **Cycle** - What **terminates** the inspiratory phase and depends on the duration and ratio of inspiratory time to total breath cycle duration.

Answer 3

Morphine improves coronary perfusion through a **reduction in preload** and a **reduction in end-diastolic pressures (EDP)** in the ventricles. The EDV is proportional to the EDP generated within the ventricle. The RV is perfused during both systole and diastole whereas the LV is perfused during diastole only. _Right-sided coronary perfusion_ pressure during systole is = (aortic systolic pressure - RVEDP). _Left-sided coronary perfusion_ pressure is the difference between (aortic diastolic pressure and left ventricular end-diastolic pressure (LVEDP)). Coronary perfusion pressure is improved by **REDUCING both RVEDP and LVEDP.**

Answer 4

Central nervous system toxicity is first noted by **circumoral and tongue numbness.** *_Visual and auditory disturbances (tinnitus) then follow_*. The clinical scenario then progresses to *_dizziness/lightheadedness, muscular twitching, unconsciousness, and seizure activity_*. These clinical signs may then be followed by cerebral edema, increased intracranial pressure, coma, respiratory arrest, and ultimately cardiovascular depression and death. Patients who are premedicated with anticonvulsants, such as benzodiazepines or barbiturates, may have masked CNS symptoms and develop cardiovascular depression before other signs are apparent.

Answer 5

**intravenous** **tracheal** **intercostal** **caudal/paracervical** **epidural** **brachial plexus** **sciatic/femoral** **spinal** **subcutaneous** Intercostal \> Caudal \> Epidural \> Brachial Plexus \> Lower Limbs \> Sub-Q "IT - ICE BaLLS" is the mnemonic

Answer 6

Areas of regional anesthesia from highest to lowest vascularity include: ## Footnote **intravenous \> tracheal \> intercostal \> caudal/paracervical \> epidural \> brachial plexus \> sciatic/femoral \> spinal \> subcutaneous.**

Answer 7

Lidocaine has been linked to **cauda equina syndrome**, causing urinary and fecal incontinence as well as gait disturbances. This association has been documented in the setting of *_high concentration (5%) intrathecal lidocaine_* administered via narrow lumen (e.g. 27 gauge) catheters. The slow administration of 5% lidocaine through these catheters allows for pooling of the drug in the region of the cauda equina. This form of local neural toxicity may be due to demyelination.

Answer 8

**Carbon monoxide and heat** are produced from the degradation of anesthetic agents in the presence of desiccated carbon dioxide absorbent. Among today’s volatile anesthetics, degradation of **desflurane** produces the most carbon monoxide. **Sevoflurane** = **Compound A**

Answer 9

Injury to a saphenous nerve can cause numbness, pain, and/or paresthesias along the **medial lower leg.** Perioperative saphenous nerve injury is relatively **uncommon** but, due to its close **proximity to the great saphenous vein, is a known complication of saphenous vein harvest (e.g., vein graft harvest for coronary artery bypass grafting)** or saphenous vein stripping. Rarely, saphenous nerve block can also cause temporary or permanent nerve injury. Damage to the saphenous nerve may result in temporary or permanent cutaneous sensory loss, pain, or paresthesias. **Anatomy:** Major sensory branch of the femoral nerve that is primarily responsible for cutaneous sensation of the medial lower leg

Answer 10

**Tibial nerve** **Common Peroneal nerve**

Answer 11

Mixed sensory and motor nerve that innervates the **peroneus longus and peroneus brevis muscles (which allow foot eversion)** Provides sensation to the **lateral lower leg and most of the dorsum of the foot.**

Answer 12

Common peroneal nerve injury is the **most common isolated mononeuropathy of the lower extremities.** Perioperative injuries can occur due to **knee hyperflexion (e.g., during lithotomy position in stirrups or boots).** **Excessive hip flexion** leading to a sciatic nerve stretch injury can also damage nerve fibers prior to their division into the common peroneal nerve.

Answer 13

Mixed sensory and motor nerve that innervates many major lower leg muscles which are primarily responsible for **foot dorsiflexion.** Provides cutaneous sensation to a **small patch of skin between the first and second toes.** Isolated injury to this nerve is most commonly caused by trauma to the **lateral knee and typically leads to foot drop.**

Answer 14

The tibial nerve is a motor and sensory branch of the **sciatic nerve.** It innervates the lower leg posterior compartment muscles primarily responsible for **foot plantar flexion**. The tibial nerve also provides cutaneous sensation to the **posterolateral lower leg and lateral foot.** Tibial nerve injury is most commonly caused by trauma to the lower leg or ankle.

Answer 15

Acute respiratory acidosis should demonstrate a **pH decrease of 0.05** and an **HCO3- increase of 1.0 mEq/L** per acute **10 mm Hg increase in PaCO2.** Chronic respiratory acidosis, **pH nearly normalizes**, and **HCO3- concentrations increase 4-5 mEq/L** per **10 mm Hg sustained increase in PaCO2.** Respiratory alkalosis becomes chronic, **pH nearly normalizes** and **HCO3- decreases 5-6 mEq/L** per **10 mm Hg sustained decrease in PaCO2**.

Answer 16

Approximately 20 genetic variants of the BCHE gene exist with the A**- and K-variants being the most common.**

Answer 17

**Echothiophate**

Answer 18

There are four phases during diastole: **Isovolumetric relaxation**: this phase begins with the closure of the aortic valve and continues till the opening of the mitral valve. During this time, the left ventricle is relaxing, however there is no change in the ventricular volume (isovolumetric). **Early rapid filling**: this phase begins with the opening of the mitral valve. The left ventricle begins to fill with blood from the left atrium. The flow of blood is driven by the transmitral pressure gradient. This phase contributes the *_largest volume of blood to the left ventricle during diastole._* **Diastasis (slow filling)**: as the left ventricle fills, the pressure difference between the left ventricle and atrium decrease. This slows down the filling considerably, and contributes approximately 5% of the preload. This phase occurs mid-diastole. **Late rapid filling (atrial contraction)**: the left atrium contracts, ejecting additional blood into the left ventricle. This phase can contribute 15-20% of the preload. Atrial contraction is the last phase of diastole. The mitral valve closes after the atrial contraction.

Answer 19

The absorption of nitrous oxide is augmented by the **concentration effect,** making the **rate of absorption faster than desflurande** despite their similar blood gas partition coefficients.

Answer 20

Carbon dioxide is transported in the blood as: **1. Dissolved CO2** Carbon dioxide is 10 times more soluble in blood than oxygen: 0.031 mmol/L/mm Hg versus 0.003 mmol/L/mm Hg, respectively. **2. Bicarbonate \*Majority\*** This occurs because red blood cells and vascular endothelium contain carbonic anhydrase, an enzyme used to convert carbon dioxide to bicarbonate. The enzyme also catalyzes the reverse reaction. In either case, a transient intermediate, carbonic acid, is created. Bicarbonate production: H2O + CO2 ↔ H2CO3 ↔ H+ + HCO3- **3. Carbamino compounds.** Carbamino compounds also transport carbon dioxide in the blood. Carbamino compounds are produced from a reaction with proteins. The small amount of CO2 transported in this manner mostly interacts with hemoglobin proteins and to a lesser extent plasma proteins. Carbamino compound production: R-NH2 + CO2 → R-NH-CO2- + H+

Answer 21

Transfusion-associated sepsis is the third leading cause of transfusion-related deaths in the United States and is most commonly caused by bacterial infection from **contaminated platelets**. Unlike other blood products, platelets are stored at room temperature which leads to increased bacterial growth.

Answer 22

A urine-to-plasma osmolar ratio **(UOSM : POSM) \>1.5** indicates prerenal oliguria (generally secondary to hypovolemia). The UOSM : POSM is used to assess the tubular response of the kidneys to dehydration or hypovolemia. In this setting of prerenal oliguria, this formula evaluates the kidneys’ ability to retain Na+ and water and produce highly concentrated urine by increasing urine osmolality above 450 mOsm/kg. By comparison, *_normal plasma osmolality is 280-300 mOsm/kg._* The UOSM : POSM indicates the kidneys' ability to concentrate urine. Tubular damage and acute renal failure, therefore, may be represented by a decreased ratio. The UOSM : POSM can also decrease with the administration of diuretics. As an aside, isosthenuria is a UOSM : POSM equal to 1.

Answer 23

**HCTZ** = It works by blocking the Na/Cl co-transporter in the DCT This causes inhibition of sodium reabsorption in the distal convoluted tubules, thereby increasing the excretion of both sodium and water. **Furosemide** = Na/K/Cl in Loop of Henle Blocked **Spirinolactone** = Blocks aldosterone receptor in DCT

Answer 24

Three factors obtained by history or physical exam that correlate with **difficult intubations in obese patients** include *_1. Increased neck circumference \*\*Best single indicator\*\*_* *_2. Mallampati class III or IV airway_* *_3. Presence of obstructive sleep apnea._* In general, increased age, male sex, TMJ pathology, and abnormal upper teeth also correlate with difficult intubations.

Answer 25

**Acoustic nerve damage** **Nephrotoxicity**

Answer 26

Vincristine: **peripheral neuropathy**

Answer 27

**Pulmonary fibrosis**

Answer 28

**Cardiotoxicity**

Answer 29

**Cardiotoxicity**

Answer 30

**Hemorrhagic Cystitis**

Answer 31

## Footnote **myelosuppression**

Answer 32

**BRIGMS(S) “Brigham’s”** Burns Relaxants - Chronic Immobility (Prolonged) Guillain-Barre Syndrome MS Stroke & Spinal Cord injury Spinal cord injury

Answer 33

The **vomiting center** is stimulated by: 1) the chemotactic trigger zone (CTZ) located in the medulla 2) gastrointestinal tract 3) pharynx 4) visual centers 5) mediastinum

Answer 34

**Anticholinergics** (e.g., scopolamine patch): ## Footnote Needs to be applied prior to going back to the operating room due to its *_2 to 4 hour onset time._* Can cause **visual changes, dry mouth, and dizziness.**

Answer 35

**Dopamine-2 receptor antagonist** (e.g., droperidol, metoclopramide): droperidol is effective as an anti-emetic. Recommended dosing is **0.625 to 1.25 mg** at the end of surgery

Answer 36

Mnemonics to help differentiate MELD from Child-Pugh: **MELD**: "I Crush Several Beers Daily" for **INR**, **creatinine**, **sodium**, ***_bilirubin_***, **dialysis** **Childs-Pugh**: "Pour Another Beer At Eleven" for **PT**, **Ascites**, ***_Bilirubin_***, **Albumin**, **Encephalopathy**

Answer 37

Normal human plasma has a SID of **40-44 mEq/L.** **SID** = ( _[Na+] + [K+] + [Ca2+] + [Mg2+]_ ) - ( *[Cl-] + [A-]* )

Answer 38

The concept of SID proposes that plasma pH is determined by three independent factors: **1. PCO2** **2. SID** Strong ion difference represents the difference between the charge of plasma strong cations (sodium, potassium, calcium, magnesium) and anions (chloride and other strong anions (A-) such as lactate, sulfate, ketoacids, and nonesterified fatty acids). **3. Atot.** The latter (Atot) represents the total plasma concentration of nonvolatile buffers (e.g., albumin, globulins, and inorganic phosphate).

Answer 39

Large volumes and rapid administration of normal saline can produce a non-anion gap hyperchloremic **metabolic acidosis**. Associated laboratory values include **decreased plasma HCO3**-, **increased plasma Cl-**, **decreased SID**, and a **normal anion gap.**

Answer 40

Subendocardial ischemia is more commonly seen than transmural injury because the **small capillaries and arterioles at the subendocardial level are subject to occlusive high intraventricular pressure**. The epicardial coronary arteries in comparison are distant from the high intraventricular pressures and thus generally unaffected unless acute occlusion from a thrombus, spasm, or embolism occurs.

Answer 41

≥ 0.1 mV in all leads **other than leads V2–V3** where the following cut-points apply: **≥ 0.2 mV** in *_men \> 40 years_* **≥0.25 mV** in *_men \< 40 years_* **≥ 0.15 mV** in women

Answer 42

New horizontal or down-sloping ST depression **≥ 0.05 mV in two contiguous leads** and/or **T inversion ≥ 0.1 mV** in two contiguous leads with prominent R wave or R/S ratio \> 1

Answer 43

Recent studies have shown that the most sensitive lead for detection of myocardial ischemia in patients who actually had an MI is **lead V4 (sensitivity of 83%)** but when two precordial leads are monitored simultaneously the **sensitivity increases to 97%**. A separate study suggested that adding **lead II with two precordial leads** increases the sensitivity for detection of **myocardial ischemia to 98%.**

Answer 44

Patients with **massive burns** demonstrate **resistance to NDNMBs**, resulting in increased dosing requirements, due to *_upregulation of ACh receptors and increased plasma protein binding._* *_**Contraindicated** = **Succinylcholine**_* **Mivacurium’s** dosing requirements are **only slightly increased** relative to other NDNMBs as it is **metabolized by pseudocholinesterase**, the levels of which are decreased in burn patients.

Answer 45

Since NDNMB's drug effect is produced by competitively inhibiting ACh receptors, the **presence of more receptors** means a higher dose of free drug is required to produce neuromuscular blockade manifesting as twitch depression. Burn patients also have **increased protein binding**, meaning less free drugs are available to bind ACh receptors, further increasing dose requirements.

Answer 46

The durations of action of commonly-used anticholinesterases and anticholinergic drugs for reversal of nondepolarizing neuromuscular blockade are **prolonged in the setting of CKD and ESRD**. However, **no dosage alterations are required** and the normal maximum recommended doses still apply.

Answer 47

Increasing the dose of anticholinesterase relative to anticholinergic drug: 1. **Increases the risk for gastrointestinal upset** 2. **Nausea/vomiting** 3. Cardiac muscarinic effects including **significant bradycardia** or other **arrhythmias.**

Answer 48

Increasing the dose of anticholinergic relative to anticholinesterase: 1. Increases the risk for **tachycardia** and other **arrhythmias** 2. **Blurred vision** 3. **Dry mouth** Confusion or hallucination may be seen with anticholinergics that cross the blood-brain barrier (e.g. atropine).

Answer 49

The risk for prolonged QT intervals is greatest in patients **taking greater than 120 mg daily**, however, lower doses and acute use can still prolong the QT interval. Because methadone is metabolized by cytochrome p450, drugs inhibiting this enzyme may lead to increased methadone toxicity and further QT prolongation.

Answer 50

It causes dose-dependent inhibition of **adrenal mitochondrial 11β-hydroxylase**. The enzyme 11β-hydroxylase is responsible for the **conversion of 11-deoxycortisol to cortisol**. Thus, administration of etomidate causes suppression of adrenal cortisol synthesis.

Answer 51

Pulmonary vascular resistance is affected by lung volumes. It is **lowest at FRC** while increasing or decreasing lung volumes beyond FRC results in an increase in PVR. **Highest at Residual Volume and Total Lung Capacity** *_Pulmonary vascular resistance increases as lung volumes increase due to compression of the smaller pulmonary vessels, notably the small arterioles._* As lung volumes increase, alveoli expand and the transmural (distending) pressure in and radii of the small blood vessels decrease. Therefore, PVR increases. Recall that resistance (R) is inversely proportional to vessel radius (r) to the fourth power (R ∝ 1/r4).

Answer 52

**First**, as the size of the alveoli decrease and especially when they collapse, the geometry of the pulmonary vessels surrounding these alveoli changes such that the vessels can essentially become kinked, resulting in a significant increase in resistance to flow. **Second**, as lung volumes decrease below normal, the volume of blood in the larger pulmonary vessels decreases. This suggests a likely decrease in vessel radius and therefore increased resistance to flow.

Answer 53

1. **Hyperosmolality** (milliosmoles per kilogram. A normal result is typically 275 to 295 milliosmoles per kilogram) 2. **Reduced Effective Circulatory Volume**

Answer 54

**Water Balance:** Stimulates water reabsorption by increasing intracellular levels of cyclic adenosine monophosphate (cAMP) and activating protein kinase A **Vasoactive** Vasoconstriction by activating G protein and phospholipase C, which releases calcium from the sarcoplasmic reticulum. There are two classes of AVP receptors: V1 receptors present in vascular smooth muscle V2 receptors present in the distal and collecting tubules of the kidney

Answer 55

Transtracheal injection of local anesthetic will block the **recurrent laryngeal nerve**

Answer 56

FFP is frozen for storage. It can be transfused *_up to 5 days after thawing_* **Factors VIII and V are the least stable factors in blood products and can degrade above 4 degreres Celcius**. Significant reductions in factor VIII (41 ±8%) and factor V (66 ±9%) levels.

Answer 57

1. **Plasma clearance** 2. **Redistribution**

Answer 58

Diastasis occurs when there is **complete left ventricular relaxation** and **filling of the ventricle eventually slows down**. It *_occurs*_ during the _*filling portion following isovolumetric relaxation_*.

Answer 59

1. ***_Baricity_*** of the local anesthetic solution (Baricity refers to the density of a substance compared to the density of human cerebrospinal fluid) Solutions that have a baricity approaching 1.000 are referred to as *_isobaric*_, as the density of the cerebrospinal fluid is approximately 1.0003+/- 0.0003. Solutions with a baricity less than 0.999 are termed hypobaric, and are usually created by mixing the local anesthetic with distilled water. _*Hyperbaric_* solutions are created by mixing dextrose 5-8% with the desired local anesthetic. *_Hyperbaric_* solutions will flow in the direction of gravity and settle in the most dependent areas of the intrathecal space. Conversely, hypobaric mixtures will rise in relation to gravitational pull. ***_2. Patient position._***

Answer 60

**1. Atropine (Blocks parasympathetic activation)** **2. Papaverine -** opium alkaloid antispasmodic drug, used primarily in the treatment of visceral spasm and vasospasm (especially those involving the intestines, heart, or brain **3. Naloxone - (**blocking opioid receptor activation)

Answer 61

Neck flexion - Risk of endobronchial intubation Neck extension - Risk of ETT herniating out of the larynx.

Answer 62

* *- Hypocalcemia - Hyperkalemia - Hypermagnesemia - Hyperlipidemia - Hyperphosphatemia**

Answer 63

Citrate Chelates both magnesium and calcium so you have: ## Footnote **Hypomagnesemia and Hypocalcemia**

Answer 64

**FFP and Platelets** | (NOT PRBC)

Answer 65

Osmolarity (mOsm/L) ***_253_*** Sodium (mEq/L) **None** Chloride (mEq/L) **None** Potassium (mEq/L) **None** Glucose (g/L) ***_50 grams / Liter_*** Lactate (mEq/L) **None**

Answer 66

## Footnote Osmolarity (mOsm/L) **355** Sodium (mEq/L) **38.5** Chloride (mEq/L) **38.5** Potassium (mEq/L) **None** Glucose (g/L) **50** Lactate (mEq/L) **None**

Answer 67

Osmolarity (mOsm/L) **308** Sodium (mEq/L) **154** Chloride (mEq/L) **154** Potassium (mEq/L) **None** Glucose (g/L) **None** Lactate (mEq/L) **None**

Answer 68

## Footnote Osmolarity (mOsm/L) **432** Sodium (mEq/L) **77** Chloride (mEq/L) **77** Potassium (mEq/L) - None Glucose (g/L) **50** Lactate (mEq/L) - None

Answer 69

Osmolarity (mOsm/L) **1026** Sodium (mEq/L) **513** Chloride (mEq/L) **513** Potassium (mEq/L) **None** Glucose (g/L) **None** Lactate (mEq/L) **None**

Answer 70

Osmolarity (mOsm/L) **273** Sodium (mEq/L) **130** Chloride (mEq/L) **109** Potassium (mEq/L) **4** Glucose (g/L) 0 Lactate (mEq/L) **28**

Answer 71

Osmolarity (mOsm/L) **525** Sodium (mEq/L) **130** Chloride (mEq/L) **109** Potassium (mEq/L) **4** Glucose (g/L) **50** Lactate (mEq/L) **28**

Answer 72

Osmolarity (mOsm/L) **294** Sodium (mEq/L) **140** Chloride (mEq/L) **98** Potassium (mEq/L) **5** Glucose (g/L) **None** Lactate (mEq/L) **None**

Answer 73

## Footnote Osmolarity (mOsm/L) **586** Sodium (mEq/L) **154** Chloride (mEq/L) **154** Potassium (mEq/L) **None** Glucose (g/L) **50** Lactate (mEq/L) **None**

Answer 74

**P1V1 = P2V2** "Water **Boyle's** at a constant temperature"

Answer 75

**V1/T1 = V2/T2** "Prince Charles is under constant pressure to be king"

Answer 76

**P1 / T1 = P2 / T2** **A Culdissac "LUSSAC" has a constant volume and mass of gas**

Answer 77

**C = kP** Henry’s law indicates that at a constant temperature, the concentration of a gas dissolved in a solution is directly proportional to the partial pressure of that gas: C = kP (where k is a solubility constant) or C ∝ P. As the volume percentage of a volatile anesthetic is increased, the alveolar partial pressure increases. **Example**: An increased alveolar partial pressure, therefore, leads to an increased concentration of the volatile anesthetic in the blood which increases the speed of induction and depth of anesthesia.

Answer 78

**P total =- P1 + P2 + P3** **Dalton's law** (also called Dalton's law of partial pressures) states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

Answer 79

Though it vaporises very readily, it is a **liquid at room temperature.** Desflurane vaporizers are typically heated to 39 °C which creates a **constant desflurane vapor pressure of 2 atm within the vaporizer**, independent of barometric pressure.

Answer 80

The maximum dose of neostigmine is **70-80 mcg/kg** at which point a "ceiling effect" takes place. This dose results in complete blockade of the acetylcholinesterase enzymes and occurs **in approximately 10 minutes.**

Answer 81

In some instances additional anticholinesterase medication **may cause paradoxical weakening**. The anticholinesterase effect *_increases the amount of acetylcholine release. In an overdose, depolarization of the endplate caused by the excess acetylcholine can lead to a depolarization block, similar to that seen with succinylcholine._*

Answer 82

1. Renal Artery Stenosis 2. Pregnancy 3. History of angioedema (whether related to ACE-I or not).

Answer 83

**Circuit Disconnect** **Esophageal Intubation** **Kinked ETT**

Answer 84

**Circuit Leak** **Partial Airway Obstruction**

Answer 85

**Pulmonary embolism** **Circulatory Collapse**

Answer 86

**1. Decreased Minute Ventilation** **2. Faulty Unidirectional Valve** **3. Soda Lime Exhaustion** **4. Insufficient Fresh Gas Flow** **5. Laparoscopes are inserted into the subcutaneous space causing ETCO2 in the skin (Subcutaneous emphysema)** **6. Malignant Hyperthermia** **7. Thyroid Storm**

Answer 87

Keep IV catheter in place initially. Aspirate about 5 mL of blood to remove as much of the drug as possible. **1. Limb elevation** **2. Warm compresses (for vasopressors, cold compress for other drugs)** **3. Irrigating with saline (Gault technique)** The Gault technique can be used to wash out the extravasated drug. It starts with injecting hyaluronidase (about 1500 units) into the subcutaneous tissue of the affected area. Four incisions are made at the site and saline (approx. 500 ml) is flushed through one of the incisions. This will irrigate the subcutaneous tissue and flow out the other three incisions. *_Hyaluronidase_* is an enzyme that breaks down hyaluronic acid found in the tissue. This allows the subcutaneous tissue to become more permeable. It is typically used for vesicants, particularly in children (e.g., infant with extravasated parenteral nutrition) **4. Injection of phentolamine** Phentolamine causes the smooth muscles of blood vessels to relax and produces vasodilation. Recommended dose is 5-10 mg within 12 hours of the extravasation. Phentolamine is typically diluted to 0.5 mg/mL then injected in multiple locations, in 1 mL increments, around the border of the extravasation site. **5. Stellate ganglion block (for upper limbs).** In situations with extravasated vasopressors, a stellate ganglion block will create a sympathectomy causing vasodilation in the upper limb.

Answer 88

Mild extravasation can lead to local necrosis and more severe extravasations may *_require open surgical debridement/fasciotomies. (Definitive treatment)_* Extravasated vasoconstrictors usually have a **4-6 hour window** before the onset of tissue necrosis. Chemotherapeutic drugs have about 72 hours before necrosis begins.

Answer 89

Accidental intra-arterial injection of drugs can cause vasospasm and thrombosis. Management includes injecting: **1. lidocaine** **2. calcium channel blocker intra-arterially** **3. A stellate ganglion block can also be useful.**

Answer 90

Acetylsalicylic acid (ASA) blocks It is non-selective for COX-1 and COX-2 enzymes Inhibition of COX-1 results in: 1. the **inhibition of platelet aggregation** for about 7-10 days (average platelet lifespan) 2. This prevents the production of **pain-causing prostaglandins** 3. Stops the conversion of **arachidonic acid to thromboxane A2 (TXA2)**, which is a potent inducer of platelet aggregation

Answer 91

Antiplatelet Blocks GP IIb/IIIa receptors

Answer 92

*_Antiplatelet_* *_Lowers calcium by elevating cAMP_*

Answer 93

*_Anti-platelet_* *_Inhibit ADP Receptor activation_*

Answer 94

Anti-platelet Lowers calcium by activating cAMP

Answer 95

*_Anti-platelet_* *_Blocks GP2b3a receptors_*

Answer 96

*_Antiplatelet_* *_Inhibit ADP Receptor Activation_*

Answer 97

*_Anti-platelet_* *_Inhibit ADP Receptor Activation_*

Answer 98

*_Anti-platelet_* *_GP2b3a receptor inhibitor_*

Answer 99

Anticoagulant Direct Factor Xa Inhibition

Answer 100

*_Anti-coagulant_* *_Direct Factor Xa Inhibition_*

Answer 101

*_Anticoagulant_* *_Antithrombin mediated inhibition of factor Xa_*

Answer 102

*_Anti-coagulant_* *_Antithrombin mediated inhibition of serine proteinases_* LMWH binds to anti-thrombin, a serine protease inhibitor, and creates a conformational change. This change accelerates its inhibition of activated factor X in conversion of prothrombin to thrombin. Thus,thrombin cannot convert fibrinogen to fibrin strands and clot formation. Once this change occurs LMWH is freed and can bind to another anti-thrombin molecules. LMWH also directly inhibits thrombin as it is a heterogenous mixture of molecules, some containing enough polysaccharide sequence, but this effect is much less than that of unfractionated heparin.

Answer 103

*_Anticoagulant_* *_Direct factor Xa inhibition_*

Answer 104

*_Anticoaglant_* *_Antithrombin mediated inhibition of serine proteinases_*

Answer 105

*_Anti-coagulant_* *_Inhibit vitamin K dependent coagulation factors (II, VII, IX, X)_*

Answer 106

The NMDA receptor is an inotropic glutamate receptor that functions as a nonspecific ion channel when activated. Activation only occurs when glutamate is bound to the receptor AND the cell is depolarized. The receptor’s effects are primarily mediated via **increased intracellular calcium.**

Answer 107

Administration of magnesium along with ketamine can **potentiate** the effects of ketamine.

Answer 108

**1. Electrode Gel** **2. Applying Force (if paddles)** - 11 lbs of pressure reduces resistance **3. Biphasic Defibrillation** - Uses less energy **4. Larger Electrodes (8-12 cm)** - Paddle size is inversely proportional to transthoracic resistance - Smaller pads can cause myocardial necrosis

Answer 109

**6 P’s** Pain out of proportion to the injury Paresthesias Pain on passive movement Palpation of a tense hard compartment Paralysis Pulselessness (Late sign) **Diagnosis: Compartment Pressures \>30 mmHg *_needs a fasciotomy within 6 hours_***

Answer 110

**(Hgb \* {4/3} \* SaO2) + (0.003 \* PaO2)**

Answer 111

Only the posterior arytenoids and the epiglottis are visible

Answer 112

**Peak Expiratory Pressure will decrease the most** In healthy patients, lumbar or low thoracic epidural anesthesia produces small (≤ 10%) changes in most pulmonary function parameters. *_However, PEP and cough strength are significantly reduced (10-40% and up to 50%, respectively) from baseline._* These two parameters are more *_dependent on abdominal musculature_* which has a higher degree of motor blockade than thoracic musculature from a lumbar or low thoracic epidural. Note a **disproportionately greater decrease in peak expiratory pressure** with only a small decrease in FEV1 is in line with FEV1 being relatively effort-independent (lower peak expiratory pressure in a weaker patient is conceptually equivalent to lower effort).

Answer 113

Tidal volume is **typically unchanged**, even with a high thoracic epidural.

Answer 114

**MAC-Awake** The MAC-awake is the MAC value at which voluntary reflexes (e.g., a patient will no longer open his or her eyes to command, shouting, or shaking) and perceptive awareness are lost. It varies between *_15-50% of standard MAC_* **MAC** minimum alveolar concentration of an inhaled anesthetic at one atmosphere that prevents movement in response to a surgical stimulus (specifically, an abdominal incision) in 50% of patients. **MAC-BAR** MAC value at which the adrenergic response (e.g., hemodynamic, sudomotor) to noxious stimuli is blunted. This has been found to be approximately 50% higher than standard MAC. Some studies estimate this value as *_1.7-2.0 MAC._*

Answer 115

Interestingly, the MAC-awake is generally **higher at induction** (40-50% standard MAC in order for loss of consciousness) than at emergence (as low as 15% standard MAC to regain consciousness) Although the mechanism is not fully understood, it is likely due to the *_differences in alveolar wash-in and wash-out of anesthetic gases_*. The theory of **neural inertia** is another proposed mechanism. **Neural inertia** is defined as the tendency of the central nervous system to resist transitions between arousal states

Answer 116

**The loss of awareness and recall typically occurs at 0.4-0.5 standard MAC** *_Isoflurane likely has the most recall-blocking activity and nitrous oxide the least_*

Answer 117

Current ASA guidelines recommend maintaining **at least 0.7 MAC** during general anesthesia to significantly reduce the risk of awareness. A MAC value of 0.627 effectively reduces awareness to **1 in 100,000 for recall of verbal stimulus.**

Answer 118

Even a single episode of hypotension decreases cerebral perfusion enough to affect outcomes. The CPP value to target lies within the **range of 50-70 mm Hg according to current BTF (Brain Trauma Foundation) guidelines.** *_Avoid CPP \< 50 mmHg_* As far as the upper limit, aggressive attempts to maintain CPP \> 70 mmHg with fluids and pressors should be avoided because of the risk of acute respiratory distress syndrome (ARDS). However, if a patient with intact autoregulation is maintaining a CPP \> 70 mmHg spontaneously, that is acceptable.

Answer 119

TBIs are categorized by level of severity: mild, moderate, and severe. **A mild TBI** is associated with a Glasgow Coma Scale (GCS) score of 13-15 and minimal to no loss of consciousness. **A moderate TBI** is associated with a GCS of 9-12 and a loss of consciousness of 30 minutes or more. **A severe TBI** is associated with a GCS of 3-8.

Answer 120

Treatment should be initiated with **ICP thresholds above 20 mmHg.**

Answer 121

Methadone also needs little adjustment in patients with renal disease.

Answer 122

Buildup of renally-excreted hydromorphone-3-glucuronide can lead to neuroexcitatory effects including **agitation, restlessness, and myoclonus (neuroexcitatory & pro-convulsant properties)**

Answer 123

Prevents the synthesis of prostaglandins. Inhibition of PG synthesis can affect renal glomerular blood flow by causing **vasoconstriction of the afferent arterioles of the glomeruli** **(KIDNEY ISSUES)** Reversibly inhibits the cyclooxygenase (COX) enzyme which prevents the formation of thromboxane from arachidonic acid. Thromboxane promotes platelet aggregation and its absence can lead to increased bleeding. **(BLEEDING AND THROMBOSIS ISSUES)**

Answer 124

**Lead V1** is the second-best lead for monitoring atrial arrhythmia and when using a full twelve lead ECG considering these two leads together is most effective. The normal p-wave morphology in V1 is biphasic with an initial upward deflection as depolarization travels from the SA node anteriorly through the right atrium. There is then a terminal deflection as the current passes posteriorly through the left atrium.

Answer 125

**#1 = Fluid Hydration** Antioxidants such as **N-acetylcysteine** and **ascorbic acid** may also play a role in renal protection but are not as effective as fluid hydration alone.

Answer 126

**SVR = [80 \* (MAP – RAP)] ÷ CO** **MAP** = mean arterial pressure (mm Hg) **RAP** = right atrial pressure (mm Hg), central venous pressure is commonly substituted for RAP CO = cardiac output (L/min) **80** = conversion factor which changes mm Hg/L/min (Woods unit) to dynes \* sec/cm^5

Answer 127

**PVR = [80 \* (MPAP – PAOP)] ÷ CO** * *MPAP** = mean pulmonary arterial pressure (mm Hg) * *PAOP** = pulmonary artery occlusion pressure or pulmonary capillary wedge pressure (mm Hg) * *CO** = cardiac output (L/min) * *80** = conversion factor which changes mm Hg/L/min (Woods unit) to dynes \* sec/cm^5 **Normal Value = 20–130**

Answer 128

Conversion of dynes \* sec/cm^5 to Woods units may be achieved by **dividing SVR by 80.** For example, 1520 / 80 = 19 Woods units

Answer 129

***_1. Thrombosis (Vascular \> Infection)_*** **2. Bleeding** **3. Pseudoaneurysms** **4. Arterial-Venous Fistula** ***_5. Infection (Lower Risk)_*** ***_6. Median Nerve Injury_*** There have been concerns that brachial artery catheterization can lead to limb ischemia due to lack of collateral vessels; however, this has not been shown to be true. The rare instances of ischemia from brachial artery use were resolved with the catheter removal. The radial artery is even more unlikely to have ischemia because of multiple collateral vessels.

Answer 130

ED95 is the effective dose of a neuromuscular blocking drug required to **achieve 95% block of a single twitch in 50% of individuals who receive this drug and dose**.

Answer 131

**NDNMB ED95 (mg/kg)** **Dose For Intubation (mg/kg)** ***_Cisatracurium_*** 0. 04 (0.032 - 0.05) 0. 15-0.2 (3.75 - 5 x ED95) ***_Pancuronium_*** 0. 07 0. 08-0.12 (1.2 - 1.8 x ED95) ***_Rocuronium_*** 0. 3 0. 6-1.0 (2 - 3.3 x ED95) ***_Vecuronium_*** 0. 05 0. 1-0.2 (2.3 - 4.7 x ED95)

Answer 132

The term P50 is designated as the partial pressure of oxygen (in mm Hg) when oxygen saturation (SaO2) is 50%. In a normal adult, **P50 is 27 mm Hg.**

Answer 133

**Left Shift** In newborns, oxygen affinity is very high and **P50 is very low (approximately 18 mm Hg).** Due to: 1. **Hemoglobin F**, which is produced in-utero, and is useful for oxygen transfer from the maternal blood to the fetus. The presence of hemoglobin F 2. **Low 2,3-diphosphoglycerate (2,3-DPG)** levels in newborns result in a very low P50 *_(Note, this would cause a left shift as well)_*

Answer 134

**Right Shift** After birth, levels of **hemoglobin F begin to decline (Right shift)** resulting in a decrease in the total hemoglobin concentration. This results in a physiological anemia of infancy. During this same period of time, **2,3-DPG levels begin to increase causing the oxyhemoglobin dissociation curve to shift to the right** (P50 increases). The P50 will surpass that of an adult (27 mm Hg) and will reach a **maximum of 30 mm Hg by about 12 months of age** **-** Children will continue to have a higher P50 for the first decade of life.

Answer 135

**P50 increases** due to: acidosis, hypercarbia, hyperthermia, increased 2,3-DPG. Shift "**RIGHT**": **R**ise **I**n 2,3-DP**G**, **H+**, and **T**emp. P50 decreases due to: alkalosis, hypocarbia, hypothermia, decreased 2,3-DPG.

Answer 136

**Age 10**

Answer 137

**Illustrates that the oxygenation of hemoglobin lowers the affinity of hemoglobin for carbon dioxide** The Haldane effect describes the relationship between the **carbon dioxide dissociation curve in blood and oxyhemoglobin (HbO2)**. The CO2 dissociation curve, specifically, *_shifts to the right_* when the concentration of HbO2 increases in the blood. This curve is linear since the CO2 content and the partial pressure of CO2 (PCO2) are directly correlated in a given sample of blood. The curve may be interpreted such that an increase in HbO2 results in an increased dissociation of CO2 from Hb (i.e., an increase in PCO2 but an overall unchanged value for CO2 content). Conversely, if the concentration of HbO2 is reduced, then the affinity for carbon dioxide increases and less CO2 is available for gas exchange.

Answer 138

The Bohr effect describes the binding effect of **H+ to Hb chains and the oxygen release and dissociation that occurs thereafter.** Acidosis, for example, will shift the oxygen-hemoglobin dissociation curve toward the right, resulting in less attraction between Hb and O2. Ultimately, this will permit more CO2 to be transported from the tissue to the lungs during gas exchange. The curve will shift to the left for a low PCO2 and high pH.

Answer 139

**Treatment: Withholding warfarin for several days is recommended.** The half-life of warfarin therapy is 2 to 4 days thus the effects may not be seen for several days.

Answer 140

Treatment: **Vitamin K can be administered orally or parenterally** - Typical adult dose is 1-2mg) - There is no difference in efficacy between oral and intravenous vitamin K - Higher risk of anaphylaxis with parenteral formulations; thus oral is preferred if the patient can tolerate and absorb the medication

Answer 141

Treatment: **Higher doses of vitamin K may be attempted (between 5-10mg).** Higher doses of vitamin K may render the patient temporarily resistant to further warfarin therapy for days to weeks.

Answer 142

## Footnote **1. Prothrombin complex concentrates** **2. IV Vitamin K**

Answer 143

**4-factor** concentrates are preferred as they contain all vitamin K dependent coagulation factors (II, VII, IX, and X) (1972) **3-factor** concentrates contain factors II, IX, and X and should be supplemented with *_recombinant factor VIIa to completely reverse anticoagulation._*

Answer 144

Contraindications: **1. DIC** **2. HIT** - PCCs are human plasma derived products that contain low doses of heparin to prevent clotting factor activation.

Answer 145

There are certainly risks associated with FFP transfusion; most notable are: ## Footnote **Transfusion related acute lung injury (TRALI)** **Febrile reactions** **Allergic reactions** **Transfusion associated circulatory overload (TACO).**

Answer 146

**Minimal Sedation** **Moderate Sedation** **Deep Sedation** **General Anesthesia**

Answer 147

1. Responsiveness 2. Airway reflexes 3. Ventilation 4. Cardiovascular Function * *Minimal Sedation** - Normal response to verbal stimulation - Airway reflexes, spontaneous ventilation, and cardiovascular function are all unaffected * *Moderate Sedation** - Purposeful response to verbal or tactile stimulation - Spontaneous ventilation is adequate and no airway intervention is required - Cardiovascular function is usually maintained * *Deep Sedation** - Purposeful response to repeated or painful stimulation (reflex withdrawal from a painful stimulus is NOT considered purposeful response) - Spontaneous ventilation may be inadequate and airway intervention may be required - Cardiovascular function is usually maintained * *General Anesthesia** - Unable to arouse even with painful stimulus - Spontaneous ventilation is frequently inadequate and airway intervention is often required - Cardiovascular function may be impaired

Answer 148

**A = Diuretics** **B = Ionotropes + Vasodilators + Diuretics** **C = Vasodilators** **D = Ionotropes and Vasodilators** **E = Ionotropes only**

Answer 149

**50% renal excretion**

Answer 150

Without = 77 minutes With = 181 minutes

Answer 151

**46 - 73 minutes**

Answer 152

**Metabolism** = 70% Hepatic **Elimination** = 10% Renal Elimination

Answer 153

## Footnote **Metabolism - 50-60% Hepatic** **Elimination - 25% Renal**

Answer 154

Triggered when the **pressure in the breathing circuit falls below atmospheric pressure by a predetermined amount (typically below -10 cm H2O).** *_Examples_* - Inhalation against an increased resistance in the circuit - Inhalation against a collapsed reservoir bag - A malfunctioning active closed scavenging system (excessive vacuum or valve dysfunction) - A blocked inspiratory limb during exhalation - Accidental Placement of Nasogastric Tube or Endoscope within the trachea and use of suction = Loss of Tidal Volume and Negative pressure

Answer 155

**Myoclonus** describes sudden jerking movements, such as those sometimes observed during induction of anesthesia It likely *_results from inhibition of descending cortical inhibitory pathways._* Myoclonus can resemble seizures but *_EEG evidence of seizures is lacking during these episodes._*

Answer 156

**1. Myoclonus** **2. Pain on Injection** **3. Hiccups**

Answer 157

**Dopamine-1 agonist** = Increases renal blood flow despite decreased systemic arterial blood pressure **Natriuretic** - Sodium excretion **Diuretic** - Free water excretion Direct renal vasodilator and can produce hypotension

Answer 158

1. A dopamine D1 receptor agonist that is used as an **antihypertensive agent** 2. It **lowers blood pressure** through **arteriolar vasodilation**. 3. Used as **renal protector** when renal vasoconstriction is anticipated 4. **Hypertensive Crisis** in those with **decreased renal function**

Answer 159

**Acute phenytoin** administration **potentiates** the neuromuscular blockade of aminosteroid NDNBDs. **Chronic phenytoin** administration **increases a patient’s resistance** to the effects of NDNBDs and reduces their duration of action **by as much as 50%** *_For benzylisoquinoloine NMB = Variable_*

Answer 160

1) Increased metabolism via **cytochrome P450 enzymes induction** (this may explain why there is a clear effect with the aminosteroid NDNBDs, which rely on hepatic metabolism, but not with the benzylisoquinolines which undergo hepatic-independent Hofmann elimination and ester hydrolysis) 2) **Increased postjunctional acetylcholine receptor density** (the weak neuromuscular blocking properties of phenytoin, see below, results in postjunctional acetylcholine receptor upregulation) 3) **Decreased sensitivity at the receptor sites** 4) **Increased end-plate anticholinesterase activity**

Answer 161

**ETT placement (MOST)** Surgical INcision DL Tetanus by nerve stimulation (LEAST)

Answer 162

## Footnote **Partial Opioid Agonist and Mixed Agonist-Antagonist**

Answer 163

0 - 8 mmHg

Answer 164

10 - 18 mmHg

Answer 165

**25 mmhg**

Answer 166

**2.5 - 4.2**

Answer 167

* *Raises** Intrathoracic Pressure * *Increase** in RV Afterload **Decrease** in Preload **Increase** in CVP **Increase** in PAP **Improved** CI **Improved** PCWP

Answer 168

**Consciousness** **Activity (Moving extremities on command)** **Respiration** **Oxygen Saturation with O2 requirements** **Circulation (BP compared to preop)**

Answer 169

**Right to Left Shunt**

Answer 170

**Elevated Anion Gap Metabolic Acidosis** Cyanide primarily causes toxicity by impairing cellular aerobic respiration. The cyanide ion (CN-) binds to the ferric ion (Fe3+) in mitochondrial cytochrome-c oxidase, inhibiting the final stage of the electron transport chain. ***_Depletion of cellular ATP_*** and the *_lactic acid produced by anaerobic metabolism can lead to profound acidosis._*

Answer 171

**Signs/Symptoms:** Altered mental status, weakness, headaches, loss of consciousness, seizures, respiratory failure, and cardiac arrest, The patients blood sample may appear *_"cherry red"_* due to normal circulating levels of oxygen with impaired utilization. **PaO2** **increases** (Oxygen present but cannot be utilized) **SvO2** **increased** (oxygen present but not being utilized)

Answer 172

A = Minute Ventilation B = 2-3 times minute ventilation C = 1-2 times minute ventilation

Answer 173

**LFT's** - Liver Dysfunction and potentially liver failure is possible

Answer 174

Radiation intensity (exposure) with respect to distance decreases according to the inverse square law: **I ∝ 1 / r^2**. *_Accordingly, doubling the distance from a radiation source decreases exposure by a factor of 4._*

Answer 175

**Hypotension** **Hypocalcemia** (Transiently binds calcium and should be cautious in hypocalcemic patients)

Answer 176

**Hypercarbia** - The reaction of 50 mEq bicarbonate produces approximately *_1,250 mL of CO2_* which must be exhaled and is seen as a transient increase in EtCO2.

Answer 177

## Footnote **Redistribution of Blood to the Pulmonary Vasculature**

Answer 178

Simply, CN 9 and CN 10 Specifically: 1. **Internal Branch of Superior Laryngeal Nerve of CN 10** 2. CN 9 - **Glossopharyngeal Nerve** 3. **Recurrent Laryngeal Nerve of CN 10**

Answer 179

1. **Arteriodilation** - Due to sympathectomy Reduction in afterload **2. Venodilation** - Due to sympathectomy Venodilation causes a reduction in preload and tends to have a more dramatic effect than arterial dilation because 75% of the total blood volume is in the venous system. 3. **Bradycardia** - 10-15% from the spinal 4. **Blockade of the cardiac accelerator fibers** can prevent an increased heart rate in response to hypotension, which would lead to further hypotension and bradycardia.

Answer 180

Parasympathetic-mediated reflex occurs when stretch receptors located mainly in LV respond to an acute decrease in LV preload The result is **bradycardia** and **reduced contractility** (and resultant hypotension). This reflex is thought to occur to *_allow the ventricle additional time to fill and increase preload._*

Answer 181

**2-6 Dermatomes** sensory block above level of the sensory block

Answer 182

Quantitative echocardiographic technique used to **determine left ventricular ejection fraction**.

Answer 183

1. Jet Velocity - (3-4 m/s) 2. Mean Gradient - (25 - 40 m/s) 3. Valve Area (1.0 - 1.5)

Answer 184

**\>20 degrees**

Answer 185

*_≥1 MAC_* **increase CBF and decrease CMRO2**, causing an uncoupling of the flow-metabolism relationship. *_\<1 MAC_* = **CBF balances and remains the same**

Answer 186

The cerebral flow-metabolism relationship and cerebral autoregulation **remain intact** with the use of thiopental. Thiopental decreases both CBF and CMRO2 by **30% with induction doses** and **by 50% upon achievement of an isoelectric EEG**.

Answer 187

Burst suppression on EEG is the goal target of reducing CMRO2 during an **open cerebral aneurysm clipping.** Burst suppression sufficiently indicates *_depressed CMRO2 while providing predictability of recovery and awakening once the IV anesthetic is turned off._*

Answer 188

1. **Elevated Mixed Venous Oxygen (PvO2)** Since cells cannot use oxygen and aerobic respiration, PVO2 becomes elevated. 2. SNP (Sodium Nitroprusside) **Tachyphylaxis** 3. **Metabolic Acidosis** (Lactate Buildup)

Answer 189

Amyl nitrate works as an antidote for **cyanide poisoning** by converting *_Hb to MetHb which avidly binds cyanide, converting it to the nontoxic cyanomethemoglobin._*

Answer 190

1. **Hydroxycobalamine** 2. **Amyl NItrate** 3. **Sodium Thiosulfate**

Answer 191

Cimetidine **1-1.5 hours**, 3-4 hours Ranitidine **1 hour,** 9-10 hours Famotidine **1 hour**, 10-12 hours

Answer 192

Histamine H2 receptor antagonists (e.g. cimetidine, ranitidine, famotidine, nizatidine) **block histamine from inducing acidic gastric fluid secretion by parietal cells**. This effectively *_raises gastric pH._* Raising the gastric pH prior to induction of anesthesia can reduce the severity and risk of perioperative aspiration pneumonitis.

Answer 193

Barium hydroxide absorbent preparations produce more carbon monoxide than soda lime due to the **decreased water content of barium hydroxide absorbents.**

Answer 194

**Soda Lime**

Answer 195

**80% calcium hydroxide** **15% water** **4% sodium hydroxide** Therefore, higher-moisture absorbents (e.g., soda lime) have more water content available to react with CO2 leading to an increased CO2 absorptive capacity.

Answer 196

**Desiccated CO2 absorbents** **Increased Temperature** **Low Fresh Gas Flows**

Answer 197

CO2 absorbents + **Sevoflurane** = Most **Heat** CO2 absorbents + **Desflurane** = Most **CO**

Answer 198

**Barium Hydroxide** **\*These have been removed from US markets**

Answer 199

**Lack Strong Bases (NaOH and KOH)** The maximum CO2 absorbed by calcium hydroxide is 10.2 liters per 100 grams absorbent whereas soda lime can absorb 26 liters of CO2 per 100 grams absorbent.

Answer 200

**Calcium hydroxide absorbents**, due to lower reactivity, have the lowest incidence of compound A and fire production

Answer 201

If you suspect a colleague of having a substance abuse problem, you **should consult your state physicians health program before intervention or confrontation.**

Answer 202

1. Correction of **excessive microvascular bleeding** (PT \>1.5 times normal, PTT \>2 times normal, or INR \>2) 2. Correction of **coagulation factor deficiencies** if the patient has been *_transfused with more than one blood volume_* (approximately 70 ml/kg) 3. Correction of **coagulation factor deficiencies** for which there are no specific replacements 4. Heparin resistance **(antithrombin III deficiency)** in a patient requiring heparin 5. Coagulopathy related to **hepatic insufficiency** 6. **TTP** 7. **Reversal of Warfarin** (PCC another option)

Answer 203

Thrombotic thrombocytopenic purpura (TTP) is a platelet destruction disorder. The inherited type involves a deficiency of vWF-cleaving protease activity (ADAMTS13 deficiency). **Fresh frozen plasma is administered in order to replete the ADAMTS13 enzyme.** Plasmapheresis may be used to treat the acquired type of TTP as it removes the acquired antibodies that damage the ADAMTS13 enzyme.

Answer 204

Esmolol is a β1-selective short acting (**t1/2 = 9 min**) agent that is Rapidly metabolized by: 1. Red blood cell (RBC) **esterase** 2. Minimally hydrolyzed by **pseudocholinesterase**.

Answer 205

Beta-blockers **reduce**: **1. blood pressure** **2. myocardial oxygen consumption** primarily by *_1. decreasing heart rate_* *_2. contractility._* They also have anti-arrhythmic properties by **decreasing AV conduction and automaticity**, and by increasing the atrial refractory period.

Answer 206

Propranolol is **non-selective** and **inhibits β1 and β2 receptors**

Answer 207

**β1, β2, and α-1 receptor blocker.**

Answer 208

The ratio of relative α:β potency of **IV labetalol is approximately 1:7** whereas *_PO labetalol is 1:3_*. The nature of this drug can be seen intraoperatively when labetalol administration results in **decreased blood pressure without baroreceptor-triggered reflex tachycardia** (as can be seen with pure vasodilating agents)

Answer 209

**Carvedilol**

Answer 210

**Hepatic Clearance** Exception: Atenolol (Which is renally cleared)

Answer 211

The pathophysiology of PRIS relates to propofol’s ability to **impair cellular free fatty acid utilization and mitochondrial activity** leading to *_inadequate aerobic metabolism and increased reliance on anaerobic metabolism._*

Answer 212

Cardiac and skeletal muscle are particularly susceptible leading to muscle damage or necrosis that can cause **cardiac failure** and **rhabdomyolysis**. **lactic acidosis** **hyperkalemia** **renal failure** **Hypertriglyceridemia** **Hepatomegaly** **Pancreatitis secondary to HLD**

Answer 213

**Green** Phenol excretion can cause this

Answer 214

## Footnote **All drop**

Answer 215

It has been shown that with head rotation greater than 30 degrees that the **left carotid artery and jugular vein overlap more than on the right.**

Answer 216

**1. Carotid embolization on the left poses a greater risk as the left cerebral hemisphere is dominant in the majority of the population.** This is also one of the reasons why right-sided carotid massage is preferred over left-sided massage. 2. Another reason is that some investigations have found a *_greater cardioinhibitory effect on the right side._*

Answer 217

Exert Pressure on Carotid Sinus and baroreceptors at the Transverse process of C6 ## Footnote The AFFERENT nerve impulses of carotid sinus baroreceptors are transmitted by the **Hering’s nerves to the glossopharyngeal nerve (CN IX) (see image below).** Arterial wall stretch at the carotid sinus, within the internal carotid artery, activates the afferent impulse. This activation leads to stimulation of the nucleus tractus solitarius (NTS) in the caudal medulla. The NTS sends excitatory signals to other regions of the medulla which in turn inhibit stimulation of the preganglionic intermediolateral nucleus of the spinal cord which mediates the body’s sympathetic innervation. The NTS may also stimulate **vagal nuclei to activate the parasympathetic nervous system via the vagus nerve**. These two effects then lead to bradycardia and hypotension.

Answer 218

**a wave: atrial contraction**

Answer 219

**c wave: TV bulging into RA during RV isovolumetric contraction**

Answer 220

**x descent: TV descends into RV with ventricular ejection and atrial relaxation**

Answer 221

**v wave: venous return to and systolic filling of the RA**

Answer 222

**y descent: atrial emptying into RV through open TV**

Answer 223

**absent a wave**

Answer 224

**Tall c waves** **Tall v waves Loss of x descent**

Answer 225

**Tall a** **Tall v waves Minimal y descent**

Answer 226

**Tall a & v waves Steep x & y descent M or W configuration**

Answer 227

**Tall a & v waves Steep x & y descent M or W configuration**

Answer 228

**Dominant x descent Minimal y descent**

Answer 229

**Ascorbic Acid** Ascorbic acid also known as vitamin C, functions as an electron receptor and aids in the reduction of Fe3+ to Fe2+. Ascorbic acid **functions to reduce hemoglobin slower than methylene blue does**. However, *_ascorbic acid does not have the hemolytic effect that methylene blue does in a G6PD deficient patient._* In a patient with G6PD *_deficiency the hexose phosphate pathway is dysfunctional and free radicals develop, which causes red blood cell lysis._*

Answer 230

Methylene blue is often the **drug of choice when treating methemoglobinemia.** Methylene blue provides an electron receptor for the reduction of methemoglobin *_using NADPH produced from the hexose phosphate pathway._* In a patient with G6PD deficiency the hexose phosphate pathway is dysfunctional and free radicals develop, which causes red blood cell lysis. Therefore, methylene blue should be avoided in patients with G6PD deficiency. Additionally, methylene blue is a potent reversible monoamine oxidase inhibitor (MAOI) and may interact with serotonergic psychiatric medications leading to life-threatening serotonin syndrome.

