CA-2 ITE Flashcards

Question

Early decells_______ Late decells_______ Varriable dcells_____

Answer 1

Early decells: fetal head compression Late decells: uretoplacental insufficiency or myocardial hypoxia Variable decells: umbilical cord compression

Answer 2

Symptomatic control; | Consider beta blockers (both symptoms and reduce T4->T3), PTU, steroids

Answer 3

``` Heparin Insulin NDNMB Glycopyrolate Sux ...also phenylephrine ```

Answer 4

- DIC (further fuels the process) - MI - Agina - PVD - CVA/stroke - Thromboembolic event PCC contains factors II, IX, X

Answer 5

- Tx of hemophelia - Reversal of anti-coagulants (i.e. warfarin) (faster and more reliable than FFP and less infection risk) - Surgical bleeding

Answer 6

Left: Arterial hypoxemia, acidosis, surgical stimulus, increased ICP Right: Volatile anesthetics (no change in slope); opioids, sedative/hypnotics, barbituates https://d1yboe6750e2cu.cloudfront.net/i/af40b03f296168c1a244ec689b8a5fdc8a7ce1f9

Answer 7

POD 1-3; be mindful with epidural placement and removal

Answer 8

vasocontstriction of portions of the lungs that are exposed to hypoxia. Smaller areas vasoconstrict more--> shunt

Answer 9

Inhibitors: hypocarbia, vasodilators, infection, metabloic alcalemia, MAC >1 Others (indirectly): hypervolemia, vasoconstricting drugs, hypothemira, PE, large hypoxic lung segment

Answer 10

1. Primary hemostasis--PLTS form clot (measure plts, VWF, clotting time) 2. Coagulation--Fibrin net/mesh (PT, INR, and specific factors) 3. Fibrinolysis--clot broken down (fibrinogen levels--reduced in DIC)

Answer 11

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

Answer 12

Liver disease reduces factors II, VII, IX, X, as well as V, XI, and thrombin; Protein C is reduced, as well

Answer 13

Factor VIII and vWF are increased in patients with liver disease. These two coagulation factors are produced extra-hepatically.

Answer 14

C6--Directly superior to the ganglion is the transverse process of C6, which is referred to as the Chassaignac tubercle (or carotid tubercle). Because of its prominence and proximity to the stellate ganglion, the Chassaignac tubercle is often used as the landmark to perform the block - used for treatment of CRPS of the upper extremity

Answer 15

Anesthetic considerations for these patients include: Preoperative hemoglobin levels Provision of leukocyte-reduced blood transfusions Cardiac, endocrine, hepatic assessments Bony deformities that may render the airway more difficult Fragile demineralized extremities that may render positioning challenging Post-splenectomy hypertension Thromboembolism prophylaxis and treatment

Answer 16

Bronchoconstriction occurs mainly due to the parasympathetic nervous system via the vagus nerve. The parasympathetic nervous system is the main pathway by which bronchoconstriction occurs in the pulmonary system. Receptors in the airways become stimulated and send a signal to the nucleus ambiguus in the brain stem. From here, the efferent signal is sent through the vagus nerve to the parasympathetic ganglia in the pulmonary system. This results in acetylcholine release and stimulation of the muscarinic receptors.

Answer 17

On a dose-response curve, drug tolerance causes a right shift of the curve, thereby increasing the median effective dose (ED50) and requiring greater dosages to achieve similar effects. LD50 (median lethal dose) does not necessarily increase with tolerance and may have serious implications.

Answer 18

Transfusion-related acute lung injury (TRALI) is treated with supportive management, and it includes intravenous fluid bolus for hypotension (C). TRALI is described as an acute respiratory distress that occurs after transfusion and is commonly associated with plasma-containing blood products. It is most frequently seen with fresh frozen plasma and least frequently seen with packed red blood cells.

Answer 19

TRALI presents within 2-6 hours after transfusion. Patients have acute onset of dyspnea, tachypnea, and hypotension. Chest radiographs show bilateral pulmonary edema that is non-cardiogenic. Since the pulmonary edema is non-cardiogenic, pulmonary wedge pressure should be low or normal.

Answer 20

the sternum, proximal tibia, distal tibia, and proximal humerus.

Answer 21

Transcutaneous nerve stimulation (TENS) provides pain relief by stimulating A-beta mechanoreceptors (which inhibit A-delta and C pain fiber signaling), increasing levels of B-endorphins, and facilitating descending inhibitory pathways.

Answer 22

Femoral triangle is bordered by the inguinal ligament superiorly, the adductor longus muscle medially, and sartorius muscle laterally.

Answer 23

Left-to-right shunt defects include VSD (most common), ASD, ECD, and PDA.

Answer 24

Obstructive defects include coarctation of the aorta, and stenosis of the atrial, mitral, or pulmonary valves.

Answer 25

Methimazole is also used in the treatment of hyperthyroidism. It interferes with the synthesis of thyroid hormones.

Answer 26

Hashimoto thyroiditis is a form of inflammation resulting in decreased thyroid hormone production (hypothyroidism). It is caused by an autoimmune disorder in which the thyroid gland is attacked by a person’s immune system. The autoantibodies block TSH receptors in the thyroid, therefore destroying the receptors instead of stimulating them. In comparison, Graves disease is when the thyroid gland is hyperfunctioning with excessive secretion of active thyroid hormone (hyperthyroidism).

Answer 27

Peritoneal dialysis is the preferred dialysis modality for patients who are intolerant of the hemodynamic changes induced by hemodialysis. This may include patients with a history of unstable angina, severe aortic stenosis, or heart failure with severely reduced ejection fraction

Answer 28

Etomidate causes a decrease in intracranial pressure, cerebral blood flow, and cerebral metabolic rate.

Answer 29

Etomidate inhibits the activity of 11-β-hydroxylase, an enzyme necessary for the synthesis of cortisol, aldosterone, 17-hydroxyprogesterone, and corticosterone. Even after a single induction dose of etomidate, adrenal suppression persists for 5 to 8 hours.

Answer 30

Infants have a CSF volume of 4 mL/kg, children have a CSF volume of 3 mL/kg, and adults have a CSF volume of 1.5-2 mL/kg

Answer 31

Infants have a high vagal tone and immature sympathetic system.

Answer 32

- Severe aortic stenosis is defined as a valve area less than 0.8 cm2 and a transvalvular pressure gradient higher than 50 mmHg. - The “triad” of symptoms include: angina, syncope, and shortness of breath (dyspnea). The degree of symptoms does not correlate with the degree of stenosis.

Answer 33

- HR: normal sinus rhythm should be maintained since loss of the left atrial contraction will result in a dramatic decrease in stroke volume and blood pressure. A normal to slower heart rate is beneficial to allow as much time for ventricular filling as possible. Furthermore, elevations in heart rate can lead to ischemia due to decreased diastolic time. - Contractility: want to maintain, avoid depression of contractility which can lower stroke volume. - Preload: want to have adequate volume. - Afterload: must be maintained distal to the stenotic lesion to ensure coronary perfusion. A decrease in blood pressure can lead to myocardial ischemia which will further worsen contractility. - Cardiac resuscitation is not typically effective in patients with AS; code situations must be avoided as it is generally not possible to created adequate stroke volume with chest compression in these patients.

Answer 34

Aortic regurgitation: - The magnitude of regurgitant volume depends on the diastolic time and the pressure gradient across the aortic valve (dependent on systemic vascular resistance). - HR: must be kept above 80 bpm to prevent increases in the time for regurgitation. Decreased heart rates, which will increase diastolic time, will allow more regurgitation. - Contractility: want to maintain. - Preload: need adequate volume loading to ensure enough volume can move forward. Want to avoid overloading patient because this will increase regurgitant volume. - Afterload: want to lower systemic vascular resistance which will attempt to prevent more regurgitation.

Answer 35

Decreasing the glucose to lipid ratio of TPN results in less incidence of steatosis and of hypoglycemia after abrupt TPN discontinuation. While it is recommended that TPN be continued perioperatively, glucose levels should be monitored frequently and treated proactively whether TPN is held or continued.

Answer 36

Post-stroke pain, paresthesias, and allodynia are likely a result of thalamic pain syndrome, which is a consequence of latent brain plasticity after a thalamic injury.

Answer 37

Total parenteral nutrition (TPN) should not be started within the first 7 days of ICU admission. Absolute indications for parenteral therapy include: short gut syndrome, small bowel obstruction, active gastrointestinal bleeding, pseudo-obstruction with complete intolerance to food, and high output enterocutaneous fistulas (unless a feeding tube can be passed distal to the fistula).

Answer 38

Opioids can lead to a number of significant adverse effects: - respiratory depression - postoperative nausea and vomiting - acute urinary retention - skeletal muscle rigidity - histamine release - pupillary miosis

Answer 39

Methods to help prevent peripheral nerve injury include injection pressure monitoring. The presence of a high opening injection pressure (> 20 PSI) is a sensitive sign of intrafascicular needle tip placement.

Answer 40

In renal failure, the following metabolites may cause neuroexcitatory (seizure, myoclonus) or neurodepressive (sedation, respiratory depression) effects: - H3G (hydromorphone inactive metabolite) - Normeperidine (meperidine active metabolite) - M6G (morphine active metabolite)

Answer 41

Nasal CPAP Neonates have higher closing capacity and a lower functional reserve capacity compared to adults. This makes them especially prone to atelectasis. CPAP keeps the small airways open. This decreases atelectasis and maintains recruitment. Advantages of the nasal route are that neonates are obligate nose-breathers (until 5 months of age) and a full facemask may cause facial/nasal pressure necrosis. Also, there is some evidence that nasal CPAP is superior to intubation and mechanical ventilation in preventing broncho-pulmonary dysplasia.

Answer 42

Von Willebrand disease can be managed with DDAVP, VWF concentrates, and cryoprecipitate.

Answer 43

Cryoprecipitate contains factor VIII, VWF, factor XIII, and fibrinogen.

Answer 44

Type 1 VWD: partial decrease in VWF concentrations Type 2 VWD: qualitative defect in VWF Type 3 VWD: total depletion of VWF

Answer 45

Recombinant factor VII is rarely used in clinical practice given the advent of prothrombin concentrate complexes. Additionally, it is used most commonly for hemophilia patients. The use of recombinant factor VII is not supported by the evidence for most cases of major bleeding.

Answer 46

Metabolic acidosis (or base excess)Cyanide primarily causes toxicity by impairing cellular aerobic respiration. The cyanide ion (CN-) binds to the ferric ion (Fe3+) in mitochondrial cytochrome-c oxidase, inhibiting the final stage of the electron transport chain. Depletion of cellular ATP and the lactic acid produced by anaerobic metabolism can lead to profound acidosis. Symptoms of cyanide toxicity include altered mental status, weakness, headaches, loss of consciousness, seizures, respiratory failure, and cardiac arrest. Blood cyanide levels will be elevated, although therapy should not be delayed for the laboratory result. The patients blood sample may appear "cherry red" due to normal circulating levels of oxygen with impaired utilization.

Answer 47

1: Pacing chambers 2: Sensing 3: Response to sensing A magnet over a permanent pacemaker will induce a magnet mode of asynchronous pacing to avoid misreading electrocautery signals. In this particular case, a magnet will set this pacer in DOO at a preset rate.

Answer 48

PAO2 = FiO2 * (Patm - PH2O) - PaCO2/RER | Patm=760; PH20=47; RER= 0.8

Answer 49

As the fetus and uterus grow, expansion of the uterus against the diaphragm leads to a decreased functional residual capacity (FRC). Yet a 20% increase in oxygen consumption and greater CO2 production lead to a higher minute ventilation mostly via increased tidal volume. In addition, progesterone centrally stimulates the respiratory center to further increase minute ventilation to 40-50% baseline and generate the physiological respiratory alkalosis of pregnancy. In this case, normal pH can vary from 7.40-7.47 and PaCO2 is closer to 30 rather than 35-40. Serum bicarbonate decreases to compensate. This combination of increased oxygen consumption and decreased FRC can lead to rapid desaturation after induction of general anesthesia.

Answer 50

Factor VIII, IX, X, and fibrinogen levels are increased while antithrombin and protein S levels decrease causing a hypercoagulable state.

Answer 51

Left pelvic tilt--even during CPR

Answer 52

Benzodiazepines are pregnancy category D and as their chronic use is associated with cleft lip, although some studies contest this. Cocaine is associated with growth retardation. Tetracyclines may inhibit fetal skeletal formation and cause tooth enamel hypoplasia. ACE inhibitors during pregnancy are associated with fetolethality. Warfarin can cause mental retardation and skeletal malformation.

Answer 53

A venous air embolism causes circulatory compromise by impeding right ventricular filling and output. Initially, this can cause hypotension and decreased cardiac output. It can then progress to pulmonary edema, cor pulmonale, and potentially cardiovascular collapse and death. If sufficient air enters the pulmonary circulation, it can trigger bronchoconstriction (which may lead to shunting), respiratory distress, and can increase dead space ventilation. If air enters the left-sided systemic circulation, it can cause myocardial infarction, arrhythmias, and cerebrovascular compromise. Air can enter the left-sided systemic circulation via right-to-left intracardiac shunts (e.g., patent foramen ovale, which may be present in up to 25% of pediatric patients), though it is also possible for air to transit directly through the pulmonary circulation and into the left-sided systemic circulation in the setting of a large VAE.

Answer 54

In order from most to least sensitive, the following modalities can be used to detect a VAE during craniotomies: 1) TEE (adults) or precordial Doppler ultrasound (infants/children), 2) EtCO2/EtN2/PAP, 3) cardiac output/CVP, 4) SpO2/BP/ECG changes. Echocardiography and Doppler ultrasound are sensitive enough to potentially detect VAE even before physiologic changes can occur.

Answer 55

Acute processes causing impaired CO2 elimination and their associations: - Cardiovascular collapse: significantly reduced cardiac index - Massive venous air embolus (VAE): increased end tidal nitrogen - Large pulmonary embolus (PE): ECG showing S1-Q3 pattern - Dislodged or kinked endotracheal tube, esophageal intubation: low and rapidly falling SpO2 Processes that cause decreased production of CO2 include: - Hypothermia - Hypothyroidism - Neuromuscular blockade

Answer 56

Neuraxial anesthesia

Answer 57

Unfractionated heparin is an indirect inhibitor of thrombin and factor Xa while low molecular weight heparin is an indirect inhibitor of only factor Xa.

Answer 58

Unfractionated heparin is an indirect inhibitor of thrombin and factor Xa while low molecular weight heparin is an indirect inhibitor of only factor Xa.

Answer 59

Ketamine is the drug of choice for cardiac tamponade induction. Its maintenance of spontaneous ventilation and sympathomimetic effects without compromising hemodynamic goals make it the ideal agent for induction of general anesthesia for a patient in acute cardiac tamponade.

Answer 60

The flow of sodium (Na+) ions across the membrane into the muscle cell and potassium ions (K+) out of the cell causes a local depolarization of the muscle cell referred to as an end plate potential. This is responsible for the generation of a muscle action potential

Answer 61

Binding of acetylcholine to ACh receptors in the motor end plate causes ion channels to open and so allow the sodium (Na+) ions to flow across the membrane into the muscle cell. The opening of the ion channel does also allow other cations to pass across the membrane

Answer 62

A diagnostic sympathetic block is the next step for failed medical management of complex regional pain syndrome.

Answer 63

Inhibit acytylcholinesterase-->increased ACH-->Increased muscarinic site activity SLUDGE Mi ("Sludge Me"): Salivation, Lacrimation, Urination, Defecation, Gastrointestinal upset, Emesis, Miosis treatment: Similar to managing the side effects of neostigmine, a cholinergic agent and competitive muscarinic blocker (e.g. atropine or glycopyrrolate) is administered to attenuate and block the muscarinic side effects of the agents.

Answer 64

Succinylcholine works by binding to the post junctional neuromuscular receptors causing depolarization, which results in muscular fasciculations.

Answer 65

Nasal intubation. Masseter muscle rigidity (MMR) is a rare event. When it occurs, the clinician should be on the lookout for malignant hyperthermia (MH) as MMR has been linked to MH, although not all MMR will progress to MH. MMR can last a significant period of time and may not immediately resolve.

Answer 66

With first-order elimination, the amount of drug eliminated is directly proportional to the serum drug concentration. All enzymes and clearance mechanisms are working at well below their maximum capacity, and the rate of drug elimination is directly proportional to drug concentration. Most drugs are eliminated in a first-order elimination process.

Answer 67

Phase 1 reactions include oxidation, reduction, and hydrolysis.

Answer 68

Phase 2 reactions, the resulting metabolites are conjugated with sulfate, glucuronide, or other groups

Answer 69

PEA: phenytoin, ethanol, aspirin.

Answer 70

MELD: "I Crush Beer Daily" for INR, Creatinine, Bilirubin, Dialysis Child-Pugh: "Pour Another Beer At Eleven" for PT, Ascites, Bilirubin, Albumin, Encephalopathy

Answer 71

AHA guidelines recommend epinephrine to be administered "as soon as feasible" for non-shockable cardiac arrest. The algorithm for shockable rhythms, on the other hand, calls for defibrillation then 2 min of CPR then defibrillation then epinephrine.

Answer 72

Inhalational induction will be faster in a pregnant patient compared with a non-pregnant patient. The combination of increased minute ventilation, with a decreased FRC, and decreased MAC requirements causes a significantly faster inhalational induction.

Answer 73

The rate of inhalational induction is inversely related to functional residual capacity (FRC). FRC is the volume of air in lungs at the end of passive exhalation. When describing an inhalational induction, FRC can be thought of as the lung volume diluting volatile anesthetics. A pregnant patient at term has a 20% reduction in FRC, thereby increasing the speed of an inhalational induction.

Answer 74

Guillain-Barré is an acute inflammatory polyneuropathy causing demyelination of peripheral nerves and restrictive lung disease. The patient loses the ability to inspire a deep breath as weakness worsens, and accessory muscles of respiration are affected. Restrictive type lung conditions demonstrate decreases in the FEV1 and FVC. However, the FEV1/FVC proportions remain normal.

Answer 75

Pregabalin is a GABAergic anticonvulsant and depressant of the central nervous system used commonly to treat neuropathic pain syndromes. Its mechanism of action is by binding to α2δ subunit-containing voltage-gated calcium channels and preventing the release of nociceptive neurotransmitters.

Answer 76

Botulinum toxin acts inside the axon terminal at the neuromuscular junction. Tetanus toxin travels via retrograde axonal transport to the CNS where it acts.

Answer 77

Hyperalimentation is commonly associated with hypophosphatemia, hypo or hyperglycemia, and acute liver injury. Patients on total parenteral nutrition (TPN) require vitamin K supplementation and often have an elevated prothrombin time.

Answer 78

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 79

Patent ductus arteriosus

Answer 80

Beta-blocker overdose can cause atropine- and catecholamine-resistant bradycardia and hypotension. Interventions including pacing, dopamine, and glucagon will increase heart rate via nonadrenergic pathways and are recommended. Glucagon enhances atrioventricular conduction, heart rate, and myocardial contractility by increasing intracellular cAMP independent of adrenergic pathways.

Answer 81

Inhalational induction is faster with infants and children due to their increased minute ventilation-to-FRC ratio. Onset of hypoxia is quicker in infants primarily due to their increased oxygen consumption of 6 mL/kg/min versus 3 mL/kg/min in adults.

Answer 82

Myotonic dystrophy is a group of hereditary (usually autosomal dominant) diseases resulting in persistent contracture of skeletal muscle (myotonia) following voluntary contraction or external stimulation. This occurs because, following release, calcium does not efficiently return to the sarcoplasmic reticulum and remains available for sustained muscle contraction.

Answer 83

Perioperative myotonia triggers include shivering from hypothermia, succinylcholine, neostigmine, and direct surgical stimulation of muscle. A myotonic episode can be treated with phenytoin, quinine, procainamide, direct infiltration of the affected muscle with local anesthetic, or a high concentration of volatile anesthetic. Paralytics are not effective for treating myotonia. Patients with myotonic dystrophy are sensitive to the CNS- and respiratory-depressant effects of anesthetic medications and may have exaggerated responses to neuromuscular blockers.

