OB MCQ

Answer:D Chestnut p.17 The HR increases 15-25% by the end of 1st trimester and remains largely unchanged until postpartum. The SV by 25-30% by the end of 2nd trimester. This is mediated by an increase in LVEDV with a constant LVESV. PCWP remains constant despite the increase in LVEDV. This is due to eccentric LV hypertrophy, accommodating a greater volume without increase in pressure. Likewise CVP is unchanged despite increase blood volume, as the RV dilates to accommodate.

11. In a normal pregnancy at term, all of the following are unchanged except? [2011] a) CVP b) Left ventricular stroke work index c) PCWP d) Left ventricular end-diastolic volume

Answer B The dose of naloxone is 0.1mg/kg IV. NRP manual p.247.

12. What is the required dose of Naloxone for an apneic infant born to a mother given Fentanyl? [2011] a) 0.01 mg/kg b) 0.1 mg/kg c) 0.4 mg/kg d) 0.5 mg/kg

ANSWER: B Risk factors for GERD in pregnancy include gestational age, heartburn antecedent to pregnancy, and multiparity. Gravidity, prepregnancy BMI, and weight gain during pregnancy do not correlate with the occurrence of reflux, whereas maternal age has an inverse correlation.

43. Risks factors for gastric reflux during pregnancy include all of the following except: [2013] a) Multiparity b) Amount of weight gain during pregnancy c) Gestational age d) Heartburn prepartum

ANSWER: D A: Forceps delivery is usually necessitated by prolonged labour and may cause genital trauma, which in turn is a mechanism of PPH. B: VBAC - perhaps trying to confuse with increased risk of uterine rupture? VBAC increases risk of uterine rupture which is in itself a cause of PPH (see Fig 38-2) D: Tocolytics Uterine atony PPH References: Chestnut ch 38 p. 889

46. What increases the risk of PPH in pregnancy? [2013] a) Forceps delivery b) VBAC c) ? d) Tocolytics

ANSWER: C / A? Answer likely IV fluid loading - evidence exists that crystalloid (either preload or coload) does not help; colloids do help. All others have very weak evidence. A: One study demonstrated a salutary effect of a prophylactic infusion of ephedrine combined with phenylephrine compared with infusion of ephedrine alone. However, another study comparing infusions of different ephedrine-to-phenylephrine ratios found that as the proportion of ephedrine increased, the incidence of hypotension and nausea/vomiting also increased, whereas umbilical cord blood pH and base excess were decreased. Loughrey et al. tested various ratios of ephedrine combined with phenylephrine, administered as a bolus, but were unable to identify a combination that reliably prevented hypotension yet avoided hypertension. B: (Spinal for C/S:) Compared with the supine position, left uterine displacement does not consistently reduce the occurrence of maternal hypotension during cesarean delivery, most likely reflecting the variable presence and significance of supine hypotension syndrome. Maternal blood pressure measured at the level of the brachial artery may not always predict uteroplacental perfusion....Thus, we consider the use of left uterine displacement mandatory during anesthesia for cesarean delivery. (Labour epidural:) The prevention of hypotension includes avoidance of aortocaval compression. C: (Spinal for C/S) Crystalloid preload is minimally effective, even when volumes as great as 30 mL/kg are infused. By contrast, a colloid preload consistently reduces the incidence and severity of hypotension. Meta-analysis of randomized trials comparing crystalloid preload to co-load did not find a difference in the incidence of hypotension. Our current practice is to administer a rapid crystalloid co-load (approximately 15 mL/ kg) to healthy parturients undergoing elective cesarean delivery with spinal anesthesia. (Labour epidural) Traditionally, intravenous "preload" (also known as "prehydration") with 0.5 to 1.5 L of crystalloid solution has been used to reduce the incidence and severity of hypotension after the initiation of neuraxial labor analgesia. However, several randomized controlled trials have shown that the incidence of hypotension after preload with 0.5 to 1.0 L of fluid is no lower than that after no preload. D: Phenylephrine is equally efficacious to ephedrine for the prevention and treatment of hypotension, and it is less likely to depress umbilical arterial blood pH and base excess. Ngan Kee et al. reduced the incidence of spinal anesthesia-associated hypotension to almost zero (1.9%) by combining a rapid crystalloid co-load with a prophylactic phenylephrine infusion (beginning at 100 μg/min); the incidence of hypotension was 28% in the women who received phenylephrine without the co-load. No difference in neonatal outcome was observed between groups. References: Chestnut ch. 23 p. 480 Chestnut ch. 26 p. 580

45. Least benefit for preventing hypotension in a parturient following neuraxial technique? [2013] a) Prophylactic ephedrine b) Prevention of aorto-caval compression c) Intravenous fluid loading d) Administration of phenylephrine

answer:C

14. A woman presents for her fourth caesarean section. What is the risk of placental accreta? [2011] a) 10% b) 30% c) 50% d) Greater than 90%

answer:C

15. All are changes associated with pregnancy except: [2011] a) Increase in plasma volume by 50% b) Increase in red blood cell mass 30% c) Increase in FRC 50% d) Increase in minute ventilation of 45%

Answer: D - Nifedipine (but no longer true, hence the obsolescence of this question). Chestnut Pg. 837-838 Based on a systematic review of antihypertensive agents for use in pre-eclampsia, magnesium sulfate was identified as inferior to labetalol, hydralazine and nifedipine for blood pressure control, and was recommended to be avoided as an antihypertensive agent (though it is still recommended for seizure prophylaxis). Labetalol - FALSE: first line agent for treatment of hypertension according to 2011 ACOG opinion. Has both alpha and beta adrenergic antagonism with a 1:7 ratio of alpha to beta (when given IV). Should be avoided in women with severe asthma or CHF. Efficacy comparable to hydralazine, but with fewer side effects. No interaction with magnesium sulfate. Nitroprusside - FALSE: a second line agent for treatment of hypertension in pregnant women who do not respond to labetalol or hydralazine. It is a smooth muscle vasodilator, and interacts with sulfhydryl groups on endothelial cells to cause the release of nitric oxide. It causes arteriolar relaxation and reduces afterload and venous return. Should be used only in emergent situations, and for a limited duration, as its metabolism results in the production of cyanide, which will be transferred to the placenta and expose the fetus to the risks of cyanide toxicity. No interactions with magnesium sulfate. Hydralazine - FALSE: a first line agent for treatment of hypertension according to 2011 ACOG opinion. Acts as a potent vasodilator, but does pose a risk of maternal hypotension if adequate volume expansion is not provided. Other side effects include tachycardia, palpitations, headache, and neonatal thrombocytopenia. Hydralazine is associated with more maternal tachycardia and palpitations when compared with Labetalol, but results in less neonatal bardycardia and hypotension. No interactions with magnesium sulfate. Nifedipine - (used to be true): commonly used agent for treatment of hypertension in pre-eclampsia. Not the first line agent advocated by an ACOG opinion piece, but a systemic review fails to back the choice of labetalol or hydralazine over nifedipine. Recommendation to chose an agent which the clinician is most familiar with. Nifedipine is a calcium channel blocker that acts through arterial/arteriolar relaxation. Should be avoided in women with known coronary artery disease, long standing diabetes, aortic stenosis, or in women older than 45 years, due to increased risk of sudden cardiac death. Earlier reports suggested coadministration of nifedipine with magnesium sulfate caused severe maternal hypotension, neuromuscular blockade, and nonreassuring fetal heart rate patterns, however subsequent studies found that these drugs are safe to use in combination.

22. 32 yo parturient with severe pre-ecclampsia, currently on MgSO4 infusion. Which drug would potentiate the anti-hypertensive effect of magnesium? [2008] **OBSOLETE QUESTION** a) Labetalol b) Nitroprusside c) Hydralazine d) Nifedipine

Answer A • Nothing in chestnut that says x drugs are teratogenic and that there are no specific data as prospective studies are impractical. I have included some of these quotes. Also answer by exclusion that he others are false. o "The American Society of Anesthesiologists Task Force on Preanesthesia Evaluation states The literature is inadequate to inform patients or physicians on whether anesthesia causes harmful effect in early pregnancy" (Chestnut pg 358) o Concern about potential harmful effects of anesthetic agents stems from their known effects on mammalian cells which include reversible decreases in cell motility prolongation of DNA synthesis and inhibition of cell division. Despite theses concerns, no data specifically link any of these cellular events with teratogenic changes" (Chestnut page 360) o The list of agents or factors that are proven human teratogens does not include anesthetic agents (which are listed as "unlikely tetratogens" or any drug routinely used during the course of anesthesia). o Human studies. Teratogensis has not been associated with the use of any of the commonly used induction agents - including barbiturates, ketamine and the benzodiazepines ... similar no evidence opioids (chestnut 364) Regarding surgery increases risk of miscarriage x 3 • Couldn't find anything specifically that comments on miscarriage especially x 3 o Did find quote on "clinical studies suggest that anesthesia and surgery during pregnancy do not increase the risk for congenital anomalies" Regarding C TIVA is anesthetic choice • No specific mention that TIVA is better o No study has found an association between improved fetal outcome and any specific technique except for a single retrospective medical record analysis which the use of general anesthesia was associated with a significantly lower birth weight despite similar gestational age at delivery (Chestnut 365) o Although volatile agents depress myometrial irritability thus are theoretically advantageous for abdominal procedures, evidence does not show that any one anesthetic agent or technique positively or negatively influences the risk for preterm labor. (Pdf 375) o A commonly used technique employs a high concentration of oxygen, a muscle relaxant and an opioid and/or a moderate concentration of a volatile halogenated agent. o Scientific evidence does not support avoidance of nitrous oxide during pregnancy, particular after the sixth week of gestation. Omission of nitrous oxide may increase fetal risk if inadequate anesthesia results or if high does volatile agent results in maternal hypotension (Chestnut 375) Regarding D Moderate maternal hyperventilation is desirable • Hyperventilation should be avoided; rather end tidal CO2 should be maintainend in the normal range for pregnancy (Chestnut page 375)

34. For a pregnant woman requiring surgery in the 1st trimester: [2012] a) No anesthetic drugs have been shown to be teratogenic b) Surgery increases risk of miscarriage 3x c) TIVA is anesthetic of choice d) Moderate maternal hyperventilation is desirable

Answer D Infants of diabetic mothers are at increased risk for developing DM later in life, likely due to both genetic and intrauterine factors. Regarding A, neuraxial analgesia or oxytocin stimulation does not change insulin requirements. Regarding B, pregnancy is a time of increased insulin resistance. This is presumed to be due to an increase in counterregulatory hormones (placental lactogen, placental growth hormone, cortisol, progesterone). GDM develops when a patient cannot mount a satisfactory insulin response during pregnancy. GDM may be a precursor to DM later in life because it unmasks impaired glucose tolerance, however, however, after delivery patients return to a normal glucose tolerance. Regarding C, GDM pregnancies are at increased risk of macrosomia (fetal weight >4000g or 4500g depending on definition), a risk for shoulder dystocia. Furthermore, when comparisons are made within birthweight categories, diabetic mothers are at increased risk of shoulder dystocia compared to nondiabetics.

37. In a pregnant woman with gestational diabetes which of the following is true: [2012] a) Neuraxial labor analgesia decreases insulin requirements b) Postpartum insulin requirements will increase c) There is no increased risk of shoulder dystocia d) The baby is at risk of diabetes later in life

Answer: A - More fetal bradycardia Chestnut Pg. 461, 503, 567-568, 584-585 More fetal bradycardia - TRUE? Chestnut mentions this finding in one study of 72 patients randomized to receive a CSE or an epidural, and found that there was an increase in FHR abnormalities (particularly prolonged decelerations and bradycardia) as well as an increase in uterine tone in the group randomized to receive CSE. This study is limited by the fact that outcomes were measured only for 15 minutes after initiation of the neuraxial technique, and the CSE/epidural techniques were not equipotent. Higher risk of PPHD compared to epidural - I'm assuming this meant PDPH, as I cannot identify an acronym to fit PPHD. There is brief mention of comparing CSE technique to a conventional epidural, and finding a quicker onset, with greater motor blockade, but no difference in incidence of maternal hypotension, nausea, headache, the use of supplemental analgesics, or overall patient satisfaction. There is another section that mentions explicitly that although dural puncture occurs with a CSE, the use of a small gauge pencil point needle does not appear to increase the risk for post dural puncture headache (though there is a concern that it may increase the risk of postpartum neuraxial infection). Complication can be a high spinal secondary to hole in dura - FALSE: Although I have heard this theoretical possibility from staff, I can't find it mentioned in Chestnut. They do mention studies finding a higher sensory block with a CSE compared with a spinal for elective cesarean sections, but attribute this to the loss of resistance to air technique used causing a decrease in the lumbar CSF. A similar study by the same group performed in laboring women for cesarean section did not find a difference in block characteristics. Chestnut mentions cautious administration of a spinal following a failed epidural due to the potential of a high block resulting from the compression of the dural sac. They suggest using a different interspace to avoid the anatomic distortions, to use a lower dose of bupivacaine, and putting the patient in a semi sitting position to limit cephalad spread. They do mention that a high block can occur from a rapid administration of local anesthetic into the epidural space when there is the presence of a large bore dural puncture (wet tap). A dural puncture epidural, where a spinal needle is used to puncture the dura (after the epidural space has been identified), but no drug is injected. The technique resulted in enhanced blockade of sacral dermatomes, not a higher block level. There is increased risk of high spinal if get dural puncture with large bore tuohy, but seemingly not secondary to small gauge CSE needle.

47. CSE for labor analgesia [2013] a) More fetal bradycardia b) Higher risk of PPHD compared to epidural c) Complication can be a high spinal secondary to hole in dura d) ?

ANSWER: B (Chestnut Ch 35 Pg 820) "Multiple gestation increases both the incidence and severity of preeclampsia." This does not mention PIH, only preeclampsia, but the other answers seem more incorrect. Regarding A: (Chestnut Ch 35 Pg 818) "Maternal plasma volume increases by an additional 750 mL with twin gestation. Relative or actual anemia often occurs." This suggests the Hct/Hb should be lower. Regarding C and D: see Box 35-4. Both are increased with twin gestation

53. Comparing to a single gestation, twin gestation is associated with: [2014] a) Increased maternal Hct/Hb b) Increase rate of pregnancy induced hypertension c) Decreased incidence of prolonged labour d) Decreased risk of postpartum hemorrhage

Answer C Motor Block low possibility D • Subdural injection would result in a minimal motor block. o A subdural block usually results in less intense motor blockade than the blockade that occurs with high or total spinal anesthesia. The difference may reflect the limited spread of the local anesthetic within the subdural space, which helps spare the anterior motor fibres (Chest pg 488) Answer D Negative aspiration for CSF • Negative aspiration of CSF would not necessarily indicate subdural. You could be in epidural, subcutaneous tissue or even subarachnoid for that matter. o Aspiration alone, particularly through a single orifice catheter, is not a complete reliable method of excluding subarachnoid placement of catheter (chestnut pg 490) Regarding A • Subdural block results in less severe hypotension that that with high or total spinal anesthesia, most likely because subdural injection leads to less sympathetic blockade than spinal anesthesia. Regarding B • Subdural injection of local anesthetic typically results in unexpectedly high (but patchy) blockade with an onset time that is intermediate between that of spinal anesthesia and and epidural anesthesia (10-20 minutes) • Cranial spread is more extensive than caudal spread of the local anesthetic so sacral analgesia typically is absent. The block may involve the cranial nerves (the subdural space, unlike the epidural space, extends intracranially). Thus apnea and unconsciousness can occur during a subdural block. Horner's syndrome has been reported.

1. Labour epidural. All would suggest subdural injection except: [2010] a) Hypotension b) Higher than expected sensory block c) Motor block d) Negative aspiration for CSF

Answer B Treatment of suspected magnesium toxicity includes immediate discontinuation of the infusion, and IV administration of calcium gluconate 1g over 10 minutes. In the rare event of respiratory compromise intubation and mechanical ventilation may be necessary until spontaneous ventilation returns. Signs include chest tightness, palpitations, nausea, blurred vision, sedation, hypotension, and rarely pulmonary edema. Chestnut p.839

10. What is the best treatment for life-threatening hypermagnesemia in a preeclamptic patient? [2011] a) Amiodarone b) Calcium c) Lidocaine d) Phenytoin

ANSWER: D ?A could still be right... slight increase for fetus, slight decrease in blood flow A: Fetal PaO2 is normally 40 mm Hg and never more than 60 mm Hg, even if the mother is breathing 100% O2. Studies of isolated human placental vessels have suggested that hyperoxia might cause uteroplacental vasoconstriction, with potential impairment of fetal oxygen delivery. This fear has proved to be unfounded, because studies in pregnant women have demonstrated better fetal oxygenation with increasing maternal Pao2. However, no significant improvement in maternal-fetal oxygen transfer occurs until very high levels of maternal Fio2 are used. At these levels, the resulting hyperoxia creates reactive oxygen species. Nonetheless, the emergency cesarean delivery of the compromised fetus should include maternal administration of a high Fio2. The greater maternal oxygen consumption and reduced fetal oxygen delivery associated with uterine contractions may exacerbate the fetal compromise; in these situations, supplemental oxygen may augment fetal oxygenation and, perhaps, reduce the severity of fetal hypoxia. However, diminishing fetal benefit appears to occur after 10 minutes. B: No mention of oxygen affecting uterine blood flow. C: Fetal Pao2 never exceeds 60 mm Hg, even when maternal Pao2 increases to 600 mm Hg, because of a large maternal-fetal oxygen tension gradient. Thus, intrauterine retrolental fibroplasia (retinopathy of prematurity) and premature closure of the ductus arteriosus cannot result from high levels of maternal Pao2 D: The use of a very high Fio2 improves oxygen delivery to hypoxic fetuses for a limited period (approximately 10 minutes); beyond this time, continued hyperoxia, especially in the setting of restored perfusion, increases reactive oxygen species, placental vasoconstriction, and fetal acidosis.

13. Which is true regarding supplemental O2 in pregnancy? [2011] a) Increases fetal oxygenation b) Increases uterine blood flow c) Increases risk of fetal retrolental fibroplasias d) Decreases uteroplacental flow

ANSWER: D A: Up to 50% incidence of pruritus, N/V, urinary retention. B: Intrathecal administration of 0.5 to 2 mg of morphine reliably produced analgesia during the first stage of labor, but the analgesia was less reliable during the second stage of labor and during instrumental vaginal delivery. C: The onset of effective spinal analgesia occurs faster than epidural analgesia, and more women have effective analgesia at 10 minutes. Intrathecal meperidine 10 mg, fentanyl 10 μg, and sufentanil 5 μg have a similar onset of analgesia (< 5 minutes). Latency of spinal morphine is 30-60mins for onset of analgesia. D: Intrathecal opioids can provide complete analgesia during early labor when the pain stimuli are primarily visceral. (Presumably the corollary of this is that sharp somatic pain from an episiotomy would not be well covered with opioid alone - also see rational for answer A above.)

16. All are associated with intrathecal opioids during labor EXCEPT: [2011] a) Significant incidence of side effects b) Minimal impact on 2nd stage of labour c) Delayed onset by 45-60 minutes d) Adequate analgesia for episiotomy

Answer:A A: Studies that have examined stomach contents have shown that approximately 80% of both pregnant and nonpregnant women have a gastric pH of 2.5 or less. Miller: Gastrin, secreted by the placenta, increases gastric hydrogen ion secretion and lowers the gastric pH in pregnant women. B: Increased gastric pressure from the enlarged uterus increase the risk for acid reflux in pregnancy. C: Upward displacement and rightward axial rotation of the stomach to accommodate the gravid uterus displaces the intra-abdominal segment of the esophagus into the thorax in most women, causing a reduction in tone of the lower esophageal high-pressure zone (LEHPZ), which normally prevents the reflux of gastric contents. Progestins also may contribute to a relaxation of the LEHPZ. D: The stomach is displaced upward toward the left side of the diaphragm during pregnancy, and its axis is rotated approximately 45 degrees to the right from its normal vertical position.

17. All are reasons for increased aspiration risk in pregnancy except: [2011] a) Increased gastric acid secretion b) Increase gastric pressure c) Decreased lower esophageal sphincter tone d) Altered gastroesophageal angle

ANSWER: A Should not try to manually remove accreta ever A: Typical attempts at removal do not usually succeed because a cleavage plane between the maternal pla- cental surface and the uterine wall cannot be formed, and continued traction on the umbilical cord may lead to uterine inversion and life-threatening hemorrhage. In patients diagnosed with placenta accreta in whom attempts at removal of the placenta are stopped, the maternal mortality is low (3%), with an average blood loss of approximately 3500 mL. B: Fetal surgery? ECV? C: If premature infant = preterm labour (otherwise, premature babies are small and would rarely require tocolysis): General consensus that acute tocolytic therapy for the treatment of preterm labor offers only limited benefit and does not reduce the rate of preterm birth. A meta-analysis suggested that nitroglycerin does not delay delivery or improve neonatal outcome in comparison with placebo or other tocolytic agents. If premature infant is breech: Most obstetricians perform cesarean delivery for the delivery of VLBW singleton fetus in a breech presentation. Head entrapment behind an incompletely dilated cervix is more common in preterm singleton fetuses with a breech presentation because the head is larger than the wedge formed by the buttocks and thighs D: In some cases, pharmacologic uterine relaxation may be required to facilitate internal version and breech extraction of twin B. Sublingual (400 to 800 μg) or intravenous (100 to 250 μg) administration of nitroglycerin should provide adequate relaxation.

18. All are indications for nitro for uterine relaxation except: [2011] a) Manual removal of placenta accrete b) ? c) Premature infant d) Delivery of second twin

Answer:D Describes the change in interval between 2 or 3 beats - FALSE: The wording of this option is somewhat ambiguous/non-intuitive. An interval is the distance between two points, so they seem to be suggesting it is the change in time between when 2 (or 3) beats occur. So this option is suggesting that variability is the change in the timing between beats (so as the FHR accelerates, the interval between beats would decrease, and as FHR decelerates, the interval between beats would increase). This is not how variability is measured/defined. The actual definition is a fluctuation in fetal heart rate of 2 or more cycles per minute, which can be visually interpreted on the FHR tracing as the amplitude from a peak in FHR to a trough in FHR. The interval between beats is not routinely measured/quantified explicitly during an NST, and variability is not defined in these terms. Occurs as a sine wave with a frequency of 3-6 per minute - FALSE: this is known as a sinusoidal pattern, which, as the name suggests, is a "smooth, sine-wave like, undulating pattern occurring in the fetal heart rate pattern, with a cycle frequency of 3-5 cycles per minute that persists for 20 min or longer". This pattern is associated with placental abruption, and is bad news!! Occurs early in a contraction - FALSE: They may be trying to confuse you with an early deceleration, which is a gradual decrease and return to baseline FHR associated with a uterine contraction. The onset, nadir, and return to baseline in the FHR coincide with the start, peak and end of a contraction. FHR is assessed over non-specific 20-40 minute periods of time, with variability in the tracing being continuously assessed. It is not tied to contractions, unless specifically referencing types of decelerations. Varies between 120-160bpm - The normal fetal heart rate varies between 110 - 160bpm. Closest answer to being correct.

19. Regarding fetal heart rate variability [2009] a) Describes the change in interval between 2 or 3 beats b) Occurs as a sine wave with a frequency of 3-6 per minute c) Occurs early in a contraction d) Varies between 120-160 bpm

Answer D - Decreased CVP - False • As demonstrated from figure in Chestnut below CVP does not change at term gestation. • The others increased HR, increased CO, decreased SVR are also shown in the table below Regarding A • Heart rate steadily increases during the first and second trimester and both PR interval and the uncorrected QT interval are shortened (Chestnut Chapter 2) Regarding B CO • Cardiac output begins to increase by 5 weeks gestation and is 35% to 40% above baseline by the end of the first trimester. • It continues to increase throughout the second trimester until it is approximately 50% greater than non pregnant values • Cardiac output does not change from this level during the third trimester • Some studies have reported a decrease in cardiac output during the third trimester, typically this is when measurements are made in the supine position and thus reflects aortocaval compression rather than a true gestational decline. • Initial increase in CO results from increase in HR which occurs by the fourth to fifth weeks of pregnancy. • Heart rate increases 15-25% above baseline by the end of the first trimester and remains relatively unchanged from the level for the remainder of the pregnancy. Cardiac output continues to increase during the second trimester because of increase in strove volume. Stroke volume increases by approximately 20% during the first trimester and by 25% to 30% above baseline during the second trimester. The increase in stroke volume correlates with increases estrogen levels. Regarding C decreased SVR • Systolic, diastolic and mean blood pressure decrease during midpregnancy and return toward baseline as the pregnancy approaches term. • Diastolic blood pressure decreases more than systolic blood pressure with early to mid gestational decreases of approximately 20%. • The changes in blood pressure are consistent with changes in SVR, which decreases during late gestation. • Unlike blood pressure SVR remains approximately 20% below non pregnant level at term. • A postulated explanation for the decreased systemic vascular resistance is the development of a low resistance vascular bed (the intervillous space) as well as vasodilation caused by prostacyclin, estrogen and progesterlone

2. Healthy pregnancy at 28 weeks. All are normal cardiovascular changes except. [2010] a) Increased HR b) Increased CO c) Decreased SVR d) Decreased CVP

Answer: A - Ruptured Membranes. OLD chestnut Ch. 8 Pg. 148. Ruptured membranes - FALSE: intact membranes are a relative contraindication. Chorioamnionitis - TRUE: a relative contraindication is the presence of infection. Maternal HSV - TRUE: a relative contraindication is the presence of infection, including HIV or HSV. Disruption of the fetal scalp allows a portal of entry for infection. Non-engaged fetal head - TRUE: a relative contraindication is the presence of intact membranes and an unengaged vertex presentation This is likely an outdated question, as both old and new Chestnut refer to fetal scalp blood pH determination as an "older method" to assess for fetal acidosis. The section on this topic in the new edition of Chestnut is further abbreviated, suggesting this is a seldom practiced technique. The idea behind this is that an endoscopic sample of fetal blood is taken to analyze capillary pH, if assessment of the FHR suggests fetal compromise. Other (relative) contraindications include a fetal coagulopathy, which presents the risk of fetal exsanguination, and the expected need for multiple samples, as this may cause trauma to the fetus. It is a technically challenging procedure to perform, and cannot be done if there is minimal cervical dilation. Acceptable pH is 7.25 or higher; a second sample should be obtained between a pH of 7.25 and 7.20, and a pH <7.20 (if confirmed with a second sample) warrants an expedited delivery. If FHR tracing abnormalities persist, it is recommended that further pH samples be taken every 30 minutes. Obviously the results need to be interpreted in the context of how the sample was obtained, and potential confounders such as a contaminated or inadequate sample. It was thought that pH sampling reduced the rate of cesarean sections (allowing a woman with an abnormal FHR tracing but acceptable pH to continue to labour), however there was no change in incidence of cesarean sections or perinatal asphyxia after this practice was phased out. An alternative to fetal pH sampling which we do see in practice is fetal scalp stimulation during a vaginal exam. The heart rate of a healthy, non-acidotic fetus normally accelerates in response to scalp stimulation, with an increase in FHR associated with a pH of at least 7.19. No response to fetal scalp stimulation indicates a pH <7.20, and therefore should be expedited

20. All are relatively contraindicated to fetal scalp pH monitoring except one. Indicate the exception. [2009] a) Ruptured membranes b) Chorioamnionitis c) Maternal HSV d) Non-engaged fetal head

Answer: C - Increase CVP Chestnut Ch. 2 Pg. 17-18 Decrease SVR - TRUE: SVR decreases during early gestation, plateaus around 20 weeks of gestational age (at 35% below pre-pregnancy levels), then increases during late gestation (but remains 20% below baseline at term). The decrease in SVR is thought to be due to the development of the intervillous space which acts as a low resistance vascular bed. In addition, prostacyclin, estrogen, and progesterone contribute to vasodilation. Increase SV - TRUE: Stroke volume increases by about 20% during the first trimester, and continues to rise to 25-30% above baseline during the second trimester. Increased stroke volume is correlated with an increase in estrogen levels. LV mass increases by 23% from the first to the third trimester. Increase CVP - FALSE: CVP, PA diastolic, and PCWP all remain within normal pre-pregnant ranges throughout pregnancy. Increase CO - TRUE: Cardiac output begins to rise by 5 weeks gestational age, and approaches 35-40% of baseline by the end of the first trimester, and approximately 50% of non-pregnant values by the end of the second trimester. There is no further change in the third trimester, despite some studies reporting a drop in CO; this is attributed to measurements made in the supine position, which would be affected by aortocaval compression. Initially, the increase in CO is attributed to an increase in heart rate (15-25% above baseline by the end of the first trimester). Heart rate does not increase further, though CO continues to rise throughout the second trimester, and this is attributed to an increase in stroke volume.

21. All are changes seen in pregnancy at the second trimester EXCEPT: [2008] a) Decrease SVR b) Increase SV c) Increase CVP d) Increase CO

Answer: D - 20 Weeks Chestnut Ch. 2, Ch. 29 Pg. 669, Ch. 16 Pg. 341, Ch. 17 Pg. 360 Miller Ch. 77 Pg. 2333 Barash Pg. 1147 Chestnut isn't very definitive on the issue. Can justify both answer C and D: Decreased lower esophageal sphincter tone and a higher risk of a difficult airway are the primary factors that increase the risk for aspiration. At term gestation, the pregnant woman who requires anesthesia should be regarded as having an incompetent LES (38-40 weeks); these physiologic changes return to their pre-pregnancy levels by 48hrs after delivery. Lower esophageal sphincter tone is impaired early in pregnancy (especially in patients with heartburn), but the mechanically induced factors that predispose to reflux (distortion of gastric and pyloric anatomy - stomach displaced upwards and to the left) do not become relevant until later in pregnancy. It is prudent to consider any pregnant patient at risk for aspiration after mid gestation (= 20 weeks); some anesthesia providers contend that pregnant women are at increased risk from the beginning of the second trimester (= 13 weeks). The prevalence of GERD is ~10% in the first trimester, 40% in the second trimester, and ~55% in the third trimester. During the second and third trimester, the lower esophageal high pressure zone gradually decreases to ~50% of baseline values, reaching a nadir by 36 weeks GA, and returning to pre-pregnancy values by 1-4 weeks postpartum. General anesthesia may be safely administered with an LMA in selected obstetric patients up until 18-20 weeks gestation. After this period, the uterus moves out of the pelvis, resulting in anatomic and intragastric pressure changes that predispose to GERD. Other anesthesia providers prefer to intubate pregnant women under a general anesthesia as early as 12-14 weeks gestation, attributing their decision to the hormonal changes that alter sphincter relaxation earlier in pregnancy. Miller suggests that pregnant women are at increased risk of aspiration after midgestation. They cite similar factors mentioned above: cephalad displacement of the stomach and pylorus, decreased lower esophageal sphincter (or high pressure zone) tone, and increases in progesterone and estrogen levels, which further add to the incompetence of the esophageal sphincter. They conflict with Chestnut on the topic of gastric acid secretion (Miller states that placental gastrin will increase hydrogen ion secretion, and lower gastric pH). All women in labour are considered to have a full stomach, and are at increased risk of aspiration. Barash quotes the ASA practice advisory, suggesting an RSI with cricoid pressure, and intubation with a cuffed ETT in pregnant women undergoing a general anesthetic from 20 weeks of gestation, "or earlier, if symptoms of reflux are present". The recommendations extend to women in the immediate postpartum period, though a safe cutoff postpartum is not provided, and a flakey statement caps off the section: "there is uncertainty as to when the risk for aspiration of stomach contents returns to normal." 6 weeks - Unlikely option. Not set at any particular cutoff date, and never mentioned. 10 weeks - Similar to option A, not mentioned in any text, and not associated with any physiologic changes that would predispose to aspiration. 14 weeks - A more conservative option, and does have some proponents. Our textbooks mention both mid-pregnancy and the start of the second trimester as cutoffs for increased aspiration risk. 20 weeks - Most likely option, though as outlined above, can argue for option C as a more conservative number to chose. In this particular question, no other risk factors are provided (no mention of GERD), so I would chose this option as the most correct.

23. At what point does a pregnant patient become an increased aspiration risk? [2008] a) 6 weeks b) 10 weeks c) 14 weeks d) 20 weeks

Answer: A - Congenital malformations and C - Placenta Previa (would pick C if had to choose, since this has never been a belief) Chestnut Pg. 1206 Congenital malformations - FALSE: initially thought to be the case based on animal studies, and retrospective human studies, however more recent literature failed to find a significant link between cocaine use and the development of congenital anomalies. Confounding in the older studies was felt to be due to concurrent exposure to other drugs, as well as low statistical power. Studies have failed to show any association of cocaine use with physical growth, developmental test scores within the first 6 years of life, or the development of any deficits in expressive or receptive language skills. There was a finding of suboptimal motor function up to 7 months of age, but the effect did not persist beyond this period. This is a 2008 question, and as such I suspect that this was intended to be a "correct" answer, leaving C as the option to chose. However, because it is 2016, this option is no longer correct. Of note, last year's group still chose C, though they quote from the old Chestnut, which still mentions that the previously believed association with congenital malformations is no longer true. Fetal acidosis - TRUE: not directly mentioned, but studies in pregnant ewes found an increased maternal heart rate and myocardial oxygen consumption, a decrease in cardiac output, an increase in blood pressure, but a decreased uterine blood flow. Presumably a decreased uterine blood flow is associated with fetal acidosis. Placenta previa - FALSE: cocaine use is associated with increased placental abruption, not placenta previa. Preterm labour - TRUE: cocaine use is associated with increased preterm labour, with an incidence of 17-29% of pregnant cocaine users developing preterm labour. This carries with it a significant increase in risk of Small for Gestational Age and Low Birth Weight infants.

24. All EXCEPT ONE of the following are associated with cocaine use during pregnancy: [2008] a) Congenital malformations b) Fetal acidosis c) Placenta previa d) Preterm labour

ANSWER: D (Chestnut Ch 36, Pg 828-9) I assumed this question was talking about risk factors for Preeclampsia rather than PIH/Gestational HTN as there are no such risk factors discussed. As per Chestnut: • Cigarette smoking during pregnancy has been associated with a DECREASED risk for preeclampsia • Women who smoke during pregnancy have a 30-40% lower risk for developing preeclampsia • Dose-related protective effect (more smoking = lower incidence) Options A, B, C are all listed in Box 36-3.

25. All are risk factors for PIH EXCEPT: [2008] a) DM b) Previous Hx of PIH c) Chronic HTN d) Smoking

ANSWER: D Background: (Chestnut Ch 8 Pg 151) Fetal heart rate variability is the fluctuation in the FHR of 2 cycles or greater per minute. The presence of normal FHR variability reflects the presence of normal, intact pathways from (and within) the fetal cerebral cortex, midbrain, vagus nerve, and cardiac conduction system. Variability is greatly influenced by the parasympathetic tone, by means of the vagus nerve; maternal administration of atropine (readily crosses placenta) can eliminate some variability. In humans, the sympathetic nervous system appears to have a lesser role in influencing variability. Maternal administration of the beta-adrenergic receptor antagonist propranolol has little effect on FHR variability. The presence of normal FHR variability predicts early neonatal health (as defined by Apgar score of greater than 7 at 5 minutes). Regarding A, B, C: (Chestnut Ch 8 Pg 153) "The differential diagnosis of decreased variability includes fetal hypoxia, fetal sleep state, fetal neurologic abnormality, and decreased CNS activity that results from exposure to drugs such as opioids."

26. All are causes of decreased fetal heart rate variability EXCEPT: [2008] a) Fetal sleep b) Chronic hypoxia c) Maternal opioids d) Propranolol

ANSWER: D (Chestnut Ch 42, Pg 985) "Hypotension should be treated with a direct-acting vasoconstrictor (phenylephrine)" Anesthetic goals of MS: • Maintenance of low-normal HR and preservation of sinus rhythm • Aggressive treatment of Afib • Avoidance of aortocaval compression • Maintenance of venous return • Maintenance of adequate SVR • Prevention of pain, hypoxemia, hypercarbia, acidosis (which may increase PVR) All the other drug options would increase the HR (which you want to avoid). According to Wikipedia, Mephentermine indirectly activates receptors and causes release of norepinephrine.

27. A parturient with moderate mitral stenosis has an epidural for labor analgesia. After the test dose of 3mL of bupivacaine (0.25%) her BP decreases to 80/50mmHg from 110/65mmHg. The BP is unresponsive to an iv fluid bolus. Which is the vasopressor of choice: [2008] a) Epinephrine b) Ephedrine c) Mephentermine d) Phenylephrine

ANSWER: C (Chestnut Appendix B - Practice Guidelines for Obstetric Anesthesia Pg 1249) • Literature supports efficacy of PCEA vs CIE (Continuous Infusion Epidural) in providing equivalent analgesia with reduced drug consumption o Also supports greater analgesic efficacy for PCEA with background infusion vs without • Meta-analyses show: o Duration of labour is longer with PCEA compared with CIE for the first stage but not the second stage of labour o Mode of delivery, frequency of motor block, and Apgar scores are equivalent for PCