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Question 1

A 26-year-old pregnant woman presents in active labor and is requesting pain control. Which of the following regional anesthetic techniques is effective ONLY for the first stage of labor?

Answer 1

Lumbar sympathetic blocks are effective methods for first-stage labor analgesia.

Question 2

A parturient in the first stage of labor requests epidural analgesia. After a catheter is threaded into the epidural space at the level of L4-L5, an initial bolus of dilute bupivacaine with epinephrine is administered. Which of the following benefits is MOST likely to be associated with the addition of epinephrine to the epidural bupivacaine solution?

Answer 2

The addition of epinephrine to a long-acting epidural local anesthetic such as bupivacaine may increase the quality and density of the block, reduce the risk of systemic bupivacaine toxicity, and allow for early detection of intravascular catheter placement. It does not result in a significantly increased duration of action.

TrueLearn Insight : Other noteworthy local anesthetic additives include sodium bicarbonate, alpha2-agonists (eg, clonidine), and opioids (eg, fentanyl). Sodium bicarbonate is added chiefly to increase the rate of onset of anesthesia by increasing local pH, thus facilitating the entry of uncharged local anesthetic into neurons. However, its administration with bupivacaine and ropivacaine is less beneficial. Opioids reduce local anesthetic toxicity, variably increase analgesic quality and duration, and do not augment motor blockade. Alpha2-agonists also intensify and prolong analgesia while reducing required perioperative anesthetic and opioid doses.

Question 3

A 25-year-old woman with type 1 von Willebrand disease (vWD) who is pregnant for the first time and has not yet delivered is admitted to the obstetrics floor for a planned cesarean section. She has had consistent care during her pregnancy, and her most recent factor VIII level is 75%. Which of the following is the MOST appropriate next step in the treatment of this patient?

Answer 3

During the second and third trimesters of pregnancy, the levels of clotting factors including factor VIII and vWF increase. Pregnant patients with type 1 vWD typically do not require treatment when their factor VIII and von Willebrand factor levels are >50%.

TrueLearn Insight : Neuraxial anesthesia is usually considered to be contraindicated in a patient with von Willebrand disease; however, in some patients with mild disease (especially type I), factor VIII and von Willebrand factor levels may normalize, and an epidural or spinal may be considered. The risks and benefits should be considered if neuraxial anesthesia will be performed in these cases.

Question 4

A 26-year-old primiparous female is requesting labor analgesia. Her pregnancy has been uncomplicated thus far. She is noticeably uncomfortable with regular contractions every 3 minutes. She then develops late decelerations despite being normotensive with an SpO2 of 98% on room air. Of the following options, which is BEST to treat fetal hypoxia?

Answer 4

Delivery of oxygen to the fetus during labor is controlled by oxygen carrying capacity (oxyhemoglobin saturation and hemoglobin concentration) and uterine blood flow. In utero resuscitation is indicated for fetal distress with the goal of improving fetal oxygenation. Measures of utero fetal resuscitation include: repositioning of mother to lateral or hands and knees position, administration of supplemental oxygen (controversial), administration of IV fluids or vasopressors if hypotensive, discontinuation of uterotonic drugs if present, and administration of a tocolytic if sustained uterine contraction is suspected.

TrueLearn Insight : Fetal hypoxia mnemonic, SPOILT: Stop oxytocin, Pressure (treat hypotension), Oxygen, IV fluid bolus, Left lateral decubitus (or all fours), Tocolytics

Question 5

Which of the following is MOST correct regarding the respiratory system in the third trimester of pregnancy compared to the nonpregnant state?

Answer 5

The closing capacity of the pregnant patient does not differ significantly from the patient’s nonpregnant baseline. However, the functional residual capacity is significantly decreased, a change that may predispose the pregnant patient to early and rapid distal airway closure when functional residual capacity is further reduced (e.g. by supine positioning).

Question 6

Increased levels of which of the following coagulation factors contribute to the hypercoagulable state found during pregnancy?

Answer 6

Pregnancy represents a hypercoagulable state due to changes in factor levels including increases in fibrinogen (factor I), factor VI, factor VIII, factor IX, factor X, and factor XII. Levels of II and V remain unchanged, while levels of factors XI, XIII, and antithrombin III decrease. Platelet levels remain the same or slightly decreased.

Question 7

Which of the following is NOT a component of a fetal biophysical profile?

Answer 7

Biophysical profile (BPP) components consist of a non-stress test (NST) and observation of fetal breathing, fetal movement, fetal tone, and amniotic fluid volume

Question 8

Which of the following values on an arterial blood gas measurement is MOST LIKELY INCREASED in a healthy pregnant patient compared with a healthy nonpregnant patient?

Answer 8

Increased minute ventilation occurs as early as the first trimester of pregnancy and leads to a respiratory alkalosis with a compensatory metabolic acidosis. On arterial blood gas analysis, this is represented by a normal to slightly increased pH, decreased PaCO2, decreased serum bicarbonate level and decreased base excess. Increased alveolar ventilation also leads to an increase in PaO2.

Question 9

A parturient who is at full term is in labor, and the fetal weight is estimated to be 5,000 g. In the event of shoulder dystocia, which of the following is the MOST appropriate initial treatment?

Answer 9

Shoulder dystocia is a fetal life-threatening emergency. Nitroglycerin provides fast-onset uterine relaxation to assist with obstetric manipulation and delivery.

Question 10

Which of the following is LEAST likely to be a complication from using terbutaline for tocolytic therapy?

Answer 10

Preterm labor can be treated with β-adrenergic agonists such as ritodrine and terbutaline. Review the table above for a list of maternal, fetal, and neonatal side effects and complications of the drugs, noting especially the cardiopulmonary and endocrine effects. Assuming the fetus has a functioning pancreas, use of β-agonists is much more likely to lead to fetal hyperinsulinemia than hypoinsulinemia.

Question 11

Which of the following is most likely to increase uterine blood flow during pregnancy and labor?

Answer 11

Uterine blood flow is decreased by systemic hypotension, uterine vasoconstriction, and uterine contractions (particularly when pharmacologically augmented). Tocolytic agents such as β2 agonists improve uterine blood flow by reducing uterine vascular resistance.

Question 12

High-dose oxytocin therapy is MOST likely to result in which of the following?

Answer 12

High-dose oxytocin stimulates antidiuresis and natriuresis which can lead to hyponatremia. Due to structural similarities between oxytocin and vasopressin, high-dose vasopressin administration can cause uterine contractions.

Question 13

Which of the following mechanisms BEST explains the analgesic effects of intrathecal fentanyl?

Answer 13

Opioids produce analgesia through their actions at multiple areas in the central nervous system. Their most significant site of action is the substantia gelatinosa in the dorsal horn, where opioids inhibit the presynaptic release of neurotransmitters such as substance P and glutamate.

TrueLearn Insight : Interestingly, it has been found that inflammation induces peripheral mu-opioid receptor expression, which allows topical opioids to interact with their receptors and produce effective analgesia at the level of the primary afferent neuron (contrary to its usual primary actions in the CNS). As at other sites, absorbed topical opioids reduce nerve excitability and block nociceptive transmission. However, the use of topical opioids remains limited by their potential to produce delayed wound healing. It has been demonstrated that topical morphine, for example, reduces macrophage and myofibroblast migration into open wounds.

Question 14

A 26-year-old G2 P1 female, with no significant past medical history, at 33 weeks gestational age presents to the obstetrical floor with contractions. Basic labs are drawn. Which of the following lab results likely needs further evaluation?

Answer 14

A serum creatinine concentration greater than 0.8 mg/dL and a blood urea nitrogen concentration greater than 13 mg/dL (which are normal values for the nonpregnant patient) suggest renal insufficiency in the pregnant woman.

Question 15

A 23-year-old pregnant female presents to the hospital at 39-weeks showing signs of active labor. Shortly after admission to the labor and delivery unit, the patient’s membranes rupture. The obstetrician notes that the amniotic fluid is meconium stained. The child appears vigorous throughout delivery. What is the best course of treatment for this infant?

Answer 15

Oropharynx suctioning prior to delivery and routine intubation for tracheal suctioning are no longer recommended.

Question 16

Which of the following INCREASES the risk for development of post dural puncture headache following accidental dural puncture with an epidural needle?

Answer 16

Unintentional dural puncture during epidural placement is a risk that occurs even with the most vigilant and experienced providers. Over 50% of patients will develop a post-dural puncture headache in this setting. Management of unintentional dural puncture depends on the clinical setting and one should take into account the difficulty of the procedure. It is not recommended to replace the CSF that was lost (in either the syringe or on the sterile field) as there may be small amounts of air in the leaked fluid that can cause pneumocephalus.

Question 17

A patient delivered a baby at 32 weeks’ gestation about 30 minutes ago. The patient has not delivered the placenta and blood loss has been within normal limits for a vaginal delivery. Which of the following is the best next management step for the patient?