Answer 231

Additionally, methylene blue is a **potent reversible monoamine oxidase inhibitor (MAOI)** and may interact with serotonergic psychiatric medications leading to *_life-threatening serotonin syndrome._*

Answer 232

**Amyl nitrite** is used to treat cyanide toxicity. Amyl nitrate oxidizes **Fe2+ to Fe3+**. *_Cyanide binds to methemoglobin more actively than it binds to normal hemoglobin_*. Thus, by inducing a low-level of methemoglobinemia the methemoglobin in turn can *_sequester cyanide as cyanmethemoglobin._*

Answer 233

Methemoglobinemia occurs when hemoglobin becomes oxidized from **Fe2+ to Fe3+**. Methemoglobin is unable to bind oxygen and causes a **functional anemia**, in addition to **left shifting** the oxygen dissociation curve. Methemoglobin has an **absorbance of 630 nm**, which correlates to an **oxygen saturation of 84-86% on pulse oximetry**. **Co-oximetry** should be used to aid in the diagnosis and treatment of methemoglobinemia. If unavailable, blood can be sent for a methemoglobin level.

Answer 234

The COHb is interpreted by the pulse oximeter as a **mixture of approximately 90% HbO2 and 10% HHb.** Thus, at high levels of COHb, the pulse oximeter will overestimate true SaO2, as may occur in patients with recent CO exposure.

Answer 235

**MetHb** is formed when the heme iron is oxidized from the ferrous (Fe2+) to the ferric (Fe3+) state. metHb is very dark and tends to absorb equal amounts of red and infrared light, resulting in a **red:infrared ratio of 1.** When extrapolated on the calibration curve, *_a ratio of 1 corresponds with a saturation of 85%._* Thus, as metHb increases, SpO2 approaches 85% regardless of the true level of HbO2.

Answer 236

Drugs capable of causing methemoglobinemia **(defined as greater than 1% metHb)** include **nitrates**, nitrites, chlorates, nitrobenzenes, antimalarial agents, amyl nitrate, **nitroglycerin**, **sodium nitroprusside**, and **local anesthetic agents**.

Answer 237

Injections of **methylene blue** produce a large and consistent spurious decrease in SpO2, with readings remaining *_below baseline for 1 to 2 minutes._* Injection of **indocyanine green** decreases SpO2 to approxi- mately 80% to 90%, which *_lasts for a minute or less._* Injection of **indigo carmine** decreases the SpO2 the least, with the decrease lasting *_approximately 30 seconds._*

Answer 238

Botulism is caused by the anaerobic bacillus, *_Clostridium botulinum_*. **Flaccid neuroparalysis** occurs due to the *_prevention of acetylcholine (ACh) release from vesicles at the NMJ_*. Acetylcholine is carried to the nerve terminal by vesicles which then fuse with the nerve terminal membrane via soluble N-ethylmaleimide-sensitive fusion associated protein receptor (SNARE) proteins. The collection of SNARE proteins facilitate exocytosis and then “repackaging” or reuptake of ACh. The various toxins of C. b**otulinum are zinc endopeptidases that cleave the SNARE proteins** and *_stop the fusion and release of ACh_* into the nerve terminal, as well as prevent reuptake back into the terminal.

Answer 239

The tetanus toxin from **Clostridium tetani** travels via *_neuronal retrograde transport up the motor neuron_* and enters the presynaptic terminal of inhibitory interneurons within the spinal cord. Normal modulation of fine motor movement from descending motor pathways triggers the interneurons to exert their inhibitory effects via γ-aminobutyric acid (GABA) release. 1. The toxin **prevents the release of GABA** from the interneurons. Therefore, the *_inhibitory mechanism is inhibited and spastic neuroparalysis occurs._*

Answer 240

**1. Sternum** **2. Proximal Humerus** **3. Proximal Tibia** **4. Distal Tibia**

Answer 241

1. **Sternum** = Azygos and Internal Mammary Vein 2. **Proximal Humerus** = Axillary Vein 3. **Proximal Tibia** = Popliteal Vein 4. **Distal Tibia** = Greater Saphenous Vein

Answer 242

**Humeral** = Flow rates are higher than tibial (200 vs. 100 mL/min) **Sternal** = Fast uptake of drugs (80-110 seconds) which is not that much longer than central access (60-80 seconds)

Answer 243

**pKa = 6.5** **Highly un-ionized form (90%)** **Lower Lipid Solubility**

Answer 244

**Remembering "4"** will get you in the appropriate range for differences between alfentanil and fentanyl. Alfentanil has about **4 times faster onset.** Alfentanil lasts about **1/4 the duration.** Alfentanil is about **1/4 the potency** (4x the dose of fentanyl).

Answer 245

Desflurane primarily **decreases arterial pressure by decreasing afterload.** Desflurane *_increases heart rate_*, particularly when the concentration is quickly increased Also causes **dose-dependent depression of myocardial function**. *_Cardiac output is maintained_* and there is **no significant effect on left ventricular diastolic function.**

Answer 246

1. **Acute dystonias** (abnormal movement or posturing due to involuntary/sustained muscle contractions) 2. **Akathisia** (restlessness and need to be in constant motion) 3. **Tardive dyskinesia** (involuntary repetitive or purposeless movements).

Answer 247

Metoclopramide has weak antiemetic effect at 10 mg (\< 20 mg) and recommended dosing for **PONV is 25-50 mg IV.** EPS occur in 0.3% with 10 mg and 0.6% with both 25 mg and 50 mg dosing. *_Marginal increase in risk of EPS to cover PONV_*

Answer 248

1. **Anticholinergics** - Benedryl 12.5 - 50 mg IV - **Benztropine** Initial dose: IM, IV, Oral: 1 to 2 mg once. Subsequent doses: Oral: 1 to 2 mg 1 to 2 times daily. *_3-8 all per True Learn but couldn't find doses_* 3. Trihyexyphenidyl 4. Atropine 5. Anti-histamines 6. Benzodiazepines 7. Beta-Blockers 8. Dopamine Receptor Agonist

Answer 249

Antihistamine (H1) Anticholinergic activity Inhibits serotonin reuptake Potentiates opioid-induced analgesia May have Local anesthetic-like properties (intracellular sodium channel blocker).

Answer 250

Although nitrous oxide administration can **worsen a venous air embolism**, the risk is not increased significantly in intestinal surgery. When the risk of venous air embolism is high, such as with sitting position neurosurgery, nitrous oxide should be avoided as it can increase the size of an air embolism should it occur.

Answer 251

**1. Tension pneumothorax** Expansion of a pneumothorax is the most rapidly occurring of those listed, with volume doubling occurring in only 10 minutes **Expansion of venous air emboli** **Worsening of pneumocephalus** **Intestinal Obstruction** 100cc of gas normally Expansion could lead to: Not closing, **ischemia from lumen** obstruction, Gas-filled spaces = bowel. One of the concerns with **Bowel Distention** sx cannot proceed **Blindness**

Answer 252

Chronic opioid therapy has a profound effect on the adrenal and gonadal axes leading to: ## Footnote **increased prolactin levels (Galactorrhea)** **Decreased testosterone, estrogen, cortisol, LH, and FSH.**

Answer 253

**Pre-renal** BUN:creatinine ratio **\>20** FENa **\<1%** Urine Sodium (UNa) **\<10 mEq/Liter** Urine Osmolality (UOsm) **\>500 mOsm/kg** **What are these values?**

Answer 254

**Intrinsic** BUN:creatinine ratio **\<15** FENa **\>2%** Urine Sodium (UNa) **\>20 mEq/Liter** Urine Osmolality (UOsm) **\<350 mOsm/kg**

Answer 255

**Post-Renal** BUN:creatinine ratio **\>15** FENa **\>4%** Urine Sodium (UNa) **\>40 mEq/Liter** Urine Osmolality (UOsm) **\<350 mOsm/kg**

Answer 256

FENa = Excreted Na/Filtered Na x 100 **(UNa x PCr)** / **(UCr x PNa x 100)** UNa – urine sodium PNa – plasma sodium UCr – urine creatinine PCr – plasma creatinine

Answer 257

Propofol *_increases the time that the GABA-A receptors remain open_* after activation. GABAA receptors, when active, *_allow Cl- to enter neurons and hyperpolarize the cell._* *_Hyperpolarization thus causes increased neuronal inhibition and unconsciousness_*

Answer 258

In some instances a bolus of dexmedetomidine can cause hypertension because of **activation of the sympathetic nervous system**.

Answer 259

Alpha2 receptors are prejunctional receptors activated by **norepinephrine (negative feedback loop).**

Answer 260

**Chloride** 1. Agonist = Alcohol 2. Antagonist = Caffeine

Answer 261

**1. PCP** **2. Nitrous Oxide** **3. Methadone** **4. Tramadol**

Answer 262

However, a second dose of succinylcholine, if given within **approximately five minutes of the first dose**, increases the risk of bradycardia. It is thought that the *_hydrolytic byproducts of succinylcholine metabolism (succinylmonocholine and choline) sensitize the myocardium to the parasympathetic effects of a second dose of succinylcholine, thus leading to bradycardia._*

Answer 263

**1. Drain CSF** **2. Decrease parenchymal volume** Diuretics Steroids **3. Decrease Cerebral Blood Flow** Adjust your PaCO2 with ventilation adjustment

Answer 264

CBF is directly related to PaCO2, and decreasing a patients PaCO2 via hyperventilation is one of the most widely used methods of decreasing CBF and therefore ICP. **CBF changes 1 to 2 mL/100 g/min with each millimeter of mercury change in PaCO2.** *_Below a PaCO2 of 25 mm Hg,_* CBF change is attenuated because severe vasoconstriction can cause local ischemia. Therefore care must be taken when utilizing hyperventilation as a strategy to decrease ICP as ischemia can be an unwanted consequence.

Answer 265

**Ions do not readily cross the blood brain barrier, but CO2 does.** For this reason, acute changes in PaCO2 affect CBF, but *_changes in blood HCO3- levels have no effect._* However, after **24-48 hours, the CSF HCO3- levels have adjusted to the change, and the CBF returns to normal.**

Answer 266

**W/ seizure history** or epilepsy can trigger a new-onset seizure. **W/O seizure history** or epilepsy, methohexital has not been known to trigger a seizures

Answer 267

**Low Dose** Venous constriction results in improved preload from venous return and may improve cardiac output. This is not seen in patients who have systolic heart failure, as the increased afterload can worsen cardiac output. Notice VENOCONSTRICTION \> arterial constriction **At high dose** Arterial & venous constriction → leads to decreased splanchnic perfusion In higher doses, CO is commonly reduced due to increases in myocardial work and afterload. The reduced splanchnic perfusion is more a result of arterial constriction than a reduction in cardiac output.

Answer 268

**(LMWH) more selectively inhibits activated factor X** when compared to unfractionated heparin (UFH) A longer polysaccharide chain (higher molecular weight) is required for the increased binding sites leading to thrombin inhibition. The shorter polysaccharide chains (lower molecular weight) of LMWH is more restricted in binding solely to ATIII, therefore more selectively inhibits Xa. **Benefit =** **1. Selective Xa inhibition** can be desirable as factor Xa has limited function outside the coagulation system, unlike thrombin which also plays a role in the immune system and inflammatory pathways. **2. Less HIT**

Answer 269

Helium has an **extremely low density** and thus has an *_increased tendency for laminar flow_*. Helium **reduces airway resistance in large and medium airways** (reduced resistance in turbulent flow). It can be used to decrease the work of breathing in pathologic conditions.

Answer 270

## Footnote **Incidence** of post spinal backache = 11-13% of patients **Treatment**: Self-Limiting (Resolves in 7 days) Mild analgesics such as acetaminophen, topical NSAIDs and patient reassurance.

Answer 271

Peripheral baroreceptors are located in both the: ## Footnote **Common carotid arteries** **Aortic arch**

Answer 272

When **blood pressure is elevated**, an increase in the baroreceptor firing in these areas causes an increase in the vagal tone (known as the baroreceptor reflex). (Stretch reflex) In converse, **decreases in blood pressure** cause an inhibition of baroreceptor discharge resulting in decreased vagal tone.

Answer 273

Infective endocarditis prophylaxis is recommended for cardiac conditions listed below PLUS: * _1) Dental (mucosal, gingival) procedures or 2) Respiratory tract (tonsillectomy, adenoidectomy, bronchoscopy with incision/biopsy) procedures or 3) Infected skin/musculoskeletal tissue procedures_* * *High risk cardiac conditions:** 1) Prosthetic cardiac valve or prosthetic material used in valve repair 2) Previous endocarditis 3) CHD only in the following categories: - *_Unrepaired_* cyanotic congenital heart disease - Completely repaired congenital heart disease with prosthetic material or device within *_six months_* - Repaired congenital heart disease with *_residual defects_* 4) Cardiac transplantation recipients with cardiac valvular disease

Answer 274

**Type A - alpha (Fastest)**, beta, gamma, delta Type B Type C - Dorsal Root and **Sympathetic (Slowest)**

Answer 275

**Alpha** = Propiroception , Motor **Beta** = Touch, Pressure **Gamma** = Muscle Spindles **Delta** = Pain, Temp, Touch

Answer 276

**Preganglionic Autonomic**

Answer 277

**Dorsal Root** = Dull pain, Temp, Touch **Sympathetic** = Postganglionic

Answer 278

**At least one month** after BMS **At least six months** after DES.

Answer 279

1. **SBO** (Promotility agent so not ideal) 2. **Parkinson's** - Increased risk of rigidity and exacerbation of extrapyramidal symptoms 3. **Pheochromocytoma**

Answer 280

St. John’s wort is an herbal medication that is taken by patients to treat depression. **St. John’s wort induces P450 3A4.** This induction causes many anesthetic-related drugs to be metabolized including alfentanil and midazolam.

Answer 281

**Amino ester (One “i” in name**) anesthetics are degraded into the metabolite para-aminobenzoic acid (PABA). *_PABA_* is the reason for reactions to most local anesthetics. **Anaphylaxis to amino amide (2 "i" in the name)** anesthetics occurs at an even lower frequency than in amino ester anesthetics. *_Methylparaben_*, a common preservative, is often found in local anesthetics. Methylparaben is structurally similar to PABA, and therefore cross reactivity is possible. In the past, PABA was widely used in sunscreens as a UV filter. Water-insoluble PABA derivatives such as padimate O are currently used in some products.

Answer 282

Occurs **30-60 minutes** after exposure for allergies but can be immediate if anaphylaxis More prone = **Health care workers, atopic patients, and patients with spina bifida.**

Answer 283

**Increased Chylothorax compared to the right** In the majority of patients the thoracic duct drains into the venous system at or near the junction of the left internal jugular (IJ) vein and the left subclavian vein (SCV) *_The most common configuration of the thoracic duct which is found in about 50% of the population involves the thoracic duct originating from the cisterna chyli at around the level of L1_*, ascending through the abdomen and thorax, and **draining into the venous system at the juncture between the left IJ vein and the left SCV.** Variations exist where the thoracic duct drains in the left IJ, left SCV, left brachiocephalic, or left external jugular vein. **Due to the duct’s location, it can potentially be injured during placement of either a central line in the left IJ or in the left SCV.**

Answer 284

The safety of **desflurane** exposure in patients with renal failure has been shown in various studies. The potentially nephrotoxic inorganic fluoride concentrations found in humans after exposure to **desflurane** are *_significantly less than that after sevoflurane exposure_* Unsure about this compared to isoflurane?

Answer 285

Succinylcholine has a Black Boxed warning specifically for this reason. Caution should also be used in patients with **muscular dystrophies (especially in children who can have potentially undiagnosed disorders)**, stroke patients, patients with neuromuscular disorders, or intensive care patients with prolonged immobilization. In some patients, such as **muscular dystrophy, hyperkalemia can occur secondary to rhabdomyolysis**.

Answer 286

**\<24 hours** It is still appropriate to use succinylcholine to safely secure the airway in these patients if their injury is \< 24 hours old, as there has not been enough time to experience nicotinic extrajunctional acetylcholine receptor upregulation.

Answer 287

Patients with neuromuscular disease such as a stroke have risk of serious hyperkalemia after succinylcholine. This usually **peaks 7-10 days after insult,** but increased K+ release may occur **as soon as 2-4 day**s after denervation injury, or after several days of immobility. Duration of risk has not been adequately characterized but is **suspected to be for 3-6 months.**

Answer 288

A patient who is already on beta blockers should have beta blocker therapy continued in the perioperative period. Continuation of beta blocker therapy is considered **Class 1 Level B evidence.** The reason for the continuation of beta-blocker therapy is that beta blocker withdrawal will allow a rebound causing **increased heart rate and increased myocardial oxygen demand in the setting of surgical stress.** This increases the likelihood of a MACE

Answer 289

Cardiac risk factors include: ## Footnote **1. Hypertension** **2. Cerebral vascular disease** **3. Peripheral vascular disease** **4. Chronic kidney disease** **5. Coronary artery disease** **6. Congestive heart failure,** **7. Diabetes.**

Answer 290

**#3 = 6 mm** **#4 = 6 mm** *_#5 = 7 mm_* *_#6 = 7 mm_*

Answer 291

**#3** = 6mm **#4** = 7mm **#5** = 8mm

Answer 292

Tonic inhibitory sympathetic control (T6-L2) predominates, but parasympathetic activation **increases contractility.** Therefore, sympathectomy induced by epidural or spinal analgesia results in increased gut motility, especially those involving epidural catheter placement at T12 or higher. The gastrointestinal hyperperistalsis has the advantage of providing **excellent surgical conditions because of a contracted gut.** Epidural analgesia **reduces the duration of postoperative ileus** The use of systemic opioids prolongs the duration of an ileus, and epidural analgesia decreases or **eliminates the need for systemic opioids by minimizing postoperative pain.** Less pain also translates into decreased amount of catecholamines released which also promotes **better gut contraction.** Postoperative epidural analgesia may also have a protective effect on the gastric mucosa because **intramucosal pH is higher during postoperative epidural analgesia than during systemic analgesia.** Local anesthetics, given either neuraxial or systemically, have also been shown to **improve intestinal perfusion** as well as reduce gastrointestinal tract irritation through their anti-inflammatory properties.

Answer 293

The **intercostobrachial nerve** provides sensory innervation to the *_medial brachium_* and does not originate from the brachial plexus. It originates from the **T2 dermatome.** Blockade of this nerve is required when an upper arm tourniquet is required and would not be successful with any brachial plexus block technique.

Answer 294

**Terminal branch of the lateral cord** **Motor**: Provides innervation to the biceps muscle (elbow flexion). **Sensory**: It gives off the lateral antebrachial cutaneous nerve which provides sensory innervation to the lateral forearm (the site of stimulus) and thus would require supplemental block to achieve adequate anesthesia for the operation. _Block by injecting can be supplemented by injecting local anesthetic into the **coracobrachialis muscle.**_

Answer 295

Buprenorphine has a **high affinity for the μ-receptor** with a *_half-life for dissociation from the receptor between 2-3 hours_* (compare to fentanyl’s 7 minutes). This leads to a low-level of physical dependence and prolonged clinical effects, up to 6 hours, despite a metabolic and elimination half-life of 3 hours.

Answer 296

Buprenorphine has an analgesic potency at low doses that is **25-40 times that of morphine.**

Answer 297

**Cytokines and Antibodies to Leukocyte Antigens**

Answer 298

**Donor Lymphocytes against a recipient**

Answer 299

*_recipient antibody_* and complement attack on donor cells *_result of recipient antibody_* and complement attack on donor cells typically secondary to **antibodies associated with the Rh, Kidd, or Kell systems**

Answer 300

recipient antibody and complement attack on donor cells result of recipient antibody and complement attack on donor cells typically secondary to antibodies associated with the **ABO Incompatibility**

Answer 301

Transfusion-related CMV is a problem primarily for: **Immunocompromised** patients **Neonates** **Allograft** recipients **Asplenic** from resection or sickle cell disease.

Answer 302

1/438 for CMV 1/366,509 for HBV 1/1,657,722 for HCV 1/1,860,883 for HIV 1/3,394,086 for HTLV.

Answer 303

- Decreased lung **compliance** - Increased **V/Q mismatch** - Increased inspiratory **pressures** - **Increased PaCO2** and **decreased blood pH**

Answer 304

- Increased **SVR**, increased **PVR**, increased **MAP** - **Increased cardiac filling** (e.g. increased thoracic pressure + head-down position) - **Arrhythmias** (tachy or brady) - **Decreased venous return** (e.g. vena cava compression + head-up position) - Decreased **ejection fraction** - Decreased **renal blood flow** - Decreased **splanchnic perfusion**

Answer 305

**Benefits:** *_Stage II (excitation) is generally avoided_* with high concentrations of sevoflurane used for induction in the adult population. Sevoflurane also has been administered by mask as an approach to the difficult adult airway because it *_preserves spontaneous ventilation and does not cause salivation._* The traditional “awake look” in the *_suspected difficult airway_* (where intravenous drugs are titrated to a level that allows direct laryngoscopy in the awake patient) has been modified to consist of spontaneous ventilation of high concentrations of sevoflurane until laryngoscopic evaluation is tolerated.

Answer 306

**Antagonist of calcium influx** through the slow channels of cell membranes **Arterial Dilator** which **decreases afterload** and **decreases** **SVR** **Coronary Dilator** (Angina/Spasms) with minimal effect on preload Sympathetic activation (25% get tachycardia - NOT Baroreceptor mediated) **Increases cardiac contractility**

Answer 307

Nicardipine, nitroglycerin, and sodium nitroprusside **inhibit hypoxic pulmonary vasoconstriction.**

Answer 308

Drugs that typically follow zero-order kinetics are THE PAW: **theophylline, heparin, ethanol, phenytoin, aspirin, warfarin.**

Answer 309

FENa = **[(PCr x UNa ) / (PNa x UCr)]** x 100

Answer 310

Uremia can lead to impaired hemostasis through a variety of mechanisms including, but not limited to: **1. Interference with von Willebrand factor (vWF) formation and release leading to impaired platelet activation at the site of vascular injury. ‘** Normally, platelets are activated and subsequently aggregate by binding to sub endothelial vWF. **Function of glycoprotein IIb-IIIa (GPIIb-IIIa)** is abnormal in uremia. This protein found on the surface of platelets is a receptor for fibrinogen, fibronectin, and vWF, and assists in platelet activation and aggregation. **Prostacyclin and nitric oxide synthesis are each increased in uremia.** These two compounds have platelet inhibitory effects. **Decreased tissue factor (factor III) activity.** This enzyme complexes with factor VIIa to activate factor X to factor Xa which converts prothrombin to thrombin.

Answer 311

**Back pain** following a large volume injection of 2-chloroprocaine is not an indication for imaging of the spine. Back pain following injection of large volumes of 2-chloroprocaine **can cause muscle spasms.** 2-chloroprocaine may contain the *_preservative disodium ethylenediaminetetraacetic acid (EDTA)._* EDTA is a known *_chelator of calcium._* Larger volumes of 2-chloroprocaine chelate the calcium of nearby muscle, which causes local muscle spasms. These spasms are **transient** and **self-relieving.** There is no need for treatment or imaging unless other signs and symptoms are present. However, there are preservative free formulations of 2-chloroprocaine readily available so this side effect is less commonly seen.

Answer 312

**CV**: bradycardia, hypotension, Prolonged QTc **Pulmonary**: pulmonary toxicity (with a pulmonary fibrosis appearance) **GI**: Elevated LFT **Endocrine**: hypothyroidism (20% of patients), life-threatening hyperthyroid storm **Dermatological**: Blue/Gray Skin and Hypersensitivities

Answer 313

**Antibody mediated destruction of parenchyma or cytotoxic process** Though the risk of developing side effects **rises with the dosage of amiodarone**, there is no set dosage limit at which it will occur. amiodarone-induced pulmonary toxicity correlates more with the **total cumulative dose** than with the daily dose or plasma concentration.

Answer 314

**Hepatically**

Answer 315

**Ester** type local anesthetic, and like other esters is broken down by **plasma cholinesterases.** The **amide** local anesthetics undergo **hepatic** metabolism.

Answer 316

2-chloroprocaine is **so rapidly metabolized** and has such low systemic toxicity that it can be delivered in much higher concentrations, up to 3%.

Answer 317

**Lipid Solubility** primary determinant of **potency** in local anesthetics.

Answer 318

**Protein Binding** primary determinant of **duration** of local anesthetics.

Answer 319

Pain control is of short duration and stops almost immediately upon deflation of the tourniquet. One important complication of IVRA is **systemic toxicity of local anesthetics.** For this reason, it is recommended that the tourniquet not be let down **less than 20-30 minutes** of local anesthetic injection The tourniquet should be gradually released to avoid a massive washout of local anesthetic, and long-acting anesthetics such as **bupivacaine should be avoided.** **Dose =** Amount: **40-50 mL of 0.5% Lidocaine (200-300 mg)** Example dose would be **12-15 mL of 2% lidocaine (240 - 300 mg)** or higher volume of dilute lidocaine

Answer 320

Intravenous regional anesthesia (IVRA), also called Bier block, is an alternative to a peripheral nerve block for short (ie, **30 to 45 minutes**) procedures on the hand and forearm such as carpal tunnel release, Dupuytren's contracture release, or reduction of wrist fracture

Answer 321

The **point of maximal amplitude of oscillations** corresponds to the mean arterial pressure (MAP).

Answer 322

*_MAPS = Most reliable_* The values of **systolic and diastolic pressures** are determined using formulas that detect the rate of change in the oscillations. Thus, **systolic and diastolic pressures are less reliable** than the mean arterial pressure. **Diastolic blood pressure measurement is more likely to be affected** by movement since this would cause changes of similar pressure magnitude, which makes the diastolic pressure the least reliable.

Answer 323

## Footnote Intraocular pressure following succinylcholine administration **can increase 5-15 mm Hg despite pretreatment with a NDNB.**

Answer 324

**Cardiac side effects** are more often seen with repeat dosing in children (**Bradycardia and Asystole**) and can be attenuated with the use of glycopyrrolate or atropine. Succinylcholine *_more commonly causes tachycardia_*, mediated by catecholamine release.

Answer 325

Administration of a NDNB can blunt the rise in ICP seen with succinylcholine use. Similar to *_IOP, inadequate anesthesia, elevated blood pressure,_* and insufficient neuromuscular blockade during tracheal intubation can **elevate ICP higher than succinylcholine alone.** Intraocular pressure following succinylcholine administration **can increase 5-15 mm Hg despite pretreatment with a NDNB**. The exact mechanism is unknown, but studies have shown that the increase in IOP occurs despite detachment of extraocular muscles. This has led to the belief that the mechanism most likely is intraocular. Currently, there is widespread recommendation to avoid succinylcholine in open-eye injuries. Importantly, inadequate anesthesia, elevated blood pressure, and insufficient neuromuscular blockade during tracheal intubation can elevate IOP higher than succinylcholine alone. There is minimal evidence that succinylcholine has led to extrusion of eye contents or blindness.

Answer 326

**Blue**, **green**, and to a lesser extent, **black** nail polish cause falsely low oxygen saturations to be displayed by standard two-wave pulse oximeters by interfering with the differential absorption of 660 and 940 nm light.

