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Question 1

643. Uterine blood flow is consistently decreased after the administration of
     A. Thiopental 4 mg/kg bolus and 1 mg/kg succinylcholine followed by intubation B. 0.5-1.5 minimum alveolar concentration (MAC) of desflurane
     C. Epidural fentanyl, uncomplicated by hypotension
     D. Clonidine 300 μg epidurally, uncomplicated by hypotension
     E. Epiduralloadedwithlocala nesthetic,uncomplicated byhypotension

Answer 1

A)
Thiopental followed by succinylcholine and tracheal intubation causes a transient but consistent 20% to 40% reduction in uterine blood flow (UBF). This appears to be related to the sympathetic response to tracheal intu- bation. Uterine blood flow is unchanged with 0.5-1.5 MAC of a volatile anesthetic (i.e., halothane, isoflurane, sevoflurane or desflurane), a propofol bolus (2 mg/kg) or with an infusion of propofol (

Question 2

644. An 38-year-old obese patient is
     receiving subcutaneous low molecular weight heparin (LMWH) for thrombopro- phylaxis. She received her epidural 14 hours after the heparin was stopped and develops a Horner’s syndrome on the left side 30 minutes after placement of an epidural for an elective cesarean section. On physical examination, a T4 anesthetic level is noted, but aside from the Horner’s syndrome no other findings are revealed. The most appropriate course of action at this time would be
     A. Remove the epidural B. Consult a neurosurgeon
     C. Obtain a computed tomographic scan D. Secure the airway
     E. Noneoftheabove

Answer 2

(E) After low dose prophylaxis with LMWH, a time of at least 12 hours should elapse prior to performing neuraxial techniques to decrease the likelihood of an epidural hematoma forming (you should wait at least 24 hours after high dose LMWH used for therapeutic anticoagulation). If the patient has back pain and unexpected neuro- logic paralysis, a workup for a hematoma should be performed. This case is a benign condition that occasionally develops after a lumbar epidural anesthetic even when the highest dermatome level blocked is below T5. It may be related to the superficial anatomic location of the descending spinal sympathetic fibers that lie just below the spinal pia of the dorsolateral funiculus (which is within diffusion range of subanesthetic concentrations of local anesthetics in the cerebrospinal fluid) as well as increased sensitivity of local anesthetics during pregnancy (Chestnut: Obstetric Anesthesia, ed 3, pp 685-688; Hughes: Anesthesia for Obstetrics, ed 4, pp 134, 417; Second Consensus Conference on Neuraxial Anesthesia and Anticoagulation, April 25- 28, 2002. www.asra.com/consensu s- statements/2.html).

Question 3

645. What percentage of all pregnancies are affected by preeclampsia? A. 2%
     B. 7% C. 12% D. 17% E. 22%

Answer 3

(B) Preeclampsia is a hypertensive disorder of pregnancy (sustained systolic blood pressure [BP] >140 mm Hg or a sustained diastolic BP >90 mm Hg) associated with proteinuria (>300 mg protein per 24 hour urine collection). It rarely occurs before the 24th week of gestation (unless a hydatidiform mole is present). It occurs with an overall incidence of approximately 5% to 9% of all pregnancies and is the third leading cause of maternal death in the United States. The incidence of preeclampsia is significantly higher in parturients with a hydatidiform mole, multiple gestations, obesity, polyhydramnios, or diabetes. Mothers with preeclampsia during their first pregnancy have a 33% chance of having preeclampsia in subsequent pregnancies. Preeclampsia can progress to eclampsia (preeclampsia accompanied by a seizure not related to other conditions). Sixty percent of eclamptic cases precede delivery. Of the rest, most occur within the first 24 hours after delivery. Approximately 5% of untreated parturients with preeclampsia will develop eclampsia (Chestnut: Obstetric Anesthesia, ed 3, pp 794-795; Hughes: Anesthesia for Obstetrics, ed 4, pp 297-298).

Question 4

646. An 18-year-old patient preeclamptic patient develops back pain after the placement of an epidural for labor analgesia. The pain is severe and the patient has more weakness of the legs than expected. The most appropriate course of action at this time would be
     A. Inject a higher concentration of a local anesthetic
     B. Add IV narcotics
     C. Replace the epidural and use epidural narcotics to decrease the motor weakness D. Consult a neurosurgeon
     E. Noneoftheabove

Answer 4

(D) he combination of severe unremitting back pain, more leg weakness than expected, tenderness over the spinal or paraspinal area, unexplained fever or a significant delay in normal recovery should alert you to the possibility of an expanding epidural hematoma forming that needs to be surgically removed quickly to decrease the chance of permanent neurologic deficits. A neurosurgeon should be contacted and if a magnetic resonance imaging (MRI) scan shows a hematoma, rapid delivery of the child should be performed followed by a neurosurgical removal of the hematoma. Rarely will an epidural hematoma form; however, a patient with a clotting disorder and perhaps marked difficulty in placing a block may lead to a hematoma formation. Because the preeclamptic patient may develop a coagulopathy, you should carefully evaluate her coagulation status prior to initiating a regional block. Most would evaluate a platelet count and look for any clinical signs for unexplained bleedingprior to initiating a regional block (Chestnut: Obstetric Anesthesia, ed 3, pp 588-590, 688; Hughes: Anesthesia for
Obstetrics, ed 4, pp 420-421).

Question 5

647. Magnesium sulfate (MgSO4) is used as an anticonvulsant in patients with preeclampsia as well as a tocolytic to prevent preterm delivery. MgSO4 may produce any of the following effects EXCEPT
     A. Sedation
     B. Respiratory paralysis
     C. Inhibition of acetylcholine release at the myoneural junction D. Antagonism of α-adrenergic agonists
     E. StimulationofNMDAreceptors

Answer 5

(E) The normal serum magnesium level is 1.5 to 2 mEq/L with a therapeutic range of 4 to 8 mEq/L. As magnesium sulfate is administered IV, patients often note a warm feeling in the vein as well as some sedation. With increasing serum levels, loss of deep tendon reflexes (10 mEq/L), respiratory paralysis (15 mEq/L), and cardiac arrest (>25 mEq/L) can occur. Note: Many labs report values in mg/dL (1 mEq/L = 1.2 mg/dL). Magnesium decreases the release of acetylcholine (ACh) at the myoneural junction and decreases the sensitivity of the motor endplate to ACh. This can produce marked potentiation of non-depolarizing muscle relaxants. The effect on depolarizing muscle relaxants is less clear and most clinicians use standard intubating doses of succinylcholine (i.e., 1 mg/kg) fol- lowed by a much reduced dose of a non-depolarizing relaxant if needed. Because magnesium antagonizes the effects of α-adrenergic agonists, ephedrine is preferred over phenylephrine if a vasopressor is needed to restore blood pressure, along with fluids, after a central neuraxial blockade. Magnesium acts as an antagonist at the N-methyl-d- aspartic acid (NMDA) receptors; however, clinically, labor analgesia is minimal (Chestnut: Obstetric Anesthesia, ed 3, pp 295-296, 619-622, 808-809, 817-818; Hughes: Anesthesia for Obstetrics, ed 4, pp 304-306, 331-334).

Question 6

648. Normal fetal heart rate (FHR) is A. 60 to 100 beats/min

B. 100 to 140 beats/min C. 120 to 160 beats/min D. 150 to 200 beats/min E. Noneoftheabove

Answer 6

(C) Fetal monitors consist of a two-channel recorder for simultaneous recording of FHR and uterine activity. In looking at the FHR one assesses the baseline rate, the FHR variability, and the periodic changes (accelerations or decelerations) that occur with uterine contractions. The normal FHR varies between 120 and 160 beats/min. Some extend the lower limit of normal to 110 beats/min. See also answer 703 (Chestnut: Obstetric Anesthesia, ed 3, pp 111-113; Hughes: Anesthesia for Obstetrics, ed 4, pp 625-630).

Question 7

649. The leading direct cause of pregnancy related deaths in the United States is A. General anesthesia (failed intubation or aspiration)
     B. Hemorrhage
     C. Thromboembolism
     D. Hypetensive disorders of pregnancy E. Infection

Answer 7

(D) The leading direct cause of pregnancy related deaths in the United States is hypertensive disorders of pregnancy (16% or 1.83 deaths/100,000 live births) followed by infection, hemorrhage other than ectopic pregnancy related, thrombotic embolism, amniotic fluid embolism, cardiomyopathy, ruptured ectopic pregnancy, cerebral accidents and complications of anesthesia. (Chestnut: Obstetric Anesthesia ed 4 pp 853-858).

Question 8

650. Drugs useful in the treatment of uterine atony in an asthmatic with severe preeclampsia include A. Oxytocin, 15-methyl prostaglandin F2a (PGF2a) and ergonovine
     B. Oxytocin and 15-methyl PGF2a
     C. Oxytocin and ergonovine
     D. 15-methyl PGF2a only E. Oxytocinonly

Answer 8

(E) Uterine atony is a common cause of postpartum hemorrhage (2%-5% of all vaginal deliveries). Treatment con- sists of uterine massage, drugs, and, in rare cases, hysterectomy. Drugs commonly used include oxytocin, ergot alkaloids (ergonovine, methylergonovine), and prostaglandins (PGE2, PGF2a, 15-methyl PGF2a). The ergot alka- loids not infrequently cause elevations in blood pressure and are relatively contraindicated in patients with hyper- tension (such as preeclampsia). Ergot alkaloids have been associated with bronchospasm (rarely) and may not be appropriate in asthmatics. The prostaglandin 15-methyl PGF2a (carboprost, Hemabate) is the only prostaglandin currently approved for uterine atony in the United States and may cause significant bronchospasm in susceptible patients (Chestnut: Obstetric Anesthesia, ed 3, pp 428, 670-671; Hughes: Anesthesia for Obstetrics, ed 4, pp 367-369).

Question 9

651. What is the P50 of fetal hemoglobin at term? A. 15

B. 20 C. 27 D. 30 E. 37

Answer 9

(B) The term P50 denotes the blood oxygen tension (Pao2) that produces 50% saturation of erythrocyte hemo- globin. The P50 value of fetal blood (75% to 85% of fetal blood is hemoglobin F) is around 19 to 21 mm Hg versus the adult value of 27 mm Hg. Thus, fetal hemoglobin has a higher affinity for oxygen than maternal hemoglobin (Chestnut: Obstetric Anesthesia, ed 3, p 69; Hughes: Anesthesia for Obstetrics, ed 4, pp 24-25).

Question 10

652. Side effects of ritodrine include all of the following EXCEPT A. Tachycardia
     B. Hypertension
     C. Hyperglycemia D. Pulmonary edema E. Hypokalemia

Answer 10

(B) Ritodrine and terbutaline are β adrenergic agonists with tocolytic properties. Side effects are similar to those of other β adrenergic drugs and include tachycardia, hypotension, myocardial ischemia, pulmonary edema, hypox- emia (inhibition of hypoxic pulmonary vasoconstriction), hyperglycemia, metabolic (lactic) acidosis, hypoka- lemia (shift of potassium from extracellular to intracellular space), anxiety and nervousness. Electrocardiogram (ECG) changes of ST segment depression, T wave flattening or inversion may occur and typically resolve after stopping the β adrenergic therapy. Whether these ECG changes reflect myocardial ischemia or hypokalemia is unclear (Chestnut: Obstetric Anesthesia, ed 3, pp 614-619; Hughes: Anesthesia for Obstetrics, ed 4, pp 323-331).

Question 11

653. Cardiac output increases dramatically during pregnancy and delivery. The cardiac output returns to nonpregnant values by how long postpartum?
     A. 12 hours
     B. 1day
     C. 2 weeks D. 1 month E. 2months

Answer 11

(C) The numerous changes that take place in the cardiovascular system during pregnancy provide for the needs of the fetus and prepare the mother for labor and delivery. During the first trimester of pregnancy, cardiac output increases by approximately 30% to 40%. At term, the cardiac output is increased 50% over nonpregnant val- ues. This increase in cardiac output is due to an increase in stroke volume and an increase in heart rate. During labor, the cardiac output increases another 10% to 15% during the latent phase, 25% to 30% during the active phase, and 40% to 45% during the expulsive stage. Each uterine contraction increases the cardiac output by about 10% to 25%. The greatest increase in cardiac output occurs immediately after delivery of the newborn when the cardiac output can increase to greater than 75% to 80% above prelabor values. This final increase in cardiac output is attributed primarily to autotransfusion and increased venous return associated with uterine involution. Cardiac output falls to prelabor values within 2 days after delivery. But it takes about 2 weeks time for the cardiac output to decrease to nonpregnant values (Chestnut: Obstetric Anesthesia, ed 3, pp 18-21; Hughes: Anesthesia for Obstetrics, ed 4, pp 6-8).