Answer 84

Volatile anesthetics are thought to manipulate background potassium channels, GABA receptors, and sodium channels

Answer 85

Ketamine, nitrous oxide, and xenon have sedative effects modulated by NMDA receptor antagonism.

Answer 86

pancuronium, pipecuronium, vecuronium, atracurium, cisatracurium, and mivacurium are the only drugs that are metabolized or degraded

Answer 87

Rocuronium itself actually undergoes no clinically significant metabolism. It is eliminated primarily by the liver, with a small fraction (≈10%) eliminated in the urine. It is taken up into the liver by a carrier-mediated active transport system where it is excreted into the bile.

Answer 88

Atracurium is metabolized through two pathways: Hofmann elimination and nonspecific ester hydrolysis. Hofmann elimination is a purely chemical process that results in loss of the positive charges by molecular fragmentation to laudanosine (a tertiary amine) and a monoquaternary acrylate, compounds that are thought to have no neuromuscular and little or no cardiovascular activity of clinical relevance. Of note, laudanosine has been shown to have central nervous system stimulating properties in animals, but in doses largely exceeding what would be obtained in a clinical situation. No deleterious effect of laudanosine has been demonstrated conclusively in humans.

Answer 89

The principal metabolite of vecuronium, 3-desacetylvecuronium, is a potent (≈80% of vecuronium) NMBD in its own right. The metabolite, however, has slower plasma clearance and longer duration of action than vecuronium. In patients with renal failure in the ICU, 3-desacetylvecuronium can accumulate and produce prolonged neuromuscular blockade.

Answer 90

Cisatracurium and atracurium are both metabolized via Hofmann elimination. An increase in body pH favors the elimination process where as a decrease in temperature slows down the process

Answer 91

The most common alpha-adrenergic receptor antagonist used to treat pheochromocytoma is phenoxybenzamine

Answer 92

Rhabdomyolysis can be triggered by the use of succinylcholine in patients with a history of Becker (X-linked recessive) and Duchenne muscular dystrophy. Both of these conditions are associated with lack of the dystrophin protein complex leading to weakening of the myocyte cytoskeleton causing cellular lysis with contraction and consequent release of potassium, myoglobin, phosphate, and CPK. This sudden increase in potassium can lead to life threatening hyperkalemia which can appear on ECG initially as peaked T-waves and lead to a wide QRS complex rhythm, then degenerate into ventricular fibrillation.

Answer 93

Malignant hyperthermia would likely present with findings of hypertension, elevated temperature, and increased end tidal CO2. There is, however, no clear increased risk of malignant hyperthermia in patients with Duchenne or Becker Muscular Dystrophy.

Answer 94

The initial reduction in core temperature in patients under general anesthesia is the redistribution of heat from the core to the periphery.

Answer 95

Important causes of methemoglobinemia include benzocaine, dapsone, and inhaled nitric oxide.

Answer 96

CaO2 = [(SaO2 * Hgb * O2 carrying capacity of Hgb) + (O2 solubility * PaO2)] SaO2 is the fraction of Hgb that is saturated with oxygen, O2 carrying capacity of Hgb is 1.34 mL of oxygen per gram of Hgb, Hgb is grams of Hgb per 100 mL of blood, PaO2 is the oxygen tension, and the solubility of oxygen in plasma is 0.003 mL of oxygen per 100 mL plasma for each mmHg PaO2.

Answer 97

CO binds with a high affinity to Hgb. (greater than 200-fold). The CO-Hgb complex causes two main effects: less oxygen binding sites and reduction in oxygen release. As less oxygen is released, this effect consequently leads to a left shift in the oxygen-hemoglobin dissociation curve. Since the color of CO-Hgb appears similar to normal oxygenated Hgb, the blood may appear light red despite having low oxygen. In addition, the PaO2 will be normal as in methemoglobinemia but the measured oxygen content will be low and severe. Conventional pulse oximetry OVERESTIMATES true SpO2 since CO-Hgb competes with oxyhemoglobin in the absorption spectrum, thus the pulse oximetry may measure a normal saturation value. Lactic acidosis is present in severe cases and can lead to metabolic disturbances. Treatment focuses on administration of 100% oxygen, which functions to displace the CO from the hemoglobin and shortens the half-life of CO. Elimination of CO can be shortened from 4 hours to 40 minutes with the use of supplemental oxygen.

Answer 98

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 99

Opioid agonists produce analgesia by binding to specific G protein-coupled receptors (GPCRs) that are located in brain and spinal cord regions involved in the transmission and modulation of pain. Some effects may be mediated by opioid receptors on peripheral sensory nerve endings.

Answer 100

Four major opioid receptor types have been identified: mu (μ, with subtypes μ1 and μ2), kappa (κ), delta (δ), and sigma (σ). All opioid receptors couple to G proteins; binding of an agonist to an opioid receptor causes membrane hyperpolarization. Opioid receptor activation inhibits the presynaptic release and postsynaptic response to excitatory neurotransmitters (acetylcholine, substance P) from nociceptive neurons.

Answer 101

Xenon produces reduction in CMRO2, but increases ICP and CBF through its action at the NMDA receptor. This is in contrast to nitrous oxide which produces elevations in all three parameters. In general, volatile agents produce increases in CBF and ICP with reduction in CMRO2 when given at > 1.0 MAC.

Answer 102

Xenon is an inhaled anesthetic that works primarily via inhibition of NMDA receptors, much like nitrous oxide. However, in contrast to nitrous oxide xenon produces a decrease in CMRO2. Additionally, 1 MAC can be achieved at one atmosphere of ambient pressure with xenon but not nitrous oxide.

Answer 103

To remember the severe MR criteria, think of 7-6-5-4: •Vena contracta greater than 0.7 cm •Regurgitant volume greater than 60 mL •Regurgitant fraction greater than 50% •Effective regurgitant orifice greater than 0.4 cm2 •Left ventricle dilation

Answer 104

Fentanyl is a potent synthetic opioid that interacts primarily with the mu-opioid receptor to give excellent analgesia (it is approximately 100 times more potent than morphine). It has a low molecular weight with high lipid solubility, making it suitable for delivery through a variety of mechanisms – oral, intravenous, intranasal, intramuscular, and transdermal. There have been numerous studies comparing transdermal fentanyl with oral sustained release morphine, especially in the chronic cancer pain population. In those patients, pain relief was as effective and preferred to the oral morphine formulations.

Answer 105

* Double lumen endotracheal tube * Single lumen endotracheal tube, cuffed or uncuffed, that is intentionally placed in the main bronchus of the non-operative lung * Single lumen endotracheal tube with bronchial blocker that is extraluminal or intraluminal * Univent endotracheal tube with a dedicated channel for the bronchial blocker

Answer 106

Garlic, ginger, ginkgo, ginseng, green tea, and saw palmetto are all thought to increase perioperative bleeding.

Answer 107

Pericardial tamponade is associated with an exaggerated X-descent and attenuated Y-descent on the central venous pressure waveform.

Answer 108

Hemodynamic goals for cardiac tamponade are best described as keeping the patient fast (tachycardia), full (hypervolemia), and tight (increased SVR). Some sources describe the goals as "fast, full, and strong" where strong relates to contractility. Either way, cardiac output becomes mostly heart rate dependent so measures that reduce heart rate should be avoided.

Answer 109

Both hypothermia (especially < 27 degrees C) and hyperthermia (especially > 42 degrees C) may increase the latency and decrease the amplitude of evoked potentials.

Answer 110

Bilateral lower extremity CRPS can be treated with serial bilateral lumbar plexus nerve blocks. In addition to intravascular, epidural, and intrathecal injection, bilateral lumbar plexus blocks can be complicated by ejaculatory failure in males.

Answer 111

Memantine is an NMDA antagonist that may be used in the treatment of CRPS.

Answer 112

Diarrhea is associated with a celiac plexus block (T5-12), which supplies innervation to all the intraabdominal organs, including most of the bowel.

Answer 113

Esophageal Doppler monitoring is a non-invasive technique for continuous intraoperative cardiac output monitoring. Probes should be placed in the esophagus at a depth of approximately 35 cm with the goal of being seen at the T5-T6 vertebral interspace on chest radiograph.

Answer 114

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

Answer 115

Intraabdominal hypertension is defined as IAP >12 mm Hg. In the setting of persistent or severe elevated IAP (especially if combined with decreased MAP), abdominal compartment syndrome can develop due to compromised organ perfusion. Clinical manifestations are seen earlier in patients with chronic renal insufficiency, cardiomyopathy, and pulmonary disease.

Answer 116

Refeeding syndrome presents as hypokalemia, hypomagnesemia and hypophosphatemia

Answer 117

Stellate ganglion: Located between C6-7. Can be blocked for pain (vascular, neuropathic, or visceral) that is related to the upper extremities and thorax. Complications include Horner syndrome, tracheal/esophageal injury, pneumothorax, and recurrent laryngeal nerve injury.

Answer 118

Celiac plexus: Located beside the aorta and inferior vena cava at the level of L1. The block is frequently done with a posterior approach with the entry point just below the 12th rib. This block is done for pain relating to abdominal cancers. Complications include bleeding, diarrhea, retroperitoneal hematoma, chylothorax, perforation of nearby structures, and pneumothorax.

Answer 119

Lumbar sympathetic chain: Located anterior to L1-L5 and the block is done via a posterior approach. This block may benefit those with neuropathic pain in the lower limbs, phantom limb pain of the lower extremities, and visceral pain involving the intestinal/urinary system. Complications involve perforation of nearby structures, genitofemoral nerve injury, and bleeding.

Answer 120

Transforaminal epidural injections are best suited for unilateral radiculopathies as compared to interlaminar epidural injections, which are better suited for bilateral neuraxial pain symptoms

Answer 121

The RCA (55%) and LCx (45%) are the main arteries involved in the blood supply to the SA node and occlusion of the vessel would lead to bradycardia, among other hemodynamic changes.

Answer 122

Extravasation of vasopressors can be managed with limb elevation, warm compresses, irrigating with saline (Gault technique), injection of phentolamine, and/or a stellate ganglion block (for upper limbs).

Answer 123

The liver is the principal site for drug metabolism. For many drugs, metabolism occurs in two phases. Phase I involves modifying the drug through oxidation, reduction, or hydrolysis. These reactions typically inactivate the drug. Phase II involves conjugation, where a molecule (glucuronic acid, sulfate) is added to the drug to make it more easily excreted from the kidneys and liver.

Answer 124

Cytochrome p450 is the most important enzyme system in phase I and catalyzes the oxidation of many drugs.

Answer 125

Arrhythmias occur with increased frequency during pregnancy. The primary indication for adenosine is paroxysmal supraventricular tachycardia, the most common arrhythmia in pregnant women. Adenosine is the agent of choice for the acute management of tachyarrhythmias.

Answer 126

Citrate toxicity occurs when a patient receives any blood product that uses citrate as an anticoagulant. Citrate toxicity is highest during fresh frozen plasma administration, however, it can occur with any blood transfusion and is more common in the pediatric patient populations, those with significant liver disease, those undergoing liver transplantation, if the patient is hyperventilated, or if the patient is cooled.

Answer 127

Fresh frozen plasma is prepared from whole blood collection or through apheresis. FFP is collected in citrate-containing anticoagulation solution. It is frozen within eight hours of collection and can be stored for up to one year at -30 degrees Celsius. FFP contains all clotting factors, fibrinogen, plasma proteins (particularly albumin), electrolytes, physiologic anticoagulants (protein C, protein S, antithrombin), and added anticoagulants (citrate).

Answer 128

Histamine release associated with morphine and atracurium can potentially induce bronchospasm in patients with reactive airway disease. Succinylcholine is also associated with histamine release, but there is no evidence to suggest an increased incidence of bronchoconstriction with its use.

Answer 129

Initial treatment of asthma typically starts with a β2-agonist inhaler, such as albuterol MDI, which should be used for rescue therapy or for treatment prior to an asthma trigger, such as exercise. Along with albuterol, an inhaled corticosteroid such as fluticasone is typically initiated. In addition to these two drugs, cromolyn (a mast cell stabilizer) and/or a leukotriene receptor antagonist such as montelukast can be added for additional anti-inflammatory activity since leukotrienes promote inflammation, especially within the airway.

Answer 130

Severe bronchospasm requires immediate action. Intravenous epinephrine and subcutaneous terbutaline both have very strong β2-agonist activity and will be helpful in this emergent acute setting. Intravenous epinephrine is also a mast cell stabilizer and works to reduce histamine release and inflammation within the bronchial tree. Intravenous anesthetics, such as ketamine and propofol, can be used to rapidly deepen the level of anesthesia and alleviate bronchospasm.

Answer 131

Massive transfusion has many complications including electrolyte imbalances such as hypocalcemia, hyperkalemia, hypernatremia.

Answer 132

ECG changes in hypocalcemia include reduced P-R interval, prolonged Q-T interval, and T-wave flattening and inversion.

Answer 133

A: Intraoperative re-dosing is needed to ensure adequate serum and tissue concentrations of the antimicrobial if the duration of the procedure exceeds two half-lives of the drug or there is excessive blood loss during the procedure.

Answer 134

Glycopyrrolate is an anticholinergic drug that works mainly at the muscarinic receptors. It is a competitive antagonist of acetylcholine at the acetylcholine receptors. Glycopyrrolate or atropine are used in conjunction with neostigmine to block the parasympathetic effects of the cholinergic surge cause by neostigmine

Answer 135

Cardiovascular: There are muscarinic receptors on the SA node of the heart. Blocking these receptors causes tachycardia. 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. Gastrointestinal - Anticholinergic activity leads to decreased salivary gland secretions and gastric secretions. (xerostomia) - Decreased gastric motility and peristalsis, which can lead to constipation. 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. Ophthalmic - Anticholinergic activity causes pupillary dilation, which could theoretically cause problems in patients with narrow angle glaucoma. It can also cause photophobia. 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 136

With increasing doses of succinylcholine (a large single dose, repeated doses, or a continuous infusion), a phase II block may occur. Continuous activation of acetylcholine receptors leads to ongoing shifts of sodium into the cell and potassium out of the cell. Despite this, the post-junctional membrane potential eventually moves in the direction of normal even in the continued presence of succinylcholine. This is due to increased activity of the sodium-potassium ATPase pump, which brings potassium into the cell in exchange for sodium. The receptor does not respond appropriately to acetylcholine, and the neuromuscular blockade is prolonged.

Answer 137

It is effectively two ACh molecules joined at the acetate methyl groups. The two quaternary ammonium radicals bind to the two α-subunits of one nicotinic receptor, and depolarization occurs. When voltage-sensitive sodium channels sense membrane depolarization (as a result of activation of the ACh receptors), they first open and thereafter close and become inactivated. The membrane potential must be reset before the sodium channels can be reactivated. This is a very rapid process with ACh (1 ms), as it is hydrolyzed by acetylcholinesterase (AChE) within the synaptic cleft. However, succinylcholine is not metabolized by AChE, so a prolonged activation of the ACh receptors is produced. The sodium receptors at the end-plate and the peri-junctional zone remain inactivated and junctional transmission is blocked. The muscle becomes flaccid.

Answer 138

Depolarization block is also called phase I or accommodation block and is often preceded by muscle fasciculation. This is probably the result of the prejunctional action of succinylcholine, stimulating ACh receptors on the motor nerve, causing repetitive firing and release of neurotransmitter. Recovery from phase I block occurs as succinylcholine diffuses away from the neuromuscular junction, down a concentration gradient as the plasma concentration decreases. It is metabolized by plasma cholinesterase (previously called pseudocholinesterase). Prolonged exposure of the neuromuscular junction to succinylcholine can result in a desensitization block or phase II block.

Answer 139

Phase II block differs from desensitization block. It occurs after repeated boluses or a prolonged infusion of succinylcholine. In patients with atypical plasma cholinesterase, phase II block can develop after a single dose of the drug. The block is characterized by fade of the train-of-four (TOF) twitch response, tetanic fade, and post-tetanic potentiation, which are all features of a competitive block. After the initial depolarization, the membrane potential gradually returns towards the resting state, even though the neuromuscular junction is still exposed to the drug. Neurotransmission remains blocked throughout.

Answer 140

With regard to nerve stimulation, a phase II block has features of a non-depolarizing block (e.g. fade is seen with tetanic and train-of-four stimulation; there is post-tetanic potentiation). This is in contrast to a phase I block in which no fade is seen with tetanic or train-of-four stimulation and there is no post-tetanic potentiation.

Answer 141

As per the JNC 8, thiazide diuretics, calcium channel blockers (amlodipine), angiotensin-converting enzyme inhibitors, or angiotensin receptor blockers are the recommended initial therapy in non-African American patients diagnosed with uncomplicated hypertension. **beta blockers are NOT first line**

Answer 142

In the setting of appropriate NPO time, the threshold inspiratory pressure via facemask ventilation for reducing gastric insufflation while still allowing proper lung tidal volumes in an adult patient is 15 cm H2O. Gastric insufflation induces gastric adaptive relaxation and a transient LES relaxation increasing the risk for aspiration.

Answer 143

The normal right ventricle is perfused throughout the cardiac cycle. Flow to the left ventricle (and the right ventricle in cases of chronic pulmonary hypertension) is largely confined to diastole.

Answer 144

Pressure support ventilation (PSV) is a ventilatory mode that is triggered by the patient's spontaneous effort and is assisted by a constant positive pressure. As such, PSV supports respiratory muscles and improves tidal volume for a given respiratory effort (the patient generates a greater volume than during spontaneous breathing). PSV can be either flow-triggered or pressure-triggered. Must be spontaneously breathing. On Draegers, PSV is not a true PSV since it has a back-up rate.

Answer 145

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

Answer 146

Inadequate analgesia in the lateral forearm after axillary block suggests sparing of the MUSCULOCUTANEOUS nerve which gives off the sensory lateral antebrachial cutaneous nerve of the forearm and can be supplemented by injecting local anesthetic into the coracobrachialis muscle.

Answer 147

The MAC-BAR is the MAC value at which the adrenergic response (e.g., hemodynamic, sudomotor) to noxious stimuli is blunted. This has been found to be approximately 50% higher than standard MAC (A). Some studies estimate this value as 1.7-2.0 MAC.

Answer 148

Brainstem manipulation or pressure on the brainstem can cause significant hemodynamic derangements. The Cushing triad of hypertension, bradycardia, and breathing alterations are due to brainstem compression (from either cerebral edema pushing down on the brainstem or from surgical manipulation intraoperatively).

Answer 149

Carbonic anhydrase inhibitors blunt sodium bicarbonate reabsorption and cause diuresis.

Answer 150

Loop diuretics inhibit the activity of the Na+/Cl-/K+ symporter in the thick ascending limb of the loop of Henle.

Answer 151

Potassium-sparing diuretics prevent K+ secretion by antagonizing the effects of aldosterone in collecting tubules.

Answer 152

When neonates are hypothermic, nonshivering thermogenesis is the primary means to generate heat (oxidation of brown fat). This increases glucose consumption and increases the risk of hypoglycemia. Maintenance of a neutral thermal environment will help decrease the risk of hypothermia and thus decrease the risk of hypoglycemia.

Answer 153

