ITE 2020 - 2021 Flashcards

Question

What are the extra articular pulmonary manifestations of Rheumatoid arthritis?

Answer 1

**Pleural effusion,** **pulmonary hypertension** and/or **pulmonary** **interstitial** **f****ibrosis** which can cause *_decreased lung volumes and vital capacity (causing a ventilation-perfusion mismatch)_*

Answer 2

**Neuro**: Peripheral neuropathies (nerve compression, carpal tunnel, tarsal tunnel), chronic pain and keratoconjunctivitis sicca (dry inflammation of the conjunctiva and cornea).

Answer 3

**Chronic Anemia** **Thrombocytopenia** **Neutropenia (Felty's Syndrome)** Felty's syndrome is a rare, potentially serious disorder that is defined by the presence of three conditions: rheumatoid arthritis (RA), an enlarged spleen (splenomegaly) and a decreased white blood cell count (neutropenia), which causes repeated infections.

Answer 4

Renal: **chronic renal failure possible** (drugs, amyloidosis, vasculitis)

Answer 5

**Increase** (Potassium sparing)

Answer 6

Blood pH Decreased - Acidemia with **carbonic anhydrase inhibitors, K+ sparing** Blood pH Increased - Alkalemia with **loop diuretics, thiazides**

Answer 7

The wind-up phenomenon is caused by **repeated stimulation of peripheral C fibers** resulting in *_increased action potentials at the dorsal horn (spinal synapse) causing an amplified response._*

Answer 8

Allodynia is a painful response to a **non-painful stimulus.** This subject was given a painful stimulus. Hyperalgesia is an *_exaggerated_* painful response to an **ordinarily painful stimulus**.

Answer 9

The **anterior superior iliac spine** is an important landmark for performing a lateral femoral cutaneous nerve block. The LFCN is best blocked where it is located between the **sartorius** (medial landmark) and **tensor fascia lata** (lateral landmark) muscles The nerve can reliably be anesthetized by injecting 10 mL of local anesthetic approximately: **- 1-2 cm medial** **- 1-2 cm inferior** to the ASIS at a depth of **0.5-1 cm from the skin.**

Answer 10

Damage to the LFCN can lead to pain and paresthesias on the lateral upper thigh, which may extend down towards the lateral knee. This condition is called **meralgia paresthetica** and is most commonly caused by entrapment and compression of the nerve as it passes between the *_inguinal ligament and the ilium_*. It may also be caused by direct nerve damage, trauma, or diabetic neuropathy.

Answer 11

**All low** Hydrogen-potassium transporters pump hydrogen ions out of cells in the setting of alkalosis in order to restore physiologic pH. Simultaneously, potassium is pumped intracellularly to ensure electroneutrality, thus leading to **hypokalemia**. Alkalosis can cause **Hypophosphatemia**. A rising cellular pH stimulates the glycolytic pathway, enhancing sugar-phosphate production. This triggers increased cellular uptake of phosphorus, thus decreasing serum phosphorus concentration. **Hypocalcemia** is caused by increased calcium binding to negatively charged plasma proteins as the proteins release hydrogen ions to restore physiologic pH.

Answer 12

1. Prosthetic cardiac valves including **transcatheter-implanted prosthetic valves** 2. Patients with **implanted prosthetic material** such as annuloplasty rings and artificial chordae tendineae 3. Patients with a **history** of infectious endocarditis 4. Patients with a history of **unrepaired** cyanotic congenital heart disease 5. Including cyanotic congenital disease patients with a **repair, but with a residual shunt or valvular regurgitation** near an implanted patch or device 6. Patients with a history of **cardiac transplantation who have a regurgitant valvular lesion due to a structurally abnormal valve**

Answer 13

First, only patients who are undergoing dental procedures that "**involve the manipulation of gingival tissue...periapical region of teeth, perforation of the oral mucosa, urinary mucosa is peiced in the setting of actuve UTI or colonizataion**" are to be considered for prophylactic antibiotics

Answer 14

**6 months**

Answer 15

Antibody screen: The **recipient's serum** is mixed with **commercially supplied RBCs** (known as screen cells) containing selected antigens commonly implicated in hemolytic transfusion reactions (other than ABO-Rh). Antigens not represented in screen cells are unlikely to cause clinically significant hemolytic reactions. **It will detect the vast majority of antibodies that can cause a hemolytic reaction.**

Answer 16

The **recipient's serum** is mixed with **donor RBCs.**

Answer 17

It is possible for some patients, especially those with a **history of multiple transfusions or pregnancies**, to carry antibodies that would not be detected during an antibody screen. However, the chance of cross matching detecting a potentially dangerous antibody that was missed by the antibody screen is **less than 1 in 10,000.**

Answer 18

**Aminoesters**, which are degraded into an allergen, para-benzoic acid (**PABA**) = *_More likely for allergic reaction_* **Aminoamides** and their metabolites are not associated with allergens and hypersensitivity reactions. It is more likely that the preservatives in the local anesthetic preparation such as **methylparaben** are responsible for any allergic reactions.

Answer 19

**Increase** in sympathetic nervous system activity **Decreased** parasympathetic nervous system activity. **Decrease** in beta receptor responsiveness **Maintained** alpha receptor responsiveness

Answer 20

Presence of excessive amounts of the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in urine. ## Footnote **24 hour urinary 5-HIAA (Metabolite of serotonin) of \> 30 mg** Normal 5-HIAA is 3-15 mg (For reference)

Answer 21

**Urinary Vanillylmandelic acid** (VMA) is elevated in patients with tumors that secrete catecholamines. Norepinephrine is metabolised into normetanephrine and VMA.

Answer 22

Cardiac manifestations are due to **fibrosis of the endocardium**, primarily on the right side. **Pulmonic stenosis** is usually predominant. The *_tricuspid valve is often fixed open resulting in regurgitation._*

Answer 23

11β-hydroxylase is responsible for the **conversion of 11-deoxycorticosterone to corticosterone** (precursor to aldosterone) and the conversion of **11-deoxycortisol to cortisol.**

Answer 24

Adenosine is produced in the space of Mall surrounding the local hepatic vasculature and diffuses into the portal vein. As **portal venous blood flow decreases**, the decreased flow allows the **accumulation of adenosine** in the hepatic vasculature. This increased concentration of **adenosine causes vasodilation of the hepatic artery** and increased hepatic arterial blood flow. As **portal venous flow increases, the increased flow washes the adenosine out** of the hepatic vascular system resulting in vasoconstriction of the hepatic artery. This is known as the “adenosine wash-out hypothesis.”

Answer 25

**Double the hepatic arterial blood flow**

Answer 26

The liver gets 20-25% of the cardiac output via the portal vein and the hepatic artery. The **portal vein is responsible for 75% of the blood flow** while the **hepatic artery is responsible for 25% of the blood flow.** However, both vascular structures **each deliver 50% of the oxygen supply to the liver.**

Answer 27

A decelerating flow pattern on inspiration is characteristic of a **pressure control breath**.

Answer 28

Volume control delivers the breath to the patient as a **fixed flow breath (square waveform).**

Answer 29

Tense abdominal ascites elicits an **extrinsic restrictive lung disease pattern**, which is indicated on pulmonary function testing by a: *_Decreased forced vital capacity (FVC) (50%)_* Both intrinsic and extrinsic restrictive forces lead to a decreased FVC due to a decrease in TLC. *_Reduced functional residual capacity (FRC)_* *_The FEV1/FVC ratio (90%) and FEF25-75% are generally normal (90%)_* The forced expiratory volume in one second (FEV1) is usually decreased as well because of the reduced lung volumes. Since both the FEV1 and the FVC are reduced with restrictive lung pathology, the FEV1/FVC ratio is usually normal. The forced expiratory flow during the middle 50% of the FVC (FEF25-75%) is typically normal in restrictive lung disease unless small airway damage is also present from other etiologies. Both the FEF25-75% and the FEV1/FVC ratio are measures of ventilatory capacity.

Answer 30

**Vital capacity (VC) is the maximal amount of air that can fill the lungs and participate in gas exchange.** VC = TLC - RV VC = IRV + ERV + TV

Answer 31

The amount of gas that can be forcefully and maximally exhaled from a maximal inhaled volume is the forced vital capacity (FVC).

Answer 32

FVC - Very low FEV1 - Very low FEV1/FVC - Normal FEF25-75% - Normal FRC - Very Low TLC - Very Low

Answer 33

FVC - Normal or slightly increased FEV1 - Very low FEV1/FVC - Very Low FEF25-75% - Very Low FRC - Normal or increased TLC - Normal or increased

Answer 34

Normally, a patient’s FEV1 is approximately **75-80% of their FVC**, meaning that they can exhale 75-80% of their vital capacity in one second.

Answer 35

Normal ranges for FEF25-75% are typically **80-120%** of the predicted value.

Answer 36

Patients with chronic obstructive pulmonary disease (COPD) have a **lower than predicted FEV1/FVC ratio**. This is due to airway collapse with forced exhalation, which leads to a decreased FEV1. Therefore, a reduction in the FEV1/FVC ratio occurs as the patient’s FVC is typically unchanged or slightly increased.

Answer 37

Patients with COPD will also have a **low FEF25-75%** due to **small airway collapse during exhalation.**

Answer 38

**Primary Hyperaldosteronism**

Answer 39

**HIgh Sodium --\> Hypertension** **Low Potassium** **Low Renin** **Metabolic Alkalosis (Chronic Loss of Hydrogen ions)**

Answer 40

**Preoperative management** = Spirinolactose (Takes weeks), Potassium Supplementation, K sparing diuresis **Intraoperative Management**- Avoid hyperventilation (Will decease K more), Cortisol eplacement with bilateral adrenalectomies for multiple aldosteronomas

Answer 41

Chronic MR is typically asymptomatic in its earlier stages due to compensatory mechanisms that reduce afterload and increase left ventricular compliance, promoting forward flow. In its more severe stages, reduced ejection fraction, increased LV pressures and regurgitant volume are seen. This can be remedied by increasing heart rate to **reduce systolic time, reducing afterload, and maintaining normal sinus rhythm and normovolemia.**

Answer 42

Acute mitral regurgitation may also occur from **posteromedial papillary muscle** rupture after a myocardial infarction. This papillary muscle has a single blood supply, rendering it more susceptible to ischemia and rupture. Lastly, functional mitral regurgitation may occur from overdistended ventricles such as in dilated cardiomyopathy. ## Footnote The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles. 1. *_Anterolateral_* muscle blood supply: left anterior descending artery - diagonal branch (LAD) and left circumflex artery - obtuse marginal branch (LCX) 2. *_Posteromedial_* muscle blood supply: right coronary artery - posterior interventricular artery (RCA) The **posteromedial muscle ruptures** more frequently because it only has one source of blood supply, hence **RCA occlusion can cause papillary muscle rupture.**

Answer 43

Also, midazolam may precipitate a **worsening of dyskinesias** in patients with Parkinson disease.

Answer 44

**Hypokalemia** Digoxin toxicity is more likely to occur in the setting of hypokalemia since *_digoxin competes with potassium for the same binding site on the Na+/K+ ATPase._* With less potassium, more **digoxin is able to bind and its effects** (and side effects) become more pronounced. Digoxin toxicity is also more likely to occur in patients concurrently taking amiodarone, quinidine, or verapamil as these drugs cause an increase in serum digoxin concentration.