Answer 17

Retained placenta can be managed conservatively for a short period of time after diagnosis if the patient is stable and abnormal placentation is not likely. Administration of medications may be helpful, depending on the patient’s clinical picture.

Question 18

A 30-year-old otherwise healthy G2P1 woman presents at 36 weeks gestational age for ex-utero intrapartum therapy (EXIT) procedure to secure the fetus’s airway due to a fetal cervical teratoma found on routine anatomy scans and confirmed with fetal MRI. Which of the following is MOST TRUE regarding the anesthetic management of this case?

Answer 18

An ex utero intrapartum therapy (EXIT) procedure is a complex and multidisciplinary surgery that allows for the partial delivery and correction of fetal pathology prior to complete delivery that would be otherwise incompatible with extrauterine life. These cases are typically performed under general endotracheal anesthesia with deep volatile anesthesia to provide uterine relaxation to allow for uteroplacental blood flow throughout the case, as well as facilitate surgical exposure of the fetus. Given this, the mother is at extreme risk for massive hemorrhage, and provisions for a rapid volume resuscitation should be established prior to the start of the case.

Question 19

A previously healthy woman is in active labor with a twin pregnancy. She has a functioning lumbar epidural catheter in place infusing bupivacaine 0.1% plus fentanyl 2 mcg/mL at 7 mL/hr. Twin A has a vertex presentation but twin B is breech. Twin A is delivered vaginally without incident. Prior to delivery of twin B, the obstetrician informs you she wants to perform an internal podalic version. Which of the following medications will NOT help to facilitate a version procedure and vaginal delivery of twin B under these circumstances?

Answer 19

Carboprost tromethamine (15-methyl prostaglandin F2α) is a uterotonic used to increase uterine muscle tone following delivery. It will not facilitate an internal version procedure of a breech fetus, which requires uterine relaxation.

Question 20

How does the Bohr effect facilitate placental oxygen exchange?

Answer 20

The Bohr effect describes the decrease in oxygen affinity of hemoglobin in the setting of increased carbon dioxide and acidity. When the placenta transfers carbon dioxide from the fetal blood to the maternal blood, the increased levels of carbon dioxide in the maternal blood decrease maternal hemoglobin oxygen affinity (rightward shift). The rightward shift of the maternal curve makes oxygen more readily available for transfer across the placenta to the fetus.

Question 21

When does creatinine clearance return to pre-pregnant levels?

Answer 21

Renal blood flow and glomerular filtration rate during pregnancy increase by 50-60% from a period of about 3 months into the pregnancy, lasting until about 8 to 12 weeks postpartum. This results in increased creatinine clearance, urea clearance, and uric acid clearance.

Question 22

Which of the following is the optimal cephalad level of the sensory block when neuraxial anesthesia is used for cesarean delivery?

Answer 22

Adequate neuraxial anesthesia for a cesarean section is best achieved through sensory blockade of the T4-S4 dermatomes.

TrueLearn Insight : For adequate analgesia for stage I labor, the T10-L1 dermatomes should be covered. The second stage of labor requires additional coverage at S2-4.

Question 23

Which of the following approximates average values for a NORMAL blood gas taken from the umbilical artery of a term fetus immediately following spontaneous vaginal delivery with an uncomplicated gestational and birth history?

Answer 23

Umbilical artery blood is thought to be representative of the acid-base status of the fetus, while umbilical vein blood is thought to be representative of placental function. Umbilical artery blood gases immediately following the delivery of a normal neonate will have the following approximate values: pH of 7.27, pCO2 of 50 mmHg, pO2 of 18 mmHg, and base excess of -2.7 mEq/L.

Question 24

Which of the following is NOT associated with obstetric polyhydramnios?

Answer 24

Polyhydramnios is increased amniotic fluid volume. It occurs in 1% of pregnancies and is associated with increased fetal urine production or fetal structural abnormalities preventing fetal swallowing. Polyhydramnios is associated with preterm labor and premature rupture of membranes as well as postpartum uterine atony.

Question 25

Which of these values will INCREASE during pregnancy?

Answer 25

Pregnancy is a hypercoagulable state due to increased levels of most coagulation factors, especially fibrinogen and factor VII.

Question 26

At one minute of life after emergency cesarean delivery for prolonged fetal bradycardia, a neonate is cyanotic, has some extremity flexion, and has a feeble cry following oropharyngeal suctioning. The heart rate is 110 and respirations are slow and irregular. What is the neonate’s Apgar score?