Unilateral recurrent laryngeal nerve injury results in weak voice, hoarseness, and paramedian (adduction) position of the ipsilateral vocal cord. Bilateral injury results in airway obstruction requiring tracheostomy.

Answer 154

Unilateral recurrent laryngeal nerve injury results in weak voice, hoarseness, and paramedian (adduction) position of the ipsilateral vocal cord. Bilateral injury results in airway obstruction requiring tracheostomy.

Answer 155

An axillary nerve block primarily targets the median nerve (sensation in medial forearm), radial nerve (sensation in dorsal hand), and ulnar nerve (sensation in palmar hand). The musculocutaneous nerve (sensation in lateral forearm) is often spared secondary to a proximal take-off from the brachial plexus and since the nerve does not travel within the axillary sheath.

Answer 156

Hepatopulmonary syndrome is a syndrome of shortness of breath and hypoxemia (low oxygen levels in the blood of the arteries) caused by vasodilation (broadening of the blood vessels) in the lungs of patients with liver disease. Dyspnea and hypoxemia are worse in the upright position (which is called platypnea and orthodeoxia, respectively). Hepatopulmonary syndrome results from the formation of microscopic intrapulmonary arteriovenous dilatations in patients with chronic liver disease. The mechanism is incompletely understood but is thought to be due to increased hepatic production or decreased hepatic clearance of vasodilators, possibly involving nitric oxide. The dilation of these blood vessels causes over-perfusion relative to ventilation, leading to ventilation-perfusion mismatch and hypoxemia. There is an increased gradient between the partial pressure of oxygen in the alveoli of the lung and adjacent arteries while breathing room air.

Answer 157

Complex regional pain syndrome is separated into types I and II according to the inciting event. Type I (formerly known as reflex sympathetic dystrophy or RSD) is usually caused by a trivial injury, sprain, crush injury, or burn. Type II (formerly known as causalgia) is caused by a traumatic injury to a major nerve trunk such as significant orthopedic trauma, gunshot injuries, or knife wounds. With either diagnosis, patients may develop burning pain and allodynia (pain to non-noxious stimuli). Both syndromes are also characterized by autonomic dysfunction, which presents with localized temperature changes, cyanosis, and/or edema. If the disease progresses without treatment, the skin can become glossy, smooth, and hairless.

Answer 158

The order for repair of hypoplastic left heart syndrome is "Not Gonna Fly": Norwood, Glenn, Fontan.

Answer 159

The primary hemodynamic derangement in obstructive shock is decreased venous return. CVP is typically elevated, CO decreased, SVR increased, and PAOP may be increased or decreased depending on the underlying etiology of obstructive shock. he primary hemodynamic derangement in obstructive shock is decreased venous return. CVP is typically elevated, CO decreased, SVR increased, and PAOP may be increased or decreased depending on the underlying etiology of obstructive shock.

Answer 160

Cardiogenic shock is a failure of the heart to generate enough cardiac output to provide adequate end organ perfusion. Similar to obstructive shock, in cardiogenic shock, CO is decreased, CVP is elevated, SVR is increased, and PAOP is increased.

Answer 161

Distributive shock is a failure of the vasculature to generate adequate SVR. In distributive shock, CVP is low, PAOP is low, SVR is low, and CO is high. Common causes of distributive shock are septic shock, anaphylactic shock, and neurogenic shock.

Answer 162

Hypovolemic shock results from intravascular volume depletion. The body has a decreased preload (CVP and PAOP) as the primary hemodynamic derangement. Hypovolemic shock results in decreased CO, increased SVR, decreased CVP, and decreased PAOP.

Answer 163

Synthetic liver function is best assessed via the PT/INR, which most closely correlates with factor VIIa levels.

Answer 164

Hypocalcemia prolongs phase 3 of the cardiac myocyte action potential which lengthens repolarization time. These effects can manifest as a prolongation of the QT interval on ECG.

Answer 165

The obturator block is performed by injecting local anesthetic between the adductor longus and brevis muscles.The mnemonic ALABAMa is used to remember the muscles from superficial to deep: Adductor Longus, Adductor Brevis, Adductor Magnus.

Answer 166

Cyanide toxicity does not lead to a decreased oxygen delivery. Instead, it affects the way that tissues can use oxygen. Cyanide is a toxin that inhibits cytochrome oxidase, leading to interference with oxidative metabolism and cellular use of oxygen. The delivery of oxygen usually increases in the acute phase of toxicity as the body tries to compensate for the cells' inability to use the oxygen.

Answer 167

DO2 = CaO2 x CO x 10 ``` CaO2 = arterial oxygen content CO = cardiac output (which is heart rate x stroke volume) ```

Answer 168

CaO2 = SaO2 x Hgb x 1.34 + (PaO2 x 0.003) CaO2 = arterial oxygen content (mL/dL) SaO2 = arterial oxygen saturation Hgb = hemoglobin concentration (g/dL) PaO2 = arterial partial pressure of oxygen (mm Hg) 1.34 is used because it is the oxygen carrying capacity of hemoglobin and 0.003 is used as it is the solubility coefficient of oxygen in plasma

Answer 169

Cyanide toxicity can occur with the use of sodium nitroprusside. Sodium nitroprusside is used as a vasodilator, however its metabolism results in the release of cyanide ions. Usually the cyanide ions are metabolized and no side effects occur. When higher doses of nitroprusside are used for prolonged periods of time, cyanide can build up and toxicity occurs. Cyanide toxicity is characterized by metabolic acidosis and cardiac arrhythmias. Treatment is with hydroxocobalamin.

Answer 170

Cardiogenic pulmonary edema occurs due to left ventricular failure, mitral stenosis, or left atrial obstruction. Increased hydrostatic pressures in the pulmonary vasculature lead to interstitial edema followed by increased alveolar fluid. Alveolar flooding occurs more in the dependent areas of the lung, which causes intrapulmonary shunting. This results in hypoxemia, hyperventilation, and hypocapnia, which can manifest in acute respiratory failure.

Answer 171

Cardiogenic pulmonary edema is most appropriately treated by supplemental oxygen, diuresis (especially loop diuretics***not osmotic diuretics, though), vasodilators, inotropes, and positive end-expiratory pressure (PEEP).

Answer 172

Sodium is the major extracellular cation while potassium is the major intracellular cation.

Answer 173

Hyperthermia, acidosis, high pCO2, and high levels of 2,3-DPG cause a shift to the right.

Answer 174

The optimal tidal volume in acute respiratory distress syndrome (ARDS) is 6 mL/kg ideal body weight (IBW).

Answer 175

A supraclavicular nerve block occurs at the level of the brachial plexus trunks and divisions, but misses the intercostobrachial fibers coming from T2 and T1 (not from the brachial plexus). The intercostobrachial nerve fibers supply the inner aspect of the upper arm and should be anesthetized in order to prevent tourniquet pain. Tourniquet pain usually begins after 45 minutes of inflation and is described as a dull aching pain and/or restlessness. The intercostobrachial nerve block is performed by subcutaneous injection of 3-5 mL of local anesthetic along the axillary crease. This is ideally performed prior to the surgery but could also be performed during surgery if the anesthesiologist is able to reach the upper arm crease, which should not be blocked by the upper arm tourniquet.

Answer 176

Interscalene blocks can be associated with incomplete coverage in the ulnar distribution due to C8 and T1 sparing (50% of the time)

Answer 177

The cardiovascular changes of laparoscopy include an increase in systemic vascular resistance (SVR) and mean arterial pressure (MAP), which is caused by increased sympathetic output from CO2 absorption and a neuroendocrine response to pneumoperitoneum. Pneumoperitoneum-related increased intra-abdominal pressure (IAP) results in activation of the sympathetic system with catecholamine release and the renin-angiotensin system with vasopressin release.

Answer 178

The sphenopalatine ganglion provides sensory innervation to the nasal mucosa and can be blocked by local anesthetic to reduce stimulation in patients undergoing FESS.

Answer 179

pH-stat management infuses extra CO2 into the blood, causing increased CBF and improved homogenous cerebral cooling during hypothermic cardiopulmonary bypass. pH-stat management adds CO2 to blood which causes a decrease in pH causing a Bohr shift with the rightward shift of the oxyhemoglobin dissociation curve (increased P50).

Answer 180

Alpha-stat management maintains normocarbia and normal pH, based on the assumption that the patient is 37 degrees Celsius. pH-stat management maintains normocarbia and normal pH, based on the actual temperature of the patient. So if the patient is being cooled to 27 degrees Celsius, then the blood gas will be corrected for a body temperature of 27 degrees Celsius. As blood gets colder the partial pressures of CO2 and O2 decrease. So in pH-stat management, the CPB circuit infuses CO2 into the blood to maintain a normal pH at whatever the body temperature is at that point in the case.

Answer 181

Radiation exposure is inversely proportional to the square of the distance (1/radius^2). By doubling the radius from the source of radiation, the resultant incident radiation is 1/4th.

Answer 182

1. Duration of disease ≥ 72 months (≥ 6 years) 2. History of a chronic respiratory disease (e.g. asthma and COPD) 3. Pyridostigmine dose of > 750 mg/day 4. Vital capacity < 2.9 liters (or < 40 mL/kg)

Answer 183

Myasthenia gravis is associated with resistance to succinylcholine and sensitivity to nondepolarizing neuromuscular blocking agents. Eaton-Lambert syndrome, or myasthenic syndrome, is associated with a sensitivity to both succinylcholine and nondepolarizing neuromuscular blockers.

Answer 184

Efficacy of epidural steroid injections (ESIs) for lumbar radiculopathy is inversely correlated with duration of symptoms.

Answer 185

Context-sensitive halftime is the time required for the drug plasma concentration (rather than drug effect) to decrease by one half following discontinuation of a drug infusion. Dexmedetomidine has a longer context-sensitive half-time than propofol. After an 8 hour infusion, the context-sensitive half-time of dexmedetomidine is about six-fold that of propofol (250 min vs 40 min)

Answer 186

Early decelerations are caused by head compression and late decelerations caused by hypoxemia.

Answer 187

Early decelerations occur simultaneously with uterine contractions and usually are less than 20 bpm below baseline. The onset, nadir, and offset of each deceleration coincides with the onset, nadir, and offset of the uterine contraction. Head compression can precipitate early decelerations which are believed to result from reflex vagal activity secondary to mild hypoxia. Early decelerations are not ominous.

Answer 188

Late decelerations lag 10 to 30 seconds behind the uterine contractions with their onset, nadir, and offset. Late decelerations are smooth and occur with every uterine contraction. Late decelerations represent a response to hypoxemia (e.g., uteroplacental insufficiency).

Answer 189

Variable decelerations, as the name suggests, vary in depth, shape, and duration. They often are abrupt in onset and offset without coinciding with uterine contractions. Variable decelerations result from baroreceptor or chemoreceptor-mediated vagal activity. Umbilical cord occlusion, either partial or complete, results in variable decelerations.

Answer 190

Caudal epidurals are performed through the sacral hiatus at the level of S4-S5.

Answer 191

Maintenance of cerebral perfusion pressure is exquisitely important when caring for a patient with a traumatic brain injury. Even a single episode of hypotension decreases cerebral perfusion enough to affect outcomes. The CPP value to target lies within the range of 50-70 mm Hg according to current BTF guidelines.

Answer 192

Preload changes demonstrate a direct relationship with the force of contraction while afterload changes demonstrate an indirect relationship with the velocity of fiber shortening.

Answer 193

Occipital nerve block is both diagnostic and therapeutic in treating occipital neuralgia. If the patient has no relief of their headache after block trial, the diagnosis of occipital neuralgia becomes unlikely.

Answer 194

Adverse effects unique to the use of thiazides include hypercalcemia and hyperuricemia

Answer 195

Triamterene and amiloride block the exchange between Na+ and both K+ and H+ in the late distal tubule and collecting duct. Excessive loss of K+ is prevented. Hyperkalemia and hyperkalemic, hyperchloremic metabolic acidoses are significant complications of the injudicious use of triamterene and amiloride.

Answer 196

As mannitol shifts water between fluid compartments, there can be effects on plasma and intracellular electrolyte concentrations, including hyponatremia and hypochloremia and intracellular increases in K+ and H+. Patients with normal renal function quickly correct these changes, but patients with renal impairment may develop significant circulatory overload with hemodilution and pulmonary edema, hyperkalemic metabolic acidosis, central nervous system depression, and even severe hyponatremia requiring urgent hemodialysis.

Answer 197

Furosemide, bumetanide, torsemide, and ethacrynic acid are classified as loop diuretics because of their action in inhibiting the reabsorption of electrolytes in the thick ascending loop of Henle. All four drugs are rapidly absorbed from the gastrointestinal tract and are highly protein bound. Although loop diuretics have no proven mortality benefit, they reduce left ventricular filling pressures and very effectively relieve the symptoms of congestion, pulmonary edema, extremity swelling, and hepatic congestion. Adverse effects of loop diuretics include hypokalemia, hyponatremia, hyperuricemia, and also acute kidney injury.

Answer 198

Intranasal administration of vasoconstrictors such as oxymetazoline and phenylephrine can help prevent epistaxis during nasotracheal intubations. Oxymetazoline is an alpha-1 adrenergic receptor agonist and alpha-2 adrenergic receptor partial agonist. When used as a nasal spray, it causes vasoconstriction of the nasal mucosal vessels. This is used to treat rhinorrhea, but can also prevent epistaxis by decreasing blood flow. Beware pf hypertension.

Answer 199

Electrolyte and acid-base abnormalities including hypokalemia, hypomagnesemia, hyponatremia, hyperuricemia, metabolic acidosis, and respiratory alkalosis are common in alcoholics.

Answer 200

Acute stretching of the peritoneum that occurs with abdominal insufflation may result in a huge vagal response. Bradycardia, bradyarrhythmias, and asystole can occur. Slow insufflation will help to avoid the vasovagal response that can occur. Additionally it will reduce the risk of gas embolism.

Answer 201

Morbidity and mortality after SAH most commonly occur secondary to rebleeding, cerebral ischemia, and hydrocephalus. Admission hemoglobin has been shown to be a predictor of cerebral infarction and outcomes in patients with SAH. Classic "triple H" therapy may contribute to complications after SAH.

Answer 202

Sympathetic activation leads to a sharper, or increased, slope of phase 4 which causes the triggering threshold of the membrane potential to be reached quicker thus leading to depolarization.

Answer 203

A pudendal nerve block can provide relief during the second stage of labor. The pudendal nerve originates at S2-S4 and supplies sensation to the penis and posterior scrotum in males as well as the clitoris and labia in females. It also innervates the perineum and anal canal. The pudendal nerve also carries sympathetic nerves responsible for ejaculation and innervates the muscles of the pelvic floor, external anal sphincter, and external urethral sphincter.

Answer 204

A high spinal. Large doses of lidocaine, bupivacaine, and 2-chloroprocaine into the intrathecal space have shown to cause serious neurological complications, such as cauda equina syndrome. Symptoms of a high spinal include bradycardia, hypotension, and difficulty breathing. Patients also complain of numbness and weakness in the arms and shoulders. The hemodynamic changes can be explained by the inhibition of the cardio-accelerator fibers (T1-T4) and the Bezold-Jarisch reflex. CSF lavage has been suggested as a technique to reverse the complication. Using the intrathecally placed epidural catheter, 10 mL of CSF is withdrawn at a time, and is replaced with 10 mL of saline.

Answer 205

The Bezold-Jarisch reflex occurs when stretch and chemo-receptors in the heart are stimulated. This results in bradycardia and hypotension. This reflex has been implicated as one of the causes for bradycardia, hypotension, and the cardiovascular collapse seen with spinal anesthesia.

Answer 206

Standard intubating doses of succinylcholine generally create a PHASE 1 depolarizing block characterized by decreased twitch height, sustained tetanus, and a TOF ratio > 0.7. Neostigmine will potentiate a phase I block while a nondepolarizing NMBD will antagonize the block. Prolonged infusions or large doses of succinylcholine create a PHASE II nondepolarizing block, which is similar to that created by nondepolarizing NMBDs.

Answer 207

Flexible bronchoscopy is appropriate during certain procedures such as whole lung lavage, transbronchial biopsies, and the evaluation of areas that the rigid bronchoscope cannot reach such as small airways. Rigid bronchoscopy is preferred for airway foreign body removal, laser procedures, and assessment of the posterior larynx.

Answer 208

Metformin acts to decrease glucose levels by decreasing hepatic gluconeogenesis and increasing insulin sensitivity.

Answer 209

Sulfonylureas and meglitinides are groups of anti-diabetic medications that stimulate insulin secretion.

Answer 210

Non-insulin injectable such as exenatide (a hormone found in the saliva of the Gila monster) decreases glucagon secretion.

Answer 211

In patients with multiple sclerosis, succinylcholine should be used very cautiously because they may have denervation or misuse myopathy leading to a higher risk for hyperkalemia

Answer 212

Myasthenia gravis is an auto-immune disorder; auto-antibodies bind to the extracellular acetylcholine receptor resulting in a functional decline of available binding sites – this causes a decreased sensitivity to succinylcholine and thus it can be used in these patients, even during an exacerbation. Lambert-Eaton syndrome is also an autoimmune disorder but the auto-antibodies attack the presynaptic voltage-gated calcium channels resulting in a decrease in acetylcholine released.

Answer 213

Although the exact cellular mechanisms have not been completely elucidated, anemia exerts effects on the coagulation cascade. Anemia is associated with a delay in the initiation of the coagulation cascade, a stronger clot, and a clot with superior viscoelastic properties.

Answer 214

SID takes into account HCO3-, albumin, phosphate, and unmeasured anions. A decrease in SID results in a decrease in pH. A large resuscitation with aline leads to decreased SID

Answer 215

The DLCO uses carbon monoxide diffusion to assess the parenchymal function of the lungs. DLCO is effected by cardiac output and hemoglobin concentration. The DLCO is elevated in conditions like: asthma, polycythemia, pulmonary hemorrhage, exercise, and left to right shunts. It is decreased in pulmonary embolism.

Answer 216

Risk factors for awareness under anesthesia include: substance abuse (opioids, benzodiazepines, cocaine), history of awareness, history of difficult intubation or anticipated difficult intubation, chronic pain patients using high doses of opioids, cesarean delivery, trauma and emergency surgery, use of neuromuscular blockade, total intravenous anesthesia, and limited hemodynamic reserve.

Answer 217

Diagnostic criteria for SIADH and CSWS include: hyponatremia, low serum osmolarity, elevated urine osmolarity, and an elevated urine sodium. SIADH is associated with a euvolemic or slightly hypervolemic state, where CSWS is associated with hypovolemia. The initial treatment for SIADH is fluid restriction with recommended intake of less than 800 mL/day.

Answer 218

The fascia iliaca compartment block is used for analgesia of the hip, anterolateral thigh, and the anterior knee. Although femoral and lateral cutaneous nerve have reliable coverage, the obturator and genitofemoral nerves do not. While it is possible for local anesthetic spread to also reach these two nerves, it is not guaranteed with even perfectly placed blocks.

Answer 219

Etomidate is a sedative-hypnotic medication that has less effect on ventilation than do other anesthetics used to induce anesthesia. It depresses airway reflexes (less so than propofol), relaxes smooth muscle in the pulmonary vascular system, and does not induce histamine release in patients with reactive airway disease. Due to its rapid onset and rapid recovery, it is an attractive agent for use during procedural sedation.

Answer 220

Etomidate is a sedative-hypnotic medication that has less effect on ventilation than do other anesthetics used to induce anesthesia. It depresses airway reflexes (less so than propofol), relaxes smooth muscle in the pulmonary vascular system, and does not induce histamine release in patients with reactive airway disease. Due to its rapid onset and rapid recovery, it is an attractive agent for use during procedural sedation.

Answer 221

Loss of fetal heart rate variability is an early sign of fetal hypoxia.

Answer 222