Answer 327

**1-2 mg/kg over 3-5 minutes** ## Footnote The drug acts as an *_electron receptor_* for NADPH methemoglobin reductase and enhances the enzyme’s effects up to 5-fold, leading to rapid reduction of MetHb to normal Hb. Methylene blue provides an electron acceptor for the reduction of methemoglobin using NADPH produced from the hexose phosphate pathway.

Answer 328

## Footnote CaO2 = [(**SaO2**)(**Hb** x 1.34)] + (0.0031 x **PaO2**) Where SaO2 is arterial oxygen saturation, Hb is hemoglobin, and PaO2 is partial pressure of arterial oxygen.

Answer 329

Insulin plasma concentration **initially decreases** during surgery due to sympathetic activity, which inhibits pancreatic β-cells via α-adrenergic receptors. Postoperatively insulin concentration **usually increases due to hyperglycemia** (although the increase is blunted compared non-stressed state) The stress response also causes **insulin resistance.**

Answer 330

**T3/T4** **GRH**

Answer 331

Patients with space-occupying extradural lesions or those that reduce the cross-sectional area of the spinal cord are most at risk for permanent or worsening neurologic injury from a neuraxial anesthetic. Examples of such lesions include: **Tumors** ***_Severe spinal stenosis_*** **Epidural lipomatosis** **Ligamentum flavum hypertrophy** **Ependymoma** In these patients, it is generally recommended to avoid neuraxial anesthetic techniques unless the benefits significantly outweigh the risks.

Answer 332

Relative Contraindications Some CNS diseases including: *_Multiple sclerosis_* *_Traumatic spinal cord injury_* *_Post-polio syndrome_* **only very rarely (\<0.3%) develop exacerbation of their disease following neuraxial anesthesia.** *_Preexisting diabetic neuropathy_* or other sensorimotor neuropathies have an **approximately 0.5-1% incidence of new or worse neurologic deficit following neuraxial anesthesia (higher than the general population).**

Answer 333

***_Tachycardia and Hypotension_*** ## Footnote **Increased HR (Chemically similar to Atropine)** Meperidine is structurally similar to atropine and, accordingly, demonstrates atropine-like effects including tachycardia. Meperidine was initially studied as an anticholinergic agent before being discovered as an analgesic. The physiologic effects of meperidine differ from other opioids mainly due to two factors: atropine-like drug effects weak local anesthetic properties. At standard analgesic doses, meperidine is associated with hemodynamic stability. However, high doses cause hypotension and tachycardia. **The hypotension is likely attributed to histamine release.**

Answer 334

In addition, **high concentrations of meperidine decrease cardiac contractility, an effect resistant to naloxone.** This is due to the local anesthetic effects of meperidine.

Answer 335

Nicardipine is primarily an **ARTERIOLAR vasodilator** and **decreases left ventricular afterload** and **systemic vascular resistance** with minimal effect upon preload. It is a short acting **(t1/2 = 3-14 minutes)** dihydropyridine calcium channel blocker that does not significantly decrease cardiac inotropy and may actually cause reflex tachycardia.

Answer 336

**Recombinant** form of human **brain natriuretic peptide (BNP)** which is normally produced by ventricular myocardium. Brain natriuretic peptide functions as a **counter-regulatory** hormone to angiotensin II, norepinephrine, and endothelin. Therefore, nesiritide facilitates cardiovascular fluid homeostasis by **down-regulating the renin-angiotensin-aldosterone system**, suppressing the sympathetic nervous system, suppressing endothelin production, and **stimulating cGMP causing arterial AND venous dilation.** Its net effects are *_vasodilation, natriuresis, and diuresis._*

Answer 337

It has a rapid onset of action and an elimination t1/2 of **15 min.** Nesiritide was once FDA approved for the treatment of **acutely decompensated congestive heart failure (CHF).** Recent studies, however, do not recommend its routine use in patients with d ecompensated CHF.

Answer 338

1. **Coagulation** is impaired by even mild hypothermia which appears to be due to a cold-induced defect in platelet function. This has been shown to increase blood loss in hip arthroplasty. 2. **Drug metabolism** can be impaired by hypothermia, the degree depends on the specific medication and the degree of hypothermia. 3. The **incidence of wound infection** is likely one of the most serious complications associated with hypothermia in terms of morbidity. 4. Hypothermia **impairs immune function** and decreases wound oxygen delivery secondary to thermoregulatory vasoconstriction to that area. 5. **Patient satisfaction** may be negatively impacted by hypothermia as patients often recall unpleasant sensations of being cold in the recovery room; this feeling can last hours even with mild hypothermia. 6. Finally, patient **shivering** can cause serious discomfort and complications since shivering increases oxygen consumption and can lead to ischemia in at risk patients (resulting in myocardial ischemia and even stroke).

Answer 339

Resting coronary blood flow in the average adult is around 250 ml/min, which represents approximately **5%** of the total cardiac output.

Answer 340

Hence, CPP of the LV (CPPLV) is equal to difference between aortic diastolic pressure (AoDP) and left ventricular end diastolic pressure (LVEDP): CPPLV = **AoDP - LVEDP.**

Answer 341

The RV receives its **greatest perfusion during peak/late systole and early diastole** and is *_least perfused during early systole._*

Answer 342

Myasthenia gravis is an autoimmune disorder with antibodies against the extrajunctional nicotinic acetylcholine receptor resulting in weakness, **enhanced response to nondepolarizing neuromuscular blockade**, and **resistance to succinylcholine** but *_does not result in upregulation of postjunctional acetylcholine receptors._* *_Augments Block to Roc_* *_Resistant to Succinylcholine but NOT contra_*

Answer 343

A gas mixture of 75% N2O can expand a pneumothorax to **double its size in 10 minutes** and to **3 times its size in 30 minutes.**

Answer 344

High BGPC = High Solubility = Greater Uptake = Slower Onset

Answer 345

How anesthetic split between two phases (Blood and Gas)

Answer 346

FA / FI = Yields value that can be used to assess relationship of delivered anesthetic by: ## Footnote **Ventilation** **Degree of Anesthetic Uptake/Removal**

Answer 347

* *Clinical risk factors for coronary disease include:** - A history of ischemic heart disease - Congestive heart failure - History of stroke - Diabetes - Chronic kidney disease.

Answer 348

Severe COPD was once considered contraindication to beta-blocker therapy, **however it is no longer considered contraindicated**. Many beta-blockers are cardiac-specific and safe in patients with COPD. The ACC/AHA 2014 guidelines recommend that patient’s on beta-blockers should have them continued through the perioperative period. Additionally, it is suggested that patients at intermediate or high risk for myocardial ischemia may benefit from perioperative beta-blocker therapy.

Answer 349

The ACC/AHA 2014 guidelines recommend that patients on beta-blockers should have them continued through the perioperative period. **Patients with 3 or more risk factors** for coronary artery disease may also benefit from beta-blocker therapy preoperatively. Clinical risk factors for coronary disease include: * *- A history of ischemic heart disease - Congestive heart failure - History of stroke - Diabetes - Chronic kidney disease.**

Answer 350

* *Class 1** – benefit is greater than risk and recommendation should be followed * *Class 2a** – benefit greater than risk and it is reasonable to perform therapy * *Class 2b** - benefit is slightly better or equal to risk and treatment should be considered * *Class 3** – no benefit and may be harmful

Answer 351

Factors that cause a leftward shift and an increased slope of a carbon dioxide ventilatory response curve include **arterial hypoxemia, metabolic acidemia, surgical stimuli, and certain CNS pathologies** **Volatile anesthetics at ≤1 MAC** cause a rightward, parallel shift of the VRC. Volatile anesthetics \>1 MAC reduce sensitivity to elevated PaCO2, cause a rightward shift, and reduce the slope of the VRC. **Opioid, barbiturate, and other sedative-hypnotic** medication administration shift the VRC to the right and depress the slope, in a dose-dependent manner. The result is a reduced minute ventilation and higher baseline PaCO2 therefore reducing minute ventilation.

Answer 352

**14 days after balloon angioplasty** Patients should wait 14 days after balloon angioplasty before elective surgery. **30 days after Bare Metal Stent** Dual Antiplatelet therapy w/ aspirin continuation only in the perioperative period **60 days if no coronary intervention** Acute coronary syndrome patients should wait 60 days prior to scheduling elective surgery. **180 days after Drug Eluting Stent** (EVeroliumus eluting stents)for elective non-cardiac surgery

Answer 353

A = Diuretics B = Vasoildators (ACE-Inhibitors or Nitroglycerine) C = Milrinone D = Ionotropes (Epi, Norepi)

Answer 354

The most commonly described side effects of spironolactone are **hyperkalemia**, **hyponatremia**, **gynecomastia**, and **impotence**.

Answer 355

The analgesic properties of ketamine are primarily **NMDA** receptor-mediated at **low** ketamine doses with proportionally more *_opioid receptor*_-mediated effects at _*higher doses._*

Answer 356

Lowering heart rate decreases cardiac work since **fewer muscle contractions** occur over a given period of time. (*_less ATP thus less oxygen_*) - Since the heart is doing less work, there is a corresponding **decrease in oxygen demand.** In addition, lowering heart rate will **increase the amount of time the heart spends in diastole**. Since coronary perfusion occurs primarily during diastole, a **longer time spent in diastole improves myocardial oxygen supply.** *_(Time during perfusion)_*

Answer 357

CPP = (Aortic DBP – LVEDP)

Answer 358

Wall tension = (**LVEDP** x **radius**) / (2 x **LV wall thickness**) Where: LVEDP = left ventricular end diastolic pressure.

Answer 359

**Myocardial oxygen *_supply_*** is determined by the arterial oxygen content of blood, coronary perfusion time, coronary pressure. **Myocardial oxygen *_demand_*** is determined by myocardial work which is primarily dependent on heart rate and wall tension. **Heart rate** is a unique variable in that it plays a role in determining both myocardial oxygen supply and demand.

Answer 360

Midazolam causes **anterograde** but *_not retrograde amnesia_*, even at large doses. Typical anxiolysis doses (e.g. 2mg IV in an adult) do not guarantee amnesia.

Answer 361

Primarily metabolized to oxymorphone-3-glucuronide and 6-hydroxy-oxymorphone. The only active metabolite of oxycodone is oxymorphone. In patients with **renal insufficiency** receiving oxycodone, the **elimination half-life is lengthened** and the excretion of metabolites is impaired potentially resulting in a prolongation of its clinical effect.

Answer 362

1. **Free Hydromorphone** (Accumulates in renal failure) 2. **Hydromorphone-3-glucoronide** (No analgesia and have be neuroexcitatory)

Answer 363

**Morphine-3-glucuronide** (M3G) (55%) **Morphine-6-glucuronide** (M6G) (10%) **Normorphine** (4%) **Parent compound** (10%)

Answer 364

**Morphine-6-Glucuronide (Active compound: 10%)**

Answer 365

**Respiratory depression** enterohepatic cycling and slow penetration of the blood-brain barrier with equally slow equilibration with systemic circulation; effects are not reversed by dialysis. **Prolonged sedation** **Myoclonus** **Seizures**

Answer 366

Halothane **decreases SBP mainly by reducing cardiac output (NOT SVR)** Other anesthetics = Decrease in SVR, while CO is maintained

Answer 367

**Succinylcholine after neostigmine** Following neostigmine administration, a dose of succinylcholine will result in an **increased duration of phase I blockade** when compared to the duration of action of succinylcholine administered alone. *_Phase I augmentation lasts about 30 minutes on average._* Multiple studies have shown that following neostigmine administration for nondepolarizing muscle relaxation reversal, a subsequent dose of succinylcholine will result in prolonged duration of action of the succinylcholine (mean duration 25-35 minutes). The increase in duration is likely complex and is not solely the result of plasma cholinesterase inhibition.

Answer 368

A phase II block is likely due to the **interaction of succinylcholine on the prejunctional acetylcholine receptors**. *_Prejunctional receptors are blocked by the higher concentration of succinylcholine leading to a decrease in cholinergic transmission and competition with the drug at the postsynaptic receptors_*. A decrease in plasma cholinesterase activity (either from congenital or acquired causes) can also result in prolonged blockade. Many medications used for anesthetic maintenance reduce plasma cholinesterase activity including remifentanil, esmolol, ester local anesthetics, and etomidate.

Answer 369

**Head-down position** Suction FiO2 of 100% Deepen anesthetic

Answer 370

**Interference with Platelet Adhesion and clot formation by decreasing glycoprotein 2b/3a availability on platelets** Platelets are not able to achieve the appropriate conformation to bind fibrinogen, which *_negatively affects platelet aggregation_*

Answer 371

Originates from the aorta between the **T9 and T12** vertebral segments in 75% of the population.

Answer 372

**Spinal Cord Perfusion Pressure (SCPP) Equation** MAP - Intrathecal Pressure or CSF pressure (SCPP = MAP - CSF pressure). Improve SCPP **1. Increase the MAP to \> 90 mmHg** (if suspected involvement) **2. Reduce CSF pressure to \< 10 mmHg** using a lumbar CSF drain.

Answer 373

Compromise: Interruption of the great radicular artery → ASA syndrome **Symptoms:** *_Motor Tract involved_* Bilateral lower extremity paraplegia Bowel and bladder dysfunction. *_Dorsal Columns / Sensory **NOT** involved_* Spared Sensation and proprioception (posterior portion of the spinal cord is supplied by two PSAs.)

Answer 374

Thoracoabdominal aortic aneurysm (TAAA) repair occurs in 10-20% of patients depending on urgency of procedure, location of the lesion, and duration of ischemia. **Paraplegia in 10-20% of surgeries** With aortic cross clamping, there may be significant hypoperfusion of the spinal cord anteriorly.

Answer 375

**Delayed-onset paraplegia** is the new onset of neurologic dysfunction several hours to days following surgery in a patient who otherwise woke up without neurologic deficits. The same principles of SCPP optimization *_persist and include increasing MAP via vasopressors and/or emergent placement of a spinal drain_*. This is an important concept since a spinal cord that was adequately protected during surgery is still at risk for ischemia and infarction postoperatively.

Answer 376

IICEBALLS: intravenous \> intercostal \> caudal \> epidural \> brachial plexus \> axillary \> lower limb \> subcutaneous

Answer 377

**Alveolar Gas Equation** **PAO2** = FiO2(PB – PH2O) – **PCO2** / RQ ``` *_PAO2_* = alveolar oxygen partial pressure FiO2 = fraction of inspired oxygen PB = barometric pressure PH2O = vapor pressure of water RQ = respiratory quotient ``` **Ex: If PCO2 is 80 mmHg, then your PAO2 would be 50 mmHg.**

Answer 378

In healthy patients, minute ventilation will normally increase linearly by approximately **2 L/min for every 1 mmHg increase in PaCO2**.

Answer 379

**Volume of Distribution (Vd)** = Drug dose / Plasma concentration ## Footnote *_The volume of distribution does not have an actual physical correlate in plasma volume. Rather, it is the theoretical size of the plasma compartment that would explain the observed plasma concentration if all of the drug given was only distributed in the plasma. Because of this, it is sometimes referred to as the "apparent" volume of distribution._*

Answer 380

*_Affinity of the drug for **tissue components***_ (tissue proteins, tissue lipids) relative to its _*affinity for **plasma components**_* (plasma proteins). Tissue proteins may include high-affinity receptor sites. Tissue lipids are an important binding site, depending on the partition coefficient of the drug in fat (and the individual's fat volume).

Answer 381

"The volume of distribution is the total drug within the body divided by the drug plasma concentration. - It is **directly** *_proportional_* to the unbound drug in the plasma and **inversely** *_proportional_* to the unbound drug in the tissue.

Answer 382

As such, drugs that are **lipophilic have a higher Vd** than drugs that are hydrophilic. Also, having **greater tissue binding** will decrease the unbound proportion in the tissue, thus increasing the volume of distribution."

Answer 383

**Indications:** 1. **Factor replacement** in hypofibrinogenemia 2. **von Willebrand disease** 3. **Hemophilia A** 4. **Massive transfusion** after several units of other blood products have been given. Checking fibrinogen levels during massive transfusion can assist with the management of cryoprecipitate.

Answer 384

**Synthesis:** Cryoprecipitate is made from fresh frozen plasma Cooled to 4 degrees Celsius slowly. Cryoprecipitate is *_high in factors 8 and 13*_ as well as _*fibrinogen*_ and _*von Willebrand factor (vWF)._*

Answer 385

Dosing: It is often given in a pooled dose of 10 or more units. *_Concentration:_* 1. Contains approximately 200 mg/unit of fibrinogen. 2. 1200 mg/dL: 1 unit is 12.5cc Therefore, administration of 10 units would add 2 gm of fibrinogen. *1. ICU* *_Ten units of cryoprecipitate (2 grams) will typically raise a 70kg patient's fibrinogen by 70 mg/dL_* *_2. Intraop_* FIBTEM A10 \<10mm Goals (Ask surgeon if we are acutely bleeding or oozing) 1. Acute Hemorrhage = We need FIBTEM A10 ~ 18 mm 2. Oozing = We need FIBTEM A10 ~ 9 mm **Treat with Fibrinogen (2 mm FIBTEM A10 increase with 1000 mg of Fibrinogen)**

Answer 386

1. Glossopharyngeal 2. Recurrent laryngeal 3. Superior laryngeal

Answer 387

**Base of Tongue** **Vallecula** **Anterior Epiglottis** **Tonsils**

Answer 388

Nerve Block Topical application of local anesthetic in the **gutters of the pharyngeal folds near the base of the tongue for 5-10 minutes** or with injection of local anesthetic at the base of the fold in the floor of the mouth.

Answer 389

**Watch out for carotids!** If blood aspirated, needle redirection medially should occur. The glossopharyngeal nerve is the sensory nerve associated with the gag reflex

Answer 390

Motor and Sensory nerve, motor involved with cough reflex Primary **motor nerve of the larynx** **Sensory innervation** to the *_vocal folds and trachea_*

Answer 391

Anesthesia of this nerve is provided by **transtracheal injection** of local anesthetic after air is aspirated with puncture through the cricothyroid membrane or through aerosolization of local anesthetic and having the patient breathe it in.

Answer 392

**Internal and External Branch**

Answer 393

**Base of the tongue** **Epiglottis** **Aryepiglottic folds** **Arytenoids**

Answer 394

It can be blocked by cotton soaked in local anesthetic applied with a right-angled clamp into the piriform sinuses for 5-10 minutes but is often blocked by initial topicalization of the pharynx. Injections can also be performed after **walking off the cornu of the hyoid bone through the thyrohyoid membrane**

Answer 395

**Motor** innervation to the cricothyroid muscle, the **only laryngeal muscle not innervated by the recurrent laryngeal nerve.**

Answer 396

**Clark**, **galvanic**, and **paramagnetic** electrodes measure oxygen

Answer 397

Severinghaus electrode measures CO2

Answer 398

**Sanz electrode** measures **pH**

Answer 399

**CPPLV = AoDP - LVEDP** Hemodynamic variables that increase LVEDP will decrease CPP.

Answer 400

**Pulmonary artery occlusion pressure (PAOP)** may be used as a proxy for LVEDP. A decrease in PAOP is generally regarded as a decrease in LVEDP, which leads to an increase in CPP.

Answer 401

**Aortic Diastolic Pressure - LVEDP**

Answer 402

**Habitus (BMI \>30)** **Gastroesophageal** High risk for aspiration of gastric contents including Known or potential for full stomach (NOT NPO) Hiatal hernia Gastroesophageal reflux disease Intestinal obstruction Delayed gastric emptying **Pulmonary** Poor lung compliance High airway resistance **Airway** Difficult Airway Glottic or subglottic airway obstruction Limited mouth opening (generally less than 1.5 cm).

Answer 403

The 11-β hydroxylase enzyme **converts deoxycorticosterone to corticosterone and 11-deoxycortisol to cortisol.**

Answer 404

Bohr Effect

Answer 405

Midazolam bioavailability among routes of administration (greatest to least): intravenous \> intramuscular \> intranasal \> rectal \> oral. *_Oral bioavailability is highly dependent on dose_*; **bioavailability is lower with higher doses**. This means that rectal bioavailability could potentially be lower than oral, but again it is dose dependent.

Answer 406

1. **\>3** years 2. Duration of surgery (**\>30 minutes**) 3. Type of **Procedure** (Strabismus and T&A) 4. **Patient** or **family** history of **PONV** Zero, 1, 2, 3, or 4 of these risk factors impart a risk of postoperative vomiting of 9%, 10%, 30%, 55%, and 70% respectively in pediatric patients.

Answer 407

Zofran 0.1 - **0.15 mg/kg** Dexamethasone **0.15 mg/kg**

Answer 408

**Weakness** Reversal of nondepolarizing neuromuscular blockade is achieved by administering an AChE inhibitor. (Neostigmine). NMBD = competitive antagonists and compete with acetylcholine (ACh) in the synaptic cleft. The chances that ACh will bind to ACh receptors (instead of the NMBD) increases with AChE inhibition (Neostigmine) **Excessive inhibition of AChE can lead to prolonged elevations in synaptic ACh concentrations**. 1. **Prolonged exposure to ACh** can lead to both presynaptic and postsynaptic inactivation of sodium channels. 2. **Inactivation of sodium channels** prohibits depolarization from occurring. 3. In addition, both presynaptic and postsynaptic ACh receptors become **desensitized to ACh.**

Answer 409

**Restrictive Disease** **Reduced diaphragmatic excursion leads to decreased lung volumes** FVC - *_Low_* FEV1 - *_Low_* FEV1/FVC - *_Normal or even high_* FEF 25-75% - *_Normal_* FRC - *_Low_* TLC - *_Low_*

Answer 410

**Obstructive** Disease with PFT will show FVC - **Normal or Increased** FEV1 - **Decreased** FEV1/FVC - **Decreased** FEF 25-75% - **Decreased** FRC - **Normal or increased** TLC - **Normal or increased**

Answer 411

**The forced expiratory flow during the middle 50% of the FVC (FEF25-75%)** **another way of saying this** *_Forced expiratory flow (FEF) is the flow (or speed) of air coming out of the lung during the middle portion of a forced expiration_* Normal ranges for FEF25-75% are typically ***_80-120% of the predicted value._*** *Wikipedia* Values ranging from 50-60% and up to 130% of the average are considered normal

Answer 412

Ketorolac can decrease GFR, especially when administered for greater than 5 days, via **inhibition of afferent renal artery vasodilation.** Blocks prostaglandins which vasodilate the afferent renal artery.

Answer 413

Both = Screen for ABO, Rh, Antibody **T&C** = Donor RBC and patient serum for antibody screening

Answer 414

Factors that decrease release of acetylcholine: 1) **Antibiotics** (clindamycin, polymyxin)

Answer 415

Factors that decrease release of acetylcholine: * *Magnesium**: antagonizes calcium * *Calcium**: Hypocalcemia

Answer 416

Factors that decrease release of acetylcholine: **Anticonvulsants**

Answer 417

Factors that decrease release of acetylcholine: **Diuretics (furosemide)**

Answer 418

Factors that decrease release of acetylcholine: **Eaton-Lambert syndrome**: inhibits P-type calcium channels **Myasthenia gravis** is due to antibodies destroying post-synaptic acetylcholine receptors. Acetylcholine release from nerve terminal is not affected.

Answer 419

**Calcium channel blockers (nifedipine, diltiazem)** *_do not_* affect P-channels. These drugs affect L-type calcium channels.

Answer 420

**Both** the botulinum and tetanus toxin **inhibit SNARE proteins.** However, *_botulinum*_ toxin acts at the level of the _*peripheral nerve_*, and the **tetanus toxin** acts at the **central nervous system**. Botulinum --\> inhibits SNARE --\> decrease acetylcholine release (peripheral nerve) Tetanus --\> inhibits SNARE --\> inhibits GABA neurons (CNS)

Answer 421

**"BLEACH P"** 1. **A**ge ≥ 59 2. **B**MI ≥ 32 3. Chronic **L**iver disease 4. **C**OPD requiring chronic bronchodilator use 5. **P**eripheral vascular occlusive disease 6. **H**igh-risk surgery 7. **E**mergency surgery

Answer 422

FRC is the capacity in the lungs after end expiration of a normal tidal volume and consists of the expiratory reserve volume (ERV) and the residual volume (RV).

Answer 423

Closing capacity is the capacity during which airway closure begins to occur and consists of the **closing volume and residual volume.**

Answer 424

A mnemonic for factors that decrease FRC is **PANGOS**: **P**regnancy **A**scites **N**eonate **G**eneral Anesthesia **O**besity **S**upine position.

Answer 425

A mnemonic for factors increasing closing capacity is **ACLS-S**: **A**ge **C**hronic bronchitis **L**V failure **S**moking **S**urgery

Answer 426

Pancuronium is eliminated primarily by the kidney and therefore should be **avoided in renal failure.**

Answer 427

Glucagon is generally not considered a first line therapy for low cardiac output (CO) states, but may be beneficial in the following situations after conventional therapies have failed: ## Footnote **1. Low CO following cardiopulmonary bypass (CPB)** **2. Low CO following myocardial infarction** **3. Chronic congestive heart failure** **4. Low CO from excess β-blockade** **5. Anaphylactic shock with refractory hypotension**

Answer 428

**Anaphylaxis** (refractory to epinephrine) in patients on beta-blocker therapy (off-label use): IV: Initial: IV 1 to 5 mg bolus Followed by an infusion of 5 to 15 mcg/minute Titrate the infusion rate to achieve an adequate clinical response (Lieberman 2015). **Beta-blocker overdose** IV: 3 to 10 mg bolus; if no clinical response may repeat bolus dose; if clinical response with bolus, start continuous infusion at 3 to 5 mg/hour; titrate infusion rate to achieve adequate hemodynamic response (ACC/AHA/HRS [Kusumoto 2018]; AHA [Vanden Hoek 2010]; Barrueto 2019).

Answer 429

This patient is taking St. John's Wort which induces cytochrome P450 isoenzymes and increases the **metabolism of cyclosporine.** This can result in subtherapeutic drug levels and an *_i**_n_**creased risk of transplant rejection_* **Warfarin therapy is therefore unreliable in patients taking St. John's Wort and puts them at risk for DVT and thromboembolism.**

Answer 430

**The lipid solubility** of an opioid is a prime determinant of the onset and duration of action of the drug as it *_affects how easily the drug is able to cross cellular (lipid) membranes._*

Answer 431

An opioid with a pKa less than physiologic pH (~7.4) will have a **much greater nonionized fraction** whereas an opioid with a pKa \>7.4 will have a greater ionized fraction. ## Footnote **Lower pKa = Increased non-ionized fraction = Faster onset**

Answer 432

Both FEV1 and FVC are decreased proportionally so that the FEV1/FVC ratio is preserved, i.e. **obesity behaves like a restrictive defect.**

Answer 433

O DAMN **O = Oxygen** **D = Drugs** (Vapor, Sedative/Hyponotic/NMBD/Atypical Pseudocholinesterase, Benzo,) - Antagonism with Naloxone, Nalbuphinie, Sugammadex, Physostigmine (For Scopalamine), ETOH or intoxication **A**ltered **M**etabolic Derangments - Hypoglycemia o Assess **blood glucose level** - Hypoxemia and/or hypercarbia o Assess vital signs including pulse oximetry and end tidal CO2. o Obtain **arterial blood gas**. Continue mechanical ventilation until corrected. - Hypothermia/hyperthermia o Assess vital signs including **temperature** (E) - Acidosis o Obtain arterial blood gas and correct underlying disorder as necessary - **Hyponatremia** (e.g. after urologic surgery) o **Obtain metabolic panel** and correct as necessary **N = Neurological insults** - New stroke, either ischemic or hemorrhagic o Perform *_full neurologic exam_* if able (pupils, cranial nerves, reflexes, withdrawal to pain) o **Consider CT scan or MRI scan** if adequate concern or suspicion - Seizure or post-ictal state - Increased intracranial pressure

Answer 434

**Delayed Emergence Rapid Panel** Vital signs (including temperature) Twitch monitor Neurologic Exam (pupils, cranial nerves, reflexes, response to pain) Fingerstick glucose ABG with electrolytes Make arrangements for naloxone, flumazenil, physostigmine, imaging (ex. CT scan)

Answer 435

Included under drug effects are: Residual anesthetic (volatile, propofol, barbiturates, ketamine) Excess narcotics – can be reversed by **naloxone (40 ucg boluses**) – remember it’s short-acting Preoperative sedatives – too much midazolam? – reversed by **flumazenil** **0.2 mg q1min up to 1 mg** **Physostigmine 1.25 mg IV** can reverse cholinergic effects (ex. scopolamine) and possibly the effects of anesthetic agents (Stanford Delayed Emergence Protocol) Inadequate reversal or no reversal of muscle relaxation or rarely pseudocholinesterase deficiency – edrophonium/atropine work faster (1-2 mins) than neostigmine/glycopyrrolate (peak effect around 10 mins) and may be indicated in this setting Acute alcohol intoxication or other illicit drugs rendering unconsciousness extending the length of the anesthetic

Answer 436

**Ulnar**: Black is Distal, Red is proximal **Face**: Black is aligned with tragus, Red is above

Answer 437

Corrugator Supercilii

Answer 438

**Induction** = Corrugator Supercilii It is the best comparison for abdominal muscle paralysis as the diaphragm and abdominal muscles are also relatively resistant to neuromuscular blockade. These muscles are the first to recover from neuromuscular paralysis. *_Corrugator supercilii monitoring is reflective of laryngeal muscle paralysis and may be used to assess for adequate intubating conditions._* **Emergence** = Adductor Pollicis The adductor pollicis muscle is innervated by the ulnar nerve and causes adduction of the thumb. The *_adductor pollicis is more sensitive_* to neuromuscular blockade than the corrugator supercilii. Therefore the adductor pollicis is less representative of abdominal muscle paralysis. The adductor pollicis is a commonly monitored muscle to assess neuromuscular blockade as it is **often accessible, visible, and correlates well with recovery of laryngeal muscle function during extubation.** A primary benefit of monitoring the adductor pollicis is upon emergence.

Answer 439

100Hz for 5 seconds correlates to about a TOF ratio of **0.85 if sustained.**

Answer 440

1: TOF \<0.7 2: TOF 0.7 - 0.9

Answer 441

**2-2.5 x the IV dose** (2.5 mg diluated in 5-10 mL of sterile water)

Answer 442

An equation for this is: Amount FFP Needed (mL) = ## Footnote **(Target Level - Present Level) \* kg**

Answer 443

1. 0 **100** 1. 4-1.6 **40** 1. 7-1.8 **30** *_1.9-2.1 **25**_* 2. 2-2.5 **20** 2. 6-3.2 **15** *_4.0-4.9 **10**_* \>5.0 **5**

Answer 444

For example, let's say we have a 70kg patient who is bleeding with an INR of 7.5 and our goal INR is 1.4. *_INR of \>5 = 5% activity_* *_INR of 1.4 = 40% activity_* We would need (40% - 5%) \* 70 kg, which is 2450 mL of FFP to make this correction. A single unit of FFP typically is 200-250 mL.

Answer 445

2. 5 **4 units** 2. 0 **3 units** 1. 8 **2 units**

Answer 446

The proliferation of extrajunctional acetylcholine receptors in muscle in paralyzed limbs can lead to an **increased response (T4:T1) to peripheral nerve stimulation** following non depolarizing neuromuscular blockade compared to a normal non paralyzed limb in the same patient.

Answer 447

**EAST** Eplerenone Amiloride Spironolactone Triamterene

Answer 448

**SaO2** - [*_VO2_* / (CO \* Hgb \* 4/3))]

Answer 449

**14** days after balloon **angioplasty** **30** days after **Bare Metal Stent** **60 days** if **no coronary intervention** **180 days** after **DES for elective noncardiac surgery.**

Answer 450

**Pulmonary Complianace (Elastic Resistance)** *_Positioning_* Abdominal Insufflation Decrease pulmonary compliance Trendelenburg Position *_Intrinsic Disease_* Ascites Intrinsic Lung Disease Obesity *_Acute Events_* Pulmonary Edema Tension Pneumothorax

Answer 451

**Two things can be happening when the peak inspiratory pressure is high** Peak pressure is high with a normal plateau pressure, indicating a problem with **resistance** Peak pressure is high with an elevated plateau pressure (normal \< 25 cm H2O) demonstrating that there is a problem with **lung and/or chest wall compliance**

Answer 452

Problem is with **airway resistance** 1. Airway compression 2. Bronchospasm 3. FBO 4. Kinked ETT tube 5. Mucuous Plug 6. Secretions

Answer 453

Stroke Volume (SV) **60 - 100 mL/beat** Stroke Volume Index (SVI) **33 - 47 mL/m^2/beat**

Answer 454

CO = BP/SVR

Answer 455

**EMLA** is a local anesthetic mixture applied transdermal to provide anesthesia for the skin. **E**utectic **M**ixture of **L**ocal **A**nesthetics **(EMLA)** EMLA *_contraindications_* include: 1. **Allergy to amide anesthetics** 2. **Concomitant class III anti-arrhythmic drugs** (e.g., amiodarone, sotalol) 3. **Congenital or idiopathic methemoglobinemia**, infants receiving treatment with methemoglobin-inducing agents. 4. **G6PD**

Answer 456

Liquid volatile anesthetic (mL/hr) ≈ **3 \* FGF (L/min) \* % anesthetic vapor.** OR

Answer 457

**Involves giving fluid and intentionally diluting the patient's blood prior to significant blood loss.** **Blood is withdrawn and stored for later autologous transfusion, and the patient receives the same volume in crystalloid or colloid to maintain euvolemia.** *_Physiological Consequences:_* Blood **viscosity** will **decrease**. The decreased blood viscosity will **decrease peripheral vascular resistance** **Cardiac output raises** to compensate for the anemia. The increase in cardiac output and decrease in peripheral vascular resistance causes an **increase in regional blood flow.** However, even with increases in regional blood flow and cardiac output, there is **no increase in oxygen delivery**. This is secondary to the significant amount of oxygen that hemoglobin can carry. Hgb of 7-8 is targeted Consequently, blood is able to move with less resistance because of the reduced viscosity, and thereby a drop in peripheral vascular resistance occurs with an increase in regional blood flow. If cardiac output can effectively compensate, **oxygen delivery to the tissues at a hematocrit of 25% to 30% is as good, but no better than, oxygen delivery at a hematocrit of 30% to 35%.**

Answer 458

**Under normal circumstances**, the brain uses glucose as its sole energy source (No ketone bodies) During periods of **fasting**, exercise, or very low carbohydrate diets, the brain will *_begin to use ketone bodies_* (acetone, acetoacetic acid, and β-hydroxybutyric acid) as an alternative source of energy. **After 3 days** of low blood glucose, ketone body metabolism supplies approximately one-third of the brain’s energy. **After 1-1.5 months**, they supply two-thirds of the brain’s energy. Glucose continues to account for the remainder. The increased use of ketones decreases the body’s demand for glucose which allows for decreased catabolism of muscle for conversion of amino acids to glucose.

Answer 459

The sodium concentration of standard 5% albumin manufactured in the United States is **145 +/- 15 mEq/L.**

Answer 460

**Extraperitoneal** perforation *_(the most common) causes periumbilical, inguinal or suprapubic pain_*, whereas **intraperitoneal** perforation causes *_diffuse or upper abdominal pain, or referred pain to chest and shoulders._*

Answer 461

As a side note, keeping the patient awake has the additional benefit of allowing for the detection of TURP syndrome, which is due to **hypo-osmolality and hyponatremia** and presents with *_CNS symptoms._*

Answer 462

Glycine toxicity causes **hyperammonemia**, which manifests as CNS symptoms and nausea. *_Transient blindness can also occur._*

Answer 463

**Onset** = 7-11 minutes **Duration** = 4-6 minutes

Answer 464

**Reduced MAC requirements**

Answer 465

The top 3 factors leading to death and permanent brain damage are: ## Footnote **Cardiovascular events** (pulmonary embolism, stroke, myocardial infarction, arrhythmia, undiagnosed conditions) **Respiratory events** (inadequate ventilation, esophageal intubation, difficult airway) **Equipment issues** (failure or misuse)

Answer 466

N2O Concentration Bowel Distension After 4 Hours 50% N2O **200% increase** 75% N2O **400% increase** 80% N2O **500% increase**

Answer 467

In patients with a coronary supply that is **right-dominant**, the *_RCA also gives rise to the AV nodal artery which supplies the AV node._* The most common cause of AV node disruption and resulting complete heart block is a myocardial infarction, most frequently a blockage in the RCA.

Answer 468

The SA node is supplied by the **RCA in about 60%** of cases and by the **LCA or its branches in about 40% of cases**. Supply of the SA node **does not depend** on coronary dominance of the patient.

Answer 469

**Thyroid Replacement Therapy** *_Levothyroxine_* is the preferred therapy because it allows the controlling enzyme systems to regulate TSH secretion as well as conversion to T3. *_Liothyronine_*, the most potent form of thyroid hormone, can be given intravenously though it risks precipitating myocardial ischemia. **Hydrocortisone** may also be given because 5% to 10% of patients with myxedema coma also have adrenal insufficiency.

Answer 470

* *S**noring * *T**ired during the day * *O**bserved apneas * *P**ressure (high blood pressure) * *B**MI \> 35 * *A**ge \>50 * *N**eck size * *G**ender (male) ## Footnote *_\<3 = Low risk of OSA_* *_≥3 = High risk of OSA_*

Answer 471

Sleep studies are scored with an **apnea/hypopnea index (AHI).** **Mild OSA** is defined as **5-15** events/hour of sleep (AHI 5-14). **Moderate OSA** is defined as **15-30** events/hour of sleep (AHI 15-29). **Severe OSA** is defined as greater than **30** events/hour of sleep (AHI 30+).

Answer 472

Sevoflurane metabolism has not resulted in the formation of TFA intermediates and the potential for hepatic toxicity is low. Instead, sevoflurane metabolism yields a compound **hexafluoroisopropanol (HFIP)**, which does not accumulate and rapidly undergoes phase II biotransformation. This contributes to the *_low hepatotoxic potential_* for sevoflurane.

Answer 473

Two types of postoperative liver injuries have been reported to be associated with halothane administration. **The first type** is a mild injury characterized by nausea, lethargy, and fever. **The second type**, mediated by the patient’s immune system, is severe acute hepatitis with histological findings of widespread hepatic necrosis. This is rare (1 in 15,000 cases on initial exposure) and associated with acute elevations in ALT and AST and onset of jaundice within 2 to 14 days of halothane administration.

Answer 474

Desflurane, as a consequence of **trifluoroacetic acid (TFA)** reactive intermediates, has been implicated in the formation of dangerous immunogenic compounds.

Answer 475

It operates on the principle that the amount of **infrared light** absorbed at a *_specific wavelength is proportional to the partial pressure of the gas_* analyzed because absorption will be greater with a greater amount of gas molecules. Intensity of IR light detected will therefore be **inversely proportional to the amount of gas** in the sample.

Answer 476

Approximately **25-30% of rocuronium is renally excreted**. It is cleared primarily by *_hepatic uptake*_ and _*hepatobiliary excretion_*.

Answer 477

Citrate intoxication occurs with massive transfusions, most notably with *_fresh frozen plasma._* The rate of transfusion needs to **exceed 1 mL/kg/min**, which is approximately equivalent to one unit of packed **red blood cells (PRBCs) every 5 minutes in an adult.**

Answer 478

**Hemodynamics** - Hypotension, Narrowed Pulse Pressure, Increased LVEDP (Decrease in Coronary Perfusion Pressure) **EKG** - Prolonged QT, Narrowed QRS, Flat T waves

Answer 479

CPDA-1 anticoagulant allows PRBC and whole blood storage for up to 35 days - **Citrate** is the anticoagulant (binds calcium necessary for clot formation) - **Phosphate** is incorporated for cellular function and ATP production - **Dextrose** is the nutrition source for glycolysis - **Adenine** is incorporated for ATP production

Answer 480

EDTA is an **irreversible** binder of calcium

Answer 481

**Minimal** Sedation - Normal rersponse to *_verbal_* **Moderate** sedation - Purposeful rersponse to *_verbal/tactile_* **Deep** - Purposeful response after *_repeated/painful_* **General anesthesia** - *_Unarousable_*

Answer 482

**Carbon Dioxide**

Answer 483

**~400L (25% full)** A full E cylinder of nitrous oxide is **8.80 kg** and has a pressure of **745 psig**, an empty cylinder is **5.90 kg.**

Answer 484

Grade III: no cords visible, only epiglottis visible. * *Grade IIIa**: only epiglottic edge visible (**epiglottis** **raised**). * *Grade IIIb**: downfolded or floppy epiglottis is visible.

Answer 485

PaCO2 is always greater than ETCO2 with a gradient of **2-5 mm Hg in spontaneously breathing, nonanesthetized patients** Yes. under anesthesia = **5-10 mm Hg in mechanically ventilated patients.** **Ex: ETCO2 is 40, you will have PaCO2 of 45-50 mmHg**

Answer 486

This is because **desflurane is near boiling point at room temperature (73 F)**, which means an unpredictable amount is in liquid form, while the rest of it may be in gaseous form. ## Footnote **This heated vaporizer reliably converts desflurane to the gaseous form.**

Answer 487

5 metabolites - but primarily undergoes glucuronide conjugation without any phase I metabolism and, because of this, is less affected by **age and renal disease** The main metabolite of lorazepam is inactive and water-soluble, thus is **excreted rapidly by the kidneys**

Answer 488

QTc prolongation (20%) Headache (11%) Transient transaminitis (5%) Constipation (4%)

Answer 489

Ondansetron is known to cause QTc prolongation in nearly 20% of patients. However, the prolongation is *_typically 20-30 msec or less, which is clinically insignificant_* (though statistically significant) **except** in patients with already **prolonged QTc intervals or those with additional risk factors for prolonged QTc intervals (e.g. hypokalemia, hypocalcemia, hypothyroidism, history of myocardial infarction, long QT syndrome, and recent use of other medications that prolong the QTc interval).**

Answer 490

**TIVA** (Vapor can prolong QTc) Correct **Potassium** (Hypo can exacerbate) Correct **Calcium** (Hypo can exacerbate) Get **TSH and Free T4** levels (Hypo can exacerbate)

Answer 491

***_HIGH RISK FACTORS_*** + ***_HIGH RISK PROCEDURES_*** ARE REQUIRED * *The high-risk factors are:** 1) Prosthetic heart valves 2) Prior history of infective endocarditis 3) Unrepaired cyanotic congenital heart disease 4) Completely repaired congenital heart defect (the first six months after procedure) 5) Repaired congenital heart disease with residual defect 6) Valvular disease in a transplanted heart Of note, prophylaxis is NOT required in patients with bicuspid aortic valve, acquired aortic/mitral disease, or hypertrophic cardiomyopathy (HOCM). * **_The high-risk procedures are:_*** 1) **Dental work** – highest risk for infective endocarditis in procedures that involve gingival tissue manipulation or perforation of the oral mucosa. For example, tooth extractions, or drainage of a dental abscess. However, routine dental cleaning is not a high-risk procedure that requires prophylaxis. 2) **Respiratory tract** procedures that warrant prophylaxis are those involving incision/biopsy of the respiratory tract mucosa. This includes tonsillectomy, adenoidectomy, and bronchoscopy with biopsy. 3) **Skin or musculoskeletal tissue procedures**

Answer 492

The current prophylactic regimen is: 1. **Amoxicillin** OR 2. **Ampicillin 2 g** given 1 hour before the procedure.

Answer 493

Those who are allergic to penicillin can be given **clindamycin 600 mg**. OR **Azithromycin 500mg** or **ceftriaxone 1g**

Answer 494

The order of non-depolarizing muscle relaxant potentiation is **desflurane** \> **sevoflurane** \> **isoflurane** \> **halothane** \> **TIVA** (e.g. propofol).

Answer 495

**Increasing the heart rate increases inotropy** through the Treppe (or Bowditch) effect?

Answer 496

Additionally, administration **should not exceed 10mg/min** because of the risk of vancomycin infusion syndrome (i.e. "red man syndrome"). Vancomycin infusion syndrome is characterized by **hypotension, tachycardia, generalized pruritus, and red rash.**

Answer 497

Methylene blue (1-2 mg/kg) is the primary pharmacologic treatment of methemoglobinemia.

Answer 498

**Methylene blue** is a *_monoamine oxidase inhibitor_*. Doses \> 5mg/kg in the setting of selective serotonin reuptake inhibitor use may precipitate **serotonin crisis**. For this reason, *_indigo carmine may be preferred for use in detecting ureteral injury._*

Answer 499

Patients with G6PD-deficiency are **unable to generate NADPH** sufficiently and therefore methylene blue is not only ineffective, but paradoxically serves as an oxidant stress leading to hemolysis. ## Footnote *_**Ascorbic acid (vitamin C) c**an serve as an electron donor (antioxidant), and is the treatment of choice of methemoglobinemia in the setting of G6PD-deficiency._*

Answer 500

Collapse \<50% suggests **volume overload** Caval Index \>50% suggests **fluid responsiveness**

Answer 501

**IVC \<1.5 cm** suggests volume depletion **IVC \>2.5 cm** suggests volume overload

Answer 502

At *_high altitudes_*, the **partial pressure of desflurane will decrease** in proportion to the reduction in atmospheric pressure as it correlates to the calibration pressure, usually 760 mmHg (1 atm) OR *_Another way of saying this is gas delivered will be inversely proportional to altitude_*

Answer 503

**Anatomic dead space** is equal to the volume in the portions of the airways not involved in gas exchange (i.e. oronasopharynx, trachea, bronchi, and most of the bronchioles). **Alveolar dead space** is the volume in the alveoli that is not being perfused and not involved in gas exchange. **Physiological Dead Space** = The sum of alveolar and anatomic dead space

Answer 504

Approximately **2 mL/kg** in the adult patient. Also, remember that the dead space to tidal volume ratio (Vd/Vt) is usually **33% since tidal volume is approximately 5-7 mL/kg.**

Answer 505

**Dead space** is **increased** in the upright position relative to the supine position. This occurs due to an increase in alveolar dead space since the *_apices of the lungs are essentially non-perfused in the upright position_* due to the effects of gravity on blood flow distribution.

Answer 506

Positive pressure ventilation (PPV) **increases alveolar dead space** and can worsen ventilation to perfusion matching. A spontaneously breathing patient with healthy lungs has a dead space to alveolar ventilation ratio of 1:2 whereas the ratio will be 1:1 with PPV. Positive intrathoracic pressure can decrease cardiac output and therefore pulmonary perfusion due to decreased venous return to the right heart.

Answer 507

Large quantities of natural licorice will induce **hyperaldosterone-like effects** including: ## Footnote *_hypokalemia_* *_hypertension_* *_hypernatremia_* *_Fluid overload_* *_metabolic alkalosis_*

Answer 508

Mixing propofol with lidocaine has been shown to **decrease the stability of the propofol emulsion** and *_may cause pulmonary embolism_*. The FDA recommends against mixing propofol with any other therapeutic medications prior to administration. _When 40 mg of lidocaine was added, droplets of greater than 5 mcm were detected at 30 minutes. The theoretic human risk of embolism occurs at droplet sizes **greater than 5 mcm**_

Answer 509

The second gas effect occurs when nitrous oxide and a volatile anesthetic are used concurrently. **Uptake of nitrous oxide is significant because of the high concentration used (the concentration effect).** When a significant amount of nitrous oxide is removed from the alveoli into the blood the relative alveolar concentration of the volatile agent being used increases. *_This increase speeds up the anesthetic onset for the volatile agent, which is **the second gas effect.**_*

Answer 510

The **concentration effect** occurs when a high concentration of anesthetic can be used. Currently the only anesthetic in clinical use in which the concentration effect can be demonstrated is nitrous oxide. This effect explains why nitrous oxide has a more rapid onset than desflurane.

Answer 511

**Measure of lipophilicity**. The oil:gas coefficient is related to *_anesthetic potency and minimum alveolar concentration (MAC)._* The higher the oil:gas coefficient the lower the MAC. *_Isoflurane_* has an oil:gas coefficient of 99 and a MAC of about 1. Whereas *_desflurane_* has an oil:gas coefficient of 19 and a MAC of about 6.

Answer 512

Solubility of commonly used anesthetics is: **desflurane** \> **nitrous oxide** \> **sevoflurane** \> **isoflurane** from least soluble to most soluble. (Note des is greater than nitrous)

Answer 513

Medial Nerve

Answer 514

Unopposed parasympathetic stimulation following spinal anesthesia causes **increased gastrointestinal secretions.**

Answer 515

After **single lung transplantation**, the capnogram would be unique for each lung, if they were to be separated. The transplanted lung, assuming it is healthy, would produce an essentially normal pattern of exhalation (see Figure 1). The native lung, however, is still diseased and will show an obstructive appearance (slow, blunted upstroke, phase 2–3) and no plateau of exhalation (phase 3-4) is reached. Combined, this causes a “double peak” appearance, as in Figure 2. The first peak is from the normal (transplanted) lung, while the second peak of the tracing represents exhalation from the native, diseased lung.

Answer 516

**Replace the Exhausted CO2 absorbent** or **increase the flows** *_Capnogram of incompetent inspiratory valve_*. The expiratory alveolar plateau is extended due to inspiration of CO2-rich gas at the beginning of inspiration. The blue arrows above indicate where inspiration actually began in the patient. The inspiratory phase is shortened, has a blunted downstroke, and the CO2 nadir may or may not reach zero.

Answer 517

**Incompentent Expiratory Valve**

Answer 518

**Bleeding**

Answer 519

**Infection** *_resulting from improper storage_* is the most common risk associated with autologous blood transfusion.

Answer 520

1. Does not place the recipient at risk of ***_immune-mediated reactions_*** 2. ***_Reduce***_ the incidence of complications associated with allogeneic donor blood, such as _***hemolytic and non-hemolytic (febrile, urticarial, and post-transfusion purpura)_*** reactions resulting from donor proteins triggering an immune-mediated reaction in the recipient

Answer 521

**Physostigmine** is an anticholinesterase with a tertiary amine structure that can be used as a treatment for central anticholinergic syndrome. ## Footnote Reversal of toxic anticholinergic effects: Note: When administering by IV injection, administer **no more rapidly than 1 mg/minute to prevent bradycardia, respiratory distress, and seizures from too rapid administration**. Slower administration (ie, over no less than 5 minutes) may be preferable (Howland 2019). **IM, IV: Initial: 0.5 to 2 mg**; may repeat every 10 to 30 minutes until response occurs. Subsequent doses may be required to manage life-threatening anticholinergic effects (Krenzelok 2010).

Answer 522

This is typically done for **hemodynamically unstable patients, such as during massive hemorrhage or trauma.** Scopolamine IV may also be given preoperatively to *_reduce the risk of awareness_* in selected populations. Sedation, amnesia: IM, IV, SubQ: *_0.3 to 0.6 mg 3 to 4 times/day_*

Answer 523

The **Poiseuille Law** states that: **Q = ΔP(π \* radius4) / (8 \* viscosity \* length)** Where: Q = flow, Δ = change in, P = pressure, π = 3.14159… (the mathematical constant).

Answer 524

Nitroprusside is metabolized to cyanide ions and toxicity can occur following lengthy infusions. The three major mechanisms for nitroprusside toxicity are 1) Cyanide ions bind to cytochrome c oxidase and _inhibit cellular aerobic respiration._ 2) Formation of **cyanmethemoglobin** which is unable to carry oxygen. 3) **Thiocyanate** production which causes *_CNS-related effects._*

Answer 525

**The internal branch of the superior laryngeal nerve (SLN)** provides sensation to the entire larynx above the glottis. Laryngospasm can result from stimulation of this nerve.

Answer 526

**Nervous System** - Decreased gray/white matter - Decreased neurotransmitters (acetylcholine, dopamine) - Decreased epidural space - Decreased CSF volume - Increased permeability of dura mater

Answer 527

Cardiovascular System - **Decreased** ventricular compliance (dependent on atrial kick) - **Decreased** beta-receptor responsiveness (decreases maximal heart rate) - **Increased** sympathetic nervous system activity - **Increased** stiffness of large arteries (Hypertension common) *_-_* ***Increased** afterload* ***Decreased** diastolic dysfunction* *LVEDP **increases** (due to decreased diastolic dysfunction)*

Answer 528

* *Respiratory System** - **Decreased** vital capacity - **Increased** residual volume - **Increased** closing capacity - **Increased** anatomic dead space - **Increased** lung compliance - **Increased** pulmonary vascular resistance

Answer 529

**Decreases**

Answer 530

**AC power source** Interference from an alternating current (AC) source produces a thick ECG tracing which alternates up-and-down 60 times a second (60 hertz) in the United States, see above. Interference can occur if an **AC power cord is lying across the ECG cable or the ECG monitor.** It can also occur if the ECG cable or monitor is too close to an AC source.

Answer 531

A right-to-left intracardiac shunt **slows the rate of inhalational induction** of anesthesia since the shunted blood is not involved in gas exchange within the alveoli. Conversely, a right-to-left shunt **speeds the rate of intravenous induction** because a portion of the drug bypasses the lungs, directly enters the left side of the heart and is quickly delivered to brain tissue. Note, if you feel these sentences contradict each other please re-read carefully.

Answer 532

**Decreased CO = Faster induction** allows for increased partial pressures of anesthetic gases within the alveoli, resulting in a faster rate of induction. The alveolar partial pressures of the anesthetic remain elevated since less blood can interface with the same number of alveoli filled with a volatile agent. The slow diffusion of a volatile agent into the blood results in faster delivery of the agent to brain tissue. This is because a greater volume of blood is saturated with volatile agent per liter of cardiac output delivered per unit of time. **Higher CO = Slower induction** more blood is involved in gas exchange resulting in increased uptake of anesthetic gas and a larger dilutional effect. This decreases the partial pressure of gas within the alveoli, reduces delivery to the brain, and slows the rate of induction.