Answer 26

0 1 2
Skin color Cyanotic Acrocyanotic (pink chest, cyanotic extremities) Pink
Heart rate Absent < 100 bpm >100 bpm
Reflex irritability No response to stimulation Grimace and/or feeble cry when stimulated Active, strong response to stimulation
Muscle tone Absent, limp Some extremity flexion Active movement
Breathing Absent Weak, irregular, slow, shallow, or gasping Strong, regular, crying

Question 27

Which of the following is MOST likely associated with anesthetizing the Frankenhauser ganglion in a paracervical nerve block during labor?

Answer 27

The major disadvantage of a paracervical nerve block during labor is a high frequency of fetal bradycardia associated with decreased fetal oxygenation and fetal acidosis.

Question 28

A 32-year-old G3P2 presents to the obstetric unit in labor. She was unable to receive epidural analgesia with her last two pregnancies because of Harrington rods, despite multiple attempts at the procedure. She refuses neuraxial anesthesia given her prior experience but requests analgesia for stage two of labor. Which of the following techniques would be appropriate for this patient?

Answer 28

Pudendal block provides analgesia for the 2nd stage of labor. By blocking the pudendal nerve vaginal and perineal distention pain is blocked. A paracervical block provides analgesia for the 1st stage of labor especially cervical dilation. However, paracervical blocks are associated with a high rate of fetal bradycardia. The rate of fetal bradycardia is increased if fetal acidosis is present.

Question 29

A 25-year-old G2P1 female has severe pre-eclampsia and is placed on magnesium until maternal steroids can be given. Prior to magnesium, her blood pressure is 169/74 mm Hg, and after the infusion begins, it settles at 143/62 mm Hg. She has a magnesium level of 5.5 mg/dL. What is the mechanism behind her change in blood pressure?

Answer 29

Magnesium decreases blood pressure and systemic vascular resistance by causing vasodilation. Vasodilation occurs by calcium antagonism in vascular smooth muscle and by increased production of nitric oxide and prostacyclin I2.

TrueLearn Insight : Treatment for magnesium toxicity includes stopping any magnesium infusion. Supporting the patient’s oxygenation, ventilation, and hemodynamics is appropriate. Additionally, calcium should be given since magnesium antagonizes calcium. Calcium chloride should be given through a central vein, but calcium gluconate can be given peripherally.

Question 30

Which of the following statements regarding uterine defects and rupture in the parturient is TRUE?

Answer 30

Uterine defects may occur at any point during the peripartum period. Fetal distress (i.e. fetal bradycardia) is the most sensitive presenting sign of uterine rupture. Anesthetic management typically includes emergent endotracheal intubation and general anesthesia.

Question 31

A 33-year-old female is recovering from a cesarean delivery that was performed under a combined spinal-epidural anesthesia. She suddenly develops shortness of breath. Her oxygen saturation is noted to be 85% on room air and her systolic blood pressure drops to the 70s. Examination of the patient shows bleeding around the incision site.

On the transthoracic echocardiography (TTE), the patient’s right ventricle appears severely dilated. Which of the following is MOST likely the cause of the increased right ventricular workload noted on the TTE?

Answer 31

AFE closely resembles a systemic inflammatory response resulting in hypotension, noncardiogenic pulmonary edema, and coagulopathy. The clinical presentation is in two phases: 1) pulmonary hypertension with right ventricular dysfunction, 2) left ventricular failure and coagulopathy. Treatment of AFE is primarily resuscitative and includes endotracheal intubation, fluids, vasopressors/inotropes, and blood products.

Question 32

In an obstetric patient with a known placenta previa, the risk of peripartum hemorrhage would be increased MOST by which of the following?

Answer 32

The combination of known placenta previa and a history of multiple previous cesarean sections put an obstetric patient at a dramatically increased risk for placenta accreta and peripartum hemorrhage.

Question 33

A 31-year-old woman who has had one pregnancy and no live births presents in active labor at 39 weeks of gestation. Fetal heart monitoring detects decelerations of >15 beats/minute lasting between 1 and 3 minutes occurring before and after uterine contractions. The mother is repositioned in the left lateral decubitus position with a resolution of the fetal heart rate abnormalities. Which of the following BEST describes the decelerations?

Answer 33

Variable decelerations are characterized by variable onset, depth, and duration in relationship with uterine contractions. They are a result of baroreceptor- or chemoreceptor-mediated vagal activity from the umbilical cord compression, leading to the decreased blood supply and transient hypoxemia in the fetus. They are a component of category II and III (not category I or normal) fetal heart tracings.