``` Typical intracardiac pressures are: RA 1-10 mmHg RV 15-30/0-8 mmHg LA 8-10 mmHg LV 90-140/4-12 mmHg ```

Answer 223

The largest pressure increase in the left ventricle is during the isovolumetric contraction phase in which the mitral valve and aortic valve is closed. Once left ventricular pressure is greater than aortic pressure, ejection occurs.

Answer 224

The foot is innervated by five nerves. Four of the five individual nerves that can be blocked at the ankle to provide anesthesia of the foot are terminal branches of the sciatic nerve: the posterior tibial, sural, superficial peroneal, and deep peroneal branches. The sciatic nerve divides at the popliteal fossa into the common peroneal and tibial nerves. The common peroneal nerve divides into the superficial and deep peroneal nerves. The tibial nerve divides into the posterior tibial and sural nerves.

Answer 225

Intravenous benzodiazepines such as midazolam and lorazepam are commonly used for ICU sedation. Midazolam can accumulate in prolonged infusions, especially in patients with kidney disease. Lorazepam can be associated with propylene glycol toxicity. Diazepam is associated with pain on injection.

Answer 226

Serotonin syndrome is a potentially life-threatening reaction that occurs with the use of drugs that elevate serotonin levels. The reaction is mediated via excess stimulation of the 5HT1A and 5HT2 receptors. Signs and symptoms can include altered mental status, autonomic hyperactivity/instability (flushing, sweating, tachycardia, hyperthermia), metabolic acidosis, tremor, clonus, and muscle rigidity. The presence of muscle rigidity and hyperthermia are associated with life-threatening toxicity. Treatment primarily includes supportive care and withdrawal of offending drugs. Sedation with benzodiazepines may be needed. Cyproheptadine, an oral 5HT1A and 5HT2A antagonist, may also be administered for serious cases.

Answer 227

The degree of ionization (pKa) of a drug is a unique physicochemical property that controls its ionization state when in solution. If the drug's pKa is the same as the pH of the solution it is dissolved in, then 50% of the drug exists ionized and 50% exists nonionized. As the pH of the solution changes, the state of ionization changes as well. Acidic environments, such as those in infected or inflamed tissues, renders many local anesthetics less effective as they remain in an ionized quaternary configuration.

Answer 228

Tracheoesophageal fistula may be part of a group of anomalies, known as the VACTERL association. VACTERL includes vertebral, anal, cardiac, tracheoesophageal, renal, and limb abnormalities. An echocardiogram should be done all infants with TEF prior to anesthesia.

Answer 229

Methohexital can have numerous deleterious effects on the cardiovascular system such as decreased cardiac output, decreased systemic vascular resistance, and a reflex tachycardia that could lead to harm in patients with coronary artery disease.Methohexital can be used for general anesthesia, sedation, and for electroconvulsive therapy as it has been shown to not increase seizure threshold. Adverse effects can include cough, twitching, hiccups, and pain on injection.

Answer 230

Sinusitis is a complication of tube feeding utilizing a nasogastric tube and a maxillofacial CT scan can reveal this source of fever and elevated WBC count. In patients who are expected to be on tube feeding for long-term, a gastrostomy or intestinal tube placement is recommended to avoid this complication.

Answer 231

Amniotic fluid embolism is associated with hypotension, dyspnea, cyanosis, cardiovascular collapse, consumptive coagulopathy, and seizures. Treatment is supportive and mortality remains high.

Answer 232

AFE is divided into two phases: cardiovascular collapse followed by consumptive coagulopathy. Hypotension is likely due to cardiogenic shock with acute pulmonary hypertension and right ventricular failure, followed by left ventricular failure. AFE is characterized by acute onset of dyspnea, arterial hypoxemia, cardiopulmonary collapse, and coagulopathy during labor, delivery, or postpartum. Cyanosis may result from arterial hypoxemia and seizures may also result with a loss of consciousness.

Answer 233

Certain things increase the risk of an acute exacerbation in patients with acute intermittent porphyria. These include stressful situations, prolonged fasting times, and certain medications. Trying to avoid or decrease the extent of these will help decrease the risk of exacerbation. This includes adequate hydration to decrease the risk of dehydration and supplementation with glucose to avoid starvation states. Additionally, avoidance of medications that are known to precipitate an exacerbation can help (in the perioperative period this includes barbiturates, sulfonamides, ethyl alcohol, and ergotamine). Also, no opperating on wharewolves.

Answer 234

Morphine 6-glucuronide is an active metabolite of morphine. The duration of action of morphine 6-glucuronide is similar to morphine and most of the analgesic activity attributed to morphine is likely secondary to morphine 6-glucuronide. Morphine 6-glucuronide is a more potent agonist than morphine. Accumulation of morphine 6-glucuronide during long-term infusions of morphine may result in respiratory depression. Also, in patients with renal failure very high levels of morphine 6-glucuronide can occur because morphine 6-glucuronide and morphine 3-glucuronide are both excreted by the kidneys.

Answer 235

Morphine 3-glucuronide is an inactive metabolite of morphine.

Answer 236

Normeperidine is a metabolite of meperidine after hepatic metabolism. Normeperidine produces CNS stimulation manifesting as myoclonus and seizures. This is particularly important in patients with impaired renal function since normeperidine can accumulate.

Answer 237

Bayes theorem is used to help develop preoperative testing algorithms by helping clinicians interpret testing results in light of the patient presentation and surgical procedure. Bayes theorem states that the post-test probability of a person having a disease is related to both the sensitivity and specificity of the test and the prevalence of the disease in the population. In other words, it describes the probability of an event, based on conditions that might be related to the event (conditional probability).

Answer 238

Static compliance measures the lung at a fixed volume unlike dynamic compliance, which measures the lung during normal rhythmic breathing.

Answer 239

Minor urticarial transfusion reactions are fairly common and a result of soluble antigens in the transfused blood products resulting in a donor allergic response via IgE (or vice versa). They should be distinguished from anaphylactic or anaphylactoid reactions via the absence of airway swelling or bronchospasm, hemodynamic stability, and lack of GI symptoms. Treatment is conservative and includes diphenhydramine. The transfusion can be continued in most instances.

Answer 240

The risk of awareness is sufficiently low if the exhaled MAC is > 0.7 with volatile inhalational agents. Several options can further help decrease this risk: premedication with benzodiazepines, avoidance of neuromuscular blockade unless necessary for the surgical procedure, and consideration of additional monitors in high-risk situations. The use of neuromuscular blocking agents significantly increases the risk of awareness.

Answer 241

Aminocaproic acid and tranexamic acid are lysine analogs that prevent the formation of the ternary complex between plasminogen, tPA, and fibrin, thus inhibiting plasmin formation and fibrin degradation. The 2015 ASA Practice Guidelines for perioperative blood management recommend the use antifibrinolytic therapy for prophylaxis of the use of allogeneic blood transfusion in patients undergoing cardiopulmonary bypass.

Answer 242

Thrombin has many prothrombotic actions, it activates factors I, V, VIII, XI, and XIII, as well as platelets. Thrombin is inhibited by argatroban, dabigatran, and bivalirudin.

Answer 243

The normal average values of an umbilical artery blood gas sample are approximately: pH 7.2-7.3, PaCO2 50-55 mm Hg, PaO2 18-25 mm Hg, bicarbonate 22-25 mEq/L, base excess -2.7 to -4.7 mEq/L.

Answer 244

First fluids, The 2016 Surviving Sepsis Campaign recommends norepinephrine as the first-line vasopressor for patients with septic shock after initial fluid resuscitation. If norepinephrine administration does not raise the MAP to the initial target of ≥65 mm Hg, the guidelines suggest adding either vasopressin or epinephrine.

Answer 245

Perioperative corticosteroid supplementation is recommended in patients taking > 10 mg/day prednisone or those previously taking > 10 mg/day whose last dose was < 3 months prior to surgery. Additional perioperative steroids are not required in patients taking high-dose steroids for immunosuppression since these doses are already supraphysiologic.

Answer 246

Opioids have a variety of different effects on many organ systems. They can lead to increased tone of the common bile duct and sphincter of Oddi, immunosuppression, skeletal muscle rigidity, and paralytic ileus.

Answer 247

It is now firmly established that opioids play a role in downregulating immune regulation. Direct effects of opioids include modulation of immune cellular activity as well as modulation of specific enzymatic degradation and regulation processes. Several immune cell populations, including T cells, macrophages, and natural killer cells, have been shown to be affected by opioids. Many experiments and studies (mostly done on rats) have shown suppressed activity of immune regulator cells after the administration of opioids.

Answer 248

The incidence of cardiac disease in patients with Duchenne muscular dystrophy is high and careful preoperative evaluation is required. All patients should have an electrocardiogram and echocardiogram, with further testing and cardiology consultation being reserved for patients who have documented findings or symptoms. There is no correlation between the severity of skeletal disease and the severity of cardiac disease. The best correlation between severe cardiac involvement and mortality is the degree of left ventricular dysfunction.

Answer 249

Lipolysis is the hydrolysis of triglycerides into glyceride and free fatty acids which are then used as an energy source. In general, lipolysis is increased by beta-2 and beta-3 adrenergic stimulation but is inhibited by alpha-2 stimulation. Increased catecholamines, cortisol, and glucagon secretion all promote lipolysis are more sensitive to the lipolytic actions of catecholamines when compared to men.

Answer 250

Activation of the nicotinic acetylcholine receptor (nAChR) on the motor endplate of the neuromuscular junction results in outward flow of potassium ions and inward flow of sodium ions. The inward flow of sodium ions results in depolarization of the muscle, ultimately leading to contraction

Answer 251

The different types of irrigation fluids used for TURP each have specific disadvantages. Glycine irrigating solution may cause transient blindness. Distilled water has the highest risk for intravascular hemolysis, hypervolemia, and dilutional hyponatremia. Balanced salt solutions (such as normal saline) cause electrical current dispersion during TURP but significantly reduce the risk of TURP syndrome. Sorbitol and mannitol solutions may lead to hyperglycemia (sorbitol), intravascular fluid expansion with absorption (mannitol) and an osmotic diuresis (sorbitol and mannitol).

Answer 252

Complications of TURP include hypothermia from room temperature irrigation fluids, transient blindness and hyperammonemia from glycine-containing fluid, intraperitoneal bladder perforation, extraperitoneal prostatic capsular perforation, cardiopulmonary compromise, and coagulopathy from fibrinolysis.

Answer 253

Sodium deficit = (140 – current sodium level) x (body weight in kg x 0.6). Symptomatic patients with serum Na+ < 120 mEq/L should have the serum osmolality corrected by 3% HS. Central pontine myelinolysis may result from a rapid increase in serum osmolality during HS therapy.

Answer 254

The effect on the cerebral circulation can be profound. Sodium nitroprusside is a cerebral vasodilator that can lead to increases in cerebral blood flow and blood volume. Rapid and profound reductions in mean arterial pressure may exceed the autoregulatory capacity of the brain to maintain adequate cerebral blood flow resulting in cerebral ischemia.

Answer 255

Cushing’s triad (hypertension, bradycardia, and respiratory changes)

Answer 256

There are only two factors in the coagulation cascade that are decreased during pregnancy and these are factor XI and factor XIII.

Answer 257

The spinal cord receives its blood supply from one anterior spinal artery providing about 75% of the blood supply, which supplies the motor tracts. The two posterior spinal arteries supply the sensory tracts.

Answer 258

For both adults and children, CPR should follow the C-A-B sequence, and high quality chest compressions should be given at a rate of 100 compressions a minute. The compression-ventilation ratio without an advanced airway in place is 30:2 for all situations, except for children and infants when two rescuers are available. When a rescuer is alone and sees an unresponsive adult or a witnessed collapse of a pediatric patient, they should first activate the ERS and obtain an AED. When a rescuer is alone and the pediatric patient had an unwitnessed collapse, they should provide two minutes of CPR prior to activating the ERS and obtaining an AED

Answer 259

Pulse oximetry (SpO2) values of conventional two-wavelength pulse oximeters trend towards 85% in the presence of high methemoglobin (MetHgb) levels. Normal MetHgb levels are < 1%. Conventional pulse oximetry can neither detect MetHgb nor accurately measure SpO2 in the presence of elevated MetHgb levels. In the setting of suspected methemoglobinemia, multi-wavelength co-oximetry should be used. Methemoglobinemia is an altered state of hemoglobin where the ferrous (Fe2+) form of heme is oxidized to the ferric form (Fe3+). Cyanosis develops when 1.5g/dL of MetHgb is present in blood, compared to the 5g/dL needed with deoxygenated blood. MetHgb levels approach 1.5g/dL when the MetHgb level is about 15%. MetHgb is unable to bind new O2, and the oxygen dissociation curve is shifted to the left. The left shift of the oxygen dissociation curve prevents the release of O2 into tissues. Generally, PaO2 levels will remain normal.

Answer 260

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

Answer 261

The Nd-YAG laser is a general-purpose laser that thermally coagulates several millimeters of tissue upon exposure. The light passes through the cornea but can permanently damage the retina within milliseconds of exposure. Protective eyewear with green filters should be worn to prevent eye damage.

Answer 262

Benzodiazepines are highly protein-bound and highly lipophilic. Differences in these characteristics determine the onset of action and duration of action. Plasma clearance is described by a two or three-compartment model. Metabolism occurs largely in the CYP 450 system via oxidation and glucuronic conjugation. Midazolam is short acting and a short context-sensitive half-time allows for continuous infusion.

Answer 263

Mnemonic for GABA-A chloride channel opening: FREnzodiazepines and barbiDURATes. Benzodiazepines increase the frequency of channel opening and barbiturates increase the duration of channel opening.

Answer 264

Carboxyhemoglobin results in falsely elevated SpO2 readings and an inaccurate assessment of arterial oxygen saturation.

Answer 265

Methemoglobin results in a default value of 85%.

Answer 266

Patients with SIADH will have hyponatremia, increased urinary sodium, and an increased urine osmolarity with decreased serum osmolarity.

Answer 267

Hyponatremia may be common after a subarachnoid hemorrhage (SAH). The cause may be attributed to SIADH or cerebral salt wasting (CSW). Cerebral salt-wasting is diagnosed by marked decrease in serum sodium levels and intravascular volume. Treatment for CSW includes volume expansion and sodium administration. A mnemonic to help remember SIADH is syndrome of INAPPropriate anti-diuretic hormone for Increased Na (sodium) in PP (urine).

Answer 268

Hypokalemia leads to characteristic ECG changes (QRS prolongation, ST-segment and T-wave depression, U-wave formation), muscle weakness, and decreased cardiac contractility. Perioperative management and decision to delay depends on the degree of hypokalemia, patient comorbidities, and the urgency of the procedure. In general, serum K+ < 2.5 mEq/L warrants delay of non-emergent surgery. Serum levels between 2.5 - 3.0 mEq/L warrants delay of elective (non-emergent or non-urgent) procedures until the cause of hypokalemia is identified and corrected.

Answer 269

The P50 of adult hemoglobin is 26-27 mm Hg while the P50 of fetal hemoglobin is 19 mm Hg (left shift, greater affinity for oxygen).

Answer 270

Hyponatremia

Answer 271

Interscalene brachial plexus blocks are the best option for regional anesthesia for shoulder surgery because they block the entire brachial plexus as well as the suprascapular nerve, which also provides some sensation to the shoulder.

Answer 272

Several complications can occur when performing an interscalene block and should be considered prior to its use. Ipsilateral hemidiaphragm paresis occurs in almost 100% of patients secondary to blockade of the phrenic nerve. Horner syndrome (ptosis, miosis, and anhidrosis) can result from blockade of the cervical sympathetic ganglion. Hoarseness is common secondary to blockade of the recurrent laryngeal nerve. Less common but potentially devastating side effects include intravascular injection of local anesthetic, epidural or spinal injection, and pneumothorax.

Answer 273

Hetastarch may lead to platelet dysfunction by causing a reduction in the availability of glycoprotein IIb-IIIa on platelets.

Answer 274

Disseminated intravascular coagulation is a pathological process characterized by the widespread activation of the clotting cascade that results in the formation of blood clots in the small blood vessels throughout the body. Thrombocytopenia is the most common laboratory finding in patients with acute DIC, manifesting in about 93% of cases.

Answer 275

Revised Cardiac Risk Index (each component counts as one point): High-risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular procedure) CAD: Ischemic heart disease (by any diagnostic criteria including Q-waves on ECG, history of myocardial ischemic event) CHF: History or present congestive heart failure CVA: History of cerebrovascular disease (including transient ischemic attack or stroke) DM: History of diabetes mellitus requiring insulin Creatinine > 2.0 mg/dL

Answer 276

: Botulinum toxin acts inside the axon terminal at the neuromuscular junction. Tetanus toxin travels via retrograde axonal transport to the central nervous system, where it acts.