Question 12

654. A 32-year-old parturient with a history of spinal fusion, severe asthma and pregnancy-induced hypertension is brought to the operating room (OR) wheezing and needs an emergency cesarean section under general anesthesia for a pro- lapsed umbilical cord. Which of the following induction agents would be most appropriate for this induction?
     A. Sevoflurane
     B. Midazolam C. Ketamine D. Thiopental E. Propofol

Answer 12

(E) Asthma occurs in about 4% of all pregnancies. Although sevoflurane is a good induction agent for asthmatics, a rapid sequence IV induction with endotracheal intubation to secure the airway is preferred. Because midazolam has a slow onset of action, it is not recommended for a rapid sequence induction. When inducing general anes- thesia in an asthmatic patient, it is imperative to establish an adequate depth of anesthesia before placing an endotracheal tube. If the patient is “light,” then severe bronchospasm may occur. In patients with mild asthma, induction may work with ketamine, thiopental, or propofol. Since thiopental can trigger histamine release in some patients it should not be used in patients with severe asthma. In a patient with severe asthma, ketamine or propofol is preferred. Because propofol does not stimulate the cardiovascular system as does ketamine, propofol would be preferred in this patient with pregnancy-induced hypertension. In patients with mild asthma who do not need the accessory muscles of respiration, regional anesthesia should be strongly considered if time permits, because it would eliminate the need for endotracheal intubation (Chestnut: Obstetric Anesthesia, ed 3, pp 920-921; Hughes: Anesthesia for Obstetrics, ed 4, pp 487-493).

Question 13

655. Uterine blood flow at term pregnancy is A. 50 mL/min

B. 250 mL/min C. 700 mL/min D. 1100 mL/min E. 1500mL/min

Answer 13

(C)
Uterine blood flow (UBF) increases dramatically from 50 to 100 mL/min before pregnancy to about 700 to 900 mL/min at term (i.e., >1 unit of blood per minute). Ninety percent of the uterine blood flow at term goes to the intervillous spaces. Uterine blood flow is related to the perfusion pressure (uterine arterial pressure minus uterine venous pressure) divided by the uterine vascular resistance. Thus, factors that decrease UBF include systemic hypotension, aortocaval compression, uterine contraction, and vasoconstriction (Chestnut: Obstetric Anesthesia, ed 3, pp 37-41; Hughes: Anesthesia for Obstetrics, ed 4, pp 22-23).

Question 14

656. Which one of the following statements is true regarding human immunodeficiency virus (HIV) infected parturients?
     A. Central neurologic blockade increases the chance of neurologic complications
     B. Ninety percent of newborns of untreated HIV seropositive mothers become infected in-utero, during vaginal
     delivery or with breastfeeding
     C. The pharmacologic effects of benzodiazepines are prolonged in patients taking protease inhibitors
     D. The risk of seroconversion after percutaneous exposure to HIV infected blood is about 5%
     E. Epiduralbloodpatchiscontraindicatedforthetreatmentofpost-duralpunctureheadaches

Answer 14

(C) Central neurologic blockade (i.e., epidural, spinal or combined spinal epidural) as well as epidural blood patches appear to be safe for the HIV infected parturients. Vertical transmission from the mother to the newborn can occur in 15% to 40% when the mother is untreated. With antiretroviral therapy and elective cesarean delivery, the rate of transmission is reduced to about 2%. The risk of developing HIV after a needlestick injury with HIV infected blood is 0.3%. (Risk of developing hepatitis B from a needlestick injury with hepatitis B infected blood is 30% and hepatitis C from a needlestick injury with hepatitic C infected blood is 2% to 4%.) Patients taking protease inhibitors as part of their drug therapy have inhibition of cytochrome P-450 and both benzodiazepines as well as narcotics have prolonged effects (Chestnut: Obstetric Anesthesia, ed 3, pp 780-793; Hughes: Anesthesia for Obstetrics, ed 4, pp 583-595).

Question 15

657. Which of the following cardiovascular parameters is decreased at term? A. Central venous pressure (CVP)
     B. Pulmonary capillary wedge pressure
     C. Systemic vascular resistance
     D. Left ventricular end-systolic volume E. Ejectionfraction

Answer 15

(C) There is no change in central venous pressure, pulmonary capillary wedge pressure, pulmonary artery diastolic pressure or left ventricular end-systolic volume. Left ventricular end-diastolic volume is increased as is stroke volume, ejection fraction, heart rate and cardiac output. Systemic vascular resistance is decreased about 20% (Chestnut: Obstetric Anesthesia, ed 3, pp 18-19).

Question 16

658. Which of the following signs and symptoms is NOT associated with amniotic fluid embolism? A. Cardiopulmonary arrest
     B. Hypertension
     C. Bleeding (disseminated intravascular coagulation)
     D. Pulmonary edema or acute respiratory distress syndrome (ARDS) E. Seizures

Answer 16

(B) Amniotic fluid embolism (AFE) is a very rare but serious complication of labor and delivery that results from the entrance of amniotic fluid and constituents of amniotic fluid into the maternal systemic circulation. About 10% of maternal deaths are caused by AFE and two thirds of these deaths occur within 5 hours. For AFE to occur, the placental membranes must be ruptured, and abnormal open sinusoids at the uteroplacental site or lacera- tions of endocervical veins must exist. The classic triad is acute hypoxemia, hemodynamic collapse (i.e., severe hypotension), and coagulopathy without an obvious cause. Pulmonary edema, cyanosis, cardiopulmonary arrest and disseminated intravascular coagulation (DIC) and fetal distress are common (>80% of cases), with seizures occurring about 50% of the time. Recently, AFE is believed to be a bit different from a pure embolic event, because findings of anaphylaxis and septic shock also are involved (Chestnut: Obstetric Anesthesia, ed 3, pp 688-691; Hughes: Anesthesia for Obstetrics, ed 4, pp 355-360).

Question 17

659. When is the fetus most susceptible to the effects of teratogenic agents? A. 1 to 2 weeks of gestation
B. 3 to 8 weeks of gestation
C. 9 to 14 weeks of gestation
D. 15 to 20 weeks of gestation
E. Greaterthan20weeksofgestation

Answer 17

(B) Organogenesis mainly occurs between the 15th to 56th days (3 to 8 weeks) of gestation in humans and is the time during which the fetus is most susceptible to teratogenic agents. Although all commonly used anesthetic drugs are teratogenic in some animal species, there is no conclusive evidence to implicate any currently used local anesthetics, IV induction agents or volatile anesthetic agents in the causation of human congenital anomalies (Chestnut: Obstetric Anesthesia, ed 3, pp 257-263; Hughes: Anesthesia for Obstetrics, ed 4, pp 251-259).

Question 18

660. A 28-week estimated gestational age (EGA), 1000-g male infant is born to a 24-year-old mother who is addicted to heroin. The mother admits taking an extra “hit” of heroin before coming to the hospital because she was nervous. The infant’s respiratory depression would be best managed by
     A. 0.1 mg naloxone IV through an umbilical artery catheter
     B. 0.1 mg naloxone IM in the newborn’s thigh muscle
     C. 0.1 mg naloxone down the endotracheal tube
     D. 0.4 mg naloxone IM to the mother during the second stage of labor E. Noneoftheabove

Answer 18

(E) Opioid abuse includes morphine, heroin, methadone, meperidine, and fentanyl. The problems associated with abuse are many and include the drug effect itself, substances mixed with the narcotics (e.g., talc, cornstarch), as well as infection and malnutrition. Newborn respiratory depression as manifested by a low respiratory rate is treated with controlled ventilation but not with naloxone. Naloxone can precipitate an acute withdrawal reac- tion and should not be administered to patients with chronic narcotic use (mother or newborn). The dose of naloxone to treat narcotic-induced respiratory depression in the nonaddicted newborn is 0.1 mg/kg (Chestnut: Obstetric Anesthesia, ed 3, pp 134, 934-935; Hughes: Anesthesia for Obstetrics, ed 4, pp 602-604, 668).

Question 19

661. Cardiac output is greatest
     A. During the first trimester of pregnancy
     B. During the second trimester of pregnancy C. During the third trimester of pregnancy D. During labor
     E. Immediatelyafterdeliveryofthenewborn

Answer 19

(E) Immediately after delivery, the cardiac output can increase up to 75% to 80% above prelabor values. This is thought to result from autotransfusion and increased venous return to the heart associated with involution of the uterus, as well as increased blood return as the result of the lithotomy position (Chestnut: Obstetric Anesthesia, ed 3, pp 18-21; Hughes: Anesthesia for Obstetrics, ed 4, pp 7-8).

Question 20

662. A 1000-g, 27-week EGA boy is born with a heart rate of 60. He is completely limp, shows no respiratory effort, and has no initial response to stimulation. He is totally cyanotic. The umbilical cord has only two vessels. The 1-minute Apgar score would be
     A. 0
     B. 1 C. 2 D. 3 E. 4

Answer 20

(B) The Apgar score is a subjective scoring system used to evaluate the newborn and is commonly performed 1 and 5 minutes after delivery. If the score is less than 7, the scoring is also performed at 10, 15, and 20 minutes after delivery. A value of 0, 1, or 2 is given to each of five signs (heart rate, respiratory effort, reflex irritability, muscle tone, and color) and totaled. In this case the child gets 1 point for heart rate and 0 for each other sign. A score of 7 to 10 is normal, 4 to 6 moderate depression, and 0 to 3 severe depression. Weight, gestational age, and sex are not factors included in the scoring system (Chestnut: Obstetric Anesthesia, ed 3, pp 126-127; Hughes: Anesthesia for Obstetrics, ed 4, pp 639-642).

Question 21

663. Which of the following respiratory parameters is NOT increased in the parturient? A. Minute ventilation
     B. Tidal volume (Vt)
     C. Arterial Pao2
     D. Oxygen consumption E. Serumbicarbonate

Answer 21

(E) The respiratory system undergoes many changes during pregnancy with an increase in minute ventilation about 45% to 50%, Vt 40% to 45%, and arterial Pao2 increases slightly due to a fall in Paco2. Oxygen consumption increases about 20% to 60%. The serum bicarbonate level falls an average of 4 mEq/L to keep pH in the nor- mal range because of the respiratory alkalosis (Paco2 to approximately 30 to 32 mm Hg) that occurs (Chestnut: Obstetric Anesthesia, ed 3, pp 15-17; Hughes: Anesthesia for Obstetrics, ed 4, pp 3-6).

Question 22

64. A lumbar epidural catheter is placed in a healthy 23-year-old gravida 1, para 0 parturient for an elective cesarean sec- tion. Twenty-five minutes after the full dose of local anesthetic is administered, the patient states that she has difficulty breathing through her nose. The most likely explanation for this is
    A. A total spinal from inadvertent subarachnoid injection of local anesthetic
    B. A total sympathectomy and nasal congestion from a high level of blockade C. Volume overload
    D. Amniotic fluid embolism
    E. Intravascularinjectionoflocalanesthetic

Answer 22

(B) The sympathetic nerve fibers exit the spinal cord through T1-L2. A high spinal or high epidural can block all of the sympathetic fibers, causing hypotension, bradycardia, and venodilation. Venodilation of the veins in the nasal mucosa causes nasal stuffiness and swelling. Because this patient can speak, the patient does not have a “total spinal.” Acute volume overload, amniotic fluid embolism (see explanation to questions 658 and 686), and intravascular injection of local anesthetic do not lead to nasal stuffiness (Hughes: Anesthesia for Obstetrics, ed 4, p 417).

Question 23

665. Which of the following pharmacologic agents decreases uterine contraction in a dose-dependent fashion? A. Barbiturates
B. Diazepam
C. Ketamine
D. Nitrous oxide
E. Localanesthetics

Answer 23

(A) Barbiturates cause a dose-dependent reduction in uterine contractions. Diazepam and nitrous oxide have no effect. Ketamine produces a dose-related oxytocic effect on uterine tone during the second trimester of preg- nancy but no increase in tone at term. Local anesthetics injected intravenously cause an increase in uterine tone and at high levels can lead to tetanic contractions (Hughes: Anesthesia for Obstetrics, ed 4, pp 41-44).

Question 24

666. In a normal sized term fetus, the normal oxygen consumption is approximately A. 7 mL/min
     B. 14 mL/min C. 21 mL/min D. 32 mL/min E. 45mL/min

Answer 24

(C) The normal term (approximately 3 kg) fetus has an oxygen consumption of 7 mL/kg/min or about 21 mL/min. Because the fetal store of oxygen is about 42 mL, in theory it would take 2 minutes to completely deplete it during an interruption in the normal blood supply of oxygen. In reality, the fetus has several compensatory mechanisms that allow it to survive for longer periods of time (e.g., 10 minutes) during periods of hypoxia, including a redistribution of blood flow to vital organs (Chestnut: Obstetric Anesthesia, ed 3, p 66; Hughes: Anesthesia for Obstetrics, ed 4, p 24).

Question 25

667. A 24-year-old gravida 2, para 1 parturient is anesthetized for emergency cesarean section. On emergence from general anesthesia, the endotracheal tube is removed and the patient becomes cyanotic. Oxygen is administered by positive- pressure mask-bag ventilation. High airway pressures are necessary to ventilate the patient, and wheezing is noted over both lung fields. The patient’s blood pressure falls from 120/80 to 60/30 mm Hg, and heart rate increases from 105 to 180 beats/min. The most likely cause of these manifestations is A. Venous air embolism B. Amniotic fluid embolism C. Mucous plug in trachea D. Pneumothorax E. Aspiration

Answer 25

(E) Many of the signs are consistent with the choices described in this question. From the temporal perspective, gastric acid aspiration is the most likely cause, because aspiration can develop not only on induction but on extubation as in this case. That is why it is so important to always empty the patient’s stomach with an oral- gastric tube after an endotracheal tube is placed in any pregnant patient undergoing general anesthesia. Morbid- ity and mortality occurring after gastric acid aspiration is determined by both the amount and the pH of the aspirated material. Aspiration of a gastric volume greater than 0.4 mL/kg with a pH less than 2.5 causes severe pneumonitis with high morbidity and mortality. Using these values, 70% of women who fasted before elective cesarean section are “at risk for aspiration.” Recently, it has been noted that the volume needed to cause aspira- tion in primates should be 0.8 mL/kg and the pH less than 3.5. Regardless of the definition of the “patient at risk,” when aspiration occurs it can be lethal. Bronchospasm (often associated with higher airway pressures) and wheezing are suggestive of gastric acid aspiration and not amniotic fluid embolism. Other signs and symptoms of aspiration include sudden coughing or laryngospasm, dyspnea, tachypnea, the presence of foreign material in the mouth or posterior pharynx, chest wall retraction, cyanosis not relieved by oxygen supplementation, tachy- cardia, hypotension, and the development of pinky frothy exudates. The onset of these signs and symptoms is usually rapid. Early treatment consists of supplemental oxygen with positive-pressure ventilation, PEEP or continuous positive airway pressure (CPAP), and suctioning of the airway can decrease the incidence of mor- tality from acid aspiration. The use of prophylactic antibiotics and/or steroids has not been helpful (Chestnut: Obstetric Anesthesia, ed 3, pp 523-534; Hughes: Anesthesia for Obstetrics, ed 4, pp 391-407).

Question 26

668. A 29-year-old gravida 1, para 0 parturient at 10 weeks of gestation is to undergo an emergency appendectomy under general anesthesia with isoflurane, N2O, and O2. Which of the following is a proven untoward consequence of general anesthesia in the unborn fetus? A. Nephroblastoma B. Cleft palate C. Mental retardation D. Behavioral defects E. Noneoftheabove

Answer 26

(E) The primary objectives in the anesthetic management of parturients undergoing general anesthesia for non- obstetric surgery are as follows: to (1) ensure maternal safety; (2) avoid teratogenic drugs; (3) avoid intrauterine fetal asphyxia; and (4) prevent the induction of preterm labor. Premature onset of labor is the most common complication associated with surgery during the second trimester of pregnancy. Performance of intra-abdominal procedures in which the uterus is manipulated is the most significant factor in causing premature labor in these patients. Neurosurgical, orthopedic, thoracic, or other surgical procedures that do not involve manipulation of the uterus do not cause preterm labor. No anesthetic agent or technique has been found to be significantly associated with a higher or lower incidence of preterm labor. Furthermore, there is no evidence that the risk of developing any of the conditions listed in this question is increased for the offspring of patients who receive general anesthesia during pregnancy (Hughes: Anesthesia for Obstetrics, ed 4, pp 249-265).

Question 27

669. A lumbar epidural is placed in a 24-year-old gravida 1, para 0 parturient with myasthenia gravis for labor. Select the true statement regarding neonatal myasthenia gravis. A. The newborn is usually affected B. The newborn is affected by maternal immunoglobulin M (IgM) antibodies C. The newborn may require anticholinesterase therapy for up to 4 weeks D. The newborn will need lifelong treatment E. Onlyfemalenewbornsareaffected

Answer 27

(C) Myasthenia gravis (MG) is an autoimmune neuromuscular disease in which immunoglobulin G (IgG) antibod- ies are directed against the ACh receptors in skeletal muscle, causing patients to present with general muscle weakness and easy fatigability. Smooth muscle and cardiac muscle are not affected. About 10% to 20% of newborns born to mothers with MG are transiently affected because the IgG antibody is transferred through the placenta. Neonatal MG is characterized by muscle weakness (e.g., hypotonia, respiratory difficulty) and may appear within the first 4 days of life (80% appear within the first 24 hours). Anticholinesterase therapy may be required for 2 to 4 weeks until the maternal IgG antibodies are metabolized (Chestnut: Obstetric Anesthesia, ed 3, pp 877-878; Hughes: Anesthesia for Obstetrics, ed 4, pp 537-539).

Question 28

670. A patient having which of the following conditions is LEAST likely to develop disseminated intravascular coagulation? A. Pregnancy-induced hypertension B. Placenta abruption C. Placenta previa (bleeding) D. Amniotic fluid embolism E. Deadfetussyndrome

Answer 28

(C) Disseminated intravascular coagulation (DIC) is an acquired coagulopathy characterized by excessive fibrin deposition, depression of the normal coagulation inhibition mechanism and impaired fibrin degradation. The formation of clots causes a depletion of platelets and factors. Laboratory diagnosis of DIC is based on the demonstration of consumption of procoagulants (decrease in fibrinogen, decrease in platelet count, and pro- longation of prothrombin time [PT] and activated partial thromboplastin time [aPTT]), demonstration of circulating fibrin-fibrinogen degradation products, and indirect evidence of obstruction of the microcirculation. Disseminated intravascular coagulation (DIC) is associated with the following obstetric conditions: placental abruption, dead fetus syndrome, amniotic fluid embolism, gram-negative sepsis, and severe pregnancy-induced hypertension. Placental abruption is the most common cause of DIC in pregnant patients. If you look at severe placenta abruptions (where the abruption is large enough to cause fetal death), about 30% of patients will develop DIC within 8 hours of the abruption. Patients with placenta previa who are bleeding do not develop DIC because the blood loss does not induce a coagulopathy (Barash: Clinical Anesthesia, ed 5, pp 237-238; Chestnut: Obstetric Anesthesia, ed 3, p 665; Hughes: Anesthesia for Obstetrics, ed 4, pp 349, 356-357, 364-365).

Question 29

671. A 28-year-old gravida 1, para 0 parturient with Eisenmenger’s syndrome (pulmonary hypertension with an intracar- diac right-to-left or bidirectional shunt) is to undergo placement of a lumbar epidural for analgesia during labor. It may be wise to avoid a local anesthetic with epinephrine in this patient because it A. Lowers pulmonary vascular resistance B. Lowers systemic vascular resistance C. Increases heart rate D. Acts as a tocolytic agent E. Causesexcessiveincreasesinsystolicbloodpressure

Answer 29

(B) Eisenmenger’s syndrome may develop in patients with uncorrected left-to-right intracardiac shunting such as ventricular septal defect, atrial septal defect, or patent ductus arteriosus. In this syndrome, the pulmonary and vascular tone and right ventricular muscle undergo changes in response to the shunt, producing pulmonary hypertension and a change in the direction of the shunt to a right-to-left or bidirectional type with peripheral cyanosis. The maternal mortality rate is 30% to 50%. Approximately 3% of all newborns with congenital heart defects will develop this condition over time. Because the pulmonary vascular resistance is fixed in these patients, this condition is not amenable to surgical correction; thus, survival beyond age 40 years is uncommon. Any event or drug that increases pulmonary vascular resistance (e.g., hypercarbia, acidosis, hypoxia) or decreases sys- temic vascular resistance will worsen the right-to-left shunt, exacerbate peripheral cyanosis, and may precipitate right ventricular heart failure in these patients. Controversy exists regarding pain management for these patients because pain can elevate pulmonary artery pressures and cause more shunting. Many practitioners prefer a narcotic-based analgesic (spinal or epidural). Because these patients are very dependent upon preload and after- load, placing invasive monitors (CVP and arterial catheter), and using the pulse oximeter to evaluate amount of shunting, aggressive treatment of any fall in preload or peripheral vascular resistance can be performed. Recall that centrally administered local anesthetics reduce preload and afterload. Low-dose epinephrine, which can be used to decrease absorption of local anesthetics, should be used cautiously, if at all, because a further decrease in systemic vascular resistance may result from the β effect of absorbed epinephrine, and intravascular injection may elevate pulmonary pressures more, exacerbating the right-to-left shunt (Chestnut: Obstetric Anesthesia, ed 3, pp 709-710; Fleisher: Anesthesia and Uncommon Diseases, ed 5, pp 118-119; Hughes: Anesthesia for Obstetrics, ed 4, pp 468-469).

Question 30

672. Which of the following patients is most likely to need an emergency hysterectomy for uncontrolled bleeding at the time of delivery? A. Patient with placenta abruption B. Patient undergoing a vaginal birth after a cesarean section C. Patient with quadruplets D. Patient with a placenta previa (not bleeding) for an elective repeat cesarean section E. Patientwithanabdominalpregnancy

Answer 30

(D) The patient with placenta previa and a previous scar in the uterus has a very high chance of needing an emergency cesarean hysterectomy for uncontrolled bleeding at the time of delivery because of a placenta accreta (abnormally adherent placenta). The incidence of placenta accreta in a patient with placenta previa and no previous cesarean section is 5% to 7%, with one previous cesarean section is about 10% to 30%, and with two or more previous sections is 40% to 70%. About two thirds of patients with placenta accreta require a cesarean hysterectomy. The average blood loss during an emergency obstetric hysterectomy is 5 to 7 units of blood (Chestnut: Obstetric Anesthesia, ed 3, pp 667-676; Hughes: Anesthesia for Obstetrics, ed 4, pp 363-364).

Question 31

673. The most common injury recorded in the ASA - Closed Claim Project regarding obstetric anesthetic claims is A. Headache B. Pain during anesthesia C. Neonatal brain damage D. Maternal brain damage E. Aspirationpneumonitis

Answer 31

(C) According to the ASA’s Closed Claim Project (850 claims as of December 2003), neonatal brain damage (18%) and maternal death (15%) were the most frequent claims. Other causes include maternal nerve damage (15%), headache (14%), back pain (9%), emotional distress (8%), pain during anesthesia (7%), maternal brain damage (6%), neonatal death (6%) and aspiration pneumonitis (3%). (Chestnut: Obstetric Anesthesia ed 4 pp 738-739).

Question 32

674. Morphine is not used routinely for labor epidurals because it A. Increases uterine tone B. Causes excessive neonatal respiratory depression C. Has a slow onset D. Decreases uterine blood flow E. AdverselyaffectsFHRvariability

Answer 32

(C) The main reason morphine is not routinely used for labor epidurals is its long onset time (i.e., 30-60 minutes) despite the high doses needed for adequate first stage analgesia (e.g., 7.5 mg morphine), and the high incidence of pruritus, nausea, vomiting, as well as drowsiness. Morphine has little effect on uterine tone, UBF, or FHR. The doses used epidurally do not cause significant neonatal depression in term newborns but may cause some mild depression in preterm newborns (Chestnut: Obstetric Anesthesia, ed 3, pp 350-353; Hughes: Anesthesia for Obstetrics, ed 4, pp 35, 162-163).

Question 33

675. Which of the following statements regarding newborns with thick meconium-stained amniotic fluid is TRUE? A. Routine intrapartum oropharyngeal and nasopharyngeal suction is not recommended B. Intubation is required for all such newborns C. Antibiotics are needed to treat the infection D. Steroids are needed to treat the inflammation E. Respiratorydistresssyndromeiscommon

Answer 33

(A) Meconium-stained amniotic fluid occurs in about 10% of all deliveries. Although intrapartum oropharyngeal and nasopharyngeal suction for all newborns born to mothers with meconium staining has been routine care for many years, current evidence shows no real benefit and it is no longer recommended. Intubation and tracheal suction should only be performed in newborns who are not vigorous and does not depend upon the consis- tency of the meconium-stained fluid as was once recommended. In newborns who are vigorous (i.e., strong respiratory efforts, good muscle tone, and heart rate >100 beats/min), no further treatment is needed. Because meconium is sterile, antibiotics are not needed. Steroids have not been necessary in the treatment of meconium- stained newborns. Respiratory distress syndrome (RDS) is a condition that occurs as a result of low levels of pul- monary surfactant in the alveoli. Respiratory distress syndrome (RDS) occurs in premature newborns, whereas meconium staining occurs typically in older, often postterm, newborns (Chestnut: Obstetric Anesthesia, ed 3, pp 136-138; Hughes: Anesthesia for Obstetrics, ed 4, pp 666-668).

Question 34

676. A 38-year-old primiparous patient with placenta previa and active vaginal bleeding arrives in the OR with a systolic blood pressure of 85 mm Hg. A cesarean section is planned. The patient is lightheaded and scared. Which of the fol- lowing anesthetic induction plans would be most appropriate for this patient? A. Spinal anesthetic with 12 to 15 mg bupivacaine B. Epidural anesthetic with 20 to 25 mL 3% 2-chloroprocaine C. General anesthetic induction with 3 to 4 mg/kg thiopental, intubation with 1 to 1.5 mg/kg succinylcholine D. General anesthesia induction with 0.5 to 1 mg/kg ketamine, intubation with 1 to 1.5 mg/kg succinylcholine E. Replacelostbloodvolumefirst,thenuseanyanestheticthepatientwishes

Answer 34

(D) Placenta previa occurs when the placenta implants on the lower uterine segment so that all (total) or part of the placenta (partial) covers the internal cervical os. A marginal placenta previa occurs when the placenta lies close to but does not cover the internal cervical os. It occurs in about 0.5% of all pregnancies and has a maternal mor- tality less than 1% but a fetal mortality approaching 20% (primarily because of prematurity and intrauterine asphyxia). Patients typically present with painless vaginal bleeding that stops spontaneously (first bleed). Deliv- ery is cesarean and is often made a few weeks after the “first” bleed when the baby’s lungs are more mature (e.g., after 37 weeks EGA). A later bleed can be uncontrolled and may be accompanied by significant hypovolemiaand hypotension. Regional anesthesia is contraindicated in severely hypovolemic patients. Replacing blood loss may not be practical because bleeding may be quicker than replacement is possible (i.e., may be greater than 1 unit per minute). A rapid-sequence general anesthetic (assuming acceptable airway) is preferred. Ketamine supports the cardiovascular system better than thiopental or propofol. In rare but severe cases of hypovolemic shock, all IV anesthetics may cause the blood pressure to fall further and succinylcholine alone may be all that is required. In these severe cases, maternal recall should be considered secondary to maternal safety. In cases where a difficult intubation is likely and the patient is hypovolemic, an infiltration local anesthetic may be best (Chestnut: Obstetric Anesthesia, ed 3, pp 436, 662-665; Hughes: Anesthesia for Obstetrics, ed 4, pp 361-364).