TrueLearn Insight : Use the acronym VEAL CHOP to remember the different types of decelerations and their causes:
Variable decelerations: Cord compression
Early decelerations: Head compression
Accelerations: Ok
Late decelerations: Placental insufficiency

Question 34

Which of the following is the MOST likely cause for shivering during labor in a patient with epidural analgesia infusion?

Answer 34

Shivering during labor occurs irrespective of whether neuraxial anesthesia is employed. It is more likely to occur in patients who have had neuraxial anesthesia and it may be secondary to changes in body temperature, although the pathophysiology is not completely understood and non-thermoregulatory factors may contribute.

Question 35

Which of the following characteristics of a drug will contribute to increased placental drug transfer?

Answer 35

Drug properties that increase the placental transfer include small size (< 1000 daltons), uncharged form (pKa), lipophilic, low protein binding, and absence of an efflux transporter for the molecule.

Question 36

A 24-year-old primigravida patient at 18 weeks gestation is being seen in the obstetrician’s office for a well pregnancy visit. Which of the following laboratory changes is MOST consistent with normal pregnancy compared to the non-pregnant state?

Answer 36

Pregnancy is a hypercoagulable state. Prothrombin time (PT) and partial thromboplastin time (PTT) decrease during pregnancy. The reason for the decrease in PT is a result of increased coagulation factors.

Question 37

A laboring patient with a history of polycystic kidney disease and preeclampsia during her current pregnancy is started on a magnesium infusion. Several hours later, a serum magnesium level is found to be supratherapeutic at 7.5 mEq/L (9.1 mg/dL). Which of the following signs or symptoms is MOST LIKELY to be present?

Answer 37

Electrocardiogram changes, such as QRS widening and PR prolongation, are often observed as serum magnesium concentrations rise above 6 mEq/L (7.3 mg/dL). Respiratory depression, bradyarrhythmias, areflexia, paralysis, and loss of consciousness are complications of more severe hypermagnesemia.

Question 38

Which of the following maternal treatments will MOST LIKELY benefit a fetus when given for preterm labor without rupture of membranes?

Answer 38

Corticosteroid therapy has been shown to improve neonatal outcome and magnesium therapy has been shown to provide some fetal neuroprotection when used in the setting of preterm labor. Tocolytic therapy is not advocated for routine use except to prolong pregnancy long enough to allow for corticosteroid administration.

Question 39

Which of the following statements about parturients with recurrent genital herpes simplex virus type 2 detected at delivery is INCORRECT?

Answer 39

Risk factors for increased neonatal transmission of genital HSV2 include parturients with primary infections, active disease at labor, use of invasive fetal monitoring, and vaginal delivery with active disease. Neuraxial anesthesia is not contraindicated with recurrent maternal HSV2 disease.

Question 40

A 24-year-old primigravida female with a history of hypertension, who has not had prior prenatal care, presents at 32 weeks gestation to the obstetrician to establish care. On screening ultrasound her amniotic fluid index measured 3 cm, which is less than the fifth percentile. Which of the following medications was she MOST likely taking for her hypertension?

Answer 40

Oligohydramnios occurs in 4% of pregnancies and is associated with fetal lung hypoplasia and musculoskeletal abnormalities. ACE inhibitor use has been linked to developing oligohydramnios and should be avoided in pregnancy.

Question 41

Which of the following is TRUE regarding nitrous oxide (N2O) E cylinders?

Answer 41

A full tank of N2O contains 1590 L at a pressure of ~745 psig. N2O is stored as a liquid and gas in a pressurized E cylinder, and the pressure within a tank of N2O will remain at ~745 psig until all liquefied gas is used up. This occurs when the tank has ~250 L (16%) N2O remaining. Note again that, as explained above, some textbooks state ~400 L (25%) N2O remaining before a pressure drop, but this is not backed by evidence.

TrueLearn Insight : Regardless of the exact volume in a N2O tank when the pressure gauge will drop, the concept of the unique property of N2O having a critical temperature above standard room temperature allows it to be stored as a liquid and gas in a pressurized cylinder, which impacts the ability to assess the remaining volume using a pressure gauge. Understanding the Boyle law calculation can assist in the precise determination of the remaining volume after the pressure gauge begins to drop.

Question 42

Which of the following electrolyte abnormalities will MOST likely occur in the setting of hyperventilation?

Answer 42

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.

Question 43

A 65-year-old man is admitted to the hospital with concerns for complicated withdrawal from ethanol requiring lorazepam administration in the Emergency Department. During his hospitalization, he develops a traumatic subdural hematoma due to an unintentional fall and is taken for emergent decompressive craniotomy. Which of the following is MOST LIKELY to extend the duration of action of lorazepam in this patient?

Answer 43

Lorazepam is unique among the commonly used benzodiazepine hypnotics in that it is metabolized exclusively through hepatic glucuronidation. This makes it less susceptible to drug-drug interactions than benzodiazepines such as midazolam or diazepam which are both metabolized via the hepatic cytochrome oxidase system.

Question 44

A 29-year-old man who takes buprenorphine presents for emergency repair of an open tibial fracture. He is in significant pain before the procedure, and intravenous fentanyl is administered as a premedication prior to transport to the operating room. Which of the following is MOST TRUE regarding the dose-response curve of fentanyl in this patient?

Answer 44

Synergistic, additive, and antagonistic drug interactions are prevalent throughout anesthesia practice. Understanding the mechanisms of actions, as well as these interactions is crucial in providing safe and appropriate perioperative care.

Question 45

Which of the following changes to an invasive arterial blood pressure monitoring system would MOST LIKELY result in overdamping of the pressure waveform?

Answer 45

Overdamping of an invasive arterial blood pressure waveform may be produced by air bubbles, additional stopcocks, or increased compliance in the circuit. When the arterial tracing is overdamped, it may appear flattened, slurred, and poorly resolved.

TrueLearn Insight : To help correct overdamping, first remove any excess stopcocks or length from the circuit to improve overall accuracy. Additional underlying causes may be corrected next (eg, flushing the arterial line to dislodge a clot or drawing off of the line to remove air). Conversely, suspected underdamping may be improved by cautiously adding a small air bubble to the tubing, though such a maneuver may result in overcorrection.

Question 46

During central venous line placement, an 18g catheter is inadvertently placed within the right carotid artery. Clear plastic tubing is attached to this catheter and blood is withdrawn to fill the tubing. If the tubing is held vertically, at about what height above the patient’s heart would the column of blood stop ascending assuming an arterial blood pressure of 120/60 mm Hg?

Answer 46

Simple manometry relies upon the force of gravity to resist the rise of a fluid in a column to measure the pressure being applied to that column. The density of the fluid in the manometry column is the primary determinant of the height that it will rise when exposed to a given pressure. 760 mm Hg is equivalent to 988 cm H2O.

Question 47

Which of the following is TRUE regarding phosgene exposure?

Answer 47

Phosgene is a chemical warfare agent that can lead to significant pulmonary damage. There is no specific antidote and treatment is generally centered around providing supportive care and minimizing the effects of the inflammatory mediator cascade.

Question 48

A 65-year-old male with a history of poorly-controlled diabetes and hypertension is now postoperative day 3 from a below-knee amputation of his right leg. He has had an epidural in place for pain control and is receiving 5000 units of subcutaneous heparin three times daily. The surgeon has requested that you remove the epidural so that the patient can be transitioned to oral medications in anticipation of discharge. Assuming the patient has just received a dose of subcutaneous heparin when is the MOST appropriate time to remove the patient’s epidural?

Answer 48

The American Society of Regional Anesthesia guidelines recommend that neuraxial or deep regional anesthesia should not be performed until 4-6 hours after the administration of low-dose subcutaneous heparin for thromboprophylaxis (5000 units given twice or three times daily). This includes waiting 4-6 hours after heparin administration prior to removing a neuraxial catheter.

Question 49

Which of the following is an indication for hyperbaric oxygen therapy?

Answer 49

There are currently 13 conditions approved by the Undersea and UHMS for which research and extensive clinical experience has proved HBOT to be beneficial. These include:
Gas-bubble disease (air embolism and decompression sickness)
Carbon monoxide poisoning
Infections (clostridial myonecrosis, other soft tissue necrotizing infections, refractory chronic osteomyelitis, intracranial abscess)
Acute tissue ischemia (crush injury, compromised skin flaps, central retinal artery or vein occlusion)
Chronic ischemia (radiation necrosis, ischemic ulcers)
Acute hypoxia (exceptional blood loss anemia when transfusion is unable to be given)
Acute thermal burn injury
Idiopathic sudden sensorineural hearing loss
Hyperbaric oxygen therapy has several approved uses including gas-bubble disease, carbon monoxide poisoning, certain infections, certain types of acute tissue ischemia, certain types of chronic ischemia, acute hypoxia from anemia, acute thermal injuries, and sensorineural hearing loss. It allows a higher fraction of oxygen to be dissolved in the plasma, thereby increasing oxygen concentration at tissues.