Answer 277

With the exception of phenobarbital, the majority of barbiturates are hepatically metabolized into inactive and water-soluble metabolites which are excreted in the urine.

Answer 278

Anterior cerebral artery strokes tend to lead to behavioral abnormalities, aphasia (if dominant cortex is involved), and contralateral lower limb weakness and sensory deficits.

Answer 279

The pediatric population does have a delayed myelinization of nerve fibers. This results in easier intraneural penetration of local anesthetics. Therefore, in the pediatric population onset time of a neuraxial or peripheral block is shortened. Also, dilute local anesthetics are as effective as more concentrated anesthetics in adults.

Answer 280

The uterus receives up to 20% of maternal cardiac output at term. Uterine arteries supply about 85% of blood flow and ovarian arteries up to 15%. Approximately 70% to 90% of uterine blood flow passes through the intervillous space in the placenta to undergo metabolic exchange with fetal terminal villi.

Answer 281

Graft versus host disease (GVHD) is due to viable T-lymphocytes in the transfused blood product reacting against the recipients tissues. When the recipient is not able to reject those lymphocytes due to immunodeficiency or immunosuppression significant morbidity can occur.

Answer 282

Transfusion related acute lung injury (TRALI) has multiple suspected pathophysiologic causes. TRALI is most likely secondary to antibodies present in the donor plasma which reacts with the recipient’s neutrophils producing inflammatory mediators and deposition of complexes in the pulmonary vasculature which causes the symptoms. TRALI can look very similar to acute respiratory distress syndrome (ARDS), however it will resolve in 24-48 hours (if not fatal)

Answer 283

Febrile non-hemolytic reaction is secondary to antibodies to leukocyte antigens and cytokines which cause a febrile reaction which is not explained by other causes (such as infection). This is the most frequently reported transfusion reaction and is self-limited.

Answer 284

Packed red blood cells (PRBCs) are used to replace oxygen carrying capacity. A typical unit of PRBCs will contain between 250 to 350 mL. PRBCs (and other blood products) should not be used as volume expansion due to the risks associated with administration. A single unit of PRBCs usually has a hematocrit of about 60% and it will typically increase the patient’s hematocrit by 3 g/dL.

Answer 285

Platelets are used to reverse thrombocytopenia – either to help stop bleeding or to prevent it from occurring. The threshold for platelet transfusion depends on the indication, most desire a platelet count above 50,000 cells/mm3 for surgical procedures and 10,000 cells/mm3 for prophylaxis. Platelets are derived from volunteer donors by either whole blood donation or through plateletpheresis. Most institutions use pooled platelets (unless specifically requested) and the typical dose contains 6 to 7 donors worth (referred to as “6 pack” or “7 pack”). The main risk of platelets is sensitization reactions due to human leukocyte antigens on the platelet cell membrane or bacterial contamination. Platelets are stored at room temperature on an auger to prevent clotting. They can be stored for as long as 8-13 days, however, most blood banks keep them for only 5 days because of the bacterial contamination risk. This storage manner increases the risk of bacterial growth and transmission. The bacteria come from the skin or blood of the donor, they grow slowly at first and thus sometimes platelets are held in the blood bank for 12-24 hours (before cultures are obtained).

Answer 286

Recurarization or "re-paralyzing" occurs when neostigmine's effects are worn off and residual muscle relaxants bind to nicotinic receptors. This causes weakness and possible paralysis. Recurarization can be prevented by ensuring that patient has appropriate train of four twitches (3+) prior to giving neostigmine. Prolonging the duration of action of neostigmine will also minimize the incidence of recurarization, and this is seen in patients with renal failure

Answer 287

patients receiving heparin for more than five days should have a platelet count checked prior to epidural placement or catheter removal. ASRA guidelines recommend waiting 4-6 hours before epidural placement in patients receiving 5000 U subcutaneous heparin BID or TID

Answer 288

Marfan syndrome is associated with aortic root dilation, aortic regurgitation, aortic aneurysm, aortic dissection. It is important to avoid extremes of blood pressures in these patients. Additionally, positive pressure ventilation should be used with caution in these patients who are at increased risk for spontaneous pneumothorax and tension pneumothorax.

Answer 289

: Although the ulnar nerve is not located inside the brachial plexus trunk sheath at the supraclavicular level, it is anesthetized >90% of the time during SCB due to its close proximity to the subclavian artery and the easy hydrodissection of local anesthetic in this region. This is in comparison to the interscalene block where 50% of cases neglect ulnar nerve blockade

Answer 290

The supraclavicular block (SCB) is known as a “do-it-all” block or the “spinal of the arm” since the nerves are closely packed and readily blocked (see attachment 2). It can be used for shoulder, elbow, and wrist surgery but most practitioners use it for surgery below the mid-humerus level. It is not commonly utilized due to the needle’s close proximity to the subclavian artery and pleura. The SCB is growing in popularity due to the increasing use of ultrasound-guidance which allows for direct visualization of the needle tip.

Answer 291

n otherwise healthy infants and children, an appropriate fluid replacement strategy is to administer 20 to 40 mL/kg of balanced salt solution during the course of the anesthetic

Answer 292

enoldopam is a selective D1 receptor agonist with direct natriuretic and diuretic properties. Fenoldopam promotes an increase in creatinine clearance and has been employed as a renal protector when renal vasoconstriction is anticipated.

Answer 293

Fresh frozen plasma (FFP) is the fluid portion obtained from whole blood donation. It is then frozen within 6 hours of collection and it contains all the coagulation factors except platelets. When needed, FFP must be thawed, a process that can take up to 45 minutes. Many large centers keep several units of plasma thawed for rapid use. Plasma transfusion is indicated in trauma patients with substantial hemorrhage, patients undergoing complex cardiovascular surgery and patients with intracranial hemorrhage requiring emergent reversal of warfarin. Patients with mild prolongation of their INR (< 1.7) do not need reversal with plasma. The volume of plasma needed depends on the cause for transfusion. To restore hemostatic clotting factor levels in patients on warfarin, 15 to 30 mL/kg may be necessary. In patients with significant liver disease, normalization of laboratory tests are not easily achieved with FFP, if at all.

Answer 294

Cryoprecipitate is a fraction of the plasma that precipitates when FFP is centrifuged. It contains a high percentage of factor VIII and fibrinogen. Cryoprecipitate is used to treat hypofibrinogenemia. One should consider administration when fibrinogen levels dip below 100 mg/dL (higher for pregnant patient). A virus-inactivated fibrinogen concentrate is also available for administration.

Answer 295

Cryoprecipitate is a fraction of the plasma that precipitates when FFP is centrifuged. It contains a high percentage of factor VIII and fibrinogen. Cryoprecipitate is used to treat hypofibrinogenemia. One should consider administration when fibrinogen levels dip below 100 mg/dL (higher for pregnant patient). A virus-inactivated fibrinogen concentrate is also available for administration.

Answer 296

Marfan syndrome is associated with aortic root dilation, aortic regurgitation, aortic aneurysm, aortic dissection. It is important to avoid extremes of blood pressures in these patients. Additionally, positive pressure ventilation should be used with caution in these patients who are at increased risk for spontaneous pneumothorax and tension pneumothorax.

Answer 297

The presence of strong bases in the carbon dioxide absorbent (barium, sodium, or potassium hydroxide) most contribute to the production of carbon monoxide

Answer 298

Pregnant patients with idiopathic intracranial hypertension presenting for labor analgesia are an interesting dilemma. If the patient has symptoms, an intrathecal catheter may be a great option to allow for removal of CSF if symptoms worsen during labor.

Answer 299

AMIODARONE EPINEPHRINE PROCAINIMIDE

Answer 300

Elevated preoperative creatinine, complex cardiac procedures, emergency surgery, and preoperative intraaortic balloon pump carry the highest risk for post cardiopulmonary bypass acute kidney injury.

Answer 301

The most effective means of preventing PHN from a herpes zoster infection is prior vaccination with the varicella vaccine. Vaccination decreases the overall incidence of virus reactivation but also decreases the severity of disease development and incidence of PHN if reactivation does occur.

Answer 302

Dabigatran is a direct thrombin inhibitor. Thrombin is at the end of the common pathway for clot formation and stabilization and plays an integral part in the amplification of secondary hemostasis. Consequently, it is a highly desirable target for antagonism. Furthermore, these agents are significantly easier to manage than warfarin. They have short half-lives and rapid onset of action which negate the need for bridging therapy. Also, they are highly bioavailable with little interindividual variability. Thus coagulation monitoring is unnecessary. Lastly, they have few drug or dietary interactions. The only dosing concern with dabigatran, in particular, is renal excretion. The dose must be reduced for patients with decreased creatinine clearance.

Answer 303

ADP receptor antagonists, such as clopidogrel, prasugrel, and ticlopidine, prevent the expression of GP IIb/IIIa on the surface of activated platelets, thereby inhibiting platelet adhesion and aggregation. Ticlopidine is an antiplatelet drug in the thienopyridine family which is an adenosine diphosphate receptor inhibitor. It irreversibly blocks the ADP receptor on the surface of platelets. Without ADP, fibrinogen does not bind to the platelet surface, preventing platelets from sticking to each other. By interfering with platelet function, ticlopidine prevents clots from forming on the inside of blood vessels. Ticlopidine’s effects persist for 3 days after discontinuing ticlopidine although it may take 1–2 weeks for platelet function to return to normal, as the medication affects platelets irreversibly. Therefore, new platelets must be formed before platelet function normalizes.

Answer 304

Dipyridamole is a phosphodiesterase (PDE) inhibitor. PDE inhibitors are primarily used for stroke prophylaxis since they increase the production of cAMP, which is an active inhibitor of platelet aggregation.

Answer 305

Eptifibatide is a GP IIb/IIIa receptor blocker. GP IIb/IIIa receptor blockers inhibit the cross-linkage of fibrinogen, the final step in the common hemostatic pathway for platelet aggregation. They include abciximab, tirofiban, and eptifibatide. These agents are administered only intravenously and primarily used for management of acute coronary syndrome. Their effects can be monitored with ACTs and are reversible with a clearance of the drug. Most of these agents are renally excreted and have half-lives around 2.5 hours except for abciximab which has a significantly longer half-life (12 hours) and clinical effects that last for approximately 48 hours. All of these drugs cause thrombocytopenia, but the effect is strongest with abciximab with an incidence of about 2.5% as opposed to 0.5% with the other receptor antagonists.

Answer 306

Wind-up" is a phenomenon that describes an exponentially progressive increase in firing of WDR neurons with repeated stimulation.

Answer 307

Bilirubin exists in two forms: conjugated and unconjugated. Unconjugated bilirubin is a product of hemoglobin metabolism, is water insoluble, and is a neurotoxin. Unconjugated bilirubin is taken up by the liver and conjugated with a glucuronic acid. This conjugation increases the solubility of bilirubin and decreases toxicity. Unconjugated bilirubin levels may be increased with liver disease or increased red blood cell turnover (e.g. hemolysis). Conjugated bilirubin levels are increased with liver disease or biliary disease. Jaundice is seen when bilirubin levels are greater than 3 mg/dL.

Answer 308

Alpha-2 receptor agonism in the dorsal horn reduces presynaptic norepinephrine release to provide analgesia.

Answer 309

Avoidance of sickling by avoiding hypoxia, acidosis, and hypothermia Aggressive pain management Hydration Coordination of care with hematology team Care of the immunosuppressed patient pre-splenectomy or post-splenectomy, who may be on prophylactic antibiotics or an immunization schedule Avoidance of hyperventilation for stroke prevention Judicious use of tourniquets, cell salvage, and cardiopulmonary bypass in order to avoid sickling

Answer 310

Cyanotic defects can be recalled by the names which start with the letter "T" and the following numerical order: One trunk - Truncus Arteriosus Two large arteries switch - Transposition of the Great Arteries Three cusp atrioventricular valve - Tricuspid atresia Four lesions - Tetralogy of Fallot Five words - Total Anomalous Pulmonary Venous Return

Answer 311

< 4-4.5 CM

Answer 312

The PT is the best test to measure synthetic function of the liver. The PT is often elevated 1.5 times normal when severe liver disease is present. The PT measures the clotting time of the extrinsic pathway involving factor VII, which has the shortest half-life of the clotting factors.

Answer 313

``` Snoring Tired during the day Observed apneas Pressure (high blood pressure) BMI > 35 Age >50 Neck size Gender (male) ```

Answer 314

Mnemonic: WEPT for Warfarin, Extrinsic, PT. Mnemonic for Vitamin K dependent factors: 1972 for 10, 9, 7, 2.

Answer 315

The liver is the largest visceral organ in the body and represents about 2% of lean body mass. The liver is unique in that it receives a dual blood supply. The hepatic artery supplies 20% of the blood to the liver and the portal vein supplies 80%. Hypoxia, hypercarbia, hypotension, and catecholamine release decrease hepatic blood flow. The liver is responsible for synthesizing nearly all the proteins in the blood. The liver is involved in glucose and fat metabolism. The liver is also responsible for the detoxification and metabolism of numerous drugs.

Answer 316

Propylthiouracil and methimazole are both medications that can be used to inhibit the production of thyroid hormone (T4). In addition, propylthiouracil blocks the peripheral conversion of T4 to T3. These anti-thyroid drugs can be used as either definitive therapy or as a bridge to treatment with surgery or radioactive iodine.

Answer 317

Severe hypertension is defined as BP > 180/110 mmHg, however, surgery may proceed if there are no signs of end-organ damage. However, if the patient has cardiac risk factors and/or is to undergo non-emergent high-risk surgery, then it would not be unreasonable to delay surgery for blood pressure control.

Answer 318

Sweat glands are innervated by the sympathetic nervous system and utilize acetylcholine with muscarinic receptors, therefore beta blockade will not prevent sweating with hypoglycemia which may be the only symptom seen in this setting.

Answer 319

Aortic valve opening occurs after isovolumetric contraction, which corresponds to the c-wave on CVP and after the QRS complex on ECG.

Answer 320

``` Snoring Tired during the day Observed apneas Pressure (high blood pressure) BMI > 35 Age >50 Neck size Gender (male) ```

Answer 321

The majority of patients with myelomeningocele also have Chiari II malformation, which involves herniation of the brainstem through the foramen magnum and frequently hydrocephalus secondary to blockage of the fourth ventricle.

Answer 322

Bottom Line: Normal CVP tracing summary: a wave: atrial contraction, absent in atrial fibrillation c wave: TV bulging into RA during RV isovolumetric contraction x descent: TV descends into RV with ventricular ejection and atrial relaxation v wave: venous return to and systolic filling of the RA y descent: atrial emptying into RV through open TV

Answer 323

Dominant x descent | Minimal y descent

Answer 324

loss of A wave

Answer 325

cannon A wave

Answer 326

Lorazepam premedication can prolong extubation times and does not improve patient satisfaction scores. Clonidine decreases MAC but can increase the risk of hypotension and bradycardia. Fentanyl premedication may actually sensitize patients to pain postoperatively. Scopolamine is more likely than atropine to cause central anticholinergic syndrome.

Answer 327

Fibronigen:Pregnancy is has been called a state of chronically compensated disseminated intravascular coagulopathy. Factors that increase include I (fibrinogen), VII, VIII, IX, X, XII, and von willebrand factor which peak at the time of parturition. Factors that decrease include XI, XIII, antithrombin III, and tPa. Also, resistance to activated protein C occurs as well as a decline in the level of protein S.

Answer 328

The second-order neuron begins with the dorsal horn of the spinal cord and decussates to the contralateral spinothalamic tract. This tract is located bilaterally in the anterolateral spine. The spinothalamic tract synapses at the ventral posterolateral nucleus of the thalamus. The signals carried include crude touch, pain, and temperature. This pathway also describes the second-order neuron of pain transmission.

Answer 329

A-delta fibers are small myelinated fibers that carry signals from peripheral mechanoreceptors and thermoreceptors to the dorsal horn of the spinal cord. This pathway describes the first-order neuron. First-order neurons secrete chemical mediators of pain, including substance P which is secreted both peripherally and in the dorsal horn. Adenosine is another local molecule that modulates dorsal horn pain transmission.

Answer 330

Consistently Effective: - Periodic inflation of the collapsed (nondependent) lung with oxygen - Continuous positive airway pressure to nondependent (operative) lung - Two-lung ventilation - Early ligation or clamping of the ipsilateral pulmonary artery (during pneumonectomy)

Answer 331

Neuraxial opioids provide analgesia via inhibition of excitatory neurotransmitters and hyperpolarization of postsynaptic neurons in the substantia gelatinosa of the dorsal horn of the spinal cord.

Answer 332

Depolarizing block, also called phase I block, is preceded by muscle fasciculation. It has no fade during repetitive stimulation (tetanic or TOF), no post tetanic potentiation and is characterized by a decrease in twitch tension. With prolonged administration of succinylcholine or in patients with abnormal genetic variants of butyrylcholinesterase, the block can change to a phase II block. Phase II block has fade during TOF and tetanic stimulation, and also has post tetanic potentiation. It is similar to what is seen with a nondepolarizing muscle relaxant. Use of antagonists (e.g. neostigmine) gives an unpredictable response in phase II block and is generally not recommended.

Answer 333

Pregnant patients with antiphospholipid syndrome carry a higher risk peripartum, especially for thrombotic events. A history of recent administration of antiplatelet and anticoagulants is important if a neuraxial anesthetic is planned. ASRA guidelines recommend waiting 4-6 hours after heparin before neuraxial block placement.

Answer 334

Morbidly obese patients typically have decreased FRC and ERV due to thoracic and abdominal fat accumulation. Chronic hypoxemia in these patients often results in polycythemia and/or pulmonary hypertension. The increased metabolic demands lead to increased oxygen consumption and compensatory increases in minute ventilation and cardiac output.

Answer 335

The phases of diastole are: isovolumetric relaxation, early rapid filling, diastasis, and atrial contraction.

Answer 336

Early rapid filling contributes the largest volume of blood during diastole

Answer 337

Slow filling (diastasis) occurs as the left ventricle fills and the pressures between atrium and ventricle become equal. This contributes about 5% of the preload.

Answer 338

Late rapid filling (atrial contraction): the left atrium contracts, ejecting additional blood into the left ventricle. This phase can contribute 15-20% of the preload. Atrial contraction is the last phase of diastole. The mitral valve closes after the atrial contraction.

Answer 339

Isovolumetric relaxation: this phase begins with the closure of the aortic valve and continues till the opening of the mitral valve. During this time, the left ventricle is relaxing, however there is no change in the ventricular volume (isovolumetric).

Answer 340

The Dalton law of partial pressures states that the total gas pressure in a system is equal to the sum of the partial pressures of the component gases.