Answer 533

The effect of cardiac output on the rate of induction is particularly accentuated in agents that have a higher blood:gas partition coefficient. This partition coefficient is a distribution ratio describing how the volatile anesthetic distributes itself between liquid (blood) phase and the gaseous phase (in the alveoli) when the partial pressures are identical in both phases. If the **blood:gas partition coefficient is \> 1**, then more drug is dissolved in the blood (higher solubility, such as isoflurane or halothane). If the **blood:gas partition coefficient is \< 1**, more drug exists in the gaseous state and not dissolved in blood (lower solubility, such as desflurane or nitrous oxide). These relationships hold as long as the partial pressures are equal in both phases. *_Blood:gas partition coefficients of key anesthetic gases_* Desflurane 0.42 Nitrous Oxide 0.46 Sevoflurane 0.69 Isoflurane 1.46 Halothane 2.54 The rate of a **rise of FA:FI as a function of cardiac output**. A decrease in cardiac output (e.g. from 10 L/min to 2.5 L/min) will increase the alveolar partial pressures of the volatile agent by slowing uptake and speeding the rise of FA:FI ratio. This effect is less pronounced in the insoluble volatile anesthetics (e.g. desflurane) and more pronounced in the soluble ones (e.g. isoflurane). The effect of changing cardiac output is less pronounced for the more insoluble anesthetics.

Answer 534

New generation carbon dioxide absorbents **do not contain strong bases** and as a result, are much less likely to react with volatile anesthetics and generate carbon monoxide.

Answer 535

Fresh frozen plasma should be **avoided in the following situations:** 1. Use to correct mildly elevated INR (\< 1.8) without signs of bleeding 2. Use to correct a vitamin K deficiency that could be corrected with vitamin K 3. Use as a primary volume expander (absolute contraindication) 4. Use to correct a factor deficiency when recombinant factor replacement is available

Answer 536

Low dosing: **0.5 to 3 mcg/kg/min** At lower concentrations, dopamine primarily acts on the **D-1 dopamine** receptors to *_produce vasodilation of the renal, mesenteric, and coronary vasculature._* The main result is an increase in the glomerular filtration rate and renal blood flow (RBF) Furthermore, low dose dopamine will result in **sodium excretion which will increase urine output.**

Answer 537

Moderate dosing: **3 to 10 mcg/kg/min** **Beta-1** Receptors 1. Contractility increases (Ionotropy) 2. Minimal change in HR anad SVR 3. Increase in splanchnic and renal blood flow

Answer 538

**High dosing: \>10 mcg/kg/min** Higher doses will stimulate the **Alpha 1 and beta-1 receptors** to increase release of norepinephrine from sympathetic nerve terminals. The end result is an increase in **heart rate, systolic blood pressure, and pulse pressure.** Diastolic blood pressure is minimally affected however pulmonary vascular resistance may increase. At the highest doses, dopamine administration will stimulate **alpha-1 receptors** which results in peripheral vasoconstriction.

Answer 539

Cyclopentolate is an **anticholinergic** drug often used during **ocular surgery** to *_induce mydriasis_* that can lead to CNS toxicity, including **convulsions**, if absorbed systemically.

Answer 540

The area postrema of the brainstem, also known as the chemoreceptor trigger zone, contains **dopamine**, **serotonin**, **acetylcholine**, **histamine**, and **neurokinin type 1** receptors. *_Dopamine_* - Haloperidol *_Serotonin_* - Zofran *_Acetylcholine_* - Diphenhydramine, Scopalamine, other Anti-cholinergics *_Histamine_* - Diphenhydramine *_Neurokinin 1_* - Aprepitant Antagonism of these receptors can help treat and prevent nausea. However, any medication leading to central antagonism of dopamine receptors can potentially cause EPS.

Answer 541

Although routinely used to decrease risk for aspiration, recent evidence suggests cricoid pressure may actually increase the risk for reflux in anesthetized patients. *_Cricoid pressure decreases LES tone without influencing gastric pressure._* This leads to a **decreased barrier pressure and therefore potentially increases the risk of aspiration.** The clinical significance of this, however, has not been determined. Opponents of cricoid pressure **affirm that succinylcholine increases LES tone**, making the need for cricoid pressure during rapid sequence induction (RSI) questionable. Cricoid pressure continues, however, to be the standard of care during RSI.

Answer 542

The duration of action of **midazolam (half-life 1.7-2.6 hours)** exceeds that of **flumazenil (half-life 0.7-1.3 hours).** This makes recrudescence of benzodiazepine-induced somnolence after metabolism of flumazenil likely in this context. ## Footnote ***_Approximately half_***

Answer 543

Efficacy is the maximum effect of a drug. It does not depend on dose. **Potency** is the *_relative dose required to achieve a given effect and is related to receptor affinity and **is dose dependent**_*

Answer 544

The *_potency_* of a partial agonist **may** be **higher** than that of a full agonist. The *_efficacy_* of a partial agonist **cannot** be **higher** than that of a full agonist.

Answer 545

Antacids such as 0.3 M sodium bicitra can be given **15-30 minutes** prior to induction to **increase gastric pH**, however, they will **increase gastric volume** which is not of particular concern as the real damage to the lungs with aspiration will be caused by the acidity of the fluid, not necessarily the volume.

Answer 546

**decrease the secretion of gastric acid**, resulting in a **reduction in gastric volume and an increase in gastric pH**. They can be used for aspiration prophylaxis in at-risk patients. H2 blockers must be given approximately **30 minutes** prior to induction of anesthesia to have effectiveness and they last for approximately **9-12 hours** (except cimetidine which only lasts 3-4 hours and has multiple side effects such as P450 inhibition, hypotension, arrhythmias and CNS depression). They have no effect on gastric fluid already present and do not speed clearance of gastric fluid already present.

Answer 547

**Metoclopramide** is a gastrokinetic drug that relaxes the pylorus and duodenum and increases upper GI motility to **increase clearance of gastric fluid, however, it does not alter gastric fluid pH**. Metoclopramide also *_increases lower esophageal sphincter tone_* because of cholinomimetic actions and can have extrapyramidal side effects as it is a D2 receptor blocker.

Answer 548

Since plasma cannot be washed of IgA, it must come from a **deficient donor.**

Answer 549

The **complement system is activated** in a hemolytic transfusion reaction that typically occurs when ABO incompatible blood is given. A hemolytic transfusion reaction will result in the **destruction of donor red blood** cells and the **release of hemoglobin in the blood.** Free circulating hemoglobin can precipitate in the *_kidneys_* resulting in kidney failure. The antibody mediated immune response results in the release of ***_bradykinin, serotonin, and histamine leading to flushing, bronchospasm, and hypotension._*** In addition, 30-50% may develop disseminated intravascular coagulation (DIC). If the patient is under general anesthesia, initial signs include hypotension and hemoglobinuria.

Answer 550

Nonhemolytic Caused by cytokines and the release of intracellular contents in leukocytes. In addition to fever, patients may have chills, myalgias, headache, and non-productive cough. The use of **leukoreduced blood** minimizes this reaction.

Answer 551

Graft versus host disease may occur in immunocompromised patients when viable **donor lymphocytes** become engrafted, proliferate, and establish an immune response **against the recipient**. Other patients at risk are individuals receiving blood from a close relative. *_The host does not recognize the lymphocytes as foreign while the donor cells recognize the host as foreign_*. **Measure =** Blood given to immunocompromised patients and blood from first degree relatives should be **irradiated** to inactivate donor lymphocytes.

Answer 552

Intubating doses of neuromuscular blocking drugs are **increased** in cirrhosis **because of the increase in volume of distribution**. *_Maintenance doses of hepatically metabolized and/or cleared drugs should be reduced_* and neuromuscular function carefully monitored as duration of action is prolonged. **\*\*Paradox\*\*** Neuromuscular blocking agents are highly water-soluble due to quaternary amine structures and thus an increase in body water, such as with cirrhosis, CHF, or renal failure, results in decreased plasma concentration of neuromuscular blockers *_requiring an increase in intubating dose._* It is important to remember, however, that *_clearance of drugs dependent on hepatic metabolism is reduced_* and therefore they will have a prolonged duration of action. Rocuronium, vecuronium, and pancuronium will all have increased duration of action secondary to impaired hepatic metabolism **(caveat: rocuronium is not metabolized but is cleared by the liver in the bile)** and therefore maintenance dosing should be reduced and neuromuscular monitoring carefully followed.

Answer 553

A breakdown product, **laudanosine**, is cleared by the liver but levels produced are insignificant clinically. ## Footnote **Laudanosine decreases the seizure threshold**, and thus it can induce seizures if present at sufficient threshold concentrations; however *_such concentrations are unlikely to be produced consequent to chemodegradable metabolism of clinically administered doses of cisatracurium or atracurium._*. Laudanosine is a **benzyltetrahydroisoquinoline** alkaloid

Answer 554

**apnea time** is increased from 3 minutes to **9 minutes.**

Answer 555

1) Anesthetic potency = **lipid solubility** - *_Higher solubility enhances diffusion_* through nerve sheaths/membranes. - *_Less lipid solubility_* results in less potent agents (Less diffusion) (ex: procaine is the least lipid-soluble and least potent LA, bupivacaine is highly lipid soluble and the most potent.

Answer 556

2) Time to onset/Onset of action = **pKa** = **dissociation constant**: determines the pH at which a drug’s ionized (charged) and unionized (uncharged) forms are in equal concentrations. This determines the amount of drug in the unionized form. This is why many local anesthetics do not work in acidic areas such as abscesses. pKa Lidocaine = 7.9 pKa Bupivicaine = 8.1 pKa Chloroprocaine = 9 (Paradox due to volume)

Answer 557

Duration of action = **protein binding.** 1. Agents that are **highly protein bound** will remain bound for longer, **increasing the duration of action**. 2. Duration of action is also influenced by **peripheral vascular effects** (such as use of vasoconstrictors) * Why we add epinephrine to our local anesthetics*

Answer 558

**ICEBALLS** Location of injection = some areas of the body will have more local anesthetic absorbed. Mnemonic: BICEPSS - **I**ntravenous (Blood) \> **I**ntercostal \> **C**audal \> **E**pidural \> **b**rachial Plexus \> **A**xillary \> (**l**ower **l**umbar) Sciatic \> **S**ubcutaneous

Answer 559

Procaine **7 mg/kg** **15-60** minutes

Answer 560

Chloroprocaine ``` Max = **11 - 14 mg/kg** (Without vs. with epinephrine) Duration = **15-30 minutes** ```

Answer 561

* *30-60** without epi * *120-360** with epi

Answer 562

mepivacaine **Max** = 7 mg/kg **Duration:** 1. 45-90 without epi 2. 120-360 with epi

Answer 563

**Bupivacaine** *_Max dose_* 2. 5 (not to exceed 175mg or 70cc) 2. 5 (not to exceed 225mg or 90cc) *_Duration_* 120-140 without epi 180-240 with epi

Answer 564

**Factors affecting the height of an intrathecal block include:** 1. Patient position 2. Baricity of anesthetic 3. Dose of local anesthetic

Answer 565

Bradycardia following spinal anesthetic injection is more common in patients with: ## Footnote **1. High baseline vagal tone** **2. Anesthetic levels above T5** **3. Associated with decreased cardiac preload (i.e. reverse Bainbridge reflex).**

Answer 566

1. **Sympathectomy of cardioaccelatory fibers** (T1 - T4) 2. **Drop in preload** **and SVR** (decreased stretch on myocardium which will result in "reversed bainbridge reflex") 3. **High Baseline vagal tone** (Young atheletes, vasovagal syndromes or autonomic nerve pathology) 4. **Decreased mechanoreceptor stretch** can induce the Bezold-Jarisch reflex with increased parasympathetic output, contributing to bradycardia. Normally, the carotid sinus baroreceptor response to hypotension (increased heart rate and contractility) dominates, but in the setting of an acute drop in ventricular preload (e.g. spinal anesthetic or nitrate use), the **Bezold-Jarisch reflex** may occur before the carotid sinus reflex.

Answer 567

Thromboelastography (TEG) is both a quantitative and graphic evaluation of clotting function. Typical management is: **R value** **K value** **Alpha Angle** **MA value**

Answer 568

**MA value decreased -\> platelets.**

Answer 569

## Footnote **Cryoprecipitate**

Answer 570

## Footnote **FFP**

Answer 571

**Anti-fibrinolytics (TXA)**

Answer 572

**Reaction time** (R) is from **time zero to initial clot formation**, defined as a width (amplitude) of **2 mm**. Normal range is **1-3 minutes.**

Answer 573

**Coagulation time** (K) measures **speed of clot formation and strengthening**. It is equal to the time from amplitude of **2 mm to 20 mm** and relies on fibrinogen. ## Footnote **Treatment = Cryoprecipitate**

Answer 574

Maximum amplitude (MA), measures the **strength of the fully formed clot.** It is the maximal width of the TEG. This *_reflects clot strength as determined by platelet number and function (primarily) as well as fibrin cross linking_*. Normal is **50-60 mm.**

Answer 575

Alpha-angle is the **speed of clot formation**, and is represented by the angle between baseline and a line tangential to the TEG at **2 mm amplitude.** Like the K value, this *_relies on **_fi_**brinogen_*. Normal alpha angle is **45-55 degrees.**

Answer 576

Echothiophate is an **anticholinesterase** used to treat refractory glaucoma by causing miosis. Systemic absorption can cause up to a 95% *_decrease in plasma butyrylcholinesterase (pseudocholinesterase) function_*. Patients using echothiophate eye drops have demonstrated prolonged neuromuscular block after succinylcholine administration. It may take up to 4-6 weeks after discontinuation of the drug for normal butyrylcholinesterase activity to return.

Answer 577

Renin secretion can be caused by **3 different mechanisms**: 1. *_Decrease in serum NaCl concentration_* sensed by the kidneys 2. *_Decrease in blood pressure_* sensed by kidney baroreceptors 3. *_Activation of renal B1_* receptors by norepinephrine.

Answer 578

**Increase in blood pressure** caused by an increase in systemic vascular resistance Activates the angiotensin1 (AT1) receptors on vascular smooth muscle cells, causing **constriction of the arterioles** **Augments the sympathetic nervous** system by inhibiting norepinephrine reuptake into nerve terminals. It also stimulates the release of catecholamines from the adrenal medulla. **Centrally mediated increased thirst** and enhances the release of vasopressin. These effects are almost immediate, but are not long-lasting. Stimulates **remodeling of the cardiovascular system**, causing hypertrophy of cardiac cells and increased collagen deposition **Decrease in the urinary excretion** of both sodium and water. **Stimulates the adrenal cortex** to synthesize and **release aldosterone**. Aldosterone also acts on the kidneys to decrease the urinary excretion of sodium and water. This ultimately leads to an increase in blood volume and therefore blood pressure.

Answer 579

**Pros** Use of opioids as adjuncts for neuraxial anesthesia and analgesia can **significantly enhance block quality, density, and duration of analgesia**. **Cons** However, this comes at the price of an increased risk of side effects **including sedation, respiratory depression, pruritus, and nausea/vomiting**, compared to local anesthetics alone.

Answer 580

The ASA recommends a longer period of monitoring for respiratory depression following a single neuraxial dose of morphine compared to fentanyl. For **lipophilic opioids**: continual monitoring for at **least 20 minutes** following administration and **then at least hourly monitoring for the *_next two hours._*** For hydrophilic opioids: **at least hourly monitoring for the first 12 hours** and then monitoring at least **every two hours for the next 12 hours.**

Answer 581

A mnemonic to help recall light absorption by wavelength is **S**e**X**y **DAR**Ling: at SiX hundred wavelength, Deoxyhemoglobin Absorbs Red Light.

Answer 582

Red light at 660 nm and infrared light at 940 nm (some manufacturers use 905, 910, or 920 nm) is pulsed through the tissue. A ratio of the absorbance of red to infrared light is calculated and that calculated number is translated to the oxygen saturation reading. At **red** wavelengths, **deoxyhemoglobin** absorbs more light than oxyhemoglobin At **infrared** wavelengths, **oxyhemoglobin** absorbs more.

Answer 583

The difference in blood pressure at 2 different sites equals the height difference in cm multiplied times the *_conversion factor 0.74._* Ex: height difference of 22 cm, equaling 16 A mnemonic to help remember which comes first (pressure or height) is "pH" or "**pH 15 20**", where a pressure of 15 mmHg correlates to a height of 20 cm.

Answer 584

**Several risks for MMR have been proposed and include:** 1. Inadequate dose of succinylcholine 2. Inadequate time for onset 3. Side effect of other induction medications (etomidate, high dose synthetic opioids) 4. Temporomandibular joint dysfunction 5. Duchenne muscular dystrophy 6. Myotonia congenita, and possibly other muscle disorders.

Answer 585

Fresh gas flow (FGF) must be greater than or equal to ***_1-2 times minute ventilation_*** in the Mapleson D semi-open breathing system to prevent rebreathing during controlled ventilation. The FGF during spontaneous ventilation must be equal to ***_2-3 times minute ventilation_*** in the Mapleson D, E, and F circuits.

Answer 586

The advantages of a Bain circuit (coaxial version of a Mapleson D system) include: (1) **conservation of moisture** due to partial rebreathing (2) **warming of fresh gas** inflow by surrounding expiratory gas (3) **scavenging waste is easier from the APL valve** (4) advantageous when access to the patient is limited.

Answer 587

Most drugs occurs via two processes, phase I and phase II metabolism. **Phase I** includes **oxidative** and **reductive** reactions including hydrolytic reactions and those catalyzed by the *_hepatic cytochrome P450 enzymes_* **Phase II** reactions involve **conjugation** of the drug or its metabolite(s) with a substrate such as *_glucuronic acid._* Once a drug is metabolized, it is much more efficiently eliminated from the body.

Answer 588

The patient’s circulatory function must be continually monitored via three mechanisms. 1. First, **continuous ECG** must be used from the beginning of anesthesia until preparing to leave the anesthetizing location. 2. Second, arterial blood pressure and heart rate must be determined and evaluated at least **every five minutes**. 3. Finally, pulse monitoring must be continually evaluated such as via **pulse palpation, heart sound auscultation, intraarterial pressure monitoring, and/or pulse plethysmography or oximetry.**

Answer 589

In all anesthetics in which “clinically significant changes in body temperature are **intended**, **anticipated**, or **suspected**” temperature must be monitored.

Answer 590

Intracellular volume (ICV) - The **ICV contains two-thirds of TBW** and represents 40% of total body weight. Extracellular volume (ECV). The **ECV contains one-third of TBW** and represents 20% of total body weight. Subdivided into plasma volume and interstitial fluid volume. ***_Plasma volume comprises 20-25% of the ECV_*** and represents 4% of total body weight. ***_Interstitial fluid volume comprises 75-80% of the ECV_*** and represents 16% of total body weight.

Answer 591

Bradycardia may occur in patients treated with sugammadex. The incidence is approximately **1% with 2 mg/kg and 4 mg/kg doses**, and *_5% with 16 mg/kg doses._*

Answer 592

Intrapulmonary shunt **reduces the speed** of inhalational induction.

Answer 593

When **perfusion** is affected (reduced cardiac output, pulmonary embolism), the **speed of induction of inhalational agents is increased**. The impact is more significant with soluble agents such as isoflurane. The rise of FA/FI is steeper with lower perfusion of the lungs. When **ventilation** is affected (intrapulmonary shunt), the **speed of induction of inhalational agents is decreased**. This occurs to a greater degree with insoluble agents (desflurane, sevoflurane). The rise of FA/FI is less steep.

Answer 594

* *The list of patients who should receive prophylaxis is below:** - Patients with a *_prosthetic cardiac valve_* - Patients who have *_history of infective endocarditis_* - Patients with *_unrepaired cyanotic congenital heart disease_* (including palliative shunts/conduits) - Patients with congenital heart defects which were *_repaired with prosthetic material within 6 months of the procedure_* - Patients with *_repaired congenital heart disease with residual defects_* at the site, or adjacent to the site, of a prosthetic patch or device - *_Cardiac transplantation recipients who develop cardiac valvulopathy_* (substantial leaflet pathology and regurgitation) * *Of note, prophylaxis only applies to certain surgical procedures:** - *_Dental*_ procedures that involve _*manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa_* - *_Invasive respiratory tract*_ procedures that involve _*incision or biopsy of the respiratory mucosa_* (e.g. tonsillectomy, adenoidectomy) - *_Infected skin, skin structure, or musculoskeletal tissue_*

Answer 595

The preferred prophylactic regimen is **Amoxicillin 2 g** given as a **one time oral dose 30-60 min** before the procedure.

Answer 596

This **negative force** can be upwards of **-50 to -100 cm H2O of pressure**. The negative pressure causes a significant **increase in preload, thereby increasing pulmonary blood volume.** There is also a significant **increase in left ventricular afterload**, which causes a *_decreased cardiac output_*. The increase in pulmonary blood volume along with a decrease in cardiac output will **increase the pulmonary transudative pressures**. With all this occurring, pulmonary vascular resistance increases causing a *_shift of the intraventricular septum_*. The ventricular septal shift to the left causes a left ventricular diastolic dysfunction, which **further increases pulmonary hydrostatic pressures.**

Answer 597

Active cardiac conditions mandate further preoperative evaluation and treatment. * *Active Cardiac Conditions:** 1) *_Unstable coronary syndromes_* (UA, MI) 2) *_Decompensated heart failure_* ``` (NYHA class III or IV, severe angina) 3) *_Significant arrhythmias_* ``` (high-grade AV block, Mobitz type II AV block, third-degree AV block, symptomatic ventricular arrhythmias, supraventricular arrhythmias (including atrial fibrillation) with uncontrolled ventricular rate \> 100 bpm at rest, symptomatic bradycardia, and newly recognized ventricular tachycardia) 4) *_Severe valvular disease_* Severe aortic stenosis (mean pressure gradient \> 40 mmHg, aortic valve \< 1.0 cm^2, or symptomatic) and symptomatic mitral stenosis (progressive dyspnea on exertion, exertional presyncope, or heart failure).

Answer 598

* *Revised Cardiac Risk Index Variables:** 1) History of ischemic heart disease 2) History of congestive heart failure 3) History of cerebrovascular disease 4) Insulin therapy for diabetes 5) Preoperative serum creatinine \> 2.0 mg/dL 6) High-risk type of surgery

Answer 599

Criteria: **1) Acute lung injury (ALI)** - Acute onset - Hypoxemia (PaO2:FiO2 ≤ 300 mm Hg or SpO2 \< 90% on room air, or other clinical evidence of hypoxemia - Bilateral infiltrates on frontal chest radiograph - No evidence of left atrial hypertension as the sole explanation for the clinical findings **2) No pre-existing ALI before transfusion** **3) Onset during or within 6 hours of transfusion** **4) No temporal relationship to an alternative risk factor for ALI**

Answer 600

New onset or exacerbation of **three or more of the following within 6 hours of transfusion:** - Acute respiratory distress (dyspnea, cough, orthopnea) **Symptoms** - Increased brain natriuretic peptide (BNP) **Labs** - Increased central venous pressure (CVP) **Hemodynamics** - Evidence of left heart failure **Clinical diganosis / Echo** - Evidence of positive fluid balance **I/O balance** - Radiographic evidence of pulmonary edema **Imaging**

Answer 601

Y axis = **% Hemoglobin Saturated (SaO2)** X axis = **PaO2**

Answer 602

Excluding patients less than one year of age, the MAC of each of the potent anesthetic gases declines with age. There is a linear model that describes the change in MAC of approximately **6% per decade**, a 22% decrease in MAC from age 40 to age 80, and a 27% decrease in MAC from age 1 to age 40 years.

Answer 603

MAC *_rises at one month of age_*, **peaks at approximately 6 months** of age, and **regresses back to normal at 1 year of age.** **Sevoflurane** demonstrates a much higher increase in MAC compared to the slight increase with desflurane and isoflurane. The MAC of sevoflurane is often up to 2.5-3% higher in patients 1 month to 1-year-old.

Answer 604

**Increases** MAC Requirements

Answer 605

Tetanus acts by **preventing neurotransmitter release (glycine and GABA) from inhibitory neurons in the spinal cord**. The lack of inhibition causes increased muscle contractions to the point of tetanus.

Answer 606

Botulism toxin has a similar mechanism of preventing neurotransmitter release (acetylcholine), but botulism affects the **alpha motor neuron causing flaccid paralysis.**

Answer 607

The classic “carcinoid triad” consists of **flushing**, **diarrhea**, and **right-sided cardiac involvement.** It is caused by *_tumor release of vasoactive amines*_ (e.g. serotonin, norepinephrine, histamine, and dopamine), _*polypeptides*_ (e.g. bradykinin, somatostatin, vasoactive intestinal peptide, and glucagon), and _*prostaglandins_*. The cardiac involvement is generally limited to only the right side of the heart since, as discussed above, most of the vasoactive hormones are metabolized while in the pulmonary circulation before returning to the left side of the heart.

Answer 608

*_KEY = Acute vs. Chronic CCB usage_* Calcium channel blockers can **augment depolarizing and nondepolarizing muscle relaxants,** particularly when the two drugs are administered concurrently to **CCB-naïve patients (Calcium channel blockers given acutely)** Consider the careful titration of NBDs in this setting. In patients taking **chronic CCBs**, the augmentation effect is **clinically insignificant.**

Answer 609

Cytochrome p450 is involved in **phase I** metabolism by **oxidizing** many drugs.

Answer 610

The MABL of a patient = [**EBV** \* (starting Hct - target Hct)] / (starting Hct). ***_Age Group. EBV (mL/kg)_*** Premature infant 90-105 Full term newborn 80-90 Infant (3 months - 1 year) 70-80 Child 1-12 years 70-75 Adult Female 60-65 Adult Male 65-70

Answer 611

**Methylparaben** is the methyl ester of para-hydroxybenzoic acid, which is structurally similar to para-aminobenzoic acid (PABA), differing only in having a hydroxyl group vs amino group in the para position. Thus, cross-sensitivity between these compounds can occur.

Answer 612

**Sulfites** such as **sodium metabisulfite** are added as antioxidants for the catecholamine content. Lidocaine vials with **epinephrine** will typically contain **metabisulfite**, which may also elicit allergic responses.

Answer 613

pH: **increases** 0.017 per °C **decrease** PaCO2: *_decreases*_ 2 mm Hg per °C _*decrease_* PaO2: *_decreases*_ 5 mm Hg per °C _*decrease_* Blood pH and the solubilities of gases in blood are inversely related to temperature while the partial pressures of gases are directly related to temperature.

Answer 614

**Class**: Antihistamine (H1 antagonist used as an antiemetic) **Dosing**: Nausea and vomiting: IV, rectal: 12.5 to 25 mg every 4 to 6 hours, as needed **Administration**: Through non-patient IV can cause tissue necrosis IV use should be avoided when possible since severe tissue damage has occurred with IV administration; in selected patients, *_promethazine has been diluted and infused at a maximum rate of 25 mg/minute_*. To minimize phlebitis, consider administering over 10 to 15 minutes, limiting initial dose to 1/4 or 1/2 the usual dose (eg, in adults 6.25 to 12.5 mg), further diluting the 25 mg/mL strength in 10 to 20 mL NS, and administering through a large bore vein (not hand or wrist) (Reynolds 2014) or via a running IV line at port farthest from patient's vein

Answer 615

A mnemonic to help is "pH 15 20" to remember the pressure of **15 mm Hg is equal to a change in height of 20 cm.**

Answer 616

**Nerve conduction studies** are beneficial in evaluating both motor and sensory deficits. Evaluate between existing subclinical polyneuropathy and some distinction of axon loss and demyelination **Electromyography** can help determine the timing of the nerve injury.

Answer 617

1. Male 2. Thin or Obese (BMI \> 38) 3. Prolonged bed rest 4. Genetic predispositon (Bilateral neuropathy found) *_Presents 48 hours after surgery_*

Answer 618

**Sensory** = Resolve in 5 days (self limiting) **Motor** = Neurology consult Always seek neurologic consultation. Sensory injuries usually resolve, **whereas motor injuries are more severe and mandate EMG** (can help determine if it was present preoperatively, as denervation signs take ~ 3 weeks to develop). Reversible motor nerve injuries usually take 3-12 months to recover and require physical therapy to prevent atrophy and contractures in the interim

Answer 619

Local anesthetics with a pKa closer to a physiologic pH will have more drug in the nonionized form, and therefore more drug available for use. ## Footnote **pH \< pKa = ionized.** **pH = pKa, 50% of the molecules will be ionized and 50% will be unionized.** **pH \> pKa = Non-ionized**

Answer 620

*_Cerebral blood flow is:_* Inversely related to **PaO2** when less than 50 mm Hg while remaining *_unchanged_* with PaO2 \> 50 mmHg Directly related to body **temperature** **PaCO2** (within normal physiologic ranges) Extremes of **MAPs** (\< 50 or \>150 mm Hg) and remains *_unchanged_* within the autoregulatory range of MAPs (50-150 mm Hg) ICP

Answer 621

Differential blockade with local anesthetics results in **sympathetic** blockade first, followed by **pain/sensory blockade**, then **motor** blockade last

Answer 622

This is (at least in part) explained by differential susceptibility of nerve fibers to local anesthetics being: **A-delta, A-gamma** \> **lA-alpha, A-beta** \> C.

Answer 623

**Compliance** = Change in Volume / Change in Pressure **Elastance** = Change in Pressure / Change in Volume

Answer 624

Remember, **Compliance** is [*_Change in Volume_*] / [*_Change in Pressure_*] calculate static respiratory system compliance: **CS = [Tidal Volume] ÷ (Plateau Pressure – PEEP)** **Dynamic** = Just replace the plateau pressure with peak pressure during inspiration

Answer 625

The gauge pressure will continue to read **745 psig (“full”)** until approximately **16%** or **253 liters** of the nitrous oxide remains.

Answer 626

A full E-cylinder of nitrous oxide is approximately **8.80 kg;** an empty cylinder is approximately **5.90 kg**. At room temperature, one gram of nitrous oxide is equivalent to 0.55 liters of gas at 20 °C. Thus, to calculate the volume of nitrous oxide in an E-cylinder based on weight, the following formula may be used: Volume remaining (L) = (cylinder weight (g) – 5900 g) x 0.55 L/g **Volume = ( 6.5 -** **5.9 ) x 0.55 = 0.33 liters**

Answer 627

Volume remaining (L) = (gauge pressure (psig) / 745 psig) x 253 L **Volume = (400/745) x 253 liters** = *_135 Liters_*

Answer 628

1. **Acute onset (within 72 hours)** 2. **Bilateral pulmonary infiltrates on chest radiograph** 3. **Noncardiogenic pulmonary edema** 4. **PaO2/FiO2 ratio of \< 300** (The Berlin definition stratifies ARDS into mild, moderate, and severe based on the PaO2/FiO2 ratio of 200-300, 100-200, and \< 100 respectively).

Answer 629

application of **PEEP**, conversion to extracorporeal membrane oxygenation (**ECMO**), use of i**nhaled nitric oxide**, or **inverse ratio ventilation.** *_Oxygen therapy is of limited value*_ with _*large intrapulmonary shunts_* due to limitation of gas exchange and requires alternative therapies to improve V/Q matching.

Answer 630

V/Q Dead space = Ventilation but no blood flow Shunt = No ventilation but blood flow

Answer 631

Nonanion gap metabolic acidosis (where the anion gap is normal at 8-12 mEq/L) is typically caused by ## Footnote **1. Chloride-containing acid administration** **2. Increased HCO3- loss or loss of HCO3- precursors** **3. Decreased renal acid excretion**

Answer 632

**Total parenteral nutrition** often contains ammonium chloride and metabolism of the amino acids it contains can create HCl. Together, hyperalimentation can lead to excess Cl- and therefore a nonanion gap acidosis.

Answer 633

Increased HCO3- loss is usually via the **gastrointestinal (GI) tract** or the kidneys. Causes of increased *_GI losses include diarrhea, GI fistulas (e.g. pancreatic, biliary, bowel), high ostomy output, or use of bile or phosphorus binding drugs._* **Renal losses** can be caused by use of *_carbonic anhydrase inhibitors (e.g. acetazolamide) or type 2 (proximal) renal tubular acidosis (RTA)._*

Answer 634

Decreased acid excretion is due to: 1. **Hypoaldosteronism** 2. Renal causes including **acute and/or chronic renal failure or type 1 (distal) RTA.**

Answer 635

**ACCRUED**: Acid infusion, Compensation for respiratory alkalosis, Carbonic anhydrase inhibitors, Renal tubular acidosis, Ureteral diversion, Extra alimentation, Diarrhea. **FUSEDCARS**: Fistula, Ureteroenterostomy, Saline administration, Endocrine (hyperparathyroidism), Diarrhea, Carbonic anhydrase inhibitors, Ammonium chloride, Renal tubular acidosis, Spironolactone.

Answer 636

In patients with a high anion gap metabolic acidosis, **HCO3- concentrations decrease as it is consumed buffering a large amount of pathologic anions**. This leads to a high anion gap.

Answer 637

Glucagon also helps raise blood sugar by three indirect effects. **First**, it *_stimulates lipolysis_* which produces two substrates for gluconeogenesis: glycerol and free fatty acids. **Second**, it i*_nhibits hepatic glycolysis_*. Since glycolysis consumes glucose to create ATP, stopping this process allows glycolytic intermediates to be shunted into the gluconeogenesis pathway. **Third**, glucagon *_inhibits hepatic glycogen synthesis_* so that available glucose is released into the bloodstream and not stored within the liver.

Answer 638

**Depolarizing** = Avoid Succinylcholine because patients have *_denervation or misuse myopathy leading to a higher risk for hyperkalemia_* **Nondepolarizing** agents (Roc, Cis, Vec) can be variable, with a resistance being seen in patients with up-regulation of acetylcholine receptors or a sensitivity in patients with muscle weakness and decreased muscle mass.

Answer 639

**Key** = think of the disorders as conditions that either up-regulate or down-regulate the number of acetylcholine receptors and then infer what use of a specific type of muscle relaxant will do based on the pathophysiology. **Up-regulation of acetylcholine receptors** include multiple sclerosis, burns, stroke, spinal cord injury, Guillain-Barre syndrome, prolonged immobility, and muscular dystrophies. - Succ = Contra - Have to use NMBD **Down-regulation of acetylcholine receptors** is myasthenia gravis. - Less susceptible to SCh, more susceptible to non-depolarizing NMBDs

Answer 640

Burns (24 hours until 1-2 years after) In patients who have suffered a burn injury, the *_Ach receptors typically start to increase after 48-72 hours._* In general, succinylcholine **should be avoided after 24-48 hours** as fatal hyperkalemia may ensue.

Answer 641

Risk of reaction increases significantly **after 16 days**

Answer 642

If using NDMR **give small doses** and monitor neuromuscular function: *_twitch monitor may not be accurate depending on site_* (orbicularis occuli underestimates muscle paralysis)

Answer 643

**Anesthetic Implications:** Sensitive to Succinylcholine Sensitive to Non-Depolarizing Neuromuscular Blockers Poor response to anti-cholinesterases = Neostigmine is ineffective for reversal of NDMR

Answer 644

*_Downregulation of ACh Receptors_* 1. Prolonged response to depolarizing paralytic (Succinylcholine) **Succinylcholine should be avoided** as it is degraded by plasma cholinesterase - may result in prolonged paralysis: **neostigmine should be avoided** since it will worsen the primary problem

Answer 645

The management steps for loss of pipeline pressure are the same as those for pipeline crossover: 1) **Open the emergency oxygen cylinder fully** (not just the three or four quick turns used for checking). 2) **Disconnect the pipeline connection** at the wall because something is wrong with the oxygen pipeline. 3) **Ventilate by hand with the anesthesia breathing circuit,** rather than with the mechanical ventilator (which may use cylinder oxygen for the driving gas if the pipeline is unavailable).

Answer 646

*_Decreased 2, 3-DPG concentration shifts the dissociation curve to the left_* and decreases oxygen unloading to the tissues. 2, 3-DPG may decrease significantly during hypoxemia. **It also decreases in the blood cell products during storage.** Red cell 2, 3-DPG in stored blood diminishes in storage and is effectively zero after 1-2 weeks (rate of decline depends on types of preservative used). **After transfusion, red cell 2, 3-DPG returns to 50% after 7 hours** and to normal level after 48 hours.

Answer 647

**Dosage Adjustments of Insulin Peri-operatively** Pre-operatively, patients on *_rapid or short-acting insulin can continue it till the day of surgery without any other changes._* Those taking *_intermediate*_ insulin (usually twice a day dose) _*should take only **75%** of the normal dose the **night before surgery***_ and _***50%** of the normal dose the **day of the surgery.**_* With **long-acting insulin, the patient needs to reduce their dose by 50% on the morning of the surgery.**

Answer 648

This has led to the recommendation that **metformin be continued until the day of the surgery.** The exception is patients with *_renal dysfunction, who will need to discontinue the metformin 24-48 hours prior to surgery._*

Answer 649

The **greater** the solubility (Ex: Isoflurane is most soluble) of an inhaled anesthetic, the **more rapid the uptake** into the bloodstream - The **greater the uptake**, the **slower the rate of rise of FA/FI** ## Footnote **(Ex: Hence why Iso is so slow)**

Answer 650

1. **Cardiac output** (Low Cardiac output will increase rate of rise but only with Iso) 2. **Solubility** (Iso vs. Des) 3. **Alveolar-to-venous partial pressure difference** (#3 Ex: Low (PArterial - PVenous), meaning less blood uptake A high pulmonary artery to pulmonary vein gradient means high solubility in the blood. A higher blood solubility means lower diffusion into the CNS, which slows onset.)

Answer 651

**Non-hemolytic febrile transfusion reaction** Non-hemolytic reaction is defined as a *_temperature increase of \>1 °C without concurrent hemolysis._* A non-hemolytic febrile transfusion reaction occurs because *_**recipient antibodies** cause lysis of **donor leukocytes** found in the red cell transfusion product._*

Answer 652

**Antibodies in the donor blood** bind to the *_recipient’s leukocytes_*, which then adhere to the vascular capillary bed in the pulmonary circulation. This causes damage and extravasation of intravascular fluid.

Answer 653

Transfusion of soluble leukocyte mediators

Answer 654

**GP IIb-IIIa receptor inhibitors** that prevent platelet aggregation and thrombus formation.

Answer 655

**adenosine diphosphate (ADP) receptor inhibitors** which impair the ADP-dependent activation of the GP IIb-IIIa complex.

Answer 656

**GP IIb-IIIa receptor inhibitors** and thus prevent platelet aggregation and thrombus formation.

Answer 657

K = Always efflux Ca = Influx

Answer 658

**Excessive bicarbonate** administration **Conversion** (such as citrate or lactate to HCO3 by the liver) **Excessive chloride loss** such as with nasogastric suctioning **Increased renal reabsorption** (hyperaldosteronism) **Volume contraction** (as seen with diuretic therapy).

Answer 659

**CV**: Cardiac depression, Arrhythmia and vasoconstriction **Pulm:** Impaired central respiratory drive and Difficult ventilator weaning **Hypokalemia**

Answer 660

**Treatment** involves correction of the cause (e.g. volume resuscitation with normal saline increases chloride, which increases renal bicarbonate losses) **Acetazolamide** (promotes renal bicarbonate loss) Infusions of acid such as **ammonium chloride** **Dialysis**.

Answer 661

A general rule of thumb is that for every **1 mEq/L increase in serum bicarbonate, the PaCO2 should increase by 0.5 mm Hg.** This mechanism is limited by stimulation of peripheral chemoreceptors to hypoxemia and thus PaCO2 **rarely increases above 55 mm Hg.**

Answer 662

The **Bainbridge reflex** *_increases heart rate*_ by inhibiting parasympathetic activity when stretch receptors located in the _*right atrial wall sense increased pressure._* **Reverse Bainbridge Reflex during after spinal** More common in patients with high baseline vagal tone, anesthetic levels above T5, and is associated with decreased cardiac preload

Answer 663

**Prevents overinflation of the lungs** When subjected to excessive stretching (e.g. during CPAP or PEEP), pulmonary stretch receptors trigger the reflex which temporarily prevents inspiration and allows expiration to occur.

Answer 664

Begins **2-3 weeks following acute injury.** It may occur with stimulation *_below the level of spinal cord injury leading to uninhibited sympathetic stimulation_* Approximately 85% of cases occur with SCI **above the T5 level.**

Answer 665

Usual dose: **20 ppm via mechanical ventilation circuit**; dosage range: 5 to 20 ppm

Answer 666

Unlike in OSA, there is **no effort to breathe during periods of apnea** in CSA. Thus one of the classic signs of OSA, **snoring, does not commonly occur** in patients with pure CSA. Most cases of CSA are **secondary to an underlying medical condition** (e.g., heart failure, stroke, certain neuromuscular disorders), narcotic use, or altitude changes.

Answer 667

**≥5 episodes per hour of sleep of complete cessation of airflow during breathing lasting ≥10 seconds** despite maintenance of neuromuscular ventilatory effort, accompanied by an **SaO2 decrease of at ≥4%**

Answer 668

The *_total number of episodes of apnea or hypopnea*_ (reduction of airflow of greater than 50%) divided by the _*total sleep time_* creates a apnea/hypopnea index (AHI). An AHI of 5-15 events per hour indicates **mild** disease An AHI of 15-30 indicates **moderate** disease **Severe** disease is indicated by an AHI of \>30.

Answer 669

1) **Primary hemostasis**: platelets form a clot to plug vascular injury. 2) **Coagulation**: fibrin forms mesh over the clot to stabilize it. 3) **Fibrinolysis**: after the injury is repaired, the clot is broken down.

Answer 670

Liver disease **affects all 3 phases** (Hemostasis, Coagulation, Fibrinolysis). Patients with advanced liver disease have dysfunction of **BOTH procoagulants and anticoagulants**. This creates a balance in the coagulation system and these patients rarely have *_spontaneous bleeding or clotting._*

Answer 671

**1. Platelet count** **2. Platelet function analysis** **3. Von Willebrand Factor (vWF)** **4. Bleeding time**

Answer 672

Appropriate platelet count is necessary to *_generate adequate thrombin levels._* This threshold is thought to be around **50-60.**

Answer 673

**Factor VIII** and **vWF**, are produced in the endothelial cells and are not reduced in liver disease. In fact, they are increased.

Answer 674

They are NOT at increased risk for spontaneous bleeding. This is because in liver disease the procoagulants and anticoagulants are both decreased. **As long as there is adequate platelet count,** patients with liver disease will continue to generate thrombin and fibrin. However, as the liver disease advances, *_it becomes more difficult to maintain hemostasis_* even with the balance that has been established. Some shift towards clotting, and others towards bleeding.

Answer 675

Coagulation management in liver disease patients: 1) Maintain platelet count at **50-60; in high-risk surgery maintain \>100** 2) Keep **fibrinogen \>100** 3) Transfuse to **maintain Hgb \> 7** 4) **Do not give FFP prophylactically or chase INR levels** - Increased INR in these patients does not necessarily reflect risk of bleeding - If FFP is to be given, dose is 20-40 mL/kg

Answer 676

One lead = **V5 (75%)** Two Leads = **II and V4 (82%)** Intraoperative monitoring of Leads II and V4 is the preferred lead combination as it allows for rhythm monitoring and is sensitive for myocardial ischemia. Alone, V5 has the highest sensitivity for myocardial ischemia, however, this is not recommended for intraoperative monitoring.

Answer 677

Meperidine’s beneficial effects are multimodal and center around the **kappa opioid receptor.**

Answer 678

Pressure measurement via simple manometry, also referred to as tube or column manometry, is performed by attaching tubing to the thin-walled needle or the catheter that has been inserted into the presumed central venous site prior to dilation. This tubing is then held below the level of the vein, allowing blood to fill the tubing followed by raising it vertically above the patient against gravity. The blood-air interface will settle at the level where hydrostatic pressure in the tubing is equal to the intravascular pressure. *_If it is misplaced in the artery, the blood will rise out the top of the tubing._***Recall that a pressure of 10 mmHg correlates with a height of 15cm.**

Answer 679

*_Indications_*: 1. Seizure Prophylaxis for preeclampsia 2. Tocolytic agent in preterm labor - relaxing uterine smooth muscle and vascular tone **1.8 - 2.5 mg/dL Normal**

Answer 680

**4.8 - 9.6 mg/dL** Therapeutic for obstetric floor *_Flushing, nausea, vomiting, sedation, dizziness, and muscle weakness_* Muscle weakness results from both a decreased release of acetylcholine (secondary to presynaptic calcium channel blockade) as well as decreased motor end plate sensitivity to acetylcholine.

Answer 681

Patient has **hypermagnesemia** therefore **hypocalcemia** If these patients need general anesthesia, one must be aware that they *_may not have fasciculations with succinylcholine_*, and they will have an **increased sensitivity to nondepolarizing neuromuscular blockers necessitating a *_decreased_* dose**

Answer 682

**6 - 12 mg/dL** ECG changes begin **Prolonged PR interval,** **widened QRS, Look for heart blocks**

Answer 683

**12 mg/dL** Loss of Deep Tendon Reflexes, Respiratory Depression **18 mg/dL** The SA and AV node blocked → complete heart block **20-25 mg/dL** Cardiac arrest (asystole)

Answer 684

1. Correction of excessive *_microvascular bleeding in the presence of a INR \> 2_* * _2.*_ Correction of excessive _*microvascular bleeding secondary to coagulation factor deficiency_* in patients transfused with more than one blood volume 3. Urgent *_reversal of warfarin_* therapy 4. Correction of known *_coagulation factor deficiencies_* for which specific concentrates are not available 5. For *_heparin resistance_*

Answer 685

**5 - 8 mL/kg** then recheck values to guide resuscitation

Answer 686

PO = Most pre-dictable IV = Can have anaphylaxis SQ/IM not recommended **24 hours to take effect regardless of route**

Answer 687

It should be noted that some products available in the U.S. contain negligible amounts of factor VII which is key for clotting in trauma patients (these products are known as **three-factor PCC**s). **Four-factor PCC** contains higher amounts of factor VII.

Answer 688

Warfarin Reversal, Urgent Surgery: INR 1.5 - 1.9: **consider PCC, FFP may not be useful**

Answer 689

**INR 1.9 - 5:** PCC or FFP 1-3 mg of IV vitamin K Kcentra, Beriplex P/N [Canadian product]: Vitamin K antagonist (VKA) reversal in patients with acute major bleeding or need for an urgent surgery/invasive procedure: IV: Individualize dosing based on current pre-dose INR. Dosage is expressed in units of factor IX activity. Administer with vitamin K concurrently. Repeat dosing is not recommended (has not been studied). Pretreatment INR: 2 to \<4: Administer **25 units/kg**; maximum dose: **2,500 units** Pretreatment INR: 4 to 6: Administer 35 units/kg; maximum dose: 3,500 units Pretreatment INR: \>6: Administer 50 units/kg; maximum dose: 5,000 units

Answer 690

* *PCC**: 50 U/kg (Max dose of 5000 units) * *FFP** (5-8 cc/kg) **Vitamin K 2-5 mg IV over 30 minutes**

Answer 691

*_Kcentra, Beriplex P/N [Canadian product]:_* Administer at room temperature at a rate of **0.12 mL/kg/minute (~3 units/kg/minute**); do not exceed 8.4 mL/minute (~210 units/minute). Do not allow blood to enter into syringe (fibrin clot formation may occur).

Answer 692

**For INR 1.5 - 1.9** 1 mg PO Vitamin K

Answer 693

**INR 1.9 - 5**: *_1 - 2.5 mg PO vitamin K*_, if INR still elevated 24 hours after dose give _*1 - 2 mg PO vitamin K_*

Answer 694

**INR 5 - 9** **2.5 - 5 mg PO vitamin K**, if INR still elevated 24 hours after dose give **1 - 2 mg PO vitamin K**

Answer 695

**Do not administer** **twice daily** prophylactic doses of LMWH while a neuraxial catheter is in place. **You may** administer **once daily prophylactic** doses of LMWH while a neuraxial catheter is in place starting 12 hours after needle insertion.

Answer 696

For patients that were receiving **therapeutic** doses (1 mg/kg) of LMWH, **wait 24 hours** after the last dose. For patients that were receiving **prophylactic** doses (30-40 mg BID) of LMWH, **wait 12 hours** after the last dose.

Answer 697

**Do not administer therapeutic doses** of LMWH while a neuraxial catheter is in place. **Do not administer *_twice daily_* prophylactic doses** of LMWH while a neuraxial catheter is in place. **You may administer once daily prophylactic** doses of LMWH while a neuraxial catheter is in place starting *_12 hours_* after needle insertion.

Answer 698

**12 hours** after last LMWH dose

Answer 699

**4 hours**

Answer 700

**Age** **Site of Injection** **Position** **Airway Pressure** **Local Anesthetic Concentration** **Local Anesthetic Volume**

Answer 701

**- Older = Greater spread** *_Decreased_* compliance of epidural space Therefore space will expand less when LA injected thus cranial & *_caudal spread increases_* *_Less fat_* in epidural space in older patients so spread is more

Answer 702

Thoracic spread **caudally** Low Thoracic spread **cephalad** Mid thoracic spread **both directions**

Answer 703

**Lateral** = More spread (Vs. Sitting) **Trendelenburg** results in greater spread of local anesthetics

Answer 704

**Airway Pressure** Mechanical ventilation with CPAP increases spread Secondary to compression of epidural space from increased intrathoracic pressure

Answer 705

**Local Anesthetic Concentration** Increase block height with higher doses Also affects block density/intensity **Local Anesthetic Volume** Most significant effect on epidural spread and the number of segments blocked

Answer 706

**Metabolism**: Liver **Elimination**: GI Tract - Bile and Feces

Answer 707

E cylinder Roughly 2000 psi for 660 L Direct Relationship I.E. 500 psi = (25% of 660L) = 165 Liters

Answer 708

**1. Anticholinergic medications** Help restore balance to the dopaminergic and cholinergic balance Preferred *_Diphenhydramine_* (Both anticholinergic and antihistamine) Benadryl 12.5 - 50 mg IV *_Benztropine_* Initial dose: IM, IV, Oral: 1 to 2 mg once. Subsequent doses: Oral: 1 to 2 mg 1 to 2 times daily. 3-8 all per True Learn but couldn't find doses Anticholinergic medications such as diphenhydramine (recall that it is both anticholinergic and antihistamine) and benztropine are considered first-line therapies for EPS since they can rapidly (five minutes or less when administered IV) improve and/or eliminate symptoms. They work by restoring the dopaminergic-cholinergic balance. 3. *_Trihexyphenidyl_* 4. *_Atropine_* 5. *_Anti-histamines_* 6. *_Benzodiazepines_* (Refractory to anticholinergics or when anticholinergics are contraindicated) Directly relieve muscle spasms 7. *_Beta-Blockers_* (Refractory to anticholinergics or when anticholinergics are contraindicated) 8. **Dopamine Receptor Agonist** 9. **Alpha Adrenergic Agonists**

Answer 709

Multiple Surgeries Healthcare workers Atopic Histories Tropic Fruits - Avocado, Kiwi, Banana, Chestnuts, Stone Fruits

Answer 710

**Grade I** involves cutaneous-mucous signs **Grade II** corresponds to mild cutaneous-mucous features that may be associated with cardiovascular and/or respiratory signs *_Grade I and II non-life threatening_* Cardinal sign of **grade III is cardiovascular collapse** that may be associated with cutaneous-mucous signs and/or bronchospasm **Grade IV** is cardiac arrest

Answer 711

Elevated in Anaphylaxis Peak between **15-60 minutes in Grade I and II** Peak between **30 - 120 minutes in Grade III/IV reactions** Half Life of tryptase = **2 hours**

Answer 712

**SSRIs inhibit CYP2D6** which *_reduces the activation of many opioids_* (e.g. codeine, hydrocodone oxycodone) to more potent forms (e.g. morphine, hydromorphone, oxymorphone).

Answer 713

**Codeine → Morphine** **Hydrocodone → Hydromorphone** **Oxycodone → Oxymorphone**

Answer 714

*_Hydrocodone_* → Hydromorphone **Slightly weaker analgesic than morphine** Conversion increases analgesic potency by a factor of 4 *_Oxycodone_* → Oxymorphone **Slightly stronger than morphine** Conversion increases its analgesic potency by a factor of 2

Answer 715

**Decrease number** and causes **aggregation**

Answer 716

**Blocks** the musculocutaneous, radial, ulnar, and median nerves **Fails to block** the medial aspect of the upper arm supplied by the *_intercostobrachial nerve*_ (not a branch of the brachial plexus) and therefore supplementation of the supraclavicular block with an _*intercostobrachial nerve block_* may be needed to prevent tourniquet pain.

Answer 717

Block the lateral & Medial antebrachial cutaneous nerve

Answer 718

**Methoxyflurane** created the largest concentrations of inorganic fluoride ions and fluoride-induced nephrotoxicity. Enflurane was related to renal concentration effects of fluoride ions causing nephrotoxicity. Sevoflurane produces more fluoride ions than enflurane while being administered, but the concentration of fluoride rapidly declines with cessation of administration, owing to its low blood and tissue solubility. Fluoride ion production: **methoxyflurane** \> **sevoflurane** \> **enflurane** \> **isoflurane** \> **desflurane**.

Answer 719

Dosing: **SubQ**: **0.25 mg/dose**; may repeat every 20 minutes for 3 doses (maximum: 0.75 mg/1-hour period) (NAEPP 2007)

Answer 720

**3U** load and begin infusion at **18U/hour** Repeat 3U loads every 3 minutes and increase gtt to **46U/hour**

Answer 721

**0.2 mg IM** q20 min x2 then q2-4 hours

Answer 722

0.25 mg IM q20 min don't exceed 8 doses in 24 hours

Answer 723

HTN Headache N/V Pulmonary Hypertension Chest Tightness

Answer 724

**N/V** **Flushing** **Bronchospasm** **Diarrhea** **Pulmonary Hypertension**

Answer 725

600 - 1000 mcg buccal mucosa/OR 10 minute onset SE: 38.1 Temp anad N/V, diarrheaa

Answer 726

**Clinically indistinguishable from anaphylaxis** **Mechanism**: Uncontrolled histamine release by a mechanism not involving IgE. **Triggers**: Protamine, IV contrast dye, opioids, d-tubocurarine, and thiopental. **Tryptase will rise**

Answer 727

Volatile anesthetics **potentiate (Increase)** neuromuscular blockade by *_DECREASING sensitivity of the postjunctional membrane to depolarization*_ and _*INCREASING skeletal muscle blood flow_* which both augment neuromuscular blockade. In addition, potentiation of neuromuscular blockade occurs by depression of upper motor neurons.

Answer 728

**Renal Allografts enhanced survival** - The only established clinical effect of TRIM

Answer 729

**PAO2 = [(Patm – PH2O) \* FiO2] – (PACO2 / R)** Where: PAO2 = alveolar oxygen tension Patm = barometric pressure PH2O = water vapor pressure FiO2 = percent of inspired oxygen PACO2 = alveolar carbon dioxide tension R = respiratory quotient (CO2 produced per O2 consumed).