TrueLearn Insight : There are several considerations an anesthesia provider must contemplate when administering anesthetics at increased pressure in hyperbaric chambers. Nitrous oxide may be used at partial pressures exceeding its MAC (thus a full MAC of nitrous oxide can be reached); most subjects have rapid onset and offset but side effects are more pronounced (especially nausea/vomiting). Additionally, with nitrous administration, the tissues may become supersaturated during decompression, allowing bubbles to form, and the risk of dilution hypoxia is higher. The halogenated agent effect is proportional to the partial pressure of the anesthetic, not the alveolar concentration. As long as the flow bypassing the calibrated bypass chamber is the same, a constant partial pressure of anesthetic should be administered. Drager isoflurane and sevoflurane vaporizers deliver constant partial pressure up to 3 atmospheres. Any degree of inhaled anesthetics may pollute the chamber and exert their effects on personnel. Total intravenous or regional anesthesia may be the best alternative to avoid these risks; intravenous anesthetics behave similarly during hyperbaric oxygen therapy. Neuromuscular-blocking drugs should be titrated using twitch monitoring because some degree of pressure reversal of the block can occur.

Question 50

Assuming the use of a standard anesthesia machine and equipment, which of the following agents is MOST LIKELY to produce the same depth of anesthesia at an elevation of 3500 meters compared to sea level without adjustment of the output setting?

Answer 50

Because the inspired partial pressure is the key factor influencing the depth of inhaled anesthesia, a modern sevoflurane variable bypass vaporizer—which delivers a constant partial pressure regardless of ambient pressure—does not require adjustment of the set concentration at altitude. Meanwhile, desflurane and non-volatile inhaled agents (i.e. nitrous oxide and xenon) are delivered at fixed concentrations and require dose adjustment to compensate for the lower ambient pressures at altitude.

Question 51

A patient with an anticipated difficult airway is prepared for awake flexible bronchoscopic intubation. Which of the following techniques would be MOST APPROPRIATE to anesthetize the tracheal mucosa for intubation?

Answer 51

The translaryngeal block can be used to safely anesthetize the tracheal mucosa, which draws sensory innervation from the recurrent laryngeal nerve. By contrast, a superior laryngeal nerve block is used to anesthetize the hypopharynx and larynx above the vocal cords, while a glossopharyngeal nerve block can be used to anesthetize much of the oropharynx and tongue base. Direct recurrent laryngeal nerve blockade is considered unsafe and is not performed.

Question 52

A 79-year-old man with a history of coronary artery disease undergoes an open abdominal aortic aneurysm repair under general anesthesia. Immediately after application of the aortic cross-clamp, ST-segment depressions are noted in leads I and aVL on the intraoperative ECG. Which of the following coronary artery branches MOST LIKELY supplies the portion of the myocardium that is affected by ischemia?

Answer 52

Coronary artery perfusion territories and ECG location: left anterior descending artery / anteroseptal / V1-V4, left circumflex artery / lateral / I, aVL, V5-V6, right coronary artery / inferior / II, III, aVF.

Question 53

A 4-year-old patient is evaluated in the postanesthesia care unit after an elective tonsillectomy. On exam, she is found to be in mild distress with loud stridor, and the decision is made to administer an inspired mixture of 70% helium and 30% oxygen. Which of the following BEST explains the respiratory benefits of this intervention?

Answer 53

Heliox, an inspired helium-oxygen mixture, may be a useful intervention for patients with postoperative stridor because of the lower density of helium compared to oxygen or ambient air. The lower density decreases the Reynolds number, which favors laminar flow rather than turbulent flow.

Question 54

Which of the following chemicals is MOST responsible for the maintenance and autoregulation of hepatic blood flow?

Answer 54

The liver has a unique dual blood supply, receiving blood from both the hepatic artery, which arises from the celiac trunk, as well as the portal vein, which is a confluence of the venous drainage from the splanchnic circulation. The hepatic artery provides 25% of the blood flow and 50% of the oxygen supply to the liver, with the portal vein providing 75% of the blood flow to the liver but only 50% of the oxygen supply. The primary means of intrinsic autoregulation of hepatic blood flow is the hepatic arterial buffer response that causes adenosine-mediated vasodilation of the hepatic artery in response to decreased blood flow in the portal vein.

Question 55

A 36-year-old man presents for a Lefort maxillary advancement. A past history of which of the following conditions BEST indicates a requirement for prophylactic antibiotics?

Answer 55

Types of high-risk cardiac conditions are (list adapted from the “Recommendation for IE Prophylaxis” table in section 2.4.2 of the 2017 AHA/ACC guideline):
Prosthetic cardiac valves, including transcatheter-implanted prosthetic valves
Patients with implanted prosthetic material, such as annuloplasty rings and artificial chordae tendineae
Patients with a history of infectious endocarditis
Patients with a history of unrepaired cyanotic congenital heart disease, including patients with a repair, but with a residual shunt or valvular regurgitation near an implanted patch or device
Patients with a history of cardiac transplantation who have a regurgitant valvular lesion due to a structurally abnormal valve

Question 56

Which of the following structures increases the surface area of the airway passages?

Answer 56

Nasal turbinates, also known as nasal concha, moisten and warm inspired cold air as it passes through the respiratory tree and into the lungs. Their flat spiral shape increases the surface area over which inspired air is treated prior to continuing its journey to the lungs.

TrueLearn Insight : Nasal cilia need moisture for proper function and mucous transport. Dry anesthetic gasses depress ciliary function and enhance mucous thickening and build-up, making it more difficult to expel. Endotracheal tubes and supraglottic airways bypass the warming and moisturizing effects of the nasal turbinates which is why we hear and see so much coughing and mucous brought up by patients after a general anesthetic.

Question 57

A 65-year-old man has been in the neurointensive care unit in a coma for 1 week after having been struck by a motor vehicle. Noncontrast head computed tomography shows a massive subarachnoid hemorrhage. Physical examination findings indicate the absence of brainstem reflexes. Past medical history is notable for severe obstructive pulmonary disease with chronic hypercarbia. Which of the following would be the MOST appropriate next step in the diagnosis of brain death?

Answer 57

Confirmatory tests for the diagnosis of brain death should not be used in lieu of clinical examination but should be used only when clinical criteria cannot be applied. Such situations include presence of heavy sedation or muscle paralysis, cranial nerves cannot be properly examined, apnea test cannot be completed such as in retainers of carbon dioxide, or to shorten the duration of the observation period. Confirmatory tests include cerebral angiography, transcranial Doppler, magnetic resonance angiography, computed tomographic angiography, radionuclide brain imaging, and electrophysiology such as electroencephalography.

Question 58

Which of the following describes a shift of the hemoglobin-oxygen dissociation curve caused by changes in carbon dioxide and pH?

Answer 58

The Bohr effect refers to the shift in the oxygen dissociation curve caused by changes in the concentration of carbon dioxide or the pH of the environment.

TrueLearn Insight : Chronic acid-base changes over 24-48 hours will alter levels of 2,3-DPG leading to a return to baseline of a shifted oxygen dissociation curve.

Question 59

A 67-year-old woman with a history of atrial fibrillation presents for exploratory laparotomy for bowel ischemia. You plan on placing an arterial catheter in the right lower extremity and notice the patient’s right foot is very cold and there is no Doppler flow through the dorsalis pedis artery. A palpable pulse is felt in the right groin and posterior to the right medial malleolus but not on the dorsal aspect of the right foot. Which of the following is the MOST likely location of a vascular occlusion?

Answer 59

The lower extremity arterial anatomy is as follows: the external iliac arteries become the common femoral artery after the groin crease. The common femoral artery branches off into the deep femoral artery (profunda femoris) and the superficial femoral artery. The deep femoral artery supplies the tissue and muscles in the thigh and proximal part of the femur. The superficial femoral artery continues down the leg and becomes the popliteal artery at the knee crease. The popliteal artery branches off into the anterior tibial artery and the tibiofibular (tibioperoneal) trunk. The tibioperoneal (TP) trunk bifurcates into the posterior tibial artery and the fibular (peroneal) artery.

Question 60

After an overnight fast, which of the following hormones is secreted to raise the level of glucose in the blood?

Answer 60

Glucagon is a polypeptide hormone secreted by the α-cells of the pancreas in response to hypoglycemia. The primary purpose of glucagon is to increase the availability of glucose for utilization by the body by stimulating gluconeogenesis, glycogenolysis, and lipolysis.

TrueLearn Insight : Glucagon is used in the treatment of β-blocker toxicity by increasing the levels of cyclic adenosine monophosphate (cAMP). This in turns increases the available intracellular calcium leading to increased contractility and heart rate.

Question 61

Which letter in the image indicates the location where one would expect to best hear the murmur of mitral regurgitation on auscultation with a stethoscope?

Answer 61

Using the axilla as a landmark for auscultation will usually allow for the best appreciation of mitral regurgitation.

TrueLearn Insight : Mnemonic: from left to right, top to bottom (normal reading order), APTM for Aortic, Pulmonic, Tricuspid, Mitral = All Physicians Take Money or All Patients Take Medicine.