Question 35

677. Which of the following lung volumes or capacities change the LEAST during pregnancy? A. Tidal volume (Vt) B. Functional residual capacity (FRC) C. Expiratory reserve volume (ERV) D. Residual volume (RV) E. Vitalcapacity(VC)

Answer 35

(E) At term pregnancy, Vt increases about 40% to 45% and the inspiratory reserve volume (IRV) increases about 5%. A decrease occurs in both the expiratory reserve volume (ERV) 20% to 25% and the residual volume (RV) 15% to 20%. A capacity is defined as two or more lung volumes. Functional residual capacity (FRC = ERV + RV) is decreased about 15% to 20% and is partly responsible for the rapid fall in maternal oxygenation that occurs with apnea during the induction of general anesthesia. Total lung capacity (TLC = Vt + IRV + ERV + RV) decreases about 5%, whereas vital capacity (VC = Vt + IRV + ERV) remains unchanged (Chestnut: Obstet- ric Anesthesia, ed 3, pp 16-17; Hughes: Anesthesia for Obstetrics, ed 4, pp 3-4).

Question 36

678. General anesthesia is induced in a 35-year-old patient for elective cesarean section. No part of the glottic apparatus is visible after two unsuccessful attempts to intubate, but mask ventilation is adequate. The most appropriate step at this point would be A. Wake up the patient B. Use an esophageal-tracheal Combitube C. Attempt a blind nasal intubation D. Continue mask ventilation and cricoid pressure E. Usealaryngealmaskairway

Answer 36

(A) Evaluation of the airway should be performed before the induction of any general anesthetic. In cases where an unrecognized difficult airway exists (unable to perform endotracheal intubation in a reasonable period of time) the patient should be awakened if the procedure is purely elective and the fetus has minimal or no fetal distress (as in this elective case). A regional anesthetic or awake intubation then can be safely performed. In cases of fetal or maternal distress, other options for securing the airway may be necessary (Chestnut: Obstetric Anesthesia, ed 3, pp 535-550; Hughes: Anesthesia for Obstetrics, ed 4, pp 217, 379-381).

Question 37

679. If 2-chloroprocaine is accidentally injected into maternal blood, it will be rapidly hydrolyzed by pseudocholinesterase. In a patient who is homozygous for atypical cholinesterase, the half-life for this drug in the blood would be expected to be A. Approximately 2 minutes B. Approximately 5 minutes C. Approximately 15 minutes D. Approximately 30 minutes E. Greaterthan1hour

Answer 37

(A) Chloroprocaine is broken down rapidly in the blood by normal pseudocholinesterase. In vitro plasma half-life is 21 seconds in maternal blood and 43 seconds in fetal blood. In patients who are homozygous for the atypical cholinesterase, the half-life is prolonged to about 2 minutes (Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 38

680. Which of the following properties of epidurally administered local anesthetics determines the extent to which epi- nephrine will prolong the duration of blockade? A. Molecular weight B. Lipid solubility C. pKa D. Amide versus ester structure E. Concentration

Answer 38

(B) Epinephrine is primarily added to local anesthetics to check for the IV placement of an epidural catheter, to decrease the vascular uptake of local anesthetics, or to increase the intensity and duration of the block. By pro- ducing vasoconstriction of the epidural blood vessels, vascular uptake of the local anesthetic is reduced, allowing more of the drug to enter the nervous tissue. The more lipid-soluble the local anesthetic, the less effect epineph- rine has (Chestnut: Obstetric Anesthesia, ed 3, pp 200-201; Hughes: Anesthesia for Obstetrics, ed 4, p 87).

Question 39

681. Which of the following opioids is unique in that it has both local anesthetic and narcotic properties? A. Morphine B. Nalbuphine C. Hydrocodone D. Meperidine E. Oxymorphone

Answer 39

(D) Meperidine demonstrates local anesthetic actions in addition to its narcotic effects (Chestnut: Obstetric Anesthe- sia, ed 3, pp 354, 477-478; Hughes: Anesthesia for Obstetrics, ed 4, p 173).

Question 40

``` 682. A 23-year-old parturient in the first trimester is brought to the OR for emergency appendectomy. General anesthesia is planned. An increased risk of congenital malformation associated with which drug has been suggested (but not proven) that almost always should be avoided? A. Thiopental B. Nitrous oxide C. Isoflurane D. Diazepam E. Noneoftheabove ```

Answer 40

(D) An increased risk of congenital malformations has been suggested by several old studies with the use of minor tranquilizers such as diazepam, meprobamate, and chlordiazepoxide during the first trimester of pregnancy.The cause-and-effect relationship has not been proven; in fact, several newer studies failed to show an associa- tion between minor tranquilizers and congenital malformations. Nevertheless, the U.S. Food and Drug Admin- istration (FDA) recommends that diazepam (caution with midazolam) should not be used in the first trimester of pregnancy (Chestnut: Obstetric Anesthesia, ed 3, p 216; Hughes: Anesthesia for Obstetrics, ed 4, p 253; Physicians Desk Reference - 2008, ed 62, p 2765).

Question 41

683. True statements regarding inclusion of intrathecal morphine, fentanyl, or sufentanil in obstetric anesthesia practice include each of the following EXCEPT A. The chief site of action is the substantia gelatinosa of the dorsal horn of the spinal column B. There is no motor blockade C. There is no sympathetic blockade D. Pain relief is adequate for the second stage of labor E. Lipophilicnarcoticsareassociatedwithlessrespiratorydepressionthannonlipophilicnarcotics

Answer 41

(D) Intrathecal opiates (e.g., morphine, fentanyl, sufentanil) are very effective in relieving the visceral pain during the first stage of labor. Intrathecal opiates administered alone (except for meperidine, which has local anesthetic properties) do not provide adequate pain relief for the second stage somatic pain (Chestnut: Obstetric Anesthesia, ed 3, pp 349-365; Hughes: Anesthesia for Obstetrics, ed 4, pp 155-180).

Question 42

684. The most common side effect of intraspinal narcotics in the obstetric population is A. Pruritus B. Nausea and vomiting C. Respiratory depression D. Urinary retention E. Headache

Answer 42

(A) The most common side effect of intraspinal narcotics is pruritus. The next most common side effects are nausea and vomiting, followed by urinary retention. Respiratory depression and headache may occur, but are relatively infrequent (Chestnut: Obstetric Anesthesia, ed 3, pp 358-360; Hughes: Anesthesia for Obstetrics, ed 4, pp 170-178).

Question 43

685. A 110-kg (242-pound), gravida 1, para 0 woman has a blood pressure of 180/95 during an office visit at the 18th week of gestation and 170/95 one week later. She has some ankle but no facial edema, and no protein detected in her urine. These findings would be classified as A. Preeclampsia B. Chronic hypertension C. Chronic hypertension with superimposed preeclampsia D. Gestational hypertension E. Anormalfinding

Answer 43

(B) Hypertension (systolic blood pressure >140 or an increase >30 mm Hg over baseline; diastolic blood pressure >90 or an increase of 15 mm Hg over baseline) occurs in about 7% of all pregnancies. It is commonly classi- fied by the American College of Obstetricians and Gynecologists as one of five types (preeclampsia-eclampsia, HELLP syndrome [Hemolysis, Elevated Liver enzymes, and Low Platelet count], chronic hypertension, chronic hypertension with preeclampsia-eclampsia, or gestational hypertension). Preeclampsia rarely occurs before 24 weeks EGA except in patients with gestational trophoblastic neoplasms (e.g., molar pregnancy) and manifests as a triad of hypertension, generalized edema, and proteinuria. Chronic hypertension is persistent hypertension before, during, and after pregnancy (e.g., >6 weeks postpartum). Some patients develop gestational hyperten- sion, which is an increase in blood pressure without generalized edema or proteinuria, which resolves by 2 to 6 weeks postpartum (Chestnut: Obstetric Anesthesia, ed 3, pp 794-806; Hughes: Anesthesia for Obstetrics, ed 4, pp 297-299).

Question 44

686. An epidural is placed into a 32-year-old parturient receiving magnesium therapy for preeclampsia. Five minutes after administration of the test dose, the bolus infusion is interrupted because of a contraction. After the contraction subsides, a slow epidural injection of the loading dose of bupivacaine and fentanyl is resumed. At the same time, the patient complains of shortness of breath. She is panic-stricken and wrestles violently with the nurses who are trying to reassure her. She repeats that she cannot breathe, becomes cyanotic, and loses consciousness. During resuscitation, blood is oozing from the IV sites and a pink froth is noted in the endotracheal tube. The most likely diagnosis is A. Amniotic fluid embolism B. High spinal C. Intravascular bupivacaine injection D. Magnesium overdose E. Eclampsia

Answer 44

(A) The four cardinal features of amniotic fluid embolism are dyspnea, hypoxemia, cardiovascular collapse, and coma. The patient may develop DIC, seizures, and pulmonary edema from left ventricular failure. Patients with a high spinal or epidural may complain of dyspnea, but they also have marked weakness and would certainly not be able to wrestle or struggle with their health care providers. Patients experiencing an intravascular injection of local anesthetic present with central nervous system (CNS) signs of toxicity (lightheadedness, visual or auditory disturbances, muscular twitching, convulsion, coma) or, at higher levels, cardiovascular collapse. Magnesium overdosage is also associated with muscle weakness. The typical eclamptic seizure is tonic-clonic. Patients with eclampsia do not complain of dyspnea, although an associated aspiration may produce similar symptoms (Chest- nut: Obstetric Anesthesia, ed 3, pp 688-691, 909-911; Hughes: Anesthesia for Obstetrics, ed 4, pp 355-359).

Question 45

687. Which of the following intraspinal opioid dose(s) would NOT be acceptable to administer in combination with 12 mg bupivacaine to a 60 kg parturient about to undergo a cesarean section? A. 25 μg fentanyl B. 5 μg sufentanil C. 0.25 mg morphine D. 15 μg fentanyl and 0.1 mg morphine E. 60mgmeperidine

Answer 45

(E) ntrathecal opioids are often mixed with local anesthetics to provide better intraoperative and postoperative pain control. Fentanyl is commonly used in doses of 10 to 25 μg, sufentanil in doses of 2.5 to 5.0 μg, and morphine in doses of 0.1 to 0.25 mg. Some anesthesiologists mix morphine with fentanyl because morphine is slow in onset but has a long duration of action and fentanyl is faster in onset but has a short duration of action. If you add meperidine to bupivacaine, the dose is 10 mg, however, if you use meperidine as a sole agent, the dose is 1 mg/kg. In this case we are adding meperidine to bupivacaine and 60 mg is too high a dose (Chestnut: Obstetric Anesthesia, ed 3, pp 355-357, 429-430; Hughes: Anesthesia for Obstetrics, ed 4, pp 170-173, 205).

Question 46

688. Which of the following is not increased during pregnancy? A. Kidney size B. Renal plasma flow C. Creatinine clearance D. Blood urea nitrogen (BUN) E. Glucoseexcretion

Answer 46

(D) The renal system undergoes dramatic anatomical (increase in kidney size as well as dilation of the ureters) and functional changes in pregnancy. Renal plasma flow increases about 75% to 85%, glomerular filtration rate (GFR) increases about 50% and is reflected by an increase in clearance of urea, creatinine, and uric acid. Because of the increased clearance, we see a decrease in BUN to 8 to 9 mg/dL, serum creatinine to 0.5-0.6 mg/dL, as well as serum urate to 2 to 3 mg/dL. Glucosuria is common and is attributed to both the increase in GFR and a reduced renal tubular resorption of glucose (Chestnut: Obstetric Anesthesia, ed 3, pp 24-25; Miller: Anesthesia, ed 6, p 2311).

Question 47

``` 689. Which inhalation anesthetic does NOT produce uterine relaxation A. Desflurane B. Isoflurane C. Sevoflurane D. Nitrous oxide E. Allproduceuterinerelaxation ```

Answer 47

(D) All halogenated anesthetic agents (halothane, enflurane, isoflurane, desflurane, sevoflurane) cause a dose-related relaxation of uterine smooth muscle. With anesthetic concentrations of 0.2 MAC, the decrease in uterine activity is slight, and these agents have been used for inhalation analgesia during labor. At 0.5 MAC, uterine relaxation is more significant but the uterine response to oxytocin remains intact. Nitrous oxide does not affect uterine activity (Chestnut: Obstetric Anesthesia, ed 3, pp 107, 320-321; Hughes: Anesthesia for Obstetrics, ed 4, pp

Question 48

690. Passive diffusion of substances across the placenta is enhanced by all of the following EXCEPT A. Decreased maternal protein binding B. Low molecular weight of the substance C. High water solubility of the substance D. Low degree of ionization of the substance E. Largeconcentrationgradientofthedrug

Answer 48

(C) Passive diffusion is the primary means for the placental transfer of drugs. Factors that promote diffusion of drugs across placental membranes include decreased maternal protein binding (although some believe this is not very important because of rapid diffusion of drugs from protein), low molecular weight (

Question 49

691. Cesarean delivery is associated with a blood loss of about A. 100 mL B. 250 mL C. 500 mL D. 750 mL E. 1000mL

Answer 49

(E) The average blood loss associated with a vaginal delivery is about 600 mL and about 1000 mL after a cesarean delivery (Chestnut: Obstetric Anesthesia, ed 3, pp 22-23).