Answer 45

**Benefits:** 1. Positive inotrope improves contractility 2. Decreases HR by slowing AV conduction through the node 3. Sympatholytic action on baroreceptors 4. Decreases renal sodium reabsorption (mild diuresis)

Answer 46

**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.

Answer 47

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 48

second enzyme called **vitamin K reductase** (encoded by the **VKORC1** gene) is responsible of regenerating active (reduced) vitamin K.

Answer 49

Warfarin is metabolized by the cytochrome P450 **2C9 isoform (CYP2C9)**

Answer 50

**Teratogenic** Warfarin must be avoided in pregnant women because it can cause **abortion**, **fetal hemorrhage**, and **birth defects** (nasal hypoplasia, stippled epiphyseal calcifications).

Answer 51

PT/INR is the method of choice to monitor warfarin therapy since it is prolonged by reduced functional levels of the vitamin K-dependent factors **II, VII, and X**. (**1**9**72** C/S) Of note, not all vitamin K-dependent factors affect PT/INR (e.g. factor IX, proteins C, S, and Z do not), while reductions in some vitamin K-independent factors, such as fibrinogen and factor V, can also prolong PT/INR.

Answer 52

Warfarin is **not present in milk** and can be **safely given to nursing mothers.** (Cannot be given during gestation as it is teratogenic)

Answer 53

**A variable INTRAthoracic airway obstruction** (e.g., distal tracheal tumor or mediastinal mass) produces a flow-volume loop with a plateaued EXPIRATORY curve and the flow rate is usually decreased. During expiration, intrathoracic pressure becomes positive which further decreases the airway diameter, enhances the degree of obstruction, and impairs airflow. The inspiratory curve is usually normal since the negative intrathoracic pressure generated during inspiration helps keep the airway open.

Answer 54

**A variable EXTRAthoracic airway obstruction** (e.g., vocal cord paralysis or dysfunction, proximal tracheal tumor, glottic strictures) produces a flow-volume loop with a plateaued INSPIRATORY curve and the flow rate is usually decreased. During inspiration, the negative inspiratory pressure causes the obstruction to increase. The expiratory curve is usually normal since the positive airway pressure generated during expiration helps keep the airway open.

Answer 55

A **fixed upper airway obstruction** or fixed large airway obstruction (e.g., foreign body, tracheal stenosis, large airway tumor) impairs BOTH inspiration and expiration leading to a flow-volume loop with plateaued and decreased inspiratory and expiratory flows.

Answer 56

Restrictive = Moves to the Right Obstructive = Moves to the Left

Answer 57

Triiodothyronine (T3) exerts direct effects on the myocardium and may result in thyrotoxic cardiomyopathy, characterized by **fibrotic and fatty changes with lymphocytic and eosinophilic infiltration.**