Answer 730

A normal A-a gradient is **\< 10 mm Hg** normal a-A ratio is **\>0.75.**

Answer 731

**Pressure on Carotid Sinus** Sensory fibers increased that send action potentials to the cardioregulatory and vasomotor centers in the medulla oblongata (See image below)

Answer 732

In doses of **25-50 mcg/kg (max dose of 4 mg)** significant amnesia may remain up to 4-6 hours after a dose without excessive sedation, *_but above 4 mg there is no added benefit and it will prolong sedation._* IV: 1 to 4 mg or **20-40 mcg/kg (maximum single dose: 4 mg)** once 5 to 20 minutes before procedure; if needed based on incomplete response and/or duration of procedure, may repeat the dose (usually at 50% of the initial dose) after ≥5 minutes

Answer 733

Midazolam = 2 hours Lorazepam = 6-8 hours

Answer 734

**Management of pipeline failure or gas crossover:** 1) Disconnect the pipeline connection at the wall. 2) Open the emergency oxygen cylinder fully. 3) Ventilate by hand with the anesthesia breathing circuit.

Answer 735

**Hypercalcemia** --\> Antagonizes non-depolarizing neuromuscular blockade therefore **you need higher doses** ## Footnote **Magnesium = Opposite**

Answer 736

**Less respiratory depression** (\<10%) compared to prop (10-25%) Onset is slower (4-10 minutes)

Answer 737

**1. Paresthesias** \>50% of patients (an abnormal sensation, typically tingling or pricking) 5 minutes after pushing burning, tingling, and/or stinging sensations and usually occur in the perianal or genital regions Can be buttock, chest, ears, nose Resolve spontaneously LA, NSAIDs, or opiates don't decrease incidence **2. Pruritits** 15-30% of patients (Genitals)

Answer 738

Acidiotic --\> more H+ attach to albumin --\> Hypercalcemia Alkalosis --\> Less H+ attach to albumin --\> Hypocalcemia

Answer 739

The signs of citrate toxicity include those associated with **hypocalcemia** **Hypotension** **Arrhythmias** **narrow** pulse pressure **Increased** intraventricular **end diastolic pressure** Increased **central venous pressure**

Answer 740

The following diagnoses should be considered in patients with a **large R wave in lead V1:** 1) Right ventricular hypertrophy (RVH) 2) Posterior wall MI 3) Wolff-Parkinson-White syndrome (WPW) 4) Muscular dystrophy 5) Right atrial enlargement (RAE) 6) Right ventricular strain with ST-T wave abnormalities

Answer 741

Hypernatremia = Increase MAC Hyponatremia = Decrease MAC

Answer 742

Hypocarbia = Increase MAC Hypercarbia = Decrease MAC

Answer 743

Coronary venous drainage ultimately converges in the coronary sinus, which subsequently empties into the posterior right atrium. While **85%** of coronary blood flow to the left ventricle empties into the **coronary sinus** **15%** will eventually drain via **Thebesian veins into the atrial and ventricular cavities.**

Answer 744

Anterior = RCA Great = LAD Middle = PDA

Answer 745

**Internal Branch of Superior Laryngeal Nerve (CN X)** = Sensory above the cords **Recurrent Laryngeal Nerve (CN X)** = Sensory below cords and Trachea

Answer 746

**Greatest to Least:** Desflurane (60% increase) Isoflurane and Sevoflurane (40%) Nitrous Oxide (20%)

Answer 747

Thromboxane 1. Responsible for **platelet aggregation (Aspirin blocks this)** The prevention of its formation by aspirin prevents platelet aggregation for the life of the platelet. 2. Thromboxane is also a potent vasoconstrictor, and its inhibition may **promote coronary perfusion.**

Answer 748

* *Characteristics of addicted anesthesiologists include:** - 50 percent \< 35 years old (bimodal distribution) **Young** - **Residents** are over-represented. "Often they are the last individuals in your department you would expect." A high proportion are members of **Alpha Omega Alpha.** - 67-88 percent are **male** - 75-96 percent are **White** - 76-90 percent **opioids** were the drug of choice - 33-50 percent of **polydrug** users - 33 percent with a **family history** of an addictive disease - 65 percent were associated with **academic departments** (greater vigilance and younger age)

Answer 749

Lithium **prolongs** action of both depolarizing and nondepolarizing neuromuscular blockers.

Answer 750

**Mivacurium**

Answer 751

Decreasing barometric pressure (higher output) will i**ncrease the output of the vaporizer.**

Answer 752

1. Urine Osmolality 2. Urine Sodium 3. FENa or FEUrea (if on diuretics) 4. BUN/Creatinine

Answer 753

**Prerenal**: UOsm of \>500, UNa of \<10, FENa of \<1%, BUN/Cr of \>20 **Intrinsic**: UOsm of \<350, UNa of \>20, FENa \>2%, BUN/Cr of \<15 **Post renal**: UOsm of \<350, UNa of \>40, FENa of \>4%, BUN/Cr of \>15

Answer 754

The gold standard for the distinction between the two is the kidneys **response to a fluid challenge**. If enough fluid is given to reverse signs of volume depletion and the serum creatinine does not return to baseline within 72 hours, **ATN** is the likely diagnosis.

Answer 755

The presence of **"muddy brown casts" of epithelial cells** found in the urine during urinalysis is pathognomonic for ATN

Answer 756

**Mechanism**: Vasopressin receptor type 2 (V2) antagonist. Indications: Tolvaptan was originally approved for use in patients with acute heart failure Now used in patients with excessive antidiuretic hormone secretion **(SIADH).**

Answer 757

The average FRC in the adult is approximately **30 ml/kg** (~2100 mL for a 70 kg adult).

Answer 758

The greatest decrease in **functional residual capacity (FRC) occurs when going from 60° upright to supine (0°)** or when being placed in Trendelenburg (head-down) more than -30°. The **FRC does not significantly decrease** when changing from a supine position to Trendelenburg less than -30°. *_However, beyond -30°, the drop in FRC is considerable_*

Answer 759

Less susceptible to **SCh** **(Give a higher dose)** more susceptible to **non-depolarizing NMBDs** (**Give a lower dose**)

Answer 760

1) Esophageal 2) Tympanic 3) Pulmonary artery 4) Nasopharyngeal

Answer 761

**Consequences of Hypothermia** Coagulopathy Increased infections Changes in oxygen delivery Increase in myocardial oxygen demand Increase in blood transfusion requirements Poor wound healing Changes in drug metabolism

Answer 762

**Decrease** in pH (Right shift) **Decrease** in 2,3 DPG (Left shift) **Increase** in Potassium Potassium gradually moves out of PRBCs during storage in order to maintain electrochemical neutrality with the hydrogen ions that are generated from anaerobic metabolism. After three weeks of storage, potassium levels may reach *_20-35 mEq/L*_, though there is usually only 20-60 mL of plasma in one unit of PRBCs. After 4-5 weeks of storage, transfusion of one unit of PRBCs can add _*5-7 mEq of potassium_*. Massive transfusions, particularly in neonates, can lead to hyperkalemia.

Answer 763

**After the first 24 hours** following the burn injury and has implications for both depolarizing and nondepolarizing neuromuscular blocking drug use. When the burned area exceeds 10% of the total body surface area (TBSA), succinylcholine administration between 24 hours and **1 year after the injury** becomes contraindicated due to exaggerated hyperkalemia.

Answer 764

**Starting 1 week** following the burn and **peaking approximately 5-6 weeks** following the injury. The resistance is primarily due to the significant increase in the number of acetylcholine receptors but is also due to production of altered isoforms of the acetylcholine receptor, increased renal excretion, and altered serum protein binding of the drugs. Resistance leads to an **increased time to onset** (slowed up to 30%), **decreased** duration of action, and **decreased** overall effect. These effects can be at least partially overcome by increasing the dosage of the drug

Answer 765

Vasodilators

Answer 766

Ionotropes and Vasodilators

Answer 767

Increase in preload (IVF bolus)

Answer 768

Incompetent Expiratory Valve **1. Replace Exhausted CO2 absorbent** **2. Increase gas flows**

Answer 769

**Incompetent Inspiratory Valve**

Answer 770

**Butorphanol** *_Mechanism:_* Partial Opioid Agonist and Mixed Agonist-Antagonist **Synthetic mu agonist-antagonist** opioid analgesic **Partial agonist** activity at the κ-opioid receptor *_Indications:_* **Relieve Biliary Colic** Side Effect: Does not cause biliary spasm, does not sufficiently contract sphincter of Oddi and increase common bile

Answer 771

The recommended precurarization dosage for a nondepolarizing agent is **10% of the ED95, given about 3-5 minutes** prior to succinylcholine. Using 10% of the intubating dose (20% of the ED95) is associated with an unacceptably high rate of side effects, including dyspnea in an awake patient. ## Footnote *_Rocuronium_* *_ED 95 - 0.3 mg/kg_* *_Precurarization - 0.03 mg/kg_*

Answer 772

**1. Decreases in SSEP amplitude** **2. Increases in latency** are indicative of insults to the somatosensory pathway such as cerebral ischemia.

Answer 773

Thromboelastography (TEG) is both a quantitative and graphic evaluation of clotting function. Decreased MA values primarily suggest quantitative and/or qualitative platelet dysfunction or, to a lesser extent, inadequate fibrinogen. ## Footnote **The best treatment is administration of platelets.**

Answer 774

Midazolam and all benzodiazepines cause a **dose dependent decrease in minute ventilation**. The decreased minute ventilation is mainly a *_result of decreased tidal volume_*. Benzodiazepines decrease the respiratory sensitivity to CO2 and act synergistically with opioids.

Answer 775

**Decrease in tidal volume**, which causes a decrease in minute ventilation. The **respiratory rate is often preserved,** but with higher doses of medication apnea may occur. The depression in minute ventilation seen after midazolam occurs rapidly (less than 5 minutes) and lasts for about 1 hour. **Synergistic with opioids to depress minute ventilation.**

Answer 776

**Lorazepam**

Answer 777

Note, these maximum allowable doses are based on the duration of action and half-life of each local anesthetic (LA). The maximum allowable doses are for the following time windows: **Chloroprocaine**: 30-60 minutes for 12 mg/kg **Lidocaine**: 60-90 minutes for: Lidocaine without Epi - 5 mg/kg Lidocaine with Epi - 7 mg/kg * *Ropivacaine**: 90-120 minutes for 3 mg/kg * *Bupivacaine**: \>120 minutes at 2.5 mg/kg

Answer 778

More likely in **females** of *_child bearing age_* having **minor surgery**

Answer 779

1. **Pretreatment** with a **nondepolarizing muscle relaxant** **2.** Administration of **lidocaine** **3. NSAIDs** have all been tested and found to decrease the incidence of myalgias from succinylcholine.

Answer 780

**Lingual** nerve, **recurrent** laryngeal nerve, and **hypoglossal** nerve. *_Risk factors_* include: Overinflation of a small-fitting cuff Prolonged operative times (\>2-4 hours) Lidocaine lubrication Difficult insertion Use of nitrous oxide Cervical joint disease

Answer 781

Hofmann elimination reaction is a pH- and temperature-dependent reaction Proceeds more readily when **pH (alkalotic) and temperature are increased**

Answer 782

An intubating dose of cisatracurium **(0.1-0.15 mg/kg)** Duration of action: **30-60 minutes** Elimination half-life: **22-25 minutes**

Answer 783

Relative contraindications to the use of closed circuit or low flow anesthetic techniques include: ## Footnote **sevoflurane use and patients with alcoholism, malnutrition, cirrhosis, or ketoacidosis.**

Answer 784

The required FGF (oxygen) can be determined by *_calculating the metabolic demand for oxygen_*, approximately **3-3.5 mL/kg/min (for adults) \* patient weight in kilograms.** **Ex: 100 kg guy should get 350 mL/min of oxygen flow**

Answer 785

Stent type: Minimum duration of DAPT: ## Footnote **Bare-metal stent 30 days** *_Drug-eluting stent 3 month minimum, 6 month ideally_*

Answer 786

1. Advancing age 2. Lower educational level 3. History of previous CVA w/o impairments

Answer 787

Small doses of succinylcholine (e.g. **0.1-0.5 mg/kg**) can be used.

Answer 788

The Larson maneuver involves medial and cephalad pressure at the laryngospasm notch. The notch is located just behind the earlobe, bordered by the base of the skull superiorly, the mastoid process posteriorly, and the ramus of the mandible anteriorly.

Answer 789

The diagnosis of carbon monoxide poisoning is made by co-oximetry, when elevated levels of **COHb (\>15%) are found on arterial or venous blood gas analysis.**

Answer 790

A bolus of **1.5 mL/kg** (20%) should be delivered over one minute followed by an infusion of **0.25 mL/kg/min**. The infusion should be run until at least 10 minutes following restoration of cardiovascular stability. The infusion may be increased to **0.5 mL/kg/min in the setting of persistent hypotension** **Bolus (1.5 mL/kg) may be repeated 2x in the setting of continued cardiovascular collapse**

Answer 791

Epinephrine by itself is **highly arrhythmogenic** and these effects may be even more pronounced in the setting of LAST. **Animal studies do not support its use** Animal studies have shown that lipid-only resuscitation of bupivacaine toxicity had better outcomes than epinephrine-only resuscitation due to the presence of severe arrhythmias seen in the latter. Despite this, the use of small doses of epinephrine is still recommended since epinephrine provides critical inotropic and vasopressor support.

Answer 792

**Afferent Branch - Internal Branch of *_superior laryngeal nerve_*** The internal branch of the superior laryngeal nerve is responsible for sensory innervation of the trachea at and above the level of the vocal cords. This means that the internal branch of the superior laryngeal nerve functions as the afferent limb of the laryngospasm reflex. **Efferent Branch - *_Recurrent Laryngeal nerve_*** The efferent branch of the laryngospasm reflex is mediated by the recurrent laryngeal nerve. The recurrent laryngeal nerve innervates all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscle. The lateral cricoarytenoid and transverse arytenoid muscles are major adductors of the vocal cords and responsible for laryngospasm

Answer 793

The central venous pressure (CVP) tracing includes 3 waves (a, c, v) and 2 descents (x, y). The **a-wave** is caused by **right atrial contraction.** The **c-wave** occurs when the **right ventricle contracts**, causing the tricuspid valve to bulge into the right atrium. The emptying of the right ventricle produces the *_x-descent._* The **v-wave** is due to the filling of the right atrium *_y-descent_* is the passive emptying of the right atrium.

Answer 794

**Nicotinic** *_Skeletal muscle*_ and _*autonomic ganglia_* **Muscarinic** End organ receptors on *_salivary/gastric glands_* *_Smooth muscle_* [bronchial, gastrointestinal, bladder, and vascular] *_SA and AV nodes of the heart_*

Answer 795

Bradycardia and Hypotension

Answer 796

Bronchospasm Increased respiratory secretions

Answer 797

Increased peristalsis, salivation, GI secretions

Answer 798

**Miosis** **Decreased intraocular pressure**

Answer 799

1. Excessive neostigmine may lead to a depolarizing block, similar to succinylcholine, because of **excessive motor end plate depolarization by acetylcholine.** 2. In addition, some animal studies have shown that **neostigmine might directly block the acetylcholine receptors in high doses**. 3. Lastly, neostigmine can **potentiate the effect of succinylcholine by inhibiting pseudocholinesterase**

Answer 800

Onset = 6-8 hours Peaks = 30 hours 24 hours to get to 50% (not easily titratable)

Answer 801

Mortality rate for physicians re-entering practice after being treated for substance abuse is between **9-13%**. For those re-entering training, mortality is **7%.**

Answer 802

**Median**

Answer 803

**Nominal** data sets refer to categorically discrete data sets, such as the name of the anesthesia delivered to a patient (e.g. general, regional, local). Remember, **NOMINAL = NAME**. The mode, which is a measure of the most frequent value in the data set, is the only measure of central tendency for nominal data sets.

Answer 804

**One-way analysis of variance (ANOVA)**

Answer 805

The Poiseuille Law is determined by the equation **Q = (P\*pi\*r4)/(8\*n\*l)** where Q = flow rate, P = pressure, r = radius, n = viscosity and l = length of tubing

Answer 806

The **density** of the fluid is not part of the equation and does not directly affect laminar flow rate. Density is not directly related to Poiseuille's Law, however, it does help predict if fluid will flow in a laminar or turbulent manner. Poiseuille's Law only relates to fluid flow that is laminar.

Answer 807

In newborns, the dural sac typically ends at **S3 and the conus medullaris at L3**. In adults, the dural sac typically **ends at S1-S2 and the conus medullaris at L1-L2.**

Answer 808

Typically, fluid with a Reynolds number **greater than 4000** will be turbulent, **less than 2300 is laminar,** and between is a transition where either can occur depending on other factors such as the roughness of the tubing or plaque in blood vessels.

Answer 809

**Chi-square** testing

Answer 810

**Platelet Function**

Answer 811

Glycopyrrolate delays gastric emptying, decreases salivary and gastric secretions, increases heart rate, relaxes bronchial smooth muscle, decreases lower esophageal sphincter tone, and causes urinary retention

Answer 812

The duration of action of glycopyrrolate is **2-4 hours** so if given shortly before anesthetic induction, the risk of aspiration is slightly increased due to the gastrointestinal side effects discussed above.

Answer 813

**Sevo \> Iso \> Des** Sevoflurane undergoes the most extensive metabolism of the inhaled anesthetics used in clinical practice today. Despite demonstrated elevations in serum fluoride concentrations in long cases, it has not been shown to cause fluoride-induced nephrotoxicity.

Answer 814

An IV bolus dose of **7 mg/kg** may last as long as 10-15 minutes.

Answer 815

**CPP = AoDP - LVEDP** CPP is coronary perfusion pressure, AoDP is aortic diastolic pressure, and LVEDP is left ventricular end diastolic pressure.

Answer 816

**Mapleson A** is the most efficient user of FGF during spontaneous ventilation, but is the least efficient for controlled ventilation.

Answer 817

**All Dogs Can Bite (spontaneously): A \> D \> C \> B Dead Bodies Can’t Argue (controlled): D \> B \> C \> A** ## Footnote **Spontaneous = A** **Controlled = D**

Answer 818

The **Mapleson F system** (also known as the Jackson-Rees modification) is relatively efficient at both *_spontaneous ventilation (FGF of 2-3 times MV*_) and _*controlled ventilation (FGF approximately 2 times MV)_*

Answer 819

The Mapleson D system with the Bain modification has the fresh gas inflow tubing running coaxially inside the corrugated breathing tubing. This modification makes it very efficient for CONTROLLED ventilation, typically requiring **FGF only 1-2 times MV.** Spontaneous ventilation requires **FGF of 1.5-3 times MV** to prevent rebreathing.

Answer 820

**Low-risk** patients are those who taking \< 5 mg/day of prednisone (or equivalent) regardless of the time duration or patients on glucocorticoid therapy for *_\< 3 weeks_* regardless of dose. **High-risk patients** are those taking \> 20 mg/day of prednisone (or equivalent) for \> 3 weeks or *_those with cushingoid symptoms._* **Intermediate-risk patients** are those taking 5-20 mg/day of prednisone (or equivalent) for \> 3 weeks; those who have discontinued glucocorticoid use within the past year; or those who use chronic inhaled or topical glucocorticoids.

Answer 821

Stimuli at the eye -\> ciliary ganglion -\> ophthalmic division of trigeminal nerve -\> Gasserian ganglion -\> trigeminal nucleus -\> vagus nerve -\> bradycardia.

Answer 822

Leukoreduction is a *_decrease or complete elimination of donor leukocytes in blood components._* This can reduce the risk of **febrile transfusion** reactions and the risk of viral transmission (e.g. **cytomegalovirus**). It does not fully protect against **bacterial infection and does not prevent graft-versus-host disease.**

Answer 823

At 1.0 MAC of isoflurane, cardiovascular effects include **increased heart rate (10-15 beats/min), decreased SVR and blood pressure, and minimal changes in CVP.** Respiratory effects include a **mild reduction in minute ventilation, a reduced tidal volume, and an increased respiratory rate.**

Answer 824

**Health care workers, atopic individuals**, and those with allergies to certain foods (**avocados, bananas, chestnuts, kiwi fruit, papayas, potatoes, tomatoes**) have an increased incidence of latex allergy.

Answer 825

Nalbuphine is a **mu antagonist** and **kappa opioid receptor agonist** which exhibits a plateau effect for *_respiratory depression._*

Answer 826

**20 minutes** The release of A2 is modulated by the renin-angiotensin-aldosterone system (RAAS). Blockade of the RAAS by angiotensin-converting enzyme inhibitors or angiotensin receptor blockers may cause profound and refractory perioperative hypotension, particularly after induction of general anesthesia.

Answer 827

Normal pulmonary wedge pressure is **6-12 mmHg**

Answer 828

A "full" E size oxygen cylinder is variously quoted in the anesthesia literature as being pressurized to **1900, 2000, or 2200 psig.** Similarly, major anesthesia textbooks differ in regards to how many liters of oxygen are in a "full" E size oxygen cylinder, most often stating it to be **600, 625, or 660.**

Answer 829

**Drug dosage, drug baricity, and patient positioning** are the most important factors influencing level of spinal blockade. **Drug volume** is an important factor during epidural blockade.

Answer 830

**At least 40%** of anesthesiology residents who were found to have substance use disorder during training relapsed.

Answer 831

**Sevoflurane \> isoflurane \> halothane.**

Answer 832

1 palpated twitch indicates \>90% suppression. 2 palpated twitches indicate 80-90% suppression. 3 palpated twitches indicate 70-80% suppression. 4 palpated twitches indicate up to 65-75% suppression. Palpation of twitches using TOF testing cannot detect the percentage of receptors bound at \< 65%.

Answer 833

Physostigmine (0.5 - 2.5 mg IV) may be able to reverse the emergence reactions that are seen with ketamine. **Physostigmine is a centrally acting acetylcholinesterase inhibitor that will increase the amount of acetylcholine in the brain**. The theory behind this mechanism of reversal is that ketamine’s emergence reactions resemble the central anticholinergic syndrome thus, giving physostigmine may shorten the response. However, data is conflicting regarding the reliability of physostigmine for reversal of symptoms.

Answer 834

**Factors that influence incidence of emergence reactions:** Age: Adult patients are more likely to report a high incidence compared to pediatrics. Gender: Females are more likely than males. Dosage: Larger doses with rapid administration increase the risk. Psychological Susceptibility: Certain personalities types are at an increased risk; those who tend to dream at home and those who score high on the Eysenck Personality Questionnaire (extrovert, neurotic) tend to have a higher risk. Concurrent Medications: Multiple medications increase the incidence although administering a benzodiazepine prior to administration of ketamine helps decrease the risk.

Answer 835

**1/C(Resp System) = 1/C (Lungs) + 1/C (Chest wall)** Where C is compliance, RS is respiratory system, L is lungs, and CW is chest wall.

Answer 836

A **simple face mask** supplies an FiO2 of approximately 35-50% with oxygen flows of 5-10 L/min. **Nasal cannulas** provide an FiO2 of 25-40% with flow rates up to 6 L/min.

Answer 837

An **IM dose of 2-5 mg** will raise blood pressure and lower heart rate typically within 10-15 minutes from injection.

Answer 838

**Ketorolac = Vasoconstriction of afferent glomerular arterioles.** Prostaglandins dilate afferent arterioles and increase glomerular capillary perfusion pressure. Ketorolac (and other NSAIDs) inhibit this vasodilatory effect and result in afferent arteriolar vasoconstriction.

Answer 839

**60-65 mmHg of PaO2**

Answer 840

1) Relatively long incisors 2) Prominent “overbite” 3) Patient cannot bring mandibular incisors anterior to maxillary incisors 4) Less than 3 cm interincisor distance 5) Uvula is not visible when tongue is protruded with patient in sitting position 6) Highly arched or very narrow palate 7) Mandibular space that is stiff, indurated or occupied by a mass 8) Less than three ordinary finger breadth thyromental distance 9) Short neck length 10) Thick neck circumference 11) Decreased extension or flexion of the neck

Answer 841

Metoclopramide is a **dopamine antagonist** that causes **increased gastric motility and increased lower esophageal sphincter tone.**

Answer 842

The Bohr and Haldane effects are complementary principles that help explain the efficient delivery of O2 to the tissue and CO2 to the lungs. The **Bohr effect** states that in areas of high CO2, the hemoglobin has less affinity for O2 which is more readily released for consumption by the tissues. The **Haldane effect** states that deoxygenated hemoglobin has a higher affinity for CO2. Once the deoxygenated hemoglobin reaches the lungs, the high O2 concentration decreases this affinity and the CO2 is released.

Answer 843

**AV nodal blockade**

Answer 844

The **equipment ground wire** is the most reliable means to prevent **microshock**. The *_ground fault interrupter*_ can prevent _*macroshocks_*, but does not reliably prevent microshocks

Answer 845

There are three main causes of auto-PEEP: 1. **Dynamic hyperinflation with intrinsic expiratory flow limitation**: this occurs in COPD patients. COPD results in loss of elements that keep the lungs open during expiration. During exhalation, the closure of the airways results in air trapping. Applying external PEEP can help relieve this type of auto-PEEP. 2. **Dynamic hyperinflation without expiratory flow limitation**: even when the airways are widely patent at the end of exhalation, if the volume delivered is too high, the exhalation time too short, or if exhalation is impeded by a blockage external to the patient (such as with blocked ETT or stuck exhalation valve) then air can get trapped. This is typically seen during rapid breathing patterns, use of high tidal volumes, when inspiration is greater than expiration, or when there is added flow resistance due to small endotracheal tubes. Removing the blockage, decreasing volume, or increasing exhalation time will help alleviate the problem. 3. **Exaggerated expiratory activity without dynamic hyperinflation**: when strong expiratory muscle activity contributes to alveolar pressure at the end of the expiratory cycle there will be an end-expiratory gradient of alveolar to central airway pressure. This results in auto-PEEP phenomena even with low lung volumes.

Answer 846

From greatest to least, the vapor pressures of the volatile anesthetics are: **desflurane \> isoflurane \> sevoflurane.**

Answer 847

Nausea and vomiting may be associated with neuraxial block in up to 20% of patients and ***_atropine_*** is almost universally effective in treating the nausea associated with high (T5) neuraxial anesthesia. **Explanation:** Unopposed parasympathetic (vagal) activity after sympathetic blockade causes increased peristalsis of the gastrointestinal tract, which can lead to nausea and is the primary mechanism behind nausea after spinal blockade. Atropine is an anticholinergic medication, thus is useful for treating nausea after high spinal blockade.

Answer 848

Transurethral surgery of the bladder usually can be performed with spinal anesthesia without further consideration. **If the tumor is along the lateral aspect of the bladder then the obturator nerve may be stimulated and the jerk reflex initiated even under spinal anesthesia.** An obturator nerve block should be performed to help prevent this. Alternatively, general anesthesia with muscle relaxation can also be performed to prevent the reflex. If neuromuscular blocking agents are not used during general anesthesia, the obturator nerve block will still need to be performed.

Answer 849

Cryoprecipitate contains **vWF, fibrinogen, fibronectin, factor VIII, and factor XIII.**

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