Answer 341

Charles Law states that volume and temperature of a gas will be directly proportional when the pressure of the system is held constant (e.g. if the temperature is increased the gas will expand)

Answer 342

The Boyle Law states that with a constant temperature the volume and pressure of a gas are inversely proportional

Answer 343

The Gay-Lussac Law states that when the volume of a gas is held constant, the temperature and pressure of a gas are proportional

Answer 344

Intravenous administration of etomidate is associated with pain on injection, postoperative nausea and vomiting, and superficial thrombophlebitis. Ways to prevent thrombophlebitis are to use larger veins, increasing the speed of injection, and pretreatment with lidocaine. Treatment options are controversial but include the use of NSAIDS and elastic stockings.

Answer 345

Total body weight: maintenance infusion dose of propofol, succinylcholine

Answer 346

Lean body weight: thiopental, induction dose of propofol, fentanyl

Answer 347

Ideal body weight: rocuronium, vecuronium

Answer 348

Metoclopramide is a dopamine antagonist with peripheral cholinergic agonism that can be used to decrease gastric volume in patients with impaired gastric emptying but has no effect on gastric pH. Metoclopramide is prokinetic and decreases gastric volume, increases lower esophageal sphincter tone, but has not been found to affect gastric pH. Metoclopramide should be used with caution in patients with Parkinson disease given its dopamine receptor antagonism centrally with the risk of rigidity and extrapyramidal symptoms. In addition it has mild antiemetic properties that are inferior to 5-HT3 antagonists.

Answer 349

Risk factors for PDPH include: age < 40 years, prior PDPH, BMI < 30, history of air travel, and multiple dural attempts. The incidence of PDPH is reduced with non-cutting, pencil-point, narrower-bore needles (e.g. Whitacre or Sprotte).

Answer 350

Citrate quenches free ions such as calcium Dextrose provides substrate for energy generation Adenine is a substrate for ATP generation Phosphate acts as a buffer

Answer 351

Treatment for hyperkalemia includes, but is not limited to, albuterol, insulin, sodium bicarbonate, sodium polystyrene sulfonate, loop diuretics, and/or hemodialysis. Albuterol and insulin are rapid acting and the most effective pharmacologic interventions for acutely lowering serum potassium. Calcium does not affect potassium levels.

Answer 352

Postoperative delirium is a syndrome characterized by acute onset of variable and fluctuating changes in level of consciousness accompanied by a range of other mental symptoms. Risk factors for developing postoperative delirium include the type of operation which includes cardiac, thoracic, and orthopedic procedures

Answer 353

Predisposing factors for postoperative delirium are age > 65 years, male sex, preexisting cognitive impairment or depression, pre-existing functional impairment, sensory impairment (e.g. visual and hearing deficiencies), medication (opioids, benzodiazepines, anticholinergics), and type of surgery.

Answer 354

Metabolic alkalosis results from an excess in serum bicarbonate and can be of multiple causes including excessive bicarbonate administration, conversion (such as citrate or lactate to HCO3 by the liver), excessive chloride loss such as with nasogastric suctioning, increased renal reabsorption (hyperaldosteronism), and from volume contraction (as seen with diuretic therapy).

Answer 355

The carotid body chemoreceptors increase ventilation when PaO2 (not PAO2, CaO2 or SaO2) decreases through afferent impulses via the glossopharyngeal nerve to CNS ventilation centers. Their function is impaired by opioids, benzodiazepines, volatile anesthetics (as low as 0.1 MAC), and bilateral carotid endarterectomy.

Answer 356

Ginseng can lead to perioperative hypoglycemia, coagulopathy with irreversible platelet inhibition, reduction of warfarin effect, and sympathomimetic effects. It should be discontinued at least 1 to 2 weeks prior to surgery and if not then blood glucose should be monitored perioperatively.

Answer 357

Beta agonists classically cause hyperglycemia and hypokalemia.

Answer 358

Ritodrine and terbutaline are beta agonists selective for β2 > β1 receptors. β1 includes heart and adipose tissue. β2 effects include smooth muscle, adipose, liver, skeletal muscle, pancreas, and salivary glands. The smooth muscle relaxation produces the desired effect of uterine relaxation. The stimulation of adenylyl cyclase increases the conversion of ATP to cAMP. This decreases the available intracellular calcium and inhibits MLCK resulting in impaired contractility.

Answer 359

Available tocolytics include ethanol, magnesium sulfate, prostaglandin inhibitors, calcium channel blockers, and β-sympathomimetics.

Answer 360

An ABG from a patient with moderate to severe CO poisoning will most likely show a metabolic acidosis with a normal PaO2 and a falsely elevated calculated SaO2 and SpO2.

Answer 361

Aprepitant is a NK1 receptor antagonist. Aprepitant undergoes hepatic metabolism and has a half-life of about 10 hours. Aprepitant has very few side-effects and they are usually relatively mild. Aprepitant is associated with malaise, nausea, and rash as its most common side-effects.

Answer 362

Droperidol is an antidopaminergic medication that is often used to prevent or treat nausea and vomiting associated with anesthesia. Droperidol has been associated with dystonic reactions and extrapyramidal symptoms. Additionally, droperidol is associated with QT prolongation and has a FDA black box warning because of it

Answer 363

Scopolamine is an antimuscarinic medication often used for motion sickness. Scopolamine can cross the blood brain barrier and acts centrally to prevent nausea. Scopolamine is often associated with dry mouth and blurred vision. Scopolamine is associated with delirium and delayed arousal in the elderly. Scopolamine can also be associated with other anticholinergic symptoms like urinary retention, tachycardia, and constipation. This patient has no contraindications to scopolamine.

Answer 364

Propofol has a significant effect on a patient’s cardiovascular system. It leads to a dose-dependent decrease in systemic vascular resistance and myocardial contractility, attenuates the body’s natural baroreceptor reflex, and leads to significant arteriolar and venodilation given it’s reduction in sympathetic activity.

Answer 365

Lidocaine 1.5 mg/kg IV adds approximately 0.3 MAC to the anesthetic. This may have reduced the hemodynamic response to laryngoscopy and intubation.

Answer 366

Left shift caused by decrease in temperature, PaCO2, hydrogen ion concentration, and 2,3-DPG.

Answer 367

The body compensates for anemia by increasing cardiac output and redistributing blood flow to favor the heart and brain. The oxygen-hemoglobin dissociation curve is shifted to the right and the oxygen extraction ratio is increased.

Answer 368

The saphenous nerve is the terminal branch of the femoral nerve. It supplies sensation to the skin on the medial side of the leg and foot.

Answer 369

Hypercapnia following administration of oxygen to a patient with chronic obstructive pulmonary disease is primarily due to ventilation-perfusion mismatching, driven by inhibition of hypoxic pulmonary vasoconstriction.

Answer 370

Factors that decrease MAC: certain drugs (opioids, ketamine, benzodiazepines, acute alcohol use), electrolyte disturbances (hyponatremia), anemia, hypercarbia, hypothermia, hypoxia, pregnancy.

Answer 371

The Bowditch effect (or Treppe phenomenon) leads to an increase in heart rate secondary to increased myocardial tension.

Answer 372

The Anrep effect is an increase in inotropy due to an increase in afterload. Increased afterload leads to decreased stroke volume and increased end-systolic volume. The inotropy from the Anrep effect partially compensates for this.

Answer 373

The oculocardiac reflex can develop during any ocular surgery and it is important to be on the lookout and prepared. Pressure on the globe or extraocular muscles can result severe hemodynamic consequences. Bradycardia to asystole has occurred. An easy way to remember this is the “five and dime” reflex – it starts in the fifth cranial nerve (trigeminal) and exits the tenth cranial nerve (vagus).

Answer 374

Aerobic metabolism produces approximately 16 times the ATP of anaerobic metabolism. The additional ATP is produced within the mitochondrion via the citric acid cycle and oxidative phosphorylation. Both anaerobic and aerobic metabolism start with glucose, but anaerobic metabolism generates lactate while aerobic metabolism produces carbon dioxide and water.

Answer 375

Sepsis and septic shock are medical emergencies and should be rapidly and aggressively managed as soon as a diagnosis is made. Broad-spectrum antibiotics should be initiated within the first hour. Sepsis-induced hypoperfusion should be treated with at least 30 mL/kg of intravenous crystalloid within the first three hours. For patients with septic shock, vasopressor therapy should be used in combination with volume resuscitation to target an initial MAP of 65 mm Hg.

Answer 376

Visceral pain is subcategorized into true visceral pain and parietal pain. True visceral pain is nonspecific and dull; often concentrated at the midline. Parietal pain, clinically called referred pain, is usually localized to a site distal from the stimulus of origin. This is likely due to embryological migration and convergence of tissue.

Answer 377

Commonly used Factor Xa inhibitors are rivaroxaban and apixaban. These medications also do not have any form of antidote in the case of overdose at this time, however, prothrombin complex concentrates (PCC) have been used.

Answer 378

GP IIb/IIIa receptor blockers inhibit the cross-linkage of fibrinogen, the final step in the common hemostatic pathway for platelet aggregation. They include abciximab, tirofiban, and eptifibatide. Their effects can be monitored with ACTs and are reversible with clearance of the drug. Most of these agents are renally excreted and have half-lives around 2.5 hours except for abciximab which has a significantly longer half-life (12 hours) and clinical effects that last for approximately 48 hours. All of these drugs cause thrombocytopenia, but the effect is strongest with abciximab with an incidence of about 2.5% as opposed to 0.5% with the other receptor antagonists.

Answer 379

Lepirudin and desirudin are recombinant forms of hirudin, a naturally occurring anticoagulant. Argatroban and bivalirudin are synthetic agents in the same class. Lepirudin, desirudin, argatroban, and bivalirudin are all drugs that directly inhibit thrombin in its free and fibrin-bound states. None of them are immunogenic and so there is no risk of heparin-induced thrombocytopenia (HIT). There are currently no known antidotes to any of the direct thrombin inhibitors and, therefore, reversal depends upon their clearance. Clinical effects can be monitored with ACT or aPTT measurements.

Answer 380

P2Y12 ADP receptor antagonists, such as clopidogrel, prasugrel, and ticlopidine, prevent the expression of GP IIb/IIIa on the surface of activated platelets, thereby inhibiting platelet adhesion and aggregation. Clopidogrel is the most commonly prescribed agent in this class and acts as a non-competitive and irreversible antagonist. It is an inactive prodrug that requires oxidation to its active metabolite. A genetic polymorphism was discovered that results in the inability to metabolize clopidogrel making it ineffective and putting patients at risk of cardiovascular morbidity and mortality. The FDA put a black box warning on the medication to remind clinicians to monitor the activity. Platelet function studies are insensitive and unreliable for clopidogrel, but tests are now available to measure the inhibition of the P2Y12 ADP receptor.

Answer 381

The effects of volatile anesthetics on the circulatory system include decreased systemic vascular resistance, decreased myocardial contractility, coronary vasodilatation (especially isoflurane), and ischemic preconditioning.

Answer 382

ischemic preconditioning effects of volatile anesthetics are related to reduced loading of calcium into myocardial cells. A preconditioning stimulus such as brief coronary occlusion and ischemia initiates a signaling cascade of intracellular events that reduces ischemia and reperfusion myocardial injury. There is a memory effect from an ischemic stimulus that offers 2 to 3 hours of protection. The volatile anesthetics that are given before (preconditioning) or immediately after (postconditioning) mimic ischemic preconditioning and trigger a similar cascade of intracellular events resulting in reduced myocardial injury and myocardial protection that lasts beyond the elimination of the anesthetic.

Answer 383

Nitrous oxide: can react with and inactivate vitamin B12, which can disrupt pathways that are dependent on it. B12 deficiency results in hematologic and neurologic dysfunction (megaloblastic anemia, myelopathy, neuropathy, and encephalopathy). These risks are higher in patients with pernicious anemia, GI malabsorption, extremes of age, malnutrition, and strict vegans. Bone marrow changes are rare in healthy individuals unless exposure is very prolonged (> 12hours), however in critically ill patients changes may be seen after only a few hours.

Answer 384

Droperidol and haloperidol cause central nervous system depression. Butyrophenones are fluorinated derivatives of phenothiazines. Their mechanism of action is quite complex with binding at dopamine, norepinephrine, serotonin, and acetylcholine receptors. There are also postulated anti-histamine and anti-adrenergic (alpha 1) receptor binding sites.

Answer 385

2,3-diphosphoglycerate (2,3-DPG) is an intermediate step in the glycolytic pathway and this product of cellular metabolism is a factor in the shifting of the oxygen-hemoglobin dissociation curve. Given that it is indicative of cellular metabolism occurring, increases in its production shifts the curve to the right, favoring oxygen unloading at the level of the tissues. Conditions where 2,3-DPG is decreased, such as in the storage of red blood cells or in the formation of glucose and glycogen, causes the curve to shift in the opposite direction

Answer 386

Decreased 2,3 DPG, alkalosis, hypothermia, hypocarbia, fetal hemoglobin, and abnormal hemoglobin species such as carboxyhemoglobin and methemoglobin.... to go LEFT, you go LOW (low age, low temp, alkaLOWsis, low CO2, low 2,3 DPG)

Answer 387

Thyroid storm is a life-threatening exacerbation of hyperthyroidism that presents with hyperthermia, tachycardia, arrhythmias, agitation, and confusion. Two conditions for its development are untreated hyperthyroidism and precipitating factor such as emergency surgery. Treatment includes hydration, beta blockers and more specific therapies (steroids, antithyroid medications, iodine).

Answer 388

Calcium channel blockers (CCBs) such as diltiazem and verapamil are contraindicated in the setting of acute malignant hyperthermia that is being treated with dantrolene. This combination can lead to arrhythmias, myocardial depression, hyperkalemia, and severe cardiovascular collapse.

Answer 389

Alpha-stat ABG management allows pH to rise naturally during cooler body temperatures. During pH-stat ABG management CO2 is added to overcome hypothermia induced alkalosis and maintain pH at 7.4

Answer 390

Blood pH and the solubilities of gases in blood are inversely related to temperature, while the partial pressures of gases are directly related to temperature. Accordingly, when arterial blood gas values are corrected to a colder temperature, PaO2 and PaCO2 decrease (they are more soluble at lower temps) while pH increases.

Answer 391

Opioids have a direct effect on the respiratory centers in the medulla, producing a dose-dependent depression of the ventilatory response to CO2.

Answer 392

The respiratory depressant effects of opioids may be divided into two components: (1) suppression of the ventilatory drive (i.e., true respiratory depression from the inactivation of respiratory neurons in the brain stem) and (2) occlusion of the upper airways either from a direct suppression of neurons in the brainstem involved in maintaining the upper airway muscle tone or from the loss of muscle tone related to sedation.

Answer 393

1) Metabolic acidosis due to increased ATOT (for example hyperphosphatemia contributes to the acidosis seen in renal failure) 2) Metabolic alkalosis due to decreased ATOT (for example hypoalbuminemia causes metabolic alkalosis) 3) Metabolic acidosis due to decreased SID (for example in a patient given large amounts of fluids with SID=0 such as 0.9% NaCl) 4) Metabolic alkalosis due to increased SID (for example in a vomiting patient who loses chloride, which is a strong anion)

Answer 394

The primary mechanism by which NSAIDs exert their analgesic effect is through inhibition of cyclooxygenase (COX) and synthesis of prostaglandins, which are important mediators of peripheral sensitization and hyperalgesia. In addition to being peripherally acting analgesics, NSAIDs can also exert their analgesic effects through inhibition of spinal COX.

Answer 395

COX-1 is the constitutive enzyme that produces prostaglandins, which are important for general “house-keeping” functions such as gastric protection and hemostasis. COX-2, on the other hand, is the inducible form of the enzyme that produces prostaglandins that mediate pain, inflammation, fever, and carcinogenesis.

Answer 396

NSAIDs lead to a decrease in the production of prostaglandins. Prostaglandin E2 is the key mediator of both peripheral and central pain sensitization. Peripherally, prostaglandins do not directly mediate pain; rather, they contribute to hyperalgesia by sensitizing nociceptors to other mediators of pain sensation such as histamine and bradykinin. Centrally, prostaglandins enhance pain transmission at the level of the dorsal horn by increasing the release of substance P and glutamate from first-order pain neurons, increasing the sensitivity of second-order pain neurons, and inhibiting the release of neurotransmitters from the descending pain-modulating pathways.

Answer 397

Cyanide causes its deleterious effects by inactivating cytochrome oxidase, which in turn causes an uncoupling of mitochondrial oxidative phosphorylation and an inhibition of cellular respiration. With aerobic respiration inhibited, cellular metabolism switches from aerobic to anaerobic and causes the production of lactic acid; this results in a metabolic acidosis.

Answer 398

Patients with cyanide toxicity can present with a myriad of symptoms, which include generalized weakness, neurological symptoms, cardiopulmonary symptoms, and GI symptoms. Cyanide toxicity should be on the differential for any patient who presents with a history of smoke exposure or burns secondary to residential or industrial fire. In rare instances, patients with prolonged IV exposure to sodium nitroprusside can exhibit cyanide toxicity.

Answer 399

Hydroxocobalamin works by combining with cyanide to form cyanocobalamin (vitamin B-12). Cyanocobalamin is renally cleared.

Answer 400

Although succinylcholine is not routinely used in pediatrics, it can be used as a rescue medication for protecting an airway. It should not be considered for this use in children with myopathy, malignant hyperthermia, immobilization, severe intraabominal sepsis, globe injuries, and motor neuron disorders.

Answer 401

Patients with muscular dystrophy typically have a sensitivity to nondepolarizing neuromuscular blockers. Patients with myasthenia gravis are particularly sensitive to nondepolarizing agents.

Answer 402

The quick sequential organ failure assessment (qSOFA) can be used to identify adult ICU patients with a suspected infection that are likely to have a prolonged ICU stay or poor outcome. It may also be used in adult out-of-hospital, emergency room, and general ward patients with suspected infection to identify those that are more likely to have poor outcomes typical of sepsis. It is scored 0-3 with one point each for altered mental status (GCS < 15), respiratory rate ≥22, and systolic blood pressure ≤100 mm Hg. A score ≥2 indicates a worse prognosis.

Answer 403

After initial adoption of the use of lead II for intraoperative monitoring for arrhythmia, London et al validated the use of leads II and V5 together to improve the sensitivity of detection of myocardial ischemia. Schwartz and Barash later proposed the use of leads II and V4 for preserved sensitivity but improved specificity over the II/V5 combination.

Answer 404

Hemolytic transfusion reactions can be defined as acute or delayed. Both are the result of recipient antibody and complement attack on donor cells. Acute hemolytic transfusion reactions are almost always due to ABO incompatibility and DHTRs are typically secondary to antibodies associated with the Rh, Kidd, or Kell systems.

Answer 405

Situations that increase airway resistance (or decrease airflow) will result in increased PIP. These include bronchospasm, kinked endotracheal tube, airway secretions, mucus plugs. Pplateau will remain unchanged.

Answer 406

Situations that increase the elastic resistance (or decrease compliance) will result in increased PIP and PPlateau. These include, intrinsic pulmonary diseases, ascites, abdominal insufflation, tension pneumothorax, and Trendelenburg position.

Answer 407

The indication for suctioning of an infant born with meconium is depressed respirations, depressed muscle tone, and/or a heart rate less than 100.

Answer 408

Preeclampsia begins with dysfunctional myometrial spiral arteries who have an increased vascular resistance. Endothelial cells become dysfunctional with increased thromboxane production and decreased nitric oxide production. Additionally, antiangiogenic proteins are produced which worsen preeclampsia, by preventing blood vessel growth.

Answer 409

Severe features of preeclampsia are: - Hypertension above 160 systolic over the course of 4 hours - New or worsening thrombocytopenia - Impaired liver function or severe and persistent right upper quadrant pain - Renal insufficiency - Pulmonary edema - New-onset cerebral or visual disturbances

Answer 410

Heart failure is a disease characterized by symptoms that occur secondary to the heart's decreasing function. The body compensates for the increase in end-diastolic volume via a cycle involving endogenous mediators leading to diuresis and increased sympathetic activity. Treatment involves medications to control blood pressure and improve volume status.

Answer 411

Quadriplegia occurs with injury above the first thoracic vertebra, meaning within the cervical segments of C1-C8

Answer 412

Coronary perfusion occurs primarily during diastole and is dependent on coronary perfusion pressure and vascular resistance. Coronary perfusion pressure is defined as diastolic aortic pressure minus left ventricular end-diastolic pressure.

Answer 413

A paired t-test compares outcomes in a single group who serve as their own control, whereas an unpaired t-test compares an outcome in two different groups.

Answer 414

Chi-square is a test used to analyze ordinal data. Ordinal data allow for rank order (e.g. 1st, 2nd, 3rd, etc).

Answer 415

Analysis of variance (ANOVA) is used to test parametric continuous data when 3 or more groups exist.

Answer 416

Microshock occurs as a result of a new grounded current that can result in electric shock with small current values (on the order of 80-200 microamps). This can result in ventricular fibrillation. The equipment ground wire is the most important measure in prevention. An equipment ground wire is essentially a very low impedance wire that allows leakage current to pass through to prevent buildup of leakage current. It also helps to prevent electric shock with patient grounding, as electricity will follow the path of least resistance (the wire instead of the patient).

Answer 417

Heliox is useful in situations where airway radius is decreased with resultant turbulent gas flow. With turbulent gas flow, resistance increases with increasing gas density. Helium has a decreased gas density as compared to oxygen or air and thus resistance to gas flow is reduced

Answer 418

Tricyclic antidepressants have multiple mechanisms for the analgesic effects including inhibition of serotonin reuptake, NMDA blockade, and opioidergic effects. Side effects include dry mouth, sedation, and difficulty with urination. Patients with chronic pain states may have comorbidities such as depression that are also treated by antidepressants. TCAs have proven beneficial in the treatment of neuropathic pain.

Answer 419

Drugs that most commonly cause EPS perioperatively are the dopamine antagonist antiemetics: droperidol, metoclopramide, and prochlorperazine.

Answer 420

Treatment options for EPS or acute dystonic reactions from dopamine receptor antagonists include anticholinergics (preferred), benzodiazepines, and beta-blockers. Additional medications that can be used to treat EPS include antihistamines, dopamine receptor agonists, and α-adrenergic agonists.

Answer 421

Anticholinergic medications such as diphenhydramine (recall that it is both anticholinergic and antihistamine) and benztropine are considered first-line therapies for EPS since they can rapidly (five minutes or less when administered IV) improve and/or eliminate symptoms. They work by restoring the dopaminergic-cholinergic balance

Answer 422

A point of care glucose test is the most appropriate test in this instance (C). The result of the test will be immediate and change the management of this patient immediately. The difference between the medication dosing of an intrathecal catheter and of an epidural catheter is quite significant (generally about ten fold). Glucose is present in the CSF at 40-70 mg/dL and is not present in normal saline. This difference, along with the quick nature of the test, makes it an accurate and effective method to determine what type of fluid is returning from the epidural needle.

Answer 423

Classic characteristics of trisomy 21 include a single palmar crease, upslanting palpebral fissures, endocardial cushion defects, atlantoaxial instability, and sleep apnea

Answer 424

Classic characteristics of trisomy 18 include VSDs, "rocker-bottom" feet, and clenched hand with overlapping digits.

Answer 425

13 is characterized by holoprosencephaly, cleft lip, absent ribs, and polydactyly.

Answer 426

Trisomy 8 is characterized by a long face, wide nose, thick lower lip, and cleft palate

Answer 427

TEA is beneficial for large thoracic and abdominal incisions, especially for patients with pre-existing chronic pain whose postoperative pain may be difficult to control. Other benefits of TEA include decreased protein catabolism, decreased duration of postoperative ileus, and decreased pulmonary complications.

Answer 428

High-dose thrombin time (HiTT) has been shown to be superior to determining heparin concentrations instead of the highly variable ACT.

Answer 429

Heparin is used in the anticoagulation of many patients, especially those undergoing cardiac procedures involving cardiopulmonary bypass (CPB). It binds to both antithrombin III and thrombin to exert its anticoagulant effect. The relatively large doses needed for initiation of CPB is due to the fact only one-third of the heparin dose contains the critical pentasaccharide segment needed for the binding to the antithrombin molecule. Heparin is dosed at 300 to 400 units per kilogram with the goal obtaining an ACT value of ~480 seconds to be able to initiate CPB safely.

Answer 430

Clinical variables that can prolong ACT include the following: hemodilution (in heparinized patients), hypothermia, thrombocytopenia, and platelet inhibitors.

Answer 431

Mixed opioid agonist-antagonists have various potencies and activities at different opioid receptors. Butorphanol is a mixed mu-opioid receptor agonist-antagonist and a kappa-opioid receptor partial agonist that is useful in treating pain, postoperative shivering, and neuraxial opioid-induced central pruritus.

Answer 432

Nalbuphine is primarily a kappa-opioid receptor agonist and a partial mu-opioid receptor antagonist. Alone, it has a similar analgesic potency to morphine, but it exhibits a ceiling effect at dosages greater than 30 mg where it does not produce further respiratory depression. In combination with other opioids, it may provide analgesia while reversing opioid-induced respiratory depression. This carries the risk of withdrawal, especially with chronic opioid users. It can also be used for opioid-induced pruritus.

Answer 433

Buprenorphine is a mu-opioid receptor partial agonist and a kappa-receptor antagonist. Combined with naloxone, it is a popular oral long-term opioid replacement therapy that deters abuse. If crushed and injected intravenously, the opioid antagonism of naloxone will induce withdrawal.

Answer 434

The anterior cardiac vein is associated with the RCA, the great cardiac vein is located with the LAD (left anterior descending artery), and the middle cardiac vein is associated with the PDA (typically from the RCA).

Answer 435

Delayed emergence can be due to residual medication effects, metabolic abnormalities, hypoxia or hypercarbia, temperature abnormalities, or neurologic events. A typical approach includes investigation and reversal of anesthetic medications, confirmation of neuromuscular reversal, laboratory analysis and treatment of metabolic abnormalities, basic neurologic exam, and neurologic imaging or consultation if necessary. Of note, though anticholinergic medications can cause delayed emergence, anticholinesterase medications do not.

Answer 436

Volatile agents delivered at levels greater than 1 MAC decrease CMR but increase CBF, known as uncoupling. This decreased neuronal metabolic demand with increased metabolic supply is called luxury perfusion. Although this can be beneficial during global ischemia, the excess blood flow to certain regions steals from other regions which can be detrimental during focal ischemia.

Answer 437

Dead space ventilation is increased by factors that increase anatomic dead space (e.g. neck extension, bronchodilators) or alveolar dead space (e.g. upright positioning, PPV, decreased cardiac output, many lung pathologies).

Answer 438

Respiratory acidosis occurs when ventilation is inadequate. Initial compensation occurs though plasma protein buffers and is followed hours to days later by the renal response.

Answer 439

Patients with familial hypokalemic periodic paralysis suffer from episodes ranging from weakness to full paralysis and hypokalemia related to abnormal potassium regulation. Published triggers include: stress, cold environment or hypothermia, carbohydrate load, infection, glucose infusion, metabolic alkalosis, alcohol, strenuous exercise, and steroids.

Answer 440

Hemophilia A patients who do not respond well to exogenous human factor VIII infusion may have developed anti-factor VIII antibodies. The treatment in the case of hemorrhage or surgery in patients with hemophilia A with anti-factor VIII antibodies involves porcine factor VIII, recombinant factor VIIa, or recombinant factor IIa.

Answer 441

Subdural injection should be considered when subarachnoid or epidural block does not behave as expected. Often the symptoms are variable but classically they are: minimal or variable motor blockade, excessive sensory blockade, excessive sympatholysis. Patients that have experienced a subdural block in the past appear to have a higher incidence of it reoccurring, and these patients may prove to be more difficult for neuraxial placement.

Answer 442

A decrease in blood pressure stimulates the release of renin into the serum from the renal tubules. Renin converts angiotensinogen to angiotensin I, which is then converted to angiotensin II by ACE. Angiotensin II causes an increase in blood pressure by direct vasoconstriction, enhancing the sympathetic nervous system, and causing an increase of aldosterone.

Answer 443

FFP for reversal of warfarin may be used if surgery is urgent and INR is significantly elevated; However, PCC has become the agent of choice over FFP. Vitamin K should be used for elective procedures including procedures that can be delayed for 24 hours.

Answer 444

Ketamine is associated with decreased incidence of emergence delirium in children and has a role in the prevention of the oculocardiac reflux. The risk of extrusion of intraocular contents on induction is greatly overstated and is not likely in closed globe injuries. Ketamine does, however, contribute to nausea and vomiting.

Answer 445

Afferent: traction on extraocular muscles, external pressure on the globe, retrobulbar block with local anesthetic --> short ciliary nerve --> ciliary ganglion --> ophthalmic branch of the trigeminal nerve (which also receives input from the long ciliary nerve) --> trigeminal (Gasserian) ganglion --> main trigeminal sensory nucleus Efferent: synapse to visceral motor nucleus of vagus nerve in reticular formation --> parasympathetic output to sinoatrial node --> sinus bradycardia, junctional bradycardia, atrioventricular block, ventricular ectopy, asystole

Answer 446

A lower RQ would decrease CO2 production and may improve the chances of successful ventilator weaning. Respiratory quotient refers to the amount of CO2 produced per unit of O2 consumed to a specific energy substrate. Generally the number 0.8 is used for the Q due to a relatively high mix of carbohydrates and proteins in the diet. Lipids have the lowest Q at 0.7 and thus will result in a decrease in CO2 production compared with carbohydrates (Q of 1) and proteins (Q of 0.8).

Answer 447

Sugammadex, a modified γ-cyclodextrin, is the first selective relaxant binding agent. It is capable of reversing any depth of neuromuscular blockade induced by steroidal neuromuscular blockers (such as rocuronium, and to a lesser extent pancuronium and vecuronium) by forming a 1:1 inactive complex and creating a concentration gradient for the neuromuscular blocker to move away from the neuromuscular junction.

Answer 448

A candidate for TAVR must have symptomatic AS and be high surgical risk with expected survival greater than 12 months.

Answer 449

Leukotrienes are synthesized after mast cell activation and produce bronchoconstriction, increased capillary permeability, vasodilation, coronary vasoconstriction, and myocardial depression. Leukotriene modifiers are used in the treatment of chronic asthma as an adjunct; they are not used for acute asthma attacks as they do not reach maximal effect for several days.

Answer 450

Bradycardia following spinal anesthetic injection is more common in patients with high baseline vagal tone, anesthetic levels above T5, and is associated with decreased cardiac preload (i.e. reverse Bainbridge reflex).

Answer 451

Early and aggressive treatment of bradycardia during spinal anesthesia can prevent progression to cardiac arrest. Atropine, ephedrine, and epinephrine are recommended to be used early when bradycardia occurs.

Answer 452

Preload in the heart causes stretch of the myocardium, which increases intrinsic activity of the heart (Bainbridge reflex). When preload falls, the intrinsic depolarization of the SA node slows resulting in another cause of bradycardia following spinal anesthesia.

Answer 453

There are a few absolute contraindications for percutaneous tracheostomy: - Active infection at the site of tracheostomy - Uncontrolled bleeding disorder - Unstable cardiopulmonary status (shock, extremely poor ventilatory status) - Patient unable to stay still - Abnormal anatomy of the tracheolaryngeal structures

Answer 454

Nausea and vomiting occurs after spinal anesthesia approximately 20% of the time. Risk factors include high block (above T5), hypotension, opioid administration, and a history of motion sickness. Unopposed parasympathetic (vagal) activity after sympathetic blockade causes increased peristalsis of the gastrointestinal tract, which can lead to nausea and is the primary mechanism behind nausea after spinal blockade. Atropine is an anticholinergic medication, thus is useful for treating nausea after high spinal blockade.

Answer 455

Factors that decrease release of acetylcholine: 1) Antibiotics (clindamycin, polymyxin) 2) Magnesium: antagonizes calcium 3) Hypocalcemia 4) Anticonvulsants 5) Diuretics (furosemide) 6) Eaton-Lambert syndrome: inhibits P-type calcium channels 7) Botulinum toxin: inhibits SNARE proteins

Answer 456

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

Answer 457

SID (Strong Ion Difference) = [strong cations] - [strong anions] = [Na+ + K+ + Ca2+ + Mg2+] - [Cl- + lactate-]

Answer 458

Disturbances that increase the SID increase the blood pH (alkalosis) while disorders that decrease the SID lower the plasma pH (acidosis). So, low pH or SID is associated with acidosis and high pH or SID is associated with alkalosis.

Answer 459

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 460

Protein binding is related to the duration of action of drugs, and is not related to the spread of opioids in the epidural space. Albumin is relatively basic and thus will bind to acidic drugs. For drugs that are basic, binding is to alpha-1 acid glycoprotein (AAG).

Answer 461

The pKa is the acid dissociation constant. When a molecule is in solution at its pKa, 50% of the molecule is ionized and 50% is unionized. Most molecules are considered in an active form when unionized, because in that form they can cross lipid membranes. The pKa has a much greater effect on local anesthetics than opioids. When considering pKa it is often associated with speed of onset of the drug, especially local anesthetics. This is the reason why sodium bicarbonate may be added to some local anesthetic mixtures.

Answer 462

Sodium bicarbonate administration is associated with transient increases in PaCO2, EtCO2, and intracranial pressure. Administration causes transient decreases in serum calcium and potassium. Sodium bicarbonate can also cause hypotension due to hypocalcemia, ventricular depressant effects, and redistribution of blood to the pulmonary vasculature.

Answer 463

Measures taken to improve this clinical scenario are fluids and alpha-agonists, such as phenylephrine. The pure alpha agonism increases afterload and helps "stent open" the left ventricular outflow tract in order to prevent the dynamic obstruction that occurs with SAM. The primary goal is to reduce cardiac contractility and improve filling. Agents that increase contractility will worsen obstruction. This is why athletes with hypertrophic obstructive cardiomyopathy (HOCM) have cardiac arrest episodes during times of athletic stress, where heart rate and contractility are both high combined with low preload from dehydration.

Answer 464

The phased array probe is a low frequency probe with a small foot print primarily used for cardiac evaluation.

Answer 465

The anterior two-thirds of the spinal cord is supplied by the anterior spinal artery and contributing radicular vessels, including the artery of Adamkiewicz (which most commonly arises between T9 and T12). The posterior one-third of the spinal cord is supplied by the two PSAs, along with collateral radicular vessels.

Answer 466

Hyperparathyroidism can cause hyperchloremia and increase renal bicarbonate loss, which may result in a normal anion gap metabolic acidosis.

Answer 467

Hepatopulmonary syndrome (HPS) is characterized by the triad of liver dysfunction, unexplained hypoxemia, and intrapulmonary vascular dilations. One of the unique features of this syndrome is orthodeoxia, which is increased dyspnea when transitioning from the supine to upright position.

Answer 468

Respiratory alkalosis, such as from hyperventilation, can cause electrolyte abnormalities such as hypocalcemia, hypokalemia, and hypophosphatemia. Hypocalcemia is caused by increased calcium binding to negatively charged plasma proteins as the proteins release hydrogen ions to restore physiologic pH.

Answer 469

The active metabolite in meperidine, normeperidine, causes seizure activity. Morphine’s primary active metabolite, M6G, has a 100-fold greater affinity for μ-receptors than morphine, promoting respiratory depression. Morphine’s inactive metabolite, M3G, may cause myoclonus and allodynia. As morphine and meperidine metabolites are typically excreted from the kidneys, their side effects are prolonged in the setting of renal failure. Barbiturates have decreased protein binding in renal failure which leads to higher concentrations of free active molecules.

Answer 470

The meperidine molecule resembles atropine. Increased heart rate may occur as a side effect of meperidine administration.

Answer 471

Hypercalcemia occurs with thiazide diuretics and these can be a treatment option for hypocalcemia. Loop diuretics are associated with hypocalcemia.

Answer 472

Diphenhydramine has antihistamine (H1) and anticholinergic activity, inhibits serotonin reuptake, potentiates opioid-induced analgesia, and may have local anesthetic-like properties (intracellular sodium channel blocker).

Answer 473

Abciximab is a GP IIb/IIIa receptor blocker mainly used during and after coronary artery procedures like angioplasty. TrueLearn Insight : Mnemonic: abciximab can be remembered as abCIX (six) imab, where II(b) * III(a) = CIX (six).

Answer 474

Chi-square testing is used for comparison of two or more populations with respect to a single variable with categorical data (nominal scale).

Answer 475

Hemodynamic changes during CEA are common and are related to surgical manipulation, denervation, and impaired sensitivity of the carotid sinus baroreceptors. Stimulation of baroreceptors results in increased parasympathetic discharge with decreased sympathetic discharge. This leads to hypotension and bradycardia, which can potentially be prevented by local anesthetic infiltration.

Answer 476

Serotonin syndrome is a complex of symptoms and signs attributable to drug-induced changes in sensitivities of serotonin receptors in the CNS. A typical cause is the combination of two or more serotonergic drug (SSRIs, TCAs, MAO inhibitors, or even St. John's Wort). Methylene blue can increase plasma serotonin concentrations and precipitate serotonin syndrome.

Answer 477

Neuroleptic malignant syndrome (NMS) is a life-threatening reaction that occasionally occurs in response to neuroleptic or antipsychotic medication. Symptoms include high fever, confusion, rigid muscles, variable blood pressure, sweating, and fast heart rate. NMS is often slower in onset (generally over one to three days) and is usually associated with hyperthermia (> 38 degC).

Answer 478

Malignant hyperthermia occurs rarely after exposure to halogenated volatile anesthetics and depolarizing muscle relaxants (succinylcholine). Its classic presentation is increased concentrations of end-tidal carbon dioxide, rigor mortis-like muscle rigidity, tachycardia, hyperthermia, and acidosis.

Answer 479

Patients with muscular dystrophy are at an increased risk in the perioperative period for hypoventilation due to compromised respiratory musculature, atelectasis, difficulty weaning from mechanical ventilation, congestive heart failure and cardiac arrhythmias. Fatal reactions to succinylcholine and volatile anesthetics have been reported thus careful patient selection and potential avoidance of these agents may be prudent.

Answer 480

Patients with muscular dystrophies have an increased risk of cardiac complications due to the involvement of the cardiac musculature. Complete cardiac evaluation in the preoperative evaluation is important and should include an electrocardiogram and echocardiogram. If there is an abnormality of cardiac function, a dobutamine stress test and/or cardiac consultation should be considered. Optimization of any arrhythmia or cardiomyopathy should occur before elective surgery as these patients are at a high risk for heart failure and potentially fatal dysrhythmias.

Answer 481

Long-standing and/or severe OSA can result in heart failure: OSA -> Hypoxia/Hypercapnia -> Pulmonary hypertension -> Right ventricle hypertrophy -> Right ventricle failure.

Answer 482

Nitroglycerin undergoes reductive hydrolysis in the liver and in the blood by glutathione-organic nitrate reductase. While endothelial and vascular smooth muscle cells are sites for nitric oxide production by nitric oxide synthase, they are not sites for nitroglycerin metabolism.

Answer 483

Nitroglycerin is a potent vasodilator. Nitrate-induced vasodilation is mediated by enzymatically produced nitric oxide (NO). This leads to activation of guanylyl cyclase in vascular smooth muscle cells. Guanylyl cyclase metabolizes guanosine triphosphate (GTP) which leads to increased levels of cyclic guanosine monophosphate (cGMP). The end result is a decrease in intracellular calcium concentrations and vascular smooth muscle relaxation.

Answer 484

Dobutamine is the most appropriate initial agent in this case of decreased cardiac output with maintained blood pressure. In some cases, dobutamine has the additional benefit that the patient could go home on an infusion. However, dobutamine is not a vasopressor and it would not be the most appropriate agent if the patient was hypotensive.

Answer 485

Norepinephrine is an alpha-1 and beta-1 agonist that can assist in treating cardiogenic shock. It compares favorably to both dopamine and epinephrine. It would be the preferred vasopressor if the patient was hypotensive.

Answer 486

Metabolism via biotransformation is the most important means of drug action termination. Renal elimination will terminate drug action for small, non-protein-bound and hydrophilic drugs. Redistribution plays a role in very lipophilic anesthetics.

Answer 487

Cytochrome P450 enzymes catalyze phase I reactions.

Answer 488

Biotransformation reactions are classified into two types: phase I (nonsynthetic) and phase II (synthetic) reactions. Phase I reactions include the process of oxidation, reduction, and hydrolysis. These reactions introduce functional groups (–OH, –SH, –NH2) that serve to promote the following phase II reactions. Some enzymes catalyzing phase I reactions include cytochrome P450, alcohol dehydrogenase, monoamine oxidase, esterases, and amidases. Phase II reactions are conjugation reactions, linking the functional groups from phase I reactions to other endogenous compounds. Enzymes catalyzing phase II reactions include glucuronyl transferase and sulfotransferase, among others.

Answer 489

Thrombocytopenia is a well-known feature of cirrhosis. Other hemostatic abnormalities in cirrhosis include a decrease in pro- and anti-coagulants (potentially causing bleeding or thrombotic complications) and low-grade fibrinolysis. Prothrombin time (PT/INR) is typically increased in cirrhosis due to decreased production of coagulation factors in the liver.

Answer 490

Cirrhosis hemodynamics are characterized by a hyperdynamic state, with increased cardiac output and low peripheral vascular resistance.

Answer 491

2,3-diphosphoglycerate levels in red blood cells are often increased in cirrhotic patients, shifting the oxygen-hemoglobin dissociation curve to the right.

Answer 492

Left ventricular afterload is increased when obstruction occurs, with the development of a significantly negative intrathoracic pressure. Additionally, the negative intrathoracic pressure causes an increase in preload, not a decrease in preload. The increased preload with increased afterload leads to increased pulmonary hydrostatic pressures.

Answer 493

The spinothalamic tract is an ascending pathway which transmits pain and temperature information to the brain. Axons of the spinothalamic tract generally cross the midline of the spinal cord and ascend in the contralateral spinothalamic tract.

Answer 494

A-delta and C fibers are the primary afferent fibers involved with the transmission of pain signals.

Answer 495

Dorsal column refers to an area of white matter in the lateral/posterior aspect of the spinal cord. It is an ascending pathway which transmits information about localized fine touch and proprioception.

Answer 496

Spina bifida cystica is a type of neural tube defect, including meningocele, myelocele, and myelomeningocele. A meningocele is where the meninges alone protrude through the defect in the vertebral column, while a myelomeningocele has the meninges, nerve roots, and cerebrospinal fluid protrude through a defect in the bony enclosure of the spinal cord. Commonly, a myelomeningocele is associated with a tethered spinal cord, hydrocephalus, and a latex allergy. Consequently, a tethered spinal cord is a relative contraindication to neuraxial anesthesia (spinal more than epidural) due to the high potential for spinal cord injury with needle insertion.

Answer 497

The chi-square test is a nonparametric test to compare nominal or ordinal data comprising of one to multiple sample tests.

Answer 498

Kidney disease has several effects on the human body. Hyperkalemia and hypocalcemia are often seen, as well as anemia from decreased epoetin. Uremia can cause symptoms of anorexia, mental status changes, and platelet dysfunction.

Answer 499

Changes seen in end-stage renal disease include: - Anemia - Hypocalcemia - Hyperkalemia - Hypermagnesemia - Hyperlipidemia - Hypertension - Hyperphosphatemia - Secondary hyperparathyroidism - Uremic bleeding diathesis

Answer 500

The liver has a dual blood supply arising from the portal vein and the common hepatic artery. The common hepatic artery is derived from the celiac axis and carries blood that is well oxygenated, supplying approximately 20 to 25 percent of the blood flow to the liver. The remaining 75 to 80 percent of the blood flow to the liver is carried by the portal vein, which is a confluence of the splenic and superior mesenteric veins. Blood transported by the portal vein is less oxygenated but rich in nutrients absorbed from the small intestine. Venous blood collects in the hepatic sinusoids and drains into the central vein of the lobule, then into venules, segmental veins, and ultimately, the blood from the liver drains into the vena cava via the hepatic veins.

Answer 501

Hydralazine is a direct arteriolar smooth muscle relaxant by increasing intracellular cyclic guanosine 3',5'-monophosphate (cGMP). It works in 5-30 minutes, which makes it appropriate for first-line treatment of acute hypertension. It is metabolized in the liver with a duration of action of 2-6 hours, which makes it difficult to titrate in the acute setting of difficult-to-treat hypertensive urgency or emergency as sometimes encountered in the post-anesthesia care unit (PACU).

Answer 502

Labetalol is a non-selective adrenergic antagonist that blocks both alpha and beta receptors to decrease blood pressure. Its onset is within 5 minutes while its duration of action is 3-6 hours until it is metabolized by the liver. Like hydralazine, its longer duration of action makes it difficult to titrate in the acute setting of refractory hypertension.

Answer 503

Clevidipine's rapid metabolism and vascular smooth muscle selectivity make it less appropriate for first-line treatment of post-operative hypertension, but ideal when the high blood pressures become dangerously difficult to control and refractory to standard treatment.

Answer 504

Esmolol is a beta-1 receptor blocker that is used as a first-line intravenous bolus therapy to quickly treat hypertension. It is also used as first-line therapy for postoperative atrial fibrillation, following the American College of Cardiology and American Heart Association guidelines. It is quickly metabolized by erythrocyte esterases, which make it an appropriate medication for infusions as well. Its cardiac selectivity, however, limits its effectiveness in treating refractory critically high blood pressures compared to clevidipine; meaning, higher doses do not further reduce blood pressure but instead reduce heart rate.

Answer 505

Barbiturates cause a decrease in cerebral blood flow, cerebral blood volume, and intracranial pressure (ICP). They decrease renal and hepatic blood flow. Barbiturate-mediated reductions in cerebral metabolic rate (CMRO2) and ICP make them useful in the anesthetic management of patients with space-occupying intracranial lesions.

Answer 506

P50 is lowest in newborns (18 mm Hg) and is highest in children over 12 months of age (30 mm Hg). After 10 years of age, P50 decreases to adult level (27 mm Hg).

Answer 507

Ways in which laminar flow will become turbulent include high gas flow rates, sharp angles within a tube, branch points within a tube, and an increase in the diameter of the tube. Increasing the density of gases flowing or decreasing viscosity also promotes turbulent flow.

Answer 508

Increasing the viscosity of a gas promotes laminar flow. When looking at the calculation for Reynolds number, viscosity is in the denominator. This means that viscosity is inversely related to the number. An example of viscosity causing laminar flow can be seen in comparing the flow of water to maple syrup. Syrup flows smoothly and does not splash, but water flowing becomes very turbulent.

Answer 509

Decreased density promotes laminar flow. Helium-oxygen is an example of using a less dense gas (helium) with oxygen to increase flow past a stenosis. The decreased density increases flow past the stenosis. This also explains why helium causes increased pitch in voice when someone speaks after inhaling helium. Additionally, when a more dense gas like nitrous oxide combines with oxygen turbulent flow occurs. Nitrous oxide has a density of 1.977 g/L and causes deepening of voice as a result of turbulent flow.

Answer 510

SvO2 = SaO2 – [VO2 ÷ (CO x Hgb x 1.36)]

Answer 511

Antidotes include hydroxocobalamin and sodium thiosulfate, with amyl nitrite and sodium nitrite as possible options in cases where carbon monoxide toxicity is ruled out

Answer 512

Acute respiratory acidosis is compensated by an increase in serum HCO3- of 2 mmol/L for every 10 mm Hg increase in PaCO2. Chronic respiratory acidosis is compensated by an increase in serum HCO3- of 4 mmol/L for every 10 mm Hg increase in PaCO2.

Answer 513

Cerebral palsy patients have an increased incidence of gastroesophageal reflux and aspiration. They are more resistant to non-depolarizing neuromuscular blockers and succinylcholine may be used.

Answer 514

Dabigatran is a direct thrombin inhibitor. This can lead to linear increases in PT and PTT, but there is no consistent correlation with therapeutic levels of the drug. No therapeutic drug monitoring is currently in place.

Answer 515

Tricyclic antidepressants can aid in the treatment of non-cancer related pain through NMDA antagonism, opioidergic effects, sodium and potassium channel blocking, and through interfering with the reuptake of serotonin. However, a dangerous side effect profile limits their use in daily practice.

Answer 516

Epinephrine is a reasonable first choice drug to treat any suspected protamine reaction. It is particularly useful for type I reactions and is the treatment of choice for type II reactions. Since type II protamine reactions are anaphylactic or anaphylactoid reactions, epinephrine is highly beneficial as it will increase cardiac output and SVR, promote bronchodilation, and will stop the allergic reaction by preventing further mast cell and basophil degranulation.

Answer 517

Spinal anesthesia causes a sympathectomy that often results in hypotension via three main mechanisms: arterial dilation (decreased afterload), venodilation (decreased preload), and bradycardia (parasympathetic dominance and/or the Bezold-Jarisch reflex).

Answer 518

Spinal anesthesia causes a sympathectomy that often results in hypotension via three main mechanisms: arterial dilation (decreased afterload), venodilation (decreased preload), and bradycardia (parasympathetic dominance and/or the Bezold-Jarisch reflex).

Answer 519

The cardiac output of the neonate is determined primarily by heart rate and their cardiac myocytes are relatively insensitive to catecholamines. Neonatal myocytes have poor lusitropy and cannot accommodate increasing preloads with increasing stroke volume. Atropine is an initial treatment option for the euvolemic neonate in response to hypotension.

Answer 520

Substance P and calcitonin gene-related peptide (CGRP) release from pancreatic vagal afferent neurons can lead to visceral pain.

Answer 521

Inhaled anesthetics undergo varying degrees of biotransformation. Hepatic CYP2E1 is particularly important in the oxidative metabolism of halogenated inhaled anesthetics. Desflurane undergoes minimal biotransformation. Sevoflurane interacts with soda lime and has been associated with compound A formation. Hepatotoxicity is primarily associated with exposure to halothane, and nephrotoxicity is associated with methoxyflurane.

Answer 522

Compartmental models are pharmacokinetic models that illustrate the kinetic processes of drug absorption, distribution, and elimination. These models can be one-compartment (central) or two-compartment (central and peripheral). They allow prediction of drug movement in the body following administration and more precise development of dosage regimens.

Answer 523

A mnemonic for factors that decrease FRC is PANGOS: Pregnancy, Ascites, Neonate, General Anesthesia, Obesity, Supine position

Answer 524

A mnemonic for factors increasing closing capacity is ACLS-S: Age, Chronic bronchitis, LV failure, Smoking, Surgery.

Answer 525

The juxtaglomerular apparatus is a key part of the renin-angiotensin-aldosterone system and responsible for releasing renin into plasma with: (1) hypotension, (2) hyponatremia, and/or (3) β1-receptor activation.

Answer 526

Primary hyperaldosteronism (Conn syndrome) is a disorder of hypertension, hypernatremia, and hypokalemia leading to decreased plasma renin concentrations due to negative feedback to the juxtaglomerular apparatus in the kidney.

Answer 527

The Purkinje fibers are part of the ventricular conduction system. When an action potential comes from the atrioventricular node, it spreads through the Purkinje fibers and bundle of His. This causes ventricular contraction. These events occur at the start of systole.

Answer 528

Hypoxemia, hypothermia, and acidosis are all associated with persistent fetal circulation. This is due to increased pulmonary pressures, which favors flow through shunts that are only functionally closed and not yet anatomically closed. Maternal NSAID use is associated with premature ductal closure and not persistent fetal circulation.

Answer 529

Risk factors for uterine atony include multiparity, multiple gestations, polyhydramnios, chorioamnionitis, prolonged labor, oxytocin-induced labor, and mechanical factors.

Answer 530

Due to the concern of postoperative opioid-induced ventilatory depression in the obese patient, opioids are best based on lean body weight. Postoperative management in the obese population also warrants close respiratory monitoring of oxygenation and ventilation, as well as a multi-modal approach to analgesia.

Answer 531

Carboprost tromethamine is contraindicated in patients with significant reactive airway disease since it has prostaglandin-like effects and can cause bronchospasm.

Answer 532

Methylergonovine maleate is contraindicated in the setting of pregnancy-induced hypertension or preeclampsia since it is an ergot derivative that may lead to hypertensive emergency.

Answer 533

``` S = Snore – do you snore loud? T = Tired – do you feel tired no matter how many hours of sleep you get? O = Observed – have others observed you stop breathing during sleep? P = Pressure – are you being treated for high blood pressure? B = BMI – is your body mass index > 35 A = Age – are you older than 50? N = Neck circumference – is the neck circumference > 40 cm? G = Gender – is the patient a male? ``` Need at least 3 points

Answer 534

Arrhythmias may occur during and after infarction, with ventricular fibrillation accounting for the majority of early deaths, and most occurring within 4 hours of symptom onset. The use of beta-blockers significantly reduces the incidence of ventricular fibrillation and thus mortality.

Answer 535

The approach to acute coronary syndrome (ACS) includes early 12 lead ECG, oxygen if saturation is less than 94% or if otherwise indicated, aspirin if not contraindicated, cautious use of nitrates, use of morphine if nitrates fail to improve pain in STEMI, and fibrinolysis within 30 minutes or PCI within 90 minutes when indicated. Complications such as arrhythmias and subsequent mortality are reduced with beta-blocker use (when appropriate), whereas prophylactic antiarrhythmics are not recommended. TrueLearn Insight : In the past, the mnemonic MONA was taught for morphine, oxygen, nitroglycerin, aspirin as initial therapies for ACS. However, newer data suggest some of these measures (e.g. morphine, oxygen) may be detrimental if given to all patients.

Answer 536

Myasthenia gravis is an autoimmune disease that starts with ocular weakness and worsens with exercise. It causes resistance to succinylcholine and sensitivity to nondepolarizing neuromuscular blocking agents. TrueLearn Insight : If you cannot avoid giving a non-depolarizing agent, use rocuronium then reverse with sugammadex because neostigmine can lead to incomplete reversal (and sometimes cholinergic crisis).

Answer 537

The following conditions should be considered contraindications to the use of intravenous barbiturates: 1) Respiratory obstruction or an inadequate airway as barbiturates may worsen respiratory depression 2) Severe cardiovascular instability, shock, or hypovolemic conditions 3) Status asthmaticus as airway control and ventilation may be worsened by barbiturates 4) Porphyria as acute attacks may be precipitated by the administration of barbiturates

Answer 538

Viral cardiomyopathy is a dilated cardiomyopathy with signs and symptoms including peripheral edema, dyspnea on exertion, orthopnea, and decreased functional status

Answer 539

The more lipophilic the drug, the shorter its duration in the epidural space. Morphine is relatively hydrophilic compared to lipophilic drugs like fentanyl. Epidural morphine can last 8-12 hours. In cases of overdose, respiratory depression may not appear until hours after injection as there is bimodal activation of opioid receptors.

Answer 540

Nitrous oxide produces irreversible inactivation of vitamin B12 through oxidation of cobalt. Vitamin B12 (cyanocobalamin) is an integral component of the formation of methionine by methylation of homocysteine. Homocysteine levels have been demonstrated to acutely increase following administration of nitrous oxide. Halogenated anesthetics have no significant effect on platelet count or coagulation studies but may transiently increase platelet aggregation.

Answer 541

Potassium-sparing diuretics prevent K+ secretion by antagonizing the effects of aldosterone in collecting tubules.

Answer 542

Loop diuretics inhibit the activity of the Na+/Cl-/K+ symporter in the thick ascending limb of the loop of Henle.

Answer 543

NSAIDs lead to a decrease in the production of prostaglandins. Prostaglandin E2 is the key mediator of both peripheral and central pain sensitization. Peripherally, prostaglandins do not directly mediate pain; rather, they contribute to hyperalgesia by sensitizing nociceptors to other mediators of pain sensation such as histamine and bradykinin. Centrally, prostaglandins enhance pain transmission at the level of the dorsal horn by increasing the release of substance P and glutamate from first-order pain neurons, increasing the sensitivity of second-order pain neurons, and inhibiting the release of neurotransmitters from the descending pain-modulating pathways.

Answer 544

This overall unopposed parasympathetic activity leads to a mnemonic SLUDGE Mi ("Sludge Me"): Salivation, Lacrimation, Urination, Defecation, Gastrointestinal upset, Emesis, Miosis. This overall unopposed parasympathetic activity leads to a mnemonic SLUDGE Mi ("Sludge Me"): Salivation, Lacrimation, Urination, Defecation, Gastrointestinal upset, Emesis, Miosis.

CA-2 ITE Flashcards

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