Question 50

692. Which of the following statements is correct in describing differences between fetal and maternal blood during labor? A. Fetal blood has a lower hemoglobin concentration than does maternal blood B. Fetal placental blood flow is twice maternal placental blood flow C. Fetal hemoglobin has a greater affinity for O2 than does maternal hemoglobin D. The fetal oxyhemoglobin dissociation curve is shifted to the right of the maternal oxyhemoglobin dissociation curve E. FetalbloodhasahigherpHthandoesmaternalblood

Answer 50

(C) The fetus has several compensatory mechanisms for dealing with low O2 pressures (umbilical vein Po2 approxi- mately equal to 30 mm Hg when mother is breathing room air) to which it is exposed. These include a higher hemoglobin concentration (15 to 20 g/dL) and the presence of fetal hemoglobin, which has a greater affinity for oxygen (the fetal oxyhemoglobin dissociation curve is shifted to the left of the maternal oxyhemoglobin dissociation curve). Fetal and maternal blood flow through the placenta are equal. Fetal blood has a lower pH than maternal blood, which may be related to the higher Paco2 levels seen in fetal blood (Hughes: Anesthesia for Obstetrics, ed 4, pp 24-25).

Question 51

``` 693. Which of the following antihypertensive drugs used to treat used to treat severe pregnancy-induced hypertension is not capable of causing increased postpartum hemorrhage? A. Nitroprusside B. Nifedipine C. Nitroglycerin D. Labetalol E. Diazoxide ```

Answer 51

(D) Nitroprusside, nifedipine, and nitroglycerin are all used successfully in patients with pregnancy-induced hyper- tension (PIH), all have direct effects on smooth muscle (such as the uterus) and are associated with increased postpartum hemorrhage. Nitroprusside and nitroglycerin’s effects are short lived after the drug is discontinued. Labetalol (adrenergic blocker) does not affect uterine contractions significantly and is often used in patients with PIH. Because diazoxide has been reported to cause sudden uncontrolled hypotension with decreased uterine blood flow and fetal distress, it is rarely used in obstetrics today. Diazoxide is also a very potent uterine relaxant and can lead to increased hemorrhage as well (Hughes: Anesthesia for Obstetrics, ed 4, pp 306-307).

Question 52

694. Which of the following is not a sign of “severe preeclampsia” A. Proteinuria greater than 5 g/24 hours B. Visual disturbances C. Urine output less than 500 mL/24 hours D. White blood cell count greater than 15,000 E. Allaresignsof“severepreeclampsia”

Answer 52

(D) Preeclampsia occurs in about 7% of all pregnancies and is associated with hypertension, proteinuria, and/or generalized edema. It usually occurs after the 24th week of gestation but patients may present earlier in cases of gestational trophoblastic disease (e.g., molar pregnancy). It is classified as either mild or severe. It becomes severe if any of the following conditions coexists: systolic BP greater than or equal to 160 mm Hg; diastolic BP greater than or equal to 110 mm Hg; proteinuria greater than or equal to 5 g/24 hr; elevated serum creatinine, urine output of less than 500 mL/24 hr; CNS disturbances (seizures, altered consciousness, headaches, visual distur- bances); pulmonary edema; epigastric or right upper quadrant pain; hepatic rupture; impaired liver function; thrombocytopenia; or HELLP syndrome. Most patients have increased cardiac output, normal or increased systemic vascular resistance, and normal or decreased blood volumes and filling pressures. The white blood count is not part of the diagnosis of preeclampsia. In fact, the white blood count progressively rises during normal pregnancy from 6000/mm3 to 9000 to 11,000/mm3. During labor the white blood count increases to 13,000/mm3 and rises to an average of 15,000/mm3 on the first postpartum day (Chestnut: Obstetric Anesthesia, ed 3, pp 794-817; Hughes: Anesthesia for Obstetrics, ed 4, pp 297-303).

Question 53

695. Which condition best describes the maternal condition with the following signs and symptoms; new onset vaginal bleeding that stops, no pain, no fetal distress? A. Vasa previa B. Placenta abruption C. Ectopic pregnancy D. Uterine rupture E. Placentaprevia

Answer 53

(E) Placenta previa is classically described as painless vaginal bleeding during the second or third trimester and is not associated with maternal shock or fetal distress with the presentation of the first bleed (Chestnut: Obstetric Anesthesia, ed 3, pp 662-663; Hughes: Anesthesia for Obstetrics, ed 4, p 361).

Question 54

696. During the second stage of labor, complete pain relief can be obtained with A. Paracervical block B. Neuraxial block with fentanyl and morphine C. Pudendal nerve block D. Lumbar epidural block with bupivacaine and no narcotic E. Bilaterallumbarparavertebralsympatheticblockswithbupivacaine

Answer 54

(D) The first stage of labor starts with the onset of labor and ends with complete cervical dilation (10 cm). It is visceral pain and is associated with uterine contractions and dilation of the cervix and is transmitted via the autonomic nervous system through the sympathetic fibers that pass through the paracervical region and enter the CNS at T10-L1 segments. The second stage of labor includes these pathways and adds the somatic fibers of the birth canal that are transmitted via the pudendal nerve entering the CNS at S2-S4. Neuraxial block (spinal and/or epidural) with only narcotics can be useful for first stage pain, however the somatic pain is not well treated with narcotics alone. A local anesthetic induced lumbar epidural block with or without narcotics can produce complete anesthesia during both first and second stage of labor pain. If a low spinal or saddle block is performed with local anesthetics (covering only sacral areas), the uterine contraction pain still will be felt. Paracervical blocks only block the first stage pain. Pudendal blocks block the somatic component during the second stage but not visceral painof contractions. Bilateral lumbar paravertebral sympathetic blocks were once used to treat first stage labor pain (no effect on second stage somatic birth canal pain) but are more of historical significance, because epidural and spinal blocks are much easier (Chestnut: Obstetric Anesthesia, ed 3, pp 290-292, 335-336, 387, 391-392; Hughes: Anesthesia for Obstetrics, ed 4, pp 123-133).

Question 55

697. Which of the following drugs should NOT be used as a tocolytic for preterm labor A. Magnesium sulfate B. Nifedipine C. Ketorolac D. Indomethacin E. Captopril

Answer 55

(E) There are several drugs that can be used for tocolytic therapy for preterm labor. Most commonly, MgSO4 and/ or β-adrenergic agonists (ritodrine, terbutaline) are used. Prostaglandin-synthetase inhibitors (indomethacin, ketorolac) and calcium entry blockers (nifedipine) have recently been used in selected cases. Ace inhibitors (cap- topril) can cause injury and even death to the developing fetus during the second and third trimester and should not be given during this part of pregnancy (Chestnut: Obstetric Anesthesia, ed 3, pp 609-625; Hughes: Anesthesia for Obstetrics, ed 4, pp 323-337; Physicians’ Desk Reference - 2008, ed 62, p 2169).

Question 56

``` 698. 15-Methyl PGF2a is administered directly into the myometrium to treat uterine atony in a 28-year-old mother. Possible effects from treatment with this drug include A. Nausea and vomiting B. Bronchospasm C. Fever D. Hypoxemia E. Alloftheabove ```

Answer 56

(E) 15-Methyl PGF2a (carboprost, Hemabate) is the preferred prostaglandin for use in the treatment of refractory uterine atony (after oxytocin). The dose is 250 μg IM, repeat as needed every 15 to 30 minutes with a maximum total dose of 2 mg. It has several important side effects, such as bronchospasm, ventilation-to-perfusion (V/Q) mismatch with an increase in intrapulmonary shunting, and hypoxemia. Other side effects include nausea, vomiting, fever, and diarrhea (Chestnut: Obstetric Anesthesia, ed 3, pp 671, 919; Hughes: Anesthesia for Obstetrics, ed 4, pp 367-369).

Question 57

699. Which of the following statements regarding MgSO4 therapy for preeclampsia is true? A. The therapeutic range for serum magnesium is 10 to 15 mEq/L B. High serum magnesium levels can be estimated by changes in deep tendon patellar reflexes in a patient with an epidural anesthetic loaded for a cesarean section C. Excessive serum magnesium levels cause widening of the QRS complex D. The antidote for magnesium toxicity is neostigmine E. Assoonasdeliveryoccurs,thechanceforeclampsianolongerexistsandthemagnesiumshouldbereversedsothat postpartum bleeding is less likely to occur

Answer 57

(C) Magnesium sulfate is the anticonvulsant of choice in the preeclamptic patient in North America and is more effective than phenytoin. In addition to its anticonvulsant effect, MgSO4 exerts a peripheral effect at the neuro- muscular junction. The therapeutic range for serum MgSO4 is 4 to 8 mEq/L. (1 mEq/L = 1.22 mg/dL). In an unanesthetized patient, a loss of deep tendon reflexes occurs at 10 mEq/L, respiratory arrest occurs at 15 mEq/L. As long as deep tendon reflexes are present, significant toxicity is unlikely. In a patient with an epidural or spinal anesthetic loaded for a cesarean section. the patellar reflex is gone; estimation of deep tendon reflexes should be done with the biceps tendon (unless a total spinal develops). Electrocardiogram (ECG) changes including P-Q interval prolongation and QRS complex widening occurs at serum levels of 5 to 10 mEq/L; sinoatrial and atrioventricular block at 15 mEq/L and cardiac arrest at levels greater than 25 mEq/L. The treatment for magnesium toxicity is calcium. Patients with therapeutic MgSO4 levels should not be reversed with calcium to decrease the chance for postpartum uterine atony and hemorrhage, since eclamptic seizures may develop. About 60% of eclamptic seizures occur before delivery. Most postpartum seizures develop in the first 24 hours after delivery but eclamptic seizures may occur as late as 22 days after delivery (Chestnut: Obstetric Anesthesia, ed 3, pp 808-809, 825-827; Hughes: Anesthesia for Obstetrics, ed 4, pp 304-306).

Question 58

700. While moving a parturient from the birthing room to the operating room for an emergency cesarean section for a prolapsed umbilical cord, the parturient develops cough, wheezing, stridor, and becomes cyanotic. The trachea is intubated and food is noted in the pharynx. Appropriate treatment in this patient should consist of A. Intravenous lidocaine to suppress the cough B. Glucocorticoids C. 100% oxygen and positive end-expiratory pressure (PEEP) D. Saline lavage E. Sodiumbicarbonatelavage

Answer 58

(C) Three different aspiration syndromes have been described in the general population: aspiration of particulate matter, aspiration of acid fluid (Mendelson’s syndrome), and aspiration of fecal material. Aspiration of fecal material has the highest mortality rate but fortunately occurs only with an associated bowel obstruction, which is rarely a problem in obstetrics. Symptoms of aspiration include coughing, tachypnea, tachycardia, broncho- spasm, and hypoxemia. Treatment is supportive and includes the Heimlich maneuver if a large foreign body is lodged in the oropharynx (which is unlikely in the fasting laboring patient), endotracheal intubation, suctioning the airway to remove particulate material, administration of increased concentrations of oxygen, and application of PEEP to achieve oxygenation goals as needed (prophylactic PEEP does not provide any benefit). Coughing is due to the airway irritation and is most effectively decreased with muscle paralysis. Intravenous lidocaine would not be effective. Use of saline or bicarbonate lavage does not decrease lung damage and can worsen hypoxemia. Glucocorticoids or other anti-inflammatory drugs have not been effective in limiting the inflammation and may increase the risk of secondary bacterial infection (Chestnut: Obstetric Anesthesia, ed 3, pp 523-529; Hughes: Anesthesia for Obstetrics, ed 4, pp 393-397).

Question 59

701. Aortocaval compression starts to become significant in a normal pregnancy at how many weeks EGA? A. 5 weeks B. 10 weeks C. 15 weeks D. 20 weeks E. 25weeks

Answer 59

(D) Aortocaval compression typically is not a problem until about 20 weeks’ gestation when the uterus is large enough to compress the aorta and vena cava when the patient assumes the supine position (Chestnut: Obstetric Anesthesia, ed 3, p 241; Hughes: Anesthesia for Obstetrics, ed 4, pp 8-10).