Answer 58

``` RV = Increases TV = No change ``` TLC = Decrease VC = Decrease

Answer 59

**Aortic Valve Insufficiency**

Answer 60

Inhaled nitric oxide is an inhaled **pulmonary vasodilator** with an **extremely short half** that is used to improve pulmonary blood flow in area that are receiving ventilation. It **optimizes V/Q mismatch** and also reduces pulmonary blood pressures.

Answer 61

**Higher frequency** (shorter wavelengths) means better resolution, but worse penetration. **Lower frequency** (longer wavelengths) gives better penetration but sacrifices resolution.

Answer 62

Resolution is actually a very complex concept and is split into: 1. Axial resolution 2. Temporal resolution 3. Lateral resolution

Answer 63

**Axial resolution** is a function of the probe frequency and pulse width and represents the resolution along the *_vertical projection of the ultrasound beam_*. Resolution is improved with higher frequency, lower wavelength, and shorter pulse width.

Answer 64

**Lateral resolution** is the resolution along the *_horizontal axis of the ultrasound image and is a function of the beam formation_*. The image has both and near and far field. The near field is columnar in shape, the length of which increases with higher frequency. The far field results in a divergence of the beam and blurring of the ultrasound image produces. Divergence increases with lower frequency and wider ultrasound probes.

Answer 65

**Temporal resolution** is the ability of the probe to differentiate moving objects in time and is the "frame rate" of the ultrasound image. With decreasing scan depth, temporal resolution improves.

Answer 66

Antithrombin III inactivates multiple coagulant factors, most notably **thrombin (factor II)**, **factor Xa**, and other factors in the intrinsic pathway (see figure below)

Answer 67

Enoxaparin similarly binds and enhances the effects of AT3. However, the enoxaparin-induced conformational change of AT3 makes enoxaparin **preferentially inhibit factor Xa**

Answer 68

Monitoring may be recommended in patients with **extreme BMIs** (high or low), **renal** **impairment**, or in **pregnant patients**.

Answer 69

Malignant hyperthermia-susceptible patients have **RYR1 defects** that, in the presence of a triggering agent (succinylcholine or any volatile anesthetic) Cause **prolonged opening of the channel** which leads to sustained muscle contraction. This produces a generalized hypermetabolic state characterized by increased **CO2,** **lactate**, and **heat** production which can progress to muscle cell breakdown and leads to *_hyperkalemia*_, _*rhabdomyolysis*_, and their sequelae (_*arrhythmias*_; _*liver, kidney, and other end-organ damage, and death_*).

Answer 70

**Diuretics** and **Mannitol** (Keep UOP 1-2 mL/kg/hr) CK levels will rise and can cause myoglobinuria **Each 20 mg Vial of Dantrolene contains 3 grams of Mannitol**

Answer 71

**Dose for Crisis**: IV: Initial: *_2.5 mg/kg*_; monitor patient continuously and give repeat doses of _*1 mg/kg*_ until symptoms subside or a _*cumulative dose of 10 mg/kg is reached_* **MOA**: Acts directly on skeletal muscle by interfering with release of calcium ion from the sarcoplasmic reticulum; prevents or reduces the increase in myoplasmic calcium ion concentration that activates the acute catabolic processes associated with malignant hyperthermia

Answer 72

1. Isocarboxazid 2. Phenelzine 3. Selegiline 4. Tranylcypromine

Answer 73

- Spontaneous *_clonus_* - Inducible *_clonus_* plus agitation or diaphoresis - Ocular *_clonus_* plus agitation or diaphoresis - Tremor plus *_hyperreflexia_* - Hypertonia plus temperature \> 38 °C plus ocular clonus or inducible clonus **Hunter Toxicity Criteria** Serotonin syndrome results from coadministration of multiple serotonergic medications. It results in **tachycardia, clonus, hyperreflexia, ataxia, and confusion.**

Answer 74

Neuroleptic malignant syndrome occurs in patients taking antipsychotic medication. It is characterized by **muscle rigidity** and **altered consciousness**. Both *_first-generation neuroleptic medications*_, such as haloperidol, and _*newer atypical antipsychotics_* have been implicated in neuroleptic malignant syndrome.

Answer 75

1. **Discontinue serotonergic agents** (Fent, SSRI, Ondansetron) 2. **Supportive care** 3. **Benzos** (Diazepam 10-20 mg IV 4. **Cyproheptadine** (Serotonergic antagonist) 12 mg PO and repeat 2 mg Q2H (Max of 32 mg / day) 5. **Dexmedeotmidine** 6. **Hyperthermia** (If severe, intubate sedate and paralyze) 7. **Chlorpromazine** (Phenothiazine with anti-serotonergic effects 50-100 mg IM

Answer 76

1. Agitation should be controlled with **Benzodiazepines** Lorazepam 2 mg IV q5 min until agitation and muscle rigidity resolves 2. **Supportive**/**Fluid resuscitation** 3. **Cooling** measures 4. **Intubation** and paralysis for severe cases, chest wall rigidity or respiratory failure Use NON-DEPOLARIZING paralytic agent

Answer 77

**Hydrocortisone** 1, 1, 8-10 hours **Prednisone** 4, 0.8, 18-36 hours **Prednisolone** 4, 0.8, 12-26 hours **Methylprednisolone** 5, 0.5, 18-36 hours **Dexamethasone** 25-30, 0, 36-54 hours **Fludrocortisone** 10, 120, 18-36 hours

Answer 78

8 mg of dexamethasone is equivalent to 200 mg of hydrocortisone and **will suffice to prevent adrenal insufficiency** with most commonly performed surgeries

Answer 79

Fludrocortisone is a potent mineralocorticoid. Even in patients with symptomatic adrenal suppression, treatment with fludrocortisone is not recommended **since most of the problems from adrenal suppression are secondary to both mineralocorticoid and glucocorticoid deficiency and thus both need to be supplemented**.

Answer 80

**Hydrocortisone** is the agent of choice for treating adrenal suppression during stressful surgeries because it has a **1:1 glucocorticoid: mineralocorticoid effect.** However, most current literature suggests that dexamethasone alone is appropriate for prophylaxis in patients with possible secondary adrenal insufficiency (e.g. due to steroid use).

Answer 81

Mineralocorticoid prophylaxis is most appropriate for patients with **primary adrenal insufficiency (unrelated to chronic steroid use).**

Answer 82

X axis = Cardiac Output Y axis = EDV (Of the LV) ***_Classes:_*** 1. Diuretics 2. Ionotropic agents 3. Vasodilators

Answer 83

Sevoflurane = 157 Isoflurane = 240 Desflurane = 669

Answer 84

*_1. Morphine - 6 - Glucuronide (Primary active metabolite)_* 100 fold potent, **yet (CAVEAT)** exhibits an equal or decreased affinity for mu-opioid receptors. Its increased potency, however, can lead to **significant respiratory depression** in renal failure due to accumulation from **delayed excretion.** *_2. Morphine - 3 - Glucuronide (Minority inactive metabolite)_* Nearly 300 fold lower affinity for the μ-receptors but it may have **neuroexcitatory effects**; **myoclonus** and **allodynia** are seen after large doses.

Answer 85

1. **Tricyclic antidepressant** (e.g. amitriptyline, nortriptyline) 2. S**erotonin-norepinephrine reuptake inhibitor** (e.g. duloxetine aka Cymbalta, milnacipran, venlafaxine) 3. **Alpha-2/delta calcium channel modulator** (e.g. gabapentin, pregabalin)

Answer 86

Oxygen is the most influential factor in the closure of the ductus in the full-term infant. The ductus arteriosus is usually functionally closed by the second day of life. In a full-term infant, a **PaO2 of about 50 mmHg constricts the vessel**. Oxygen tension is not as influential in closing the preterm neonate's ductus arteriosus

Answer 87

**RCA** = Right heart and basal septum **Middle septum** = RCA or LAD **Apical septum** = LAD **Lateral wall** = LAD or Circumflex

Answer 88

Inferior Wall (Left) = RCA Anterior Wall (right) = LAD

Answer 89

Posterior wall (left) = RCA or Circumflex Anteroseptal wall (right and base) = LAD

Answer 90

Notice, the distribution depends on coronary dominance

Answer 91

*_"**I SM**i**LN RO**"_* 1. **IV** 100% 2. **SQ** 96% 3. **IM** 85-87% 4. **SL / Buccal** 74.5% 5. **Intranasal** 50-83% 6. **Rectal** 18-52% 7. **Oral** 15-52%

Answer 92

~2000 psi (1900- 2200) 660 Liters

Answer 93

1590 Liters 745 psg

Answer 94

1590 Liters 838 psi

Answer 95

(Appoximately Same as Oxygen) 1900 psi 620 Liters

Answer 96

500 Liters 1600 psi

Answer 97

X axis = LV Volume Y Axis = LV pressure

Answer 98

1. **Thyroid Replacement** - *_Levothyroxine_* preferred (TSH secretion regulation and conversion to T3) - *_Liothyronine_* (most potent form) can precipitate myocardial ischemia 2. **Hydrocortisone** (5-10%) of patients can have adrenal insufficiency

Answer 99

The lumbar plexus gives rise to the **femoral nerve, obturator nerve, and lateral femoral cutaneous nerve**. The sacral plexus gives rise to the **posterior cutaneous nerve of the thigh and sciatic nerve.**

Answer 100

The sciatic nerve provides cutaneous innervation to the **posterior thigh and all of the leg and foot below the knee, except for a medial strip supplied by the saphenous nerve.**

Answer 101

**Tibial** and **common peroneal** nerves

Answer 102

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 103

Autosomal Dominant

Answer 104

Strenuous exercise Excitement High sodium Carbohydrate meals

Answer 105

Fibrinolysis (fibrin breakdown), a normal hematologic activity that leads to removal of thrombus when endothelium heals, is conducted mostly by the enzyme **plasmin**, the product of cleavage of **plasminogen** by tissue plasminogen activator (**tPA**).

Answer 106

**Fibrinolysis can be excessive and lead to bleeding**, for example after cardiopulmonary bypass (cardiopulmonary bypass causes the endothelium to release tPA). Currently available **antifibrinolytic agents (aminocaproic acid and tranexamic acid) are analogs of the amino acid lysine**, and as such they *_competitively inhibit the binding of plasmin(ogen) lysine binding sites to the lysine residues in fibrin_*. In other words, they prevent the formation of the ternary complex mentioned above. Antifibrinolytic agents have been shown to reduce total perioperative blood loss and the number of patients transfused in major cardiac, orthopedic, or liver surgery. Currently, the ASA guidelines give a recommendation to "use" such agents for prevention of bleeding in patients undergoing cardiopulmonary bypass, but only of "consider using" for other indications.

Answer 107

**fibrinolysis**, **massive transfusion**, and low fibrinogen concentration (definitions of "low" vary and are typically higher in pregnancy).

Answer 108

1. Competitively **inhibits activation of plasminogen** (via binding to the kringle domain), thereby *_reducing conversion of plasminogen to plasmin_* (fibrinolysin), an **enzyme that degrades fibrin clots, fibrinogen, and other plasma proteins, including the procoagulant factors V and VIII.** ## Footnote 2. Directly inhibits plasmin activity, but higher doses are required than are needed to reduce plasmin formation.

Answer 109

**M**edian Nerve, **B**rachial Artery, **R**adial Nerve

Answer 110

It is the largest nerve in the body that is not protected by muscle or bone, is the **ULNAR NERVE** The ulnar nerve travels down the medial aspect of the upper and lower arm. It could be considered the most medial neurovascular structure in the arm at the level of the elbow, however at the level of the antecubital fossa it courses posterior to the medial epicondyle of the humerus

Answer 111

**MELD**: "I Crush Several Beers Daily" for INR, creatinine, sodium, bilirubin, dialysis "C DIBS" on MELD

Answer 112

Childs-Pugh: "Pour Another Beer At Eleven" for PT, Ascites, Bilirubin, Albumin, Encephalopathy

Answer 113

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 114

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.**

Answer 115

Surgical stimulus and heightened states of arousal (e.g. fear or anxiety) cause hyperventilation. This typically causes a **leftward shift and increased slope of the carbon dioxide ventilatory response curve (VRC).**

Answer 116

Increased chest wall stiffness, loss of muscle mass, flattening of the diaphragm, and increased compliance of lung parenchyma lead to several physiologic changes in elderly respiration. The volume at which small airways collapse increases with aging, such that by the mid-60s, **closing capacity surpasses (increases) functional residual capacity and will eventually surpass tidal volume.**

Answer 117

**I ∝ 1 / r²** Where: I = intensity, S = source strength, r = radius (distance from source) Ex: 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 118

General anesthetic effects on the brain most resemble the naturally occurring **non-rapid eye movement (NREM) sleep pattern**

Answer 119

General anesthetic effects on the brain most resemble the naturally occurring non-rapid eye movement (NREM) sleep pattern on **EEG (slow-frequency, large-amplitude).** There is a transition from the _low amplitude, fast-frequency pattern of wakefulness_, to the **high amplitude, slow-frequency EEG of NREM sleep.**

Answer 120

Blood PCO2 is measured by a **Severinghaus electrode** using a method that builds upon the pH electrode mechanism. Carbon dioxide from the blood sample equilibrates across a semipermeable membrane with a bicarbonate solution. The reaction generates H+ ions and the PCO2 is determined by the degree of pH change resulting from the H+ ion generation.

Answer 121

Base excess (or deficit) is calculated from the measured sample pH and calculated bicarbonate concentration based on the following formula, called the **Van Slyke equation**. Note it is not necessary to memorize this formula for testing purposes. **BE = 0.9287 \* [HCO3- – 24.4 + (pH – 7.4)]** This formula determines what is called the standardized base excess and represents serum base excess. Prior to the 1960s, whole-blood base excess was measured instead. The standardized base excess better reflects the true base excess in the extracellular fluid since it is not complicated by (and corrects for) the ability of hemoglobin to buffer acid.

Answer 122

The metabolic component of the acid–base balance is reflected in the base excess. This is a calculated value derived from blood pH and PaCO2. It is **defined as the amount of acid required to restore a litre of blood to its normal pH (7.4) at a PaCO2 of 40 mmHg**. The base excess *_increases in metabolic alkalosis*_ and _*decreases (or becomes more negative)_* in metabolic acidosis, but its utility in interpreting blood gas results is controversial.

Answer 123

Blood PO2 is most commonly directly measured by a **Clark electrode** which detects the amount of current that flows between the two electrodes (amperometric). Oxygen from the blood sample diffuses across a semipermeable membrane and is reduced at the cathode, resulting in a reaction that produces a measurable current that is directly proportional to the PO2.

Answer 124

pH is measured via the **Sanz electrode** Blood pH is directly measured using an optical absorbance technique or a pH electrode. The latter measures the potential difference between a measuring electrode (which contains the blood sample in contact with a special glass membrane permeable only to H+ ions) and a reference electrode with a stable, known pH.

Answer 125

It is important to commit the following to memory: **pO2** is measured via the Clark electrode (as per above) **pCO2** is measured via the Severinghouse electrode **pH** is measured via the Sanz electrode

Answer 126

One easy pneumonic to remember drugs that do NOT cross the placenta and are also considered safe is: He Is Going Nowhere Soon (**Heparin, Insulin, Glycopyrrolate, NDNMB, Succinylcholine**).

Answer 127

Oxygen diffuses across the placenta from the higher maternal oxygen concentration to the **lower fetal concentration of about 40 mmHg** Oxygen diffuses across the placenta from the higher maternal oxygen concentration to the lower fetal concentration of about 40 mmHg. The fetal oxyhemoglobin dissociation curve is left-shifted causing it to more tightly hold onto the oxygen it receives. Carbon dioxide transfer to the maternal circulation is limited by blood flow rather than diffusion.

Answer 128

Because fetal blood is more acidotic than maternal blood, certain drugs such as local anesthetics will form higher concentrations of their ionized forms **(Quaternary Amines)** preventing the drugs from readily diffusing back across the placenta despite having a higher concentration gradient than the maternal circulation. This is termed ion trapping. With local anesthetics, this can lead to toxic effects in the fetus such as **decreased muscle tone, arrhythmias, and cardiovascular depression**

Answer 129

***_Neuromuscular blockade reversal_*** IV: **15 to 30 mcg/kg** administered with neostigmine *_(Glyco dose is 10-15 mcg/kg for reference so its 1.5 to 2x the dose)_*

Answer 130

**Neostigmine Dosing** 30 - 70 mcg/kg of Neostigmine depending on twitches 1-3 twitches use 50-70 mcg/kg of neostigmine 4 twitches with fade 50 mcg/kg of neostigmine 4 twitches without fade 20 mcg/kg **Glycopyrrolate Dosing** 10 - 15 mcg/kg of Glycopyrrolate depending on HR OR 200 mcg for each 1 mg of Neostigmine

Answer 131

The dose delivered is **0.5 to 1 mg/kg of edrophonium** and **7 to 14 mcg/kg of atropine**. An edrophonium dose of 1 mg/kg should rarely be exceeded. Note: Monitor closely for bradyarrhythmias.

Answer 132

IV: 15 to 30 mcg/kg administered with neostigmine IV: 7 to 14 mcg/kg administered with edrophonium

Answer 133

**high unionized fraction** of alfentanil (**low pKa**) leads to a more rapid onset

Answer 134

The hard palate (**maxilla** and **palatine** bones) forms the anterior two-thirds of the roof of the mouth. (The palatine bone is highlighted in green in the image)

Answer 135

The tongue is anchored to the mandible by the **genioglossus** muscle. When sleeping or under general anesthesia, the tongue often displaces posteriorly into the oropharynx causing upper airway obstruction

Answer 136

larynx **begins at the epiglottis**, includes the thyroid cartilage and **ends at the cricoid cartilage**.

Answer 137

Chula formula: ETT depth = **0.1 \* [height (cm)] + 4** **18 cm** for **under 4'9"** **19 cm** for **4'10" to 5'2"** **20 cm** for **5'2" to 5'5"** **21 cm** for **5'5" to 5'9"** **22 cm** for **5'9" to 6'1"** **23 cm** for **over 6'1" to 6'5"**

Answer 138

In **adults**, the spinal cord ends at about **L1-L2 (conus medullaris)** and the dural sac ends at about **S1-S2** In an **infant**, these landmarks are shifted slightly caudad with the spinal cord ending at **L3-L4** and the dural sac terminating at **S3-S4**.

Answer 139

The lateral antebrachial cutaneous nerve is a branch of the **musculocutaneous** nerve. It provides cutaneous innervation to the **lateral half of the forearm.** It arises from **C5-C6** and therefore is part of the brachial plexus and would most likely be blocked by a **supraclavicular nerve block.**

Answer 140

SSEPs are quantified by the amplitude of the signal generated and the latency of the signal, which is the time it takes for the impulse to reach the cortex. Anything that decreases the amplitude or increases the latency is concerning. This could be from direct damage to the nerve or ischemic insult. A clinically significant **decrease in amplitude is 50% from baseline** and a **10% increase in latency.**

Answer 141

SSEPs are quantified by the **amplitude of the signal generated and the latency of the signal, which is the time it takes for the impulse to reach the cortex.** Motor evoked potentials (MEP) are used to **evaluate the integrity of the descending motor neuronal pathways**.

Answer 142

Clinically significant change in MEP is a **50% decrease in amplitude from baseline.** Latency is less important than compared to SSEPs.

Answer 143

Both SSEPs and MEPs are sensitive to volatile anesthetic agents, but **this is more so with MEPs**. ## Footnote *_Unlike SSEPs, MEPs require that paralytic agents not be used, although occasionally a low dose neuromuscular blocker may be requested to minimize the background noise of the MEPs._*

Answer 144

**BAEP (Brainstem auditory) is extremely resistant** to all anesthetic techniques. MEPs are very sensitive to and supressed by volatile agents, and total intravenous anesthesia is the preferred anesthetic if MEPs are to be used. **VEPs (Visual) are the most sensitive** of the evoked potentials to volatile anesthetics.

Answer 145

Lambert-Eaton Myasthenic Syndrome (LEMS) is a paraneoplastic syndrome strongly associated with **small cell carcinoma** of the lung, **sarcoidosis**, **thyroiditis**, a collagen related **vascular disease**, or other malignancies.

Answer 146

As *_inspiration_* occurs, **intrapleural pressure grows more negative,** which leads to an increase in transmural pressure across both vena cava and right atrium. This leads to an expansion of chamber size and facilitates venous return given the decreased pressure in the right atrium. **Simply stated, right atrial pressure falls during inspiration, creating a pressure gradient that drives an increased venous return**. *_Expiration_* leads to a more **positive intrapleural pressure** thus decreasing transmural pressure and decreasing chamber volume. This leads to a decreased venous return.

Answer 147

**Off-pump**: *_Initial bolus: 0.75 mg/kg_*, followed by continuous infusion 1.75 mg/kg/hour to maintain ACT \>300 seconds (Dyke 2007). If patient needs to go on-pump, some have recommended an additional 0.25 mg/kg bolus and increasing the *_i_**_nfusion rate to 2.5 mg/kg/hour_* (Angiomax Canadian product labeling 2016). **On-pump**: *_Initial bolus: 1 mg/kg*_, followed by continuous infusion _*2.5 mg/kg/hour_*; 50 mg bolus added to priming solution of cardiopulmonary bypass (CPB) circuit. Additional boluses of *_0.1 to 0.5 mg/kg_* may be given to maintain ACT \>2.5 times baseline ACT. *_Discontinue infusion 10 to 15 minutes_* prior to weaning from CPB (Salter 2016).

Answer 148

**Mean: 1.5 hours**; Range: 1 to 2 hours Affected by obesity, renal function, malignancy, presence of pulmonary embolism, and infections.

Answer 149

**1. 1 mg** of protamine neutralizes **~100 units of heparin** Maximum single dose: 50 mg **2. Go back to see what time the Heparin was given** Because blood heparin concentrations decrease rapidly after heparin administration (*_half-life of heparin is ~60 to 90 minutes_*), may adjust the protamine dosage depending upon the duration of time since heparin administration. For example, if 2 hours has elapsed since heparin overdose, consider administering half of the calculated initial protamine dose; this is more conservative compared to product labeling, **which suggests administering half of the calculated dose at 30 minutes after heparin administration**. If patient is not bleeding, consider not administering protamine since risks may outweigh benefits of administration (Howland 2019).

Answer 150

**Classically, a goal of 480 seconds** has been used. However, with improvements in bypass circuits, some providers initiate **CPB at a value of 400 seconds.**

Answer 151

1. AT 3 concentrate 2. FFP (2-3 Units)

Answer 152

**Donor atrium** is responsible for heart rate generation

Answer 153

**Normal** In the normal innervated heart, the response to a sudden reduction in intravascular volume is an **increase in heart rate and contractility.** *_Transplants_* The initial response is an *_increase in stroke volume dependent on an adequate preload_* and not an acute increase in heart rate or contractility. The increased contractility and heart rate is a secondary effect and is predominantly dependent on circulating catecholamine levels. *_Therefore, the transplanted heart is critically preload dependent._*

Answer 154

Anesthetic Implications **Anticholinergic agents** which are *_indirect acting agents_* (e.g. atropine, glycopyrrolate, pancuronium) have minimal effect on heart rate. The response to **anticholinesterases is unpredictable.** The transplanted heart does retain its **responsiveness to direct acting agents** *_(i.e.) isoproterenol, epinephrine, norepinephrine, dopamine, and dobutamine_*

Answer 155

**90-110 bpm** (**Higher** due to *_loss of parasympathetic_* tone) with **less variability**

Answer 156

* *The list of patients who should receive prophylaxis is below:** - Patients with a *_prosthetic cardiac valve_* - Patients who have *_previously had IE_* - Patients with *_unrepaired cyanotic congenital heart diseas_*e (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 157

**Amoxicillin 2 g given as a one time oral dose 30-60 min before the procedure.**

Answer 158

**1. Microoganisms in a vegetation** - Culture or histological examination of a vegetation - Vegetation that has embolized - Intracadiac abscess specimen **2. Pathological lesions** **-** Vegetation or intracardiac abscess confirmed by histological examination showing active endocarditis

Answer 159

**1. Blood cultures positive for endocarditis** - 2 separate cultures - Microorganisms consistent with IE from persistently positive blood cultures - Single positive culture for Coxiella Burnetii or Antiphase I IgG antibody titer \> 1:800 **2. Evidence of Endocardial Involvement** - Echocardiogram positive for IE - New partial dehiscence of prosthetic valve - New valvular regurgitation Note: Worsening or changing pre-existing murmur NOT sufficient

Answer 160

**1. IVDU or Predisposing Heart Condition** **2. Fever** **3. Vasular Phenomenon** - Emboli (Major aterial) - Septic Pulmonary infarcts - Mycotic aneurysm - Intracranial hemorrhage - Conjunctival hemorrhages - Janeway Lesions **4. Immunological Phenomemon** - Glomerulonephritis - Osler's Nodes - Roth's Spots - Rheumatoid Factor **5. Microbiological evidence** - Positive Blood culture that does not meet major criterion as noted in definitive/major role - Serological evidence of active infection with organism consistent with IE

Answer 161

1. **Meets Pathological Criteria** (Vegetation histology) 2. **One Major and 3 minor** 3. **5 Minor**

Answer 162

Butorphanol is a mixed **mu-opioid receptor agonist-antagonist** and a **kappa-opioid receptor partial agonist** Agonist of kappa opiate receptors and partial agonist of mu opiate receptors in the CNS, causing inhibition of ascending pain pathways, altering the perception of and response to pain; produces analgesia, respiratory depression, and sedation similar to opioids

Answer 163

1. Treating pain 2. Postoperative shivering 3. Neuraxial opioid-induced central pruritus Butorphanol is a mixed mu-opioid receptor agonist-antagonist and a kappa-opioid receptor partial agonist. Its **mu receptor** activity makes it useful in treating **pain** and **neuraxial opioid-induced central pruritus**. Meanwhile, its *_kappa receptor*_ activity makes it a good treatment for _*postoperative shivering_*.

Answer 164

**Boyle P1V1 = P2V2** - Boils have a high *_TEMPERATURE_* **Charles = V1 / T1 = V2 / T2** - King Charles under *_PRESSURE_* **Gay-Lussac P1/T1 = P2/T2** - Think of Cul de SACC (Lussac) have constant *_Volume_* of space

Answer 165

This pairs with the higher SVR goal, as the **higher SVR will encourage a higher coronary perfusion pressure** (diastolic blood pressure - left ventricular end-diastolic pressure) to ensure that the thick LV is adequately perfused. An elevated SVR in the setting of AS may seem counter-intuitive, as there is an obstructive lesion in the LV outflow tract, however in cases of severe or critical AS, this **stenotic aortic valve provides much greater resistance to LV outflow than any physiologic SVR that can be generated**

Answer 166

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

Answer 167

As opioids cross the dura and enter the CSF, highly lipophilic drugs will remain primarily at the level of injection. However, opioids with a **low lipid solubility, like morphine, will diffuse greatly and have a widespread in the CSF.** When placed in the epidural space, opioids act through diffusion into the CSF. Spread of opioids is related to the hydrophilicity and lipophilicity of the opioid. Fentanyl is very lipid soluble and remains near the spinal level it is injected at, whereas morphine has a widespread in the CSF.

Answer 168

**pKa** and **Tissue diffusibility** **Lower pKa =** More rapid onset of action (more RN molecules present to diffuse through the nerve sheath)

Answer 169

**Lipid Solubility** & **Vasodilator** activity

Answer 170

**Protein Binding** & **Vasodilator** Activity

Answer 171

Local anesthetics "PLOPS" ## Footnote **P**otency - **L**ipid Solubility **O**nset **= p**Ka **P**otency - Lipid **S**olubility

Answer 172

Diagnosis - **Cerebral Salt Wasting** Mechanism of Action - **Excess secretion of Na and Water** Volume Status - **Hypovolemia** Serum [Na] - **Decreased** Urine [Na} - **Increased** Urine Output - **Increased**

Answer 173

**SIADH** Mechanism of Action - **Water retention due to elevated ADH** Volume Status - **Normovolemic or Hypervolemic** Serum [Na] - **Decreased** Urine [Na] - **Increased** Urine Output - **Normal**

Answer 174

**Diabetes Insipidus** Mechanism of Action - **Free Water loss due to decreased ADH** Volume Status - **Hypovolemia** Serum [Na] - **Increased** Urine [Na} - **Decreased** Urine Output - **Increased**

Answer 175

In normal healthy adults, **PVR is lowest when breathing at normal tidal volumes, with a nadir at functional residual capacity (FRC).** Increasing or decreasing lung volumes beyond FRC and normal tidal volumes results in an increase in PVR, creating a U-shaped curve, illustrated below. This general relationship exists for both normal breathing and positive-pressure breathing.

Answer 176

Remember to get an: Echo EKG ABG **Hypovolemia** **Hypoxia** **Hydrogen ions (Acidosis)** **Hyper and Hypokalemia** **Toxins** **Tamponade** **Tension Pneumothorax** **Thrombosis** **Trauma**

Answer 177

1. **Re-bleeding** (~24 hours after initial hemorrhage) 2. **Vasopasm** (3-10 days, Peaks at 5th -10th day, Resolve 10-14 days) 3. **Hydrocephalus**

Answer 178

Neuraxial fentanyl results in rapid onset of analgesia primarily through **activation of mu receptors in the substantia gelatinosa in the dorsal horn of the spinal cord.** Opioids activate G-protein coupled inhibitory receptors both pre and postsynaptically to inhibit the release of excitatory neurotransmitters (presynaptic) and hyperpolarize postsynaptic neurons to inhibit neuronal transmission. In the brain, exogenous and endogenous **opioids work in the area of the periaqueductal gray matter of the midbrain and rostral ventromedial medulla and modulate descending inhibitory pain pathways**. Systemic administration, ascent in the CSF to the brain (hydrophilic opioids such as morphine), and absorption from neuraxial administration (primarily with lipophilic opioids such as fentanyl) activate these descending inhibitory pathways. Neuraxial administration of opioids results in analgesia primarily by action in the **dorsal horn of the spinal cord in the substantia gelatinosa** where they inhibit release of excitatory neurotransmitters such as substance P and glutamate and inhibit afferent neural transmission to the brain from incoming peripheral pain neurons.

Answer 179

Gastrointestinal - Anticholinergic activity leads to decreased salivary gland secretions and gastric secretions. This can lead to the side effect of a **dry mouth** for patients upon awakening from anesthesia. - **Decreased gastric motility and peristalsis**, which can lead to **constipation**.

Answer 180

Respiratory - Muscarinic receptors in the airway mucosa and bronchi are responsible for **salivation** and **respiratory secretions**. Blocking these receptors therefore inhibits these secretions, which is beneficial when performing a fiberoptic intubation. - Blocking muscarinic receptors in the bronchial smooth muscle leads to **relaxation and decreased airway resistance.**

Answer 181

Genitourinary - Blocking muscarinic receptors in the smooth muscle of the bladder causes relaxation and decreased bladder and ureter tone. This can lead to **urinary retention**, particularly in males with an enlarged prostate.

Answer 182

Ophthalmic - Anticholinergic activity causes **pupillary dilation,** which could theoretically cause problems in patients with narrow angle glaucoma. It can also cause **photophobia**

Answer 183

Neurologic - **Glycopyrrolate** does not cross the blood brain barrier and therefore does **not have any neurologic side effects**. Other *_anticholinergics*_ such as _*atropine*_ and _*scopolamine*_, however, can lead to _*altered mental status and hallucinations._*

Answer 184

**1. Including increased risk of sepsis** **2. Coagulopathy** **3. Irreversible bleeding** **4. Acidosis** One complication of massive transfusion is the classic triad of coagulopathy, hypothermia, and acidosis. This is also called the "trauma triad of death." These three factors are closely linked and contribute to worsening outcomes in patients receiving massive transfusions.

Answer 185

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

Answer 186

Glucocorticoids act to **produce more aldosterone** and *_inhibit the phospholipase A2 enzyme (PLA2)_*. The PLA2 enzyme converts phosphatidylcholine to arachidonic acid, a precursor to prostaglandins, leukotrienes, and other proinflammatory mediators (e.g. TNF-α, interleukin-1, interleukin-6, cellular adhesion molecules).

Answer 187

The suggested dose is **200 mg IV hydrocortisone per day**. There is no commonly recommended dosing regimen (bolus vs divided doses vs infusion). Spreading doses apart or using an infusion can reduce some of the side effects, such as hyperglycemia. Steroids should be tapered once vasopressors are no longer required.

Answer 188

Hypoventilation does not increase the risk of toxicity; the reverse is true. **Hyperventilation increases the risk of citrate toxicity** in a certain subset of patients because it causes a **decrease in ionized calcium ions**. This is why signs of hypocalcemia can be seen in patients who have anxiety attacks and hyperventilate. In certain patients, hyperventilation will result in ionized calcium ions binding to proteins. **Since citrate toxicity is actually due to hypocalcemia, anything that decreases the ionized calcium ions will increase the risk for citrate toxicity.**

Answer 189

Pediatric patients are more likely to experience citrate toxicity. This is especially true of the neonatal population due to **decreased metabolism secondary to hepatic immaturity.**

Answer 190

**Fresh frozen plasma** is more likely to cause citrate toxicity compared with other blood products because more citrate is used.

Answer 191

**Deepening Anesthetic** (Propofol or Volataile except Desfluranae) **B****eta-adrenergic agonists (Albuterol)** **Epinephrine** 10-20 mcg IV **M****uscarinic antagonists (Glyco 0.2, atropine 0.1 - 0.5 mg)**, **Magnesium** (Acute severe exacerbations) (off-label use): IV: **2 g as a single dose over 20 minutes** (GINA 2019; NAEPP 2007); recommended as adjunctive therapy for severe life-threatening exacerbations and for exacerbations that remain severe after 1 hour of intensive conventional therapy (NAEPP 2007). **K****etamine (**doses as high as**60 mcg/kg**/minute (3.6 mg/kg/hour) have been reported in patients with refractory bronchospasm (Youssef-Ahmed 1996) and **Theophylline (**SQ: 0.25 mg/dose; may repeat every 20 minutes for 3 doses (maximum: 0.75 mg/1-hour period)

Answer 192

**Elevated blood urea (BUN)** levels usually occur in the setting of decreased clearance due to renal dysfunction. Common symptoms include fatigue, nausea, vomiting, altered mental status, and metabolic acidosis. One of the **major pharmacologic effects of uremia is decreased protein-binding of drugs**. Because it is the free-fraction of a medication that exerts its physiologic effect, **decreased protein binding of midazolam would cause an exaggerated effect and the dosage should, therefore, be decreased**. Additionally, premedication in any patient with an altered mental status should be avoided. Medications that are rapidly metabolized in the bloodstream, such as remifentanil and esmolol, or those that are not metabolized at all, such as volatile anesthetics, do not require a significantly decreased dosage.

Answer 193

Elevated Intracranial Pressure Gold Standard: A **ventriculostomy catheter** is the most cost-effective, accurate, and reliable method of monitoring intracranial pressure (ICP) and is currently the gold standard for ICP measurement. It is also very useful in that it provides a way to drain cerebrospinal fluid (CSF), and samples for lab analysis.

Answer 194

1. **Intraventricular** 2. **Intraparenchymal** 3. **Subarachnoid** 4. **Epidural** (lumbar subarachnoid catheter). 5. A non-invasive option is measuring **optic nerve sheath diameter via ultrasound**

Answer 195

In ***_fibrinolysis_*** candidates, it should be **lowered if above 185 mm Hg systolic or 110 mm Hg diastolic.** Treatment options include labetalol, nicardipine infusion, or clevidipine infusion. Significant blood pressure decreases should be avoided. Once blood pressure is controlled, fibrinolysis can proceed. **Following *_fibrinolysis_* for 24 hours, or during treatment, systolic blood pressure above 180 mm Hg or diastolic above 105 mm Hg can be treated with additional doses of labetalol or other antihypertensives.** For **asymptomatic** patients who have not undergone fibrinolysis, guidelines indicate it is reasonable to use antihypertensives to **reduce blood pressure below 220 mm Hg systolic, or 120 mm Hg diastolic.**

Answer 196

The goal to fibrinolysis is **60 minutes from presentation**, with a **recommended cutoff of 3 to 4.5 hours** from onset of symptoms.

Answer 197

Ketamine is known as a more “stable” induction agent because it often maintains hemodynamic parameters. Ketamine is one of the only induction medications that stimulate the sympathetic nervous system. It can lead to an increase in blood pressure and heart rate, up to **30% above baseline**. These changes are **often seen within five minutes of intravenous injection** and up to **twenty minutes after an intramuscular injection**. The changes often ***_last for 20 minutes_*** after intravenous injection and there is a wide variation in individual response.

Answer 198

**Inhibits reuptake of catecholamines and nitric oxide endothelial production. This results in vasoconstriction and a *_positive_* inotropic state. Additionally, ketamine acts as a vagal nerve inhibitor.** In states where the *_sympathetic nervous system may be exhausted, ketamine may have a **negative** inotropic effect_*. This is secondary to a depletion of catecholamines that occurs in these states. An example of this is critical illness or shock states. Given this potential, ketamine should be used cautiously in patients with decompensated ventricular failure or catecholamine depletion.

Answer 199

The pathophysiology of ischemia-reperfusion injury is complex, however one of the mechanisms is thought to be **disruption of the sodium potassium pumps secondary to decreased adenosine triphosphate and glycogen.**

Answer 200

The **preanhepatic** stage begins with *_incision and ends with cross-clamping of the major vessels of the liver_* (portal vein, hepatic artery, inferior vena cava, or hepatic vein). The **anhepatic** stage starts with *_cross clamping and continues until anastomosis are made and perfusion restarts_* – in other words from occlusion of vascular inflow to start of graft reperfusion. The **neohepatic** phase begins with *_unclamping of the portal vein when reperfusion of the donor liver starts and continues during hepatic artery, biliary duct anastomosis, and abdominal closure._*

Answer 201

During an ultrasound-guided interscalene block, the probe should be moved **laterally and posteriorly** after identifying the carotid artery, and the plexus is found between the anterior and middle scalene muscles.

Answer 202

However, the **ulnar nerve (or inferior trunk)** is frequently spared

Answer 203

Potential problems include **phrenic nerve blocks**, **pneumothorax**, **recurrent laryngeal** and **vagus nerve** injury, **epidural**, **intrathecal**, or **intravascular** injection.

Answer 204

Amniotic fluid embolism is an **anaphylactoid syndrome** that is thought to result from the seeding of amniotic fluid or fetal cells in the maternal circulation causing hypoxia due to bronchospasm, pulmonary hypertension, and eventual cardiovascular collapse Amniotic fluid embolism is sometimes referred to as **'anaphylactoid syndrome of pregnancy'.**

Answer 205

Amniotic fluid contains many **vasoactive and procoagulant factors**, the entry of this fluid into systemic circulation results in a *_massive inflammatory release*_ and eventual _*disseminated intravascular coagulopathy_*

Answer 206

One of these vasoactive agents, **endothelin**, can cause both **bronchoconstriction and pulmonary and coronary vasoconstriction** and may be responsible for the initial cardiopulmonary collapse seen during the initial phases of AFE.

Answer 207

Tests that assess for a circulating antigen found in meconium may have some diagnostic utility, however, the test for **serum sialyl Tn (STN) antigen** is likely unavailable at most medical facilities. Chest radiography is typically non-specific but may demonstrate bilateral areas of increased homogeneity, similar to pulmonary edema.

Answer 208

**T10 to L1** spinal segment coverage is needed to relieve the pain of contractions and cervical dilation

Answer 209

**S2-S4** spinal segment coverage is needed to relieve the pain of vaginal and perineal distention.

Answer 210

Lidocaine and 2-chloroprocaine are not used for maintenance epidural anesthesia in clinical practice because **tachyphylaxis may develop more rapidly with these agents when compared to longer acting local anesthetics.** Both bupivacaine and ropivacaine have been used and there is no evidence that one has any advantages over the other.

Answer 211

**Ergot alkaloids (e.g. methylergonovine aka Methergine)** are not recommended as they may cause tetanic uterine contractions which can delay placental expulsion and make manual extraction more difficult

Answer 212

In some cases, excessive cervical and/or uterine contractions may prevent expulsion of the placenta. In these cases, **nitroglycerin administration may help facilitate placental delivery**. Careful blood pressure monitoring must occur as a drop is typically seen. Intraumbilical vein injection of oxytocin with saline may be another treatment modality although the WHO states that the evidence may not be strong. *_Other experts recommend against this practice._*

Answer 213

The variation from one beat to another can range from **5-25 BPM**. Variability in the FHR is a sign of a healthy autonomic nervous system, chemoreceptors, baroreceptors, and cardiac responsiveness. FHR becomes non-reassuring if the variability is **\< 5 or \> 25.** A decrease in FHR variability can be due to **fetal sleep state, fetal acidosis, or maternal sedation from drugs**.

Answer 214

Sinusoidal FHR pattern: a smooth sine wave (no variability present). It is rare, however, is associated with *_high rates of fetal morbidity and mortality_*. This **pattern is indicative of severe fetal anemia** **OR** **IV administration of opioid to the mother**

Answer 215

**Occurrence of acute fetal hypoxia**

Answer 216

***_Treatment (PANDAS M.D.)_*** P acemaker A nticoagulation N euraxial plan D elivery A ntibiotics S equalae M onitoring D isposition

Answer 217

**(1) the development of heart failure in the last month** of pregnancy or **within five months of delivery (2 temporal guidelines)** **(2) absence of an identifiable cause** **(3) no history of heart disease** prior to the last month of pregnancy **(4) left ventricular systolic dysfunction** as determined by echocardiogram.

Answer 218

**Nitroglycerin** is the most appropriate initial drug for shoulder dystocia. In order to assist with fetal manipulation, **nitroglycerin is recommended as a fast and efficient tocolytic that resolves quickly.** An appropriate dose and route is 0.4 mg sublingual. **If IV dosing is needed, then 50-200 mcg IV is typical.***_Chloroprocaine*_ may also be useful for quick analgesia in patients who already have an _*epidural_*. In the worst cases of dystocia, the obstetrician may need to intentionally break the fetal clavicle or the anesthesiologist may need to induce general anesthesia in order to emergently deliver.

Answer 219

The characteristic cardiac signs and symptoms of AFE may be divided into 2 stages. **The early stage (1st stage)** generally lasts *_less than 30 minutes*_ and is characterized by transient, often intense, pulmonary vasospasm. The resultant _*right heart dysfunction can progress to fatal right heart failure_*. Low cardiac output then leads to ventilation-perfusion mismatch, hypoxemia, and hypotension. **The second phase of AFE** is characterized by *_left ventricular dysfunction or failure and pulmonary edema_* due to the previous right heart dysfunction. Interestingly, right heart function may return close to normal during this phase. Left or biventricular failure is often fatal unless supportive care is initiated.

Answer 220

One of these states is preeclampsia which occurs in 3% to 8% of pregnancies. The diagnosis of preeclampsia does ***_not_*** require proteinuria. The diagnosis is made when the patient has **elevated blood pressure during pregnancy or in the postpartum period with some degree of end-organ dysfunction.**

Answer 221

Ephedrine is generally avoided, particularly repeated or infusion doses, as some studies have revealed an **increased risk of fetal acidosis.**

Answer 222

Overall maternal mortality has increased over the last several decades in the **United States**, with the most common cause attributable to maternal **cardiovascular conditions (34%).** Hemorrhage, hypertensive disorders of pregnancy, and anesthetic complications have declined in incidence. *_Hemorrhage is the leading cause of maternal death worldwide_*, but only responsible for 11% of pregnancy-related deaths in the United States in 2011-2016. Also note that hemorrhage is mostly related to labor and delivery, while cardiovascular complications can occur at any time during pregnancy including the post-partum period.

Answer 223

The National Institute for Occupational Safety and Health (NIOSH) recommends a maximum exposure of nitrous oxide to healthcare providers of **25 parts per million.**

Answer 224

In the unmedicated parturient, oxygen demand increases by **40% in the first stage** and **75% in the second stage of labor**. This increased oxygen requirement is driven by hyperventilation, the physical effort of pushing out the infant, and uterine contractility. Epidural analgesia will mitigate this increased oxygen demand during the first and second stages of labor.

Answer 225

NIOSH recommends, and other hospital accrediting groups and professional orga- nizations support, that gases inhaled by operating room personnel contain no more than **0.5 ppm of volatile anesthetics.**

Answer 226

1.0 to prevent awareness May need to switch to TIVA From induction to delivery of the infant **1.0 MAC is given to avoid maternal awareness**. After delivery, volatile anesthetics are decreased to 0.5 – 0.75 MAC and oxytocin is given concurrently to decrease the uterine relaxation and thus blood loss. **Less than 0.75 MAC interfere with oxytocin’s effects and at elevated doses lead to uterine atony**. Nitrous oxide, opioids, and ketamine at less than 2 mg/kg have minimal if any effect.

Answer 227

Fetal accelerations are defined by an **abrupt increase** (onset to peak \< 30 seconds) with a **peak of 15/min or more above fetal heart rate (FHR)** baseline and a **duration of 15 seconds** or more from onset to return in a fetus **at least 32 weeks gestation.**

Answer 228

**Reactive non-stress tests** have **≥2 accelerations within a 20-40–minute time period**.

Answer 229

A nonreactive stress test **does not have sufficient FHR accelerations during a 40-minute time period.**

Answer 230

Nitroglycerin - 1.5 - 2.5 mcg/kg Esmolol - 500 to 1000 mcg/kg

Answer 231

Alveolar dead space is reduced during active labor secondary to a **significant increase in cardiac output.** Alveolar dead space consists of alveolar units that are ventilated but not perfused; it is air that is inhaled but does not participate in gas exchange in the alveolar-capillary unit. Because cardiac output increases 10%-40% during active labor, the parturient's **lung units are well perfused with resultant improvement in gas exchange at the level of the alveolar-capillary unit,** reducing the functional alveolar dead space volume

Answer 232

**Oxygen consumption during labor increases** 40%-75% due to increased respiratory efforts and uterine metabolism. Hyperventilation secondary to pain in active labor can lead to a **left shift of the oxyhemoglobin dissociation curve due to alkalosis**. Between contractions, this can lead to a decreased respiratory rate, which can cause **hypoxemia secondary to hypoventilation**. Oxygen requirements also increase due to painful contractions. All of these factors can contribute to fetal hypoxemia. Also catecholamines associated with labor pain **may reduce uteroplacental blood flow** *_Said another way:_* Painful uterine contractions during labor cause hyperventilation, which is followed by hypoventilation in between contractions. The detrimental effect of this “hyperventilation-hypoventilation” cycle is twofold. First, the overall respiratory status is one of hyperventilation, with hypocarbia and leftward shift of hemoglobin and reduced oxygen delivery to the fetus. Second, when hypoventilation occurs between contractions, maternal PaO2 may decrease as well. This cycle is effectively blunted by neuraxial analgesia. *_Effective labor analgesia during labor can ameliorate many of these physiologic changes._*

Answer 233

Pencil-point needles such as the **Sprotte and the Whitacre (non-cutting)** have less risk than a cutting needle such as the **Quincke and Touhy (cutting)**

Answer 234

The incidence of deep vein thrombosis (DVT) in pregnancy is estimated to be 0.02 to 0.36%. Of these, 15 to 24% of women who do not receive treatment for DVT will **develop a PTE which carries a 12-15% mortality rate**. If DVTs are treated, however, the incidence of PTE is reduced to 0.7 to 4.5% with a reduced mortality rate of 0.7%.

Answer 235

**By using the earliest gestational age for delivery estimation**, there is a decreased risk of meconium passage and a thereby decreased chance of meconium aspiration. Earlier gestational newborns are much less likely to pass meconium than term or postdate newborns. The earlier gestational age decreases the likelihood of postdate delivery and significantly decreases the chances of meconium passage. **The primary risk factor for meconium passage is later gestational age.** Using the earliest gestational age for estimating delivery is recommended to help prevent meconium aspiration. Gestational age is the largest risk factor when considering the passage of meconium.

Answer 236

Congenital bicuspid aortic valve Rheumatic Supravalvular Subvalvular

Answer 237

**Normal** aortic valve area is between **3.0 and 4.0 cm**²with **no significant pressure gradient** across the valve (under resting normal cardiac output states) **Symptoms generally develop** when the valve area is **\< 1.0 cm²** and the pressure gradient is **greater than 40 mmHg**

Answer 238

An aortic valve area **less than 1.0 to 1.5 cm²** and a **mean valve gradient of 25 to 50 mmHg** generally define the group of pregnant patients with a high risk for cardiovascular complications

Answer 239

**SEVERE STENOSIS:** The caveat is that patients with *_severe or critical stenosis should probably have general anesthesia_*, though this is debated particularly if preparations are made for managing anticipated neuraxial hemodynamic changes. For example, placing an arterial line before the procedure, starting a phenylephrine infusion upon spinal local anesthetic injection, and aggressively managing hypotension with phenylephrine or norepinephrine. **MILD TO MODERATE STENOSIS** In patients with less significant stenosis, *_neuraxial is less debated and has been thought to be relatively contraindicated due to the simultaneous decrease in preload and afterload_*, however, several case reports have shown successful administration. The goals of anesthesia management are the maintenance of sinus rhythm with a normal heart rate, maintenance of intravascular volume, avoidance of aortocaval compression and avoidance of myocardial depression.

Answer 240

in the subgroup of women with previa, the risk for placenta accreta was **3%, 11%, 40%, 61%, and 67%** for first, second, third, fourth, and fifth or more repeat cesarean deliveries, respectively.

Answer 241

**2nd trimester (13 to 26 weeks)** The first trimester is a period of rapid development and organogenesis, thus performing surgery at this time may risk teratogenesis. In the third trimester, the size of the uterus makes abdominal surgery more difficult and the risk of preterm labor is the highest.

Answer 242

**Preterm Labor** **Low Fetal Birth weight** **Fetal Loss**

Answer 243

**30-55%**

Answer 244

While no widespread consensus exists regarding a minimum platelet count needed to ensure safety with neuraxial procedures, expert opinion suggests that a **platelet count of 80,000/μL is generally sufficient for neuraxial analgesia and/or removal of a neuraxial catheter.**

Answer 245

A 2017 report published in Anesthesiology calculated the risk for epidural hematoma to be **11%** for a platelet count \< 49,000/μL **3%** for 50,000-69,000/μL **0.2%** for 70,000-100,000/μL

Answer 246

Increase = 7 and Fibrinogen Decrease = 9, 11, 13

Answer 247

**Ipsilateral phrenic nerve block** resulting in diaphragmatic paresis occurs in 100% of patients undergoing interscalene blockade, even with dilute solutions of local anesthetics, and is associated with a **25% reduction in pulmonary function.**

Answer 248

Interscalene block affects the **roots** and **trunks** of the plexus.

Answer 249

The approach is to place local anesthetic between the **anterior and middle scalene muscles**

Answer 250

The most common level for placement is at the **cricoid cartilage or C6 vertebrae level**, where the cervical nerve roots **C5-7 leave the spine.**

Answer 251

**Total spinal** that would cause **loss of consciousness** and **respiratory insufficiency or apnea**. Intrathecal injection at the cervical level would likely cause **hypotension** as a result of blockade of the sympathetic chain and even **bradycardia** as from blockade of the cardiac accelerating fibers (T1-4). Additionally, a patients with a cervical intrathecal injection would likely **develop bilateral dilated non-reactive pupils**. The pupillary reaction is a result of *_parasympathetic inhibition of the Edinger-Westphal nucleus (midbrain)._*

Answer 252

**Caudad needle direction** decreases the incidence of intrathecal injection. Additionally, if a nerve simulator is used, **twitch response seen with less than 0.2 mA** could occur inside the dural sleeve and lead to intrathecal spread of local anesthetic.

Answer 253

Pathophysiology: **Increased ICP causes pressure on the medulla resulting in medullary ischemia.** The central vasomotor center is a critical structure within the medulla. Upon the induction of **ischemia in this region, the vasomotor center will induce activation of the sympathetic nervous system**. The immediate result of this is to increase systemic vascular tone, myocardial contractility, and heart rate in an effort to improve cerebral perfusion pressure and avoid further ischemia. The profound increase in systemic vascular tone, however, **results in reflex bradycardia mediated by baroreceptors** and the ultimate clinical presentation of the hypertensive and bradycardic Cushing reflex.

Answer 254

Early side effects from this increase in intracellular calcium include an **increase in ventricular ectopy (Ectopic beats)** as well as a **slowing of electrical conduction through the atrioventricular node (AV nodal blockade also common)**

Answer 255

Digoxin exerts these effects through **inhibition of the sodium-potassium adenosine triphosphatase (Na/K ATPase)** pump that is located in the myocardium. This inhibition of this crucial transporter in the myocardial cell membrane results in an **increase in the concentration of intracellular sodium.** This increased sodium in the myocyte decreases the activity of another membrane protein known as the **sodium-calcium exchanger** Because this molecule will normally extrude a single calcium molecule from the intracellular cytoplasm in exchange for bringing three sodium molecules into the intracellular space, and increased intracellular sodium concentration will tend to increase the concentration of calcium within cardiac myocytes. **This increased intracellular calcium** is the primary means by which digoxin exerts its clinical effect.

Answer 256

In fact, **atrial tachycardia with a 2:1 AV block** is pathognomonic for advanced digoxin toxicity

Answer 257

In the event of life-threatening arrhythmia or cardiac arrest that is attributed to digoxin toxicity, *_an antidote in the form of digoxin-specific antibody fragments does exist that directly complexes with molecules of digoxin in the patient's plasma_*, effectively reducing the circulating volume of digoxin following its administration. Of note, in cardiac arrest where digoxin overdose is suspected and digoxin antibodies are administered, cardiopulmonary resuscitation should continue for at **least 30 minutes to allow for adequate time for the antidote molecules to circulate.**

Answer 258

Correct needle position at the lumbar sympathetic plexus is at the **anterolateral aspect of lumbar vertebral bodies (L1-L5)**. The best approach is just cephalad to the **middle of the L3 vertebral body** due to the highest rate of successful block.

Answer 259

A lumbar sympathetic plexus block may offer significant pain relief to patients with: ## Footnote **1. Lower extremity complex regional pain syndrome** **2. Phantom limb pain** **3. Postherpetic neuralgia** **4. Renal colic** **5. Analgesia for first stage of labor**

Answer 260

Given following **clamping of the external iliac artery to stimulate diuresis during reperfusion.** This practice has been shown to *_decrease the incidence of ATN in renal transplantation_*

Answer 261

The **duration of the oldest lead** (generally \> 5 years for implantable cardiac defibrillator (ICD) leads) due to length of endotheliazation that can develop resulting in greater incorpation of the lead into the vessel wall **Female gender** (Smaller blood vessels) **BMI of less than 25 kg/m2** Te **removal of ICD leads** when compared to pacemaker leads. (Due to larger scar tissue formation)

Answer 262

**Indications included:** 1. Device or systemic infection 2. Thrombotic complication 3. Lead fracture causing malfunction or arrhythmias 4. Device recall

Answer 263

**Procedure Types:** 1. **Explant** which is typically performed on leads that have been implanted for **\<1 year.** These explants are typically considered low-risk and usually only require gentle traction on the lead for removal. **2. Lead extraction,** and often requires the use of a specialized laser to ablate scar tissue that is holding the pertinent lead in place. These laser lead extractions (LLE) are generally considered **higher risk and require anesthetic support.** Consideration for the management of pericardial tamponade should be made prior to the procedure.

Answer 264

**Flow that travels away** from the transducer (negative Doppler shift) is depicted in **blue** **Flow that is traveling toward** the transducer (positive Doppler shift) is depicted in red, with lighter shades of each color denoting higher velocities. TrueLearn Insight : Color Doppler mnemonics: BART, blue = away, red = towards, and "That blew (blue) me away"

Answer 265

**1. Angles of blood flow to the ultrasound beam that \> 20 degrees will significantly attenuate the Doppler shift** and render this imaging modality inaccurate. 2. **PWD has a maximum velocity that it is able to measure that is defined by the frequency at which it sends pulses of ultrasound energy**. Because this technology requires the pulse of energy to return before the next one can be sent, the greater the depth at which the sample area is being measured, the lower the velocity that is able to be measured. **Called the Nyquist limit** and will typically cause imaging artifacts called aliasing at blood-flow velocities of *_around 1 meter/second*_. Because pathologic valvular lesions may generate flows _*above 5 meters/second_*, this imaging modality is best used to characterize flow velocities through vessels or the mitral valve, both of which are areas of relatively slow blood flow.

Answer 266

**Continuous-wave Doppler (CWD)** In order to determine the maximum velocity of blood flow through an area of relatively high flow such as a stenotic heart lesion, CWD is used. One ultrasound crystal will **continuously emit an ultrasound signal** while another will continuously receive an ultrasound signal. **Because CWD does not allow for a single pulse to return** before sending a second one, it is **impossible to determine the precise location where a location of frequency shift (Doppler effect) may have occurred.** In exchange for this lack of spatial accuracy, CWD has an effectively **unlimited Nyquist limit** and **no effective maximum velocity** that it can measure. This maximum velocity in itself can be incredibly useful, especially when interpreted in the context of the modified Bernoulli equation that states that the change in pressure across stenosis is equal to four times the square of the velocity across the stenosis: **ΔP = 4V^2**

Answer 267

A progressive decrease in body temperature causes a progressive decrease in power on electroencephalogram, with **burst suppression occurring below 25 degrees Celsius** **Complete suppression** of electrical activity typically **occurring below 18 degrees Celsius.**

Answer 268

Position 5 of the standard North American Society of Pacing and Electrophysiology (NASPE)/British Pacing and Electrophysiology Group (BPEG) Generic Code is used to denote **multisite pacing.** In this example, position 5 is “A” **denoting multisite atrial pacing**, thus the most reasonable answer is that this patient has multiple atrial leads, such as in a biatrial configuration.

Answer 269

1. **Chambers Paced** (A, V, D, O is none) Position I specifically denotes the chambers which are actively paced by the pacemaker when it determines a therapeutic pacing signal is necessary. 2. **Chambers Sensed** (A, V, D, O is none) Position II denotes the chambers which “sense” spontaneous cardiac depolarizations outside of the programmed refractory period of the pacemaker. It must be noted that the signals that are sensed can be erroneous, as can be the case when electrocautery is used during a surgery which may lead to improper pacemaker function. 3. **Response to Sensing** (Triggered, Inhibited, Dual, and None) Position III denotes the response that the pacemaker has to a sensed spontaneous cardiac depolarization. It can either immediately trigger a pacing signal as in this question's example of AATOA for the treatment of paroxysmal atrial fibrillation, or it can inhibit a pacing signal. An example of VVI being used is in the case of an incomplete atrioventricular blockade, where the ventricular lead will not trigger a therapeutic pacing signal if it detects a ventricular beat within a predefined threshold of time. 4. **Rate Modulation** (None = O, R = rate modulation) Position IV is used to demonstrate the presence or absence of rate modulation. This is an advanced function of a pacemaker that attempts to replicate an increase in heart rate with increased physical exertion. The pacemaker will attempt to use mechanical vibration, acceleration, or minute ventilation to determine when the patient is exerting themselves, and will accordingly increase the paced heart rate if this mode is activated. 5. **Multisite Pacing** (A, V, D, O is none) Position V is used to indicate the presence of multisite pacing. The presence of biatrial or biventricular leads can be denoted by this position as denoted in the table above. The utility of these lead configurations is not fully understood, however, their presence can be shown using this position.

Answer 270

Preoperative preparation of a patient scheduled for excision of a pheochromocytoma includes initiating adequate α-adrenergic receptor blockade **(ideally 10-14 days prior to surgery)** and ensuring normovolemia. *_Beta-blockers may be added after α-blockade_* in patients with persistent tachycardia, hypertension, and/or dysrhythmias.

Answer 271

Spinal anesthesia provides adequate levels of analgesia that extends to the sacral nerve roots that innervate the pelvic floor, and it also relaxes the muscles of the pelvic floor which facilitates the surgeon's approach to the prostate. When an epidural is performed for this surgery, often it will not extend to the sacral nerve roots adequately and the patient may experience painful stimuli during the surgery requiring supplemental analgesics. The use of a regional technique with monitored anesthesia care allows for an awake patient. This facilitates monitoring for two of the most feared complications of TURP **Bladder perforation** **TURP syndrome itself**

Answer 272

**The desired dermatomal spinal level during a TURP procedure is T10**. The *_prostate*_ is generally innervated by the _*S2 and S3 nerve roots*_, while bladder sensation is supplied by the _*hypogastric plexus which is formed from the T11 to L2 nerve roots._* Thus, a T10 dermatomal level is sufficient to prevent the sensation of any noxious stimuli, while at the same time allowing for monitoring of the initial signs and symptoms of bladder or prostatic capsule perforation.

Answer 273

TURP syndrome arises from **endovascular translocation of the cystoscopic irrigant fluid used during the procedure**. If distilled water is used, the patient may become severely *_hyponatremic*_ and _*hypoosmolar_*. Should this state be approached, hemolysis is common given the lack of plasma osmolarity, and is characteristic of this syndrome. If a **glycine**-containing solution is used, glycine is biotransformed into **ammonium** which, in adequate concentrations, can cause **blindness**. Other solutes for the irrigant solution include **sorbitol, mannitol, and glucose**, all of which have potential side effects if **excessive volumes** are absorbed into circulation.

Answer 274

Medications that **induce CYP-3A4** include carbamazepine, phenytoin, phenobarbital, St. John’s wort, **dexamethasone**, topiramate, and oxcarbazepine. Chronic use of these medications may make premedication with commonly used benzodiazepines such as midazolam and diazepam less effective

Answer 275

What are the objective measures to assess post - operative

Answer 276

The **solubility of CO2 will increase** as the patient's temperature decreases, resulting in a relative respiratory alkalosis in a hypothermic patient as the partial pressure of CO2 above the solution decreases as more CO2 is dissolved in the serum. This **respiratory alkalosis (pH high and PaCO2 low)** is not apparent when the arterial blood sample is rewarmed to 37 degrees Celsius and it is common for the arterial blood gas to appear normal.

Answer 277

In alpha-stat management, **cerebral blood flow is decreased** as it would be any other time that a patient becomes hypocapneic (**Low PaCO2 and high pH**). This **decreased cerebral blood flow may result in a less cerebral embolic load than other acid-base management strategies**. The alpha-stat management strategy is primarily used in the adult cardiothoracic surgery population.

Answer 278

**The Haldane effect** is the process of oxygen binding to hemoglobin and displacing carbon dioxide, which will result in a downward shift in the carbon dioxide dissociation curve. This facilitates the removal of carbon dioxide from the body.

Answer 279

**The Bohr effect** is the process of carbon dioxide binding to hemoglobin causing oxygen to be displaced, which will result in a rightward shift of the oxygen-hemoglobin dissociation curve.

Answer 280

TrueLearn Insight : Order in which frequency decreases and amplitude increases: BAT Drink Beta wave: \> 14 Hz, low amplitude Alpha wave: 8-13 Hz, high amplitude Theta wave: 4-7 Hz, high amplitude Delta wave: 0.5-4 Hz, maximum amplitude **Gamma** waves have a frequency of 25 to 100 Hz and are thought to be involved in **cortical processing.** **Beta** waves are typically \> 14 Hz in frequency and are usually found in patients who are concentrating, or sometimes in patients under **anesthesia. (or sedation)** **Alpha** waves have a frequency of 8 to 13 Hz & found in **awake patients resting with their eyes closed.** **Theta** waves have a frequency of 4 to 7 Hz and are also associated with **sleep and sedated states.** **Delta** waves have a frequency of 0.5 to 4 Hz and are found in patients under **deep sleep, sedation or general anesthesia.**

Answer 281

A “double peak” appearance is commonly observed with capnography in patients with **chronic obstructive pulmonary disease (COPD) who have received a single lung transplant**, reflecting the difference in function of the transplanted and native lung. A capnogram from a patient with a single lung transplantation due to chronic obstructive pulmonary disease will show a “double peak” pattern, reflecting the difference in function between the healthy transplanted lung and the diseased native lung. *_The rapid initial exhalation from the healthy, transplanted lung produces the first peak, while the slower rate of rise of exhaled carbon dioxide from the diseased, obstructed lung produces the second peak._* 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 282

A double lung transplant in a patient with COPD should reveal a **normal-appearing capnography** tracing, assuming the transplanted lungs are healthy and no rejection has developed.

Answer 283

An **incompetent inspiratory valve** allows exhaled gas (containing CO2) to enter the inspiratory limb of the breathing circuit during expiration. Therefore, the CO2-containing gas is inspired by the patient during the following inspiration. This extends the expiratory alveolar plateau (phase 3–4). A decrease in CO2 occurs after the extended plateau and represents the sampling of CO2-free gas that arrived from further proximal in the inspiratory limb. Thus the inspiratory downstroke (phase 4–1) is significantly blunted and the inspiratory phase is shortened (see Figure 3). During the latter portion of inhalation, the CO2 concentration may or may not reach zero, depending on fresh gas flow (FGF).

Answer 284

**Incompent Expiratory Valve** Capnogram of incompetent expiratory valve. The capnograph shows a markedly elevated inspiratory segment that does not return to zero, representative of rebreathing of CO2. Over time, the ETCO2 will rise, but the shape of the tracing is otherwise essentially normal.

Answer 285

**Cold ischemic time** refers to the amount of time that an organ is chilled or cold and not receiving a blood supply. Cold ischemic time varies widely by organ, but in general, the sooner an organ can be transplanted, the better. Generally accepted cold ischemic times are: Heart: 4 hours Lungs: 4-6 hours Liver: 6-10 hours Pancreas: 12-18 hours Intestines: 6-12 hours Kidneys: 24 hours (may go up to 72 hours if placed on a perfusion pump following recovery)

Answer 286

Deposits in the tongue cause **macroglossia**. Coupled with a *_large **goiter** that can extend beneath the sternum_*, hypothyroid patients may have difficult airways.

Answer 287

**Cardiac function** may be depressed due to **decreased heart rate, contractility, and an attenuated sympathetic response** that can result in congestive heart failure. Decreased cardiac output causes reactive peripheral vasoconstriction to increase systemic vascular resistance, which clinically appears as cool, mottled extremities. **Mucopolysaccharide deposits in the pericardium can cause pericarditis, pericardial effusion, and tamponade**. This can similarly occur in the pleura causing pleuritis and pleural effusion and in the peritoneum as wel

Answer 288

Four monitoring sites are considered to be the most accurate measures of core temperature. These include: ## Footnote * *1. Distal Esophagus 2. Nasopharynx 3. Tympanic Membrane 4. Pulmonary Artery**

Answer 289

When demyelination occurs **muscle fibers receive less neural input.** With less input the muscle begins to **synthesize immature acetylcholine receptors (AChR)** as a compensatory mechanism. Immature AChR have an **epsilon subunit** as opposed to a gamma subunit. These receptors remain **open longer and allow a larger efflux of potassium from the muscle cells.** This increases serum potassium to a greater degree than normal AChRs.

Answer 290

Should the disease progress to the point that respiratory support is required, the patient will display a r**estrictive pattern of pulmonary disease**. This muscular weakness will not allow the patient to make normal inspiratory or expiratory efforts and will manifest on spirometry as described above, with proportionate decreases in both FEV1 and FVC. **Change the I:E time (Increase inspiratory time) to favor Restrictive disease** This is due to the involvement of the **phrenic and intercostal nerves**, leading to respiratory muscle weakness and diminished ventilatory capacity. This will manifest on spirometry as a decrease in both the forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC). This muscular weakness will not allow the patient to make normal inspiratory or expiratory efforts and will manifest on spirometry as described above, with proportionate decreases in both FEV1 and FVC.

Answer 291

It should be noted that upon intubation of this patient, their **lung compliance will be normal and not in any way restricted.** Because the restrictive lung disease, in this case, is purely due to decreased innervation of the relevant muscles, there is no structural issue that impairs airflow within the lungs as with most other forms of restrictive lung disease.

Answer 292

**MOST** TEE Precordial Doppler Pulmonary Artery Cathter Transcranial Doppler **Moderate** ETN2 ETCO2 **Low** Oxygen Saturation Diect Visualization Esophageal Stethoscope ECG

Answer 293

According to American Heart Association guidelines, "**Avoid relying on atropine in type II second-degree or third-degree AV block or in patients with third-degree AV block with a new wide-QRS complex where the location of block is likely to be in non-nodal tissue** (such as in the bundle of His or more distal conduction system). These bradyarrhythmias are *_not likely to be responsive to reversal of cholinergic effects by atropine and are preferably treated with TCP or β-adrenergic support_* as temporizing measures while the patient is prepared for transvenous pacing."

Answer 294

**Misuse of equipment** is the most likely cause of equipment related to adverse outcome. According to a review of the anesthesia closed claims database, **misuse was three times more likely** to result in adverse outcome than equipment failure. This is likely due to the human component associated with misuse.

Answer 295

Extubation Plan In fact, when epidural analgesia is used during the surgery, it is reasonable to consider extubating patients with a **predicted postoperative FEV1 (ppoFEV1) between 30% and 20%** assuming all other variables are controlled and optimized. These patients traditionally always remained intubated and were slowly weaned from the ventilator in the ICU, however, early extubation facilitated by the pain control provided by a thoracic epidural in these patients has been shown to decrease respiratory complications when compared to continued postoperative mechanical ventilation.

Answer 296

**Absence** **seizures** classically consist of a rhythmic, generalized spike pattern at a frequency of 3 Hz.

Answer 297

**K-complexes, commonly followed by sleep spindles**, are common findings on EEG during stage 2 of non-REM sleep.

Answer 298

Convulsions and seizure-like activity typically present as **high-voltage, rhythmic spike and slow-wave patterns** on the electroencephalogram.

Answer 299

**Category A** **Control Studies show no risk to the fetus** Drugs which have been taken by many pregnant women and women of childbearing age without an increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.

Answer 300

**No human studies performed** ***_Animal studies_*** show ***_no risk_***

Answer 301

**No control studies** have been performed in either **animals** or **fetus**

Answer 302

Evidence to human risk exists Benefits may outweigh risks in certain situations

Answer 303

Control studies in both animals and humans demonstrate fetal risk No maternal benefit in any situation

Answer 304

D This means it should be used only in life-threatening emergencies when no safer drug is available and there exists positive evidence of human fetal risk.

Answer 305

Use during the third trimester is associated with **floppy infant syndrome** and significant **neonatal withdrawal symptoms**

Answer 306

The initial uptake and distribution of anesthetic medications in pregnant women vary when compared to the general population primarily through: *_1. The decreased functional residual capacity_* *_2. Decreased serum albumin concentrations respectively._* Uptake of volatile anesthetic agent is sped by the decrease in functional residual capacity, and the decreased serum albumin can lead to **increased free fractions of highly protein-bound medications following their own administration.**

Answer 307

Thrombocytopenia is a feature of cirrhosis, mostly due to **hypersplenism**, and also due to decreased liver synthesis of **thrombopoietin** (glycoprotein hormone produced by the liver and kidney which regulates the production of platelets) In some specific liver diseases, other factors may play a role, including **bone marrow suppression secondary to alcoholism** or medications such as **interferon**, and platelet destruction from **immune-mediated platelet-associated IgG (ITP)**

Answer 308

**1) Platelets:** Both platelet number and activity are decreased, although this is partly compensated by an increase in von Willebrand factor levels (a protein that causes platelet-platelet and platelet-collagen adhesion). The increase in von Willebrand factor levels may be explained by a decrease in ADAMTS13 (a protease that cleaves von Willebrand factor and is synthesized in the liver).\ **2) Coagulation:** Most coagulation factors are synthesized in the liver (except for thromboplastin and calcium). Factor VIII is produced both in the liver and also endothelial cells outside the liver. An increase in the INR in cirrhotic patients can reflect both a quantitative decrease in coagulation factors, as well as a decrease in the level of gamma-carboxylation due to decreased vitamin K. However, liver-produced anticoagulant factors like protein C, S, Z, and antithrombin III are also decreased and the final balance between pro- and anti-coagulant factors is not necessarily reflected by the INR. **3) Fibrinolysis:** There is a decrease in hepatic clearance of t-PA (tissue plasminogen activator) as well as a decrease in the synthesis of antifibrinolytic factors like plasmin activator inhibitor-1 (PAI-1) and thrombin-activatable fibrinolysis inhibitor (TAFI). This may lead to low-grade accelerated fibrinolysis in some patients with end-stage liver disease, however, overt DIC is not a feature of stable chronic liver disease.

Answer 309

Cirrhosis hemodynamics are characterized by a **hyperdynamic** state **increased cardiac output** and **low peripheral vascular resistance** ***_Rx:_*** ***_1. Norepinephrine_*** ***_2. Vasopressin_***

Answer 310

CO poisoning Hypothermia Hypocapnia Alkalemia Reduced concentrations of 2,3-bisphosphoglycerate (an enzyme formed during anaerobic metabolism which readily binds deoxygenated hemoglobin) Hypophosphatemia

Answer 311

Midazolam produces an **increase in heart rate.** Midazolam produces a **decrease in blood pressure due to a decrease in systemic vascular resistance.**

Answer 312

Dose dependent **decrease in ventilation.** In **healthy** patients, the respiratory depression is **insignificant**. However, in patients with **chronic obstructive pulmonary disease** there is **greater depression of ventilation.** *_Transient apnea_* may occur after rapid injection of large doses of midazolam especially when given with opioid medications. Benzodiazepines also depress the *_swallowing reflex and upper airway activity_*

Answer 313

Midazolam produces a **decrease in cerebral metabolic oxygen requirement (CMRO2)** With respect to CMRO2 there is a **ceiling effect to decreased CMRO2** at increasing doses of midazolam.

Answer 314

Local anesthetic can then be deposited beneath the **fascia iliaca** or between the two layers of **fascia iliaca** containing the femoral nerve. While performing an ultrasound-guided femoral nerve block, a “pop” through the fascia iliac is felt while advancing the needle just prior to the successful deposition of local anesthetic. You will have a sudden change in resistance once in this space.

Answer 315

Half-life is 9-15 hours.

Answer 316

Reversibility: **Andexanet alfa** is an FDA approved antidote for apixaban. **Andexanet alfa**, sold under the trade name **Andexxa** among others, is an antidote for the medications rivaroxaban and apixaban, when reversal of anticoagulation is needed due to uncontrolled bleeding. It has not been found to be useful for other factor Xa inhibitors. It is given by intravenous injection

Answer 317

Rivaroxaban is also a direct factor Xa inhibitor. Its half-life is **5-9 hours in healthier patients** but can be increased to **11-13 hours in the elderly.**

Answer 318

The **PT is the most sensitive test** for detecting rivaroxaban but cannot accurately describe the full effects of its presence.

Answer 319

**TT (Thrombin Time)** is the most sensitive coagulation assay to determine if dabigatran is present.

Answer 320

Dabigatran is a direct thrombin inhibitor with a half-life of **12-17 hours**.

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