Question 60

702. Which agent is the most useful for raising the gastric pH just before induction of general anesthesia for emergency cesarean section? A. Cimetidine B. Metoclopramide C. Ranitidine D. Sodium citrate E. Magnesiumhydroxideandaluminumhydroxide

Answer 60

(D) Cimetidine and ranitidine are H2-receptor antagonists that will increase gastric pH but take at least 30 minutes to work. Metoclopramide is not an antacid but may be useful by increasing the lower esophageal sphincter tone. Only liquid antacids raise gastric pH quickly. Sodium citrate, a clear nonparticulate antacid (0.3 M sodium citrate) is preferred over particulate antacids (aluminum hydroxide, magnesium trisilicate, magnesium hydrox- ide) because clear nonparticulate antacids cause less pulmonary damage if aspirated. Sodium citrate 30 mLneutralizes 255 mL of HCl with a pH of 1.0. Neutralization of gastric acid occurs rapidly (i.e.,

Question 61

703. Causes of fetal bradycardia include all of the following EXCEPT? A. Hypoxemia B. Acidosis C. Neostigmine and glycopyrrolate reversal of neuromuscular blockers D. Maternal smoking E. Umbilicalcordcompression

Answer 61

(D) Causes of fetal bradycardia include hypoxemia, acidosis, complete heart block, and some drugs. Atropine read- ily crosses the placenta but at low doses does not seem to cause fetal tachycardia; at high doses, it may produce tachycardia. The combination of neostigmine, which crosses the placenta slightly, and glycopyrrolate, which does not cross the placenta well, has been associated with fetal bradycardia, which is why neostigmine with atropine is preferred when reversing neuromuscular blockers if a fetus is present. Bradycardias are associated with early decelerations (head compression with vagal stimulation), late decelerations (fetal hypoxemia with vagal stimulation or myocardial failure), variable decelerations (umbilical cord compressions with vagal stimula- tion). Causes of fetal tachycardia include infection, fever, maternal smoking, fetal paroxysmal supraventricular tachycardia, and some drugs (ritodrine, terbutaline, atropine) (Chestnut: Obstetric Anesthesia, ed 3, pp 111-115, 264; Hughes: Anesthesia for Obstetrics, ed 4, pp 625-630).

Question 62

704. Etiology of cerebral palsy occurs most frequently A. Antepartum B. During the first stage of labor C. During the second stage of labor D. Immediately after delivery E. Inthefirst30daysoflife

Answer 62

(A) Cerebral palsy (CP) is a nonprogressive disorder of the central nervous system and is associated with impairment of motor function. Mental retardation may or may not be present and is not an essential diagnostic criterion. The cause is unknown and most likely multifactorial. Associated conditions include maternal mental retarda- tion, birth weight of less than 2000 grams and fetal malformations, but many other factors may play a role. It occurs in about 2 per 1000 live births. At one time, fetal heart rate monitoring was thought to be able to prevent CP but this has not happened. In fact, among patients with new onset late deceleration patterns the false posi- tive rate is 99% if used to predict the development of CP. This is not to say that intrapartum asphyxial insults do not cause damage, they might, and probably account for about 6% of cases of CP. There is also a very weak association of low Apgar scores and CP, in fact most children who develop CP had a 5 minute Apgar score that was normal (Chestnut: Obstetric Anesthesia, ed 3, pp 148-163; Hughes: Anesthesia for Obstetrics, ed 4, p 634).

Question 63

705. All of the following statements regarding pregnant diabetic patients are true EXCEPT for A. 2% to 5% of all pregnancies are associated with gestational diabetes mellitus (GDM) B. Insulin requirements increase during pregnancy C. Preeclampsia is more common in diabetics D. Insulin readily crosses the placenta and causes larger babies E. Diabeticketoacidosis(DKA)occursin8%to9%oftypeIDMpregnancies

Answer 63

(D) Diabetes mellitus is the most common endocrine problem associated with pregnancy. Type I diabetes mel- litus (due to a decrease in insulin secretion) occurs in one of every 700 to 1000 gestations. Gestational diabe- tes, which occurs only during pregnancy, is seen in about 2% to 5% of all pregnancies. Although substantial advances in the obstetric and anesthetic management of diabetic parturients has been made, maternal and fetal mortality are still higher in these patients than in parturients without diabetes. Diabetic ketoacidosis (DKA) occurs in 8% to 9% of type I DM pregnancies. One important goal of insulin therapy in these patients is to avoid both hyperglycemia and hypoglycemia. In general, insulin requirements are increased during pregnancy from 0.7 units/kg/day at 2 weeks of gestation to 0.8 units/kg/day at 18 weeks and 0.9 to 1.0 units/kg/day at 32 weeks and more of gestation. Insulin does not readily cross the placenta and therefore does not have any direct effects on glucose metabolism in the fetus. Glucose, however, readily crosses the placenta. Preeclampsia and large-for-gestational-age fetuses occur more frequently in parturients with diabetes. Because of fetal macro- somia, cesarean section is more common in diabetics than nondiabetics (Chestnut: Obstetric Anesthesia, ed 3, pp 734-744; Hughes: Anesthesia for Obstetrics, ed 4, pp 497-505).

Question 64

706. In addition to the postural component of a postdural puncture headache (PDPH), signs and symptoms may include any of the following EXCEPT A. Double vision B. Nausea and vomiting C. Hearing changes D. Neck stiffness E. Fever

Answer 64

(E) Postdural puncture headaches (PDPH) are positional headaches (exacerbated by sitting or standing and relieved with recumbency). They are bilateral and typically located in the fronto-occipital regions. In one prospective series of non-obstetric patients with PDPH, symptoms included nausea 60%, vomiting 24%, neck stiffness 43%, ocular changes (photophobia, diplopia, difficulty in accommodation) 13%, and auditory changes (hearing loss, hyperacusis, tinnitus), 12%. Although postpartum seizures have been associated with PDPH, other etiologies are more likely. Seizures, lethargy, fever, nuchal rigidity, focal neurologic deficits (other than listed above) and a unilateral location suggest other headache etiologies (Chestnut: Obstetric Anesthesia, ed 3, pp 562-574; Hughes: Anesthesia for Obstetrics, ed 4, pp 414-415).

Question 65

707. Variable decelerations may occur in response to A. Fetal head compression B. Uteroplacental insufficiency C. Maternal hypotension D. Umbilical cord compression E. Severefetalanemia

Answer 65

(D) There are several periodic FHR patterns. Accelerations in FHR in response to fetal movement signify fetal well- being. Early decelerations are decreases in FHR usually less than 20 beats/min and occur concomitantly with uterine contractions. Typically they are smooth and are mirror images of the uterine contractions. They are not associated with fetal compromise and are caused by head compression, which produces a vagal slowing of the FHR. Late decelerations are decreases in FHR that occur 10 to 30 seconds after the onset of a contraction and end 10 to 30 seconds after the end of a contraction. They are due to uteroplacental insufficiency and can result whenever uterine blood flow decreases. The delayed onset is due to the time required to sense a low oxygen tension. The decrease in FHR may be a vagal reflex (mild cases) or due to direct myocardial depression fromhypoxia (severe cases). Typically, in severe cases beat-to-beat variability is decreased or absent as well. Variable decelerations are decreases in FHR that vary in shape, depth, and duration from contraction to contraction. They are thought to be due to transient umbilical cord compression. A sinusoidal pattern is a regular smooth wavelike pattern with no short-term variability. It may be caused by severe fetal anemia or result from the maternal administration of narcotics (Chestnut: Obstetric Anesthesia, ed 3, pp 114-115; Hughes: Anesthesia for Obstetrics, ed 4, pp 625-633).

Question 66

708. Agents that are useful for decreasing the incidence of shivering during cesarean section under epidural analgesia include all of the following EXCEPT A. Administration of epidural sufentanil B. Warming of IV fluids C. Administration of epidural meperidine D. Warming the epidural anesthetic solutions to body temperature E. Intravenousmeperidine

Answer 66

(D) Shivering occurs in 10% of all normal deliveries. The frequency increases from 20% to 70% of patients receiving epidural or spinal anesthesia for labor or cesarean deliveries. It is more common with spinal than epidural anes- thesia. Use of epidural sufentanil (50 μg), fentanyl (100 μg), or meperidine (25 mg) with the local anesthetic and warming the IV fluid can help decrease the incidence of shivering. It is postulated that the greater efficacy of epidural meperidine may reside in its properties as both a μ- and a κ-receptor agonist within the spinal cord. Warming the epidural anesthesia solution to body temperature has no effect (Chestnut: Obstetric Anesthesia, ed 3, p 487; Hughes: Anesthesia for Obstetrics, ed 4, p 417; Hughes: Anesthesia for Obstetrics, ed 3, pp 439-440).

Question 67

709. An umbilical arterial blood gas sample at the time of a STAT cesarean delivery shows a Po2 of 20 mm Hg, a Pco2 of 50 mm of Hg, a bicarbonate value of 22 mEq/L and a pH of 7.25. This shows A. Severe hypoxemia B. Respiratory acidosis C. Metabolic acidosis D. Mixed respiratory and metabolic acidosis E. Normalvalues

Answer 67

(E) These are normal umbilical cord values. Chart is modified from values listed in Chestnut’s and Hughes’ books. (Chestnut: Obstetric Anesthesia, ed 3, pp 127-129; Hughes: Anesthesia for Obstetrics, ed 4, pp 659-660.)

Question 68

710. Which condition most frequently requires blood transfusions during or after a cesarean delivery? A. Multiple gestations B. Preeclampsia C. Intrauterine fetal demise D. Placenta abruption E. Placentaprevia

Answer 68

(E) Overall, the incidence of transfusion of blood for parturients (not including placenta previa) is 1%. However, about 3.5% of cesarean sections receive blood during or after cesarean section with the most frequent indication being placenta previa (Chestnut: Obstetric Anesthesia, ed 3, p 676).

Question 69

711. All of the following are appropriate techniques or drug doses and may be needed to resuscitate a severely depressed 3 kg term newborn EXCEPT A. 30 breaths with 90 chest compressions per minute B. 0.1 to 0.3 mL/kg of 1:1000 solution of epinephrine IV C. 10 mL/kg of normal saline, Ringer’s lactate or type O Rh negative blood given IV D. 0.1mg/kg(1mg/mLor0.4mg/mLsolution)ofnaloxonegivenIVorIM E. 4mL/kgof4.2%sodiumbicarbonatesolutiongivenIV

Answer 69

(B) After clearing the airway, drying and stimulating the newborn, the apneic newborn receives positive pressure ventilation at a rate of 40 to 60 breaths/minute. After 30 seconds of assisted ventilation and if the heart rate is less than 60, chest compressions are started. At this point the newborn receives 30 breaths and 90 compres- sions/min (e.g., one and two and three and breath). If after another 30 seconds the newborn is not improving, epinephrine is administered. The correct dose is 0.1 to 0.3 mL/kg of a 1:10,000 (not 1:1000) solution. Intu- bation can be performed any time during resuscitation based on the skill level of the resuscitation team and equipment availability. If the newborn is intubated and IV access has not yet been achieved, consider admin- istering a higher dose of epinephrine such as 0.3 to 1.0 mL/kg of a 1:10,000 solution down the endotracheal tube (the higher dose is used since blood levels are unpredictable after endotracheal instillation). If volume expansion is needed, normal saline, Ringer’s lactate or, if severe fetal anemia is suspected or documented, type O Rh negative blood is administered IV at an initial dose of 10 mL/kg given over 5 to 10 minutes and repeated as needed. If the newborn has depressed respirations that are thought to be due to narcotic administration, naloxone at a dose of 0.1 mg/kg (1 mg/mL or 0.4 mg/mL solution) IV or IM is given. Recall that naloxone is not given to a newborn if the mother is addicted to narcotics or is on a methadone maintenance program or else the newborn could withdraw suddenly and develop seizures. With severe metabolic acidosis and adequate lung ventilation, a dilute solution of sodium bicarbonate (4.2% or 0.5 mEq/mL) at a dose of 2 mEq/kg is given slowly, no faster than 1 mEq/kg/min. Drugs used in newborn resuscitation that can be given down the endotracheal tube include Oxygen, Naloxone, and Epinephrine (ONE) (Kattwinkel: Textbook of Neonatal Resuscitation, ed 5, pp 1-11, 3-22, 4-10, 6-7, 6-10, 7-10, 7-14).

Question 70

712. Failed intubation is how many times greater in the obstetric population than the general population? A. The incidence is the same B. Double C. Four times D. Eight times E. Twentytimes

Answer 70

(D) The incidence of failed intubation is 8 times higher in the obstetric population than the general population with an estimated rate of 1 in 280 obstetric patients (Chestnut: Obstetric Anesthesia, ed 3, p 535).

Question 71

713. Compared with a healthy 25-year-old primigravida, which of the following conditions is NOT associated with a significantly higher incidence of pregnancy-induced hypertension (PIH)? A. Young primigravida (35) E. Smoking(>1pack/day)

Answer 71

(E) Although the cause of PIH is not known, several associated factors are noted. Pregnancy-induced hypertension (PIH) is 5 times more common in primigravidas younger than 20 years of age compared with primigravidas older than 20 years of age. When there is rapid growth of the uterus, PIH is significantly more common (e.g., twins, type 1 DM, polyhydramnios, hydatidiform mole). The incidence of PIH is progressive with increas- ing body mass index (BMI) (4.3% with BMI 35). Although smoking is associated with many adverse pregnancy outcomes, there appears to be a lower incidence of PIH (Cunningham: Williams

Question 72

714. Adverse effects (on the mother) associated with aortocaval compression by the gravid uterus include A. Nausea and vomiting B. Pallor C. Changes in cerebration D. Decreases in uterine blood flow E. Alloftheabove

Answer 72

(E) Aortocaval compression can occur in up to 15% of pregnant patients at term. Compression of the vena cava reduces venous return, producing symptoms of hypotension, nausea and vomiting, pallor, and changes in cere- bration. Compression of the aorta decreases uterine blood flow (Hughes: Anesthesia for Obstetrics, ed 4, pp 8-10).

Question 73

715. Which of the following statements regarding a pregnant patient abusing cocaine is TRUE? A. Hypotensioniscommonwiththerapidsequenceinductionofgeneralanesthesiaintheacutelyintoxicatedpatient B. The MAC for general anesthetics is increased in chronic cocaine addicts C. Hypertension is common with the induction of epidural anesthesia for labor D. Some states consider in utero drug exposure to be a form of child abuse and require physicians to report these patients E. Ifavasopressorisneededtotreathypotension,ephedrineispreferredoverphenylephrine

Answer 73

(D) Cocaine can produce life-threatening complications that are usually related to the accumulation of catecholamines and patients may present with the classic signs of toxemia (i.e., hypertension, proteinuria and edema). Because some states consider in utero cocaine exposure a form of child abuse that requires physicians to report positive drug tests in pregnant women, many cocaine abusing patients have no prenatal care. Urine tests may be positive for 24 to 72 hours after cocaine use (depending on the amount used). Life-threatening events are more common with general than regional anesthesia. The most frequent problem with induction of general anesthesia is severe hypertension. The MAC is increased in patients who are acutely intoxicated, whereas chronic abusing cocaine addicts have a lower MAC (depletion of catecholamines). These patients are at risk of having hypotension com- monly seen after induction of regional anesthesia for cesarean section. Ephedrine may not be an effective vasopres- sor in these catecholamine depleted patients. Phenylephrine, a direct acting drug is a better vasopressor (Chestnut: Obstetric Anesthesia, ed 3, pp 929-933; Hughes: Anesthesia for Obstetrics, ed 4, pp 604-608).

Question 74

716. Each of the following is correct when advising the surgeon to perform infiltration anesthesia for an emergency cesarean delivery when general and neuraxial anesthesias are contraindicated EXCEPT A. A midline incision is most desirable B. The rectus muscle should be injected to provide good skin analgesia C. The skin incision is the most painful part of the surgery D. Bupivacaine with bicarbonate is the local anesthetic of choice E. Mildsedationwithketamineandmidazolamispermissible

Answer 74

D) In cases of emergency cesarean section when general anesthesia is contraindicated (e.g., poor airway when you question your ability to intubate and/or ventilate the patient), and neuraxial anesthesia is contraindicated (e.g., severe hypovolemia or coagulopathy), emergency infiltration anesthesia is acceptable. All of the choices are cor- rect except the choice of local anesthetic. As the surgeon will be injecting a fair volume of local anesthetic (often 100 mL) and bupivacaine has a slow onset and potentially dangerous cardiac toxicity with large doses, bupiva- caine is a poor choice. A dose of 0.5% lidocaine (plasma half-life of 90 minutes) is often used because it is readily available and relatively safe. Chloroprocaine may be safer because it also has a fast onset and its plasma half-life is extremely short (23 seconds). Both midazolam and ketamine may lead to some amnesia for the patient which may be advantageous in this emergency situation, however, too much of the IV drugs could obtund the patient and may lead to aspiration of gastric contents. A good coach at the head of the bed may be invaluable for reas- suring the patient as to the care (Chestnut: Obstetric Anesthesia, ed 3 p 438).

Question 75

``` 717. A 24-year-old primiparous woman is undergoing an elective cesarean section (breech position). After prehydration with 1500 mL of saline, a spinal anesthetic is performed and 5 minutes later the blood pressure is noted to be 80/40 and the heart rate is 100. The best treatment (best fetal pH) after assuring that adequate left uterine displacement is performed would be A. Phenylephrine B. Ephedrine C. Epinephrine D. 1000 mL D5LR E. 1000mLhetastarch ```

Answer 75

(A) The most common complication after a spinal or epidural anesthetic is placed is systemic hypotension. Treatment is threefold: increasing left uterine displacement (LUD); administering more intravenous fluids; and evaluating the need for vasopressors. Although IV fluids are used to decrease the incidence of hypotension after spinal anesthesia and should be rapidly infused if the parturient has not received prehydration fluids along with left uterine displacement, vasopressors are often needed. Initial studies suggested that ephedrine was a better choice compared with phenylephrine and other α-adrenergic agonists, as noted in animal studies looking at changes in uterine blood flow. More recent human studies looking at ephedrine and phenylephrine use have noted no difference in the prophylactic or treatment use of these drugs for maternal hypotension; maternal bradycardia was more common with phenylephrine whereas maternal tachycardia was more common with ephedrine; and neonatal arterial pH was higher when phenylephrine was used as compared with ephedrine. Why this occurs is unclear but may be related to ephedrine’s ability to cross the placenta causing β-adrenergic stimulation in the newborn. In this patient who has LUD, adequate IV hydration and a heart rate of 100 beats/min, phenylephrine would be the preferred vasopressor. Epinephrine is rarely needed but should be available and used when there is severe hypotension not responsive to phenylephrine or ephedrine, especially when there is associated fetal bradycardia. Intravenous fluids with dextrose are used only for maintenance fluids and should not be used to prevent or treat hypotension from regional anesthesia because the fluid load causes significant maternal and fetal hyperglycemia and hyperinsulinemia. After delivery, the sugar supply for the newborn stops but the insulin response continues, often causing fetal hypoglycemia post delivery. Hetastarch solutions are not only expensive but may alter platelet function, producing more bleeding at the time of delivery, and are not recommended for routine use to treat hypotension (Chestnut: Obstetric Anesthesia, ed 3, pp 422-426; Hughes: Anesthesia for Obstetrics, ed 4, pp 32-33, 204-207).

Question 76

719. The action of epidural narcotics is antagonized by the prior or concomitant administration of which of the following epidurally administered local anesthetics?A. LidocaineB. BupivacaineC. RopivacaineD. Chloroprocaine E. Noneoftheabove

Answer 76

(D) 2-Chloroprocaine administered epidurally appears to decrease the quality and duration of subsequently admin- istered fentanyl or morphine. The exact mechanism is unclear but does not seem to be related to the acid pH of chloroprocaine (because neutralization with bicarbonate has similar antagonistic properties). Butorphanol (a ҝ-receptor agonist) does not appear to be antagonized (Chestnut: Obstetric Anesthesia, ed 3, pp 178, 199; Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 77

720. Factors associated with advanced molar pregnancy (i.e., >14-16 week size uterus) include all of the following EXCEPT A. Pregnancy-induced hypertensionB. HypothyroidismC. Acute cardiopulmonary distressD. Hyperemesis gravidarumE. Malignantsequelae(metastasis)

Answer 77

(B) Earlier diagnosis of complete molar pregnancies has decreased the incidence of medical complications. How- ever, excessive uterine size occurs in up to one half of patients with a complete molar pregnancy and is associated with a high incidence of medical complications. Medical complications when the uterine size is greater than 14 to 16 weeks gestational size include ovarian theca-lutein cysts 4% to 50%, hyperemesis gravidarum 15% to 30%, pregnancy induced hypertension 11% to 27%, anemia with hemoglobin less than 10 in 10% to 54%, acute cardiopulmonary distress 6% to 27%, malignant sequelae (metastasis) 4% to 36%, and hyperthyroidism 1% to 7% (Chestnut: Obstetric Anesthesia, ed 3, pp 249-251).

Question 78

721. Refractory cardiac arrest is most likely after the rapid unintentional IV injection of which of the following local anestheticsA. LidocaineB. BupivacaineC. RopivacaineD. Levobupivacaine E. Chloroprocaine

Answer 78

(B) Several cases of maternal cardiac arrest have occurred in pregnant women who were administered bupivacaine (Marcaine, Sensorcaine). Typically, the patients received an unintentional IV bolus of 0.75% bupivacaine intended for the epidural space. They had a brief grand mal seizure followed by cardiovascular collapse. Successful treatment may be prolonged and involves basic resuscitation (intubation, ventilation with 100% oxygen, cardiac compres- sion with left uterine tilt, defibrillation, epinephrine, vasopressin, amiodarone), as well as rapid delivery of the fetus (if possible within 4 to 5 minutes). Delivery of the fetus makes successful resuscitation of the mother more likely. Incremental small injections of local anesthetic looking for toxicity should decrease the chance for cardiovascular collapse. Bupivacaine 0.75% now is considered contraindicated for use in the epidural space of parturients. Recent literature has shown that the IV injection of 20% Intralipid (dose 4 mL/kg followed by 0.5 mL/kg/min) may make resuscitation both easier and more likely. Both levobupivacaine (Chirocaine) and ropivacaine (Naropin) were developed to have a long duration of action, like bupivacaine, but with less cardiac toxicity. Although these compounds have less cardiac toxicity than bupivacaine, they are more cardiac toxic than lidocaine (intermediate duration of action) and chloroprocaine (short duration of action) (Barash: Clinical Anesthesia, ed 5, pp 464-467; Chestnut: Obstetric Anesthesia, ed 3, pp 194-195; Hughes: Anesthesia for Obstetrics, ed 4, pp 81-87, 436-437).

Question 79

722. Transient neurologic syndrome (TNS) is most commonly seen after the spinal anesthetic injection of which local anesthetic?A. Lidocaine B. Bupivacaine C. Prilocaine D. Tetracaine E. Procaine

Answer 79

(A) Transient neurologic syndrome (TNS) occurs most commonly after spinal anesthesia with lidocaine (Xylo- caine). Symptoms include back pain that develops after the block resolves and radiates to the buttocks and legs. The pain is not associated with motor or sensory loss or electromyographic changes. It can be severe, requiring hospital admission of outpatients and typically resolves within 1 to 4 days. It appears to occur more commonly when patients are operated on when they are in the lithotomy position and appears less likely when patients are pregnant (Chestnut: Obstetric Anesthesia, ed 3, p 196; Hughes: Anesthesia for Obstetrics, ed 4, pp 79-81).

Question 80

723. Chloroprocaine-induced severe back pain is associated with epidural anesthesia and A. MetabisulfiteB. MethylparabenC. PregnancyD. Disodium ethylenediaminetetraacetic acid (EDTA) E. Highconcentrationssuchas3%

Answer 80

(D) Chloroprocaine undergoes oxidative decomposition and has undergone several different formulations over the years to decrease this decomposition. When EDTA was used, the incidence of severe deep back pain that lasted several hours become noted. This back pain was felt to be related to calcium chelation from the EDTA in the local anesthetic solution that leaked out of the intervertebral foramen and produced hypocalcemic tetany of the paraspinal muscles. Currently, the EDTA has been removed and the chloroprocaine manufactured today is in colored vials to reduce the rate of oxidation (Chestnut: Obstetric Anesthesia, ed 3, pp 195-196; Hughes: Anesthesia for Obstetrics, ed 4, pp 75-76).

Question 81

724. Which of the following local anesthetics is associated with methemoglobinemia A. LidocaineB. BupivacaineC. PrilocaineD. Levobupivacaine E. Chloroprocaine

Answer 81

(C) The metabolic product of prilocaine (Citanest) is ortho-toluidine, which can produce methemoglobinemia. This occurs when doses of prilocaine greater than 600 mg are used (Hughes: Anesthesia for Obstetrics, ed 4, p 81).

Question 82

725. Which local anesthetic has the most rapid metabolism in maternal and fetal blood? A. LidocaineB. BupivacaineC. PrilocaineD. Levobupivacaine E. Chloroprocaine

Answer 82

(E) Chloroprocaine (Nesacaine) is an ester-type local anesthetic with a very short half-life in both maternal and fetal blood. The in vitro half-life is 21 seconds for maternal blood and 43 seconds for fetal blood. All the other local anesthetics are amides and require liver metabolism (Chestnut: Obstetric Anesthesia, ed 3, p 333, Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 83

718 A woman has been admitted for a dilation and evacuation at 10 weeks estimated gestational age. She has some persistent bleeding and cramping after the expulsion of some tissue. Her obstetric condition is called A. A threatened abortionB. An inevitable abortionC. A complete abortionD. An incomplete abortionE. A habitual abortion

Answer 83

D) A threatened abortion is defined as uterine bleeding without cervical dilation before 20 weeks gestation. Bleed- ing may be accompanied by cramping or backache. Half of these cases will go on to spontaneously abort. An inevitable abortion has cervical dilation and/or rupture of membranes and will spontaneously abort. A complete abortion occurs when there is complete expulsion of the fetus and the placenta, and in these cases there is no need for a D&C. If there is only partial expulsion of tissue, as in this case, an incomplete abortion has occurred and these require a D&E to remove the remaining fetal or placental tissue. In these cases the cervix has usually dilated some and the patient usually can be managed with some mild sedation, because the most painful part of a D&E is cervical dilation. A habitual or recurrent abortion refers to the occurrence of three of more consecutive spontaneous abortions (Chestnut: Obstetric Anesthesia, ed 3, pp 244-247).

Question 84

719. The action of epidural narcotics is antagonized by the prior or concomitant administration of which of the following epidurally administered local anesthetics?A. LidocaineB. BupivacaineC. RopivacaineD. Chloroprocaine E. Noneoftheabove

Answer 84

(D) 2-Chloroprocaine administered epidurally appears to decrease the quality and duration of subsequently admin- istered fentanyl or morphine. The exact mechanism is unclear but does not seem to be related to the acid pH of chloroprocaine (because neutralization with bicarbonate has similar antagonistic properties). Butorphanol (a ҝ-receptor agonist) does not appear to be antagonized (Chestnut: Obstetric Anesthesia, ed 3, pp 178, 199; Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 85

720. Factors associated with advanced molar pregnancy (i.e., >14-16 week size uterus) include all of the following EXCEPT A. Pregnancy-induced hypertensionB. HypothyroidismC. Acute cardiopulmonary distressD. Hyperemesis gravidarumE. Malignantsequelae(metastasis)

Answer 85

(B) Earlier diagnosis of complete molar pregnancies has decreased the incidence of medical complications. How- ever, excessive uterine size occurs in up to one half of patients with a complete molar pregnancy and is associated with a high incidence of medical complications. Medical complications when the uterine size is greater than 14 to 16 weeks gestational size include ovarian theca-lutein cysts 4% to 50%, hyperemesis gravidarum 15% to 30%, pregnancy induced hypertension 11% to 27%, anemia with hemoglobin less than 10 in 10% to 54%, acute cardiopulmonary distress 6% to 27%, malignant sequelae (metastasis) 4% to 36%, and hyperthyroidism 1% to 7% (Chestnut: Obstetric Anesthesia, ed 3, pp 249-251).

Question 86

721. Refractory cardiac arrest is most likely after the rapid unintentional IV injection of which of the following local anestheticsA. LidocaineB. BupivacaineC. RopivacaineD. Levobupivacaine E. Chloroprocaine

Answer 86

(B) Several cases of maternal cardiac arrest have occurred in pregnant women who were administered bupivacaine (Marcaine, Sensorcaine). Typically, the patients received an unintentional IV bolus of 0.75% bupivacaine intended for the epidural space. They had a brief grand mal seizure followed by cardiovascular collapse. Successful treatment may be prolonged and involves basic resuscitation (intubation, ventilation with 100% oxygen, cardiac compres- sion with left uterine tilt, defibrillation, epinephrine, vasopressin, amiodarone), as well as rapid delivery of the fetus (if possible within 4 to 5 minutes). Delivery of the fetus makes successful resuscitation of the mother more likely. Incremental small injections of local anesthetic looking for toxicity should decrease the chance for cardiovascular collapse. Bupivacaine 0.75% now is considered contraindicated for use in the epidural space of parturients. Recent literature has shown that the IV injection of 20% Intralipid (dose 4 mL/kg followed by 0.5 mL/kg/min) may make resuscitation both easier and more likely. Both levobupivacaine (Chirocaine) and ropivacaine (Naropin) were developed to have a long duration of action, like bupivacaine, but with less cardiac toxicity. Although these compounds have less cardiac toxicity than bupivacaine, they are more cardiac toxic than lidocaine (intermediate duration of action) and chloroprocaine (short duration of action) (Barash: Clinical Anesthesia, ed 5, pp 464-467; Chestnut: Obstetric Anesthesia, ed 3, pp 194-195; Hughes: Anesthesia for Obstetrics, ed 4, pp 81-87, 436-437).

Question 87

722. Transient neurologic syndrome (TNS) is most commonly seen after the spinal anesthetic injection of which local anesthetic?A. Lidocaine B. Bupivacaine C. Prilocaine D. Tetracaine E. Procaine

Answer 87

(A) Transient neurologic syndrome (TNS) occurs most commonly after spinal anesthesia with lidocaine (Xylo- caine). Symptoms include back pain that develops after the block resolves and radiates to the buttocks and legs. The pain is not associated with motor or sensory loss or electromyographic changes. It can be severe, requiring hospital admission of outpatients and typically resolves within 1 to 4 days. It appears to occur more commonly when patients are operated on when they are in the lithotomy position and appears less likely when patients are pregnant (Chestnut: Obstetric Anesthesia, ed 3, p 196; Hughes: Anesthesia for Obstetrics, ed 4, pp 79-81).

Question 88

723. Chloroprocaine-induced severe back pain is associated with epidural anesthesia and A. MetabisulfiteB. MethylparabenC. PregnancyD. Disodium ethylenediaminetetraacetic acid (EDTA) E. Highconcentrationssuchas3%

Answer 88

(D) Chloroprocaine undergoes oxidative decomposition and has undergone several different formulations over the years to decrease this decomposition. When EDTA was used, the incidence of severe deep back pain that lasted several hours become noted. This back pain was felt to be related to calcium chelation from the EDTA in the local anesthetic solution that leaked out of the intervertebral foramen and produced hypocalcemic tetany of the paraspinal muscles. Currently, the EDTA has been removed and the chloroprocaine manufactured today is in colored vials to reduce the rate of oxidation (Chestnut: Obstetric Anesthesia, ed 3, pp 195-196; Hughes: Anesthesia for Obstetrics, ed 4, pp 75-76).

Question 89

724. Which of the following local anesthetics is associated with methemoglobinemia A. LidocaineB. BupivacaineC. PrilocaineD. Levobupivacaine E. Chloroprocaine

Answer 89

(C) The metabolic product of prilocaine (Citanest) is ortho-toluidine, which can produce methemoglobinemia. This occurs when doses of prilocaine greater than 600 mg are used (Hughes: Anesthesia for Obstetrics, ed 4, p 81).

Question 90

725. Which local anesthetic has the most rapid metabolism in maternal and fetal blood? A. LidocaineB. BupivacaineC. PrilocaineD. Levobupivacaine E. Chloroprocaine

Answer 90

(E) Chloroprocaine (Nesacaine) is an ester-type local anesthetic with a very short half-life in both maternal and fetal blood. The in vitro half-life is 21 seconds for maternal blood and 43 seconds for fetal blood. All the other local anesthetics are amides and require liver metabolism (Chestnut: Obstetric Anesthesia, ed 3, p 333, Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 91

718 A woman has been admitted for a dilation and evacuation at 10 weeks estimated gestational age. She has some persistent bleeding and cramping after the expulsion of some tissue. Her obstetric condition is called A. A threatened abortionB. An inevitable abortionC. A complete abortionD. An incomplete abortionE. A habitual abortion

Answer 91

D) A threatened abortion is defined as uterine bleeding without cervical dilation before 20 weeks gestation. Bleed- ing may be accompanied by cramping or backache. Half of these cases will go on to spontaneously abort. An inevitable abortion has cervical dilation and/or rupture of membranes and will spontaneously abort. A complete abortion occurs when there is complete expulsion of the fetus and the placenta, and in these cases there is no need for a D&C. If there is only partial expulsion of tissue, as in this case, an incomplete abortion has occurred and these require a D&E to remove the remaining fetal or placental tissue. In these cases the cervix has usually dilated some and the patient usually can be managed with some mild sedation, because the most painful part of a D&E is cervical dilation. A habitual or recurrent abortion refers to the occurrence of three of more consecutive spontaneous abortions (Chestnut: Obstetric Anesthesia, ed 3, pp 244-247).

Question 92

719. The action of epidural narcotics is antagonized by the prior or concomitant administration of which of the following epidurally administered local anesthetics?A. LidocaineB. BupivacaineC. RopivacaineD. Chloroprocaine E. Noneoftheabove

Answer 92

(D) 2-Chloroprocaine administered epidurally appears to decrease the quality and duration of subsequently admin- istered fentanyl or morphine. The exact mechanism is unclear but does not seem to be related to the acid pH of chloroprocaine (because neutralization with bicarbonate has similar antagonistic properties). Butorphanol (a ҝ-receptor agonist) does not appear to be antagonized (Chestnut: Obstetric Anesthesia, ed 3, pp 178, 199; Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 93

720. Factors associated with advanced molar pregnancy (i.e., >14-16 week size uterus) include all of the following EXCEPT A. Pregnancy-induced hypertensionB. HypothyroidismC. Acute cardiopulmonary distressD. Hyperemesis gravidarumE. Malignantsequelae(metastasis)

Answer 93

(B) Earlier diagnosis of complete molar pregnancies has decreased the incidence of medical complications. How- ever, excessive uterine size occurs in up to one half of patients with a complete molar pregnancy and is associated with a high incidence of medical complications. Medical complications when the uterine size is greater than 14 to 16 weeks gestational size include ovarian theca-lutein cysts 4% to 50%, hyperemesis gravidarum 15% to 30%, pregnancy induced hypertension 11% to 27%, anemia with hemoglobin less than 10 in 10% to 54%, acute cardiopulmonary distress 6% to 27%, malignant sequelae (metastasis) 4% to 36%, and hyperthyroidism 1% to 7% (Chestnut: Obstetric Anesthesia, ed 3, pp 249-251).

Question 94

721. Refractory cardiac arrest is most likely after the rapid unintentional IV injection of which of the following local anestheticsA. LidocaineB. BupivacaineC. RopivacaineD. Levobupivacaine E. Chloroprocaine

Answer 94

(B) Several cases of maternal cardiac arrest have occurred in pregnant women who were administered bupivacaine (Marcaine, Sensorcaine). Typically, the patients received an unintentional IV bolus of 0.75% bupivacaine intended for the epidural space. They had a brief grand mal seizure followed by cardiovascular collapse. Successful treatment may be prolonged and involves basic resuscitation (intubation, ventilation with 100% oxygen, cardiac compres- sion with left uterine tilt, defibrillation, epinephrine, vasopressin, amiodarone), as well as rapid delivery of the fetus (if possible within 4 to 5 minutes). Delivery of the fetus makes successful resuscitation of the mother more likely. Incremental small injections of local anesthetic looking for toxicity should decrease the chance for cardiovascular collapse. Bupivacaine 0.75% now is considered contraindicated for use in the epidural space of parturients. Recent literature has shown that the IV injection of 20% Intralipid (dose 4 mL/kg followed by 0.5 mL/kg/min) may make resuscitation both easier and more likely. Both levobupivacaine (Chirocaine) and ropivacaine (Naropin) were developed to have a long duration of action, like bupivacaine, but with less cardiac toxicity. Although these compounds have less cardiac toxicity than bupivacaine, they are more cardiac toxic than lidocaine (intermediate duration of action) and chloroprocaine (short duration of action) (Barash: Clinical Anesthesia, ed 5, pp 464-467; Chestnut: Obstetric Anesthesia, ed 3, pp 194-195; Hughes: Anesthesia for Obstetrics, ed 4, pp 81-87, 436-437).

Question 95

722. Transient neurologic syndrome (TNS) is most commonly seen after the spinal anesthetic injection of which local anesthetic?A. Lidocaine B. Bupivacaine C. Prilocaine D. Tetracaine E. Procaine

Answer 95

(A) Transient neurologic syndrome (TNS) occurs most commonly after spinal anesthesia with lidocaine (Xylo- caine). Symptoms include back pain that develops after the block resolves and radiates to the buttocks and legs. The pain is not associated with motor or sensory loss or electromyographic changes. It can be severe, requiring hospital admission of outpatients and typically resolves within 1 to 4 days. It appears to occur more commonly when patients are operated on when they are in the lithotomy position and appears less likely when patients are pregnant (Chestnut: Obstetric Anesthesia, ed 3, p 196; Hughes: Anesthesia for Obstetrics, ed 4, pp 79-81).

Question 96

723. Chloroprocaine-induced severe back pain is associated with epidural anesthesia and A. MetabisulfiteB. MethylparabenC. PregnancyD. Disodium ethylenediaminetetraacetic acid (EDTA) E. Highconcentrationssuchas3%

Answer 96

(D) Chloroprocaine undergoes oxidative decomposition and has undergone several different formulations over the years to decrease this decomposition. When EDTA was used, the incidence of severe deep back pain that lasted several hours become noted. This back pain was felt to be related to calcium chelation from the EDTA in the local anesthetic solution that leaked out of the intervertebral foramen and produced hypocalcemic tetany of the paraspinal muscles. Currently, the EDTA has been removed and the chloroprocaine manufactured today is in colored vials to reduce the rate of oxidation (Chestnut: Obstetric Anesthesia, ed 3, pp 195-196; Hughes: Anesthesia for Obstetrics, ed 4, pp 75-76).

Question 97

724. Which of the following local anesthetics is associated with methemoglobinemia A. LidocaineB. BupivacaineC. PrilocaineD. Levobupivacaine E. Chloroprocaine

Answer 97

(C) The metabolic product of prilocaine (Citanest) is ortho-toluidine, which can produce methemoglobinemia. This occurs when doses of prilocaine greater than 600 mg are used (Hughes: Anesthesia for Obstetrics, ed 4, p 81).

Question 98

725. Which local anesthetic has the most rapid metabolism in maternal and fetal blood? A. LidocaineB. BupivacaineC. PrilocaineD. Levobupivacaine E. Chloroprocaine

Answer 98

(E) Chloroprocaine (Nesacaine) is an ester-type local anesthetic with a very short half-life in both maternal and fetal blood. The in vitro half-life is 21 seconds for maternal blood and 43 seconds for fetal blood. All the other local anesthetics are amides and require liver metabolism (Chestnut: Obstetric Anesthesia, ed 3, p 333, Hughes: Anesthesia for Obstetrics, ed 4, p 75).

Question 99

718 A woman has been admitted for a dilation and evacuation at 10 weeks estimated gestational age. She has some persistent bleeding and cramping after the expulsion of some tissue. Her obstetric condition is called A. A threatened abortionB. An inevitable abortionC. A complete abortionD. An incomplete abortionE. A habitual abortion

Answer 99

D) A threatened abortion is defined as uterine bleeding without cervical dilation before 20 weeks gestation. Bleed- ing may be accompanied by cramping or backache. Half of these cases will go on to spontaneously abort. An inevitable abortion has cervical dilation and/or rupture of membranes and will spontaneously abort. A complete abortion occurs when there is complete expulsion of the fetus and the placenta, and in these cases there is no need for a D&C. If there is only partial expulsion of tissue, as in this case, an incomplete abortion has occurred and these require a D&E to remove the remaining fetal or placental tissue. In these cases the cervix has usually dilated some and the patient usually can be managed with some mild sedation, because the most painful part of a D&E is cervical dilation. A habitual or recurrent abortion refers to the occurrence of three of more consecutive spontaneous abortions (Chestnut: Obstetric Anesthesia, ed 3, pp 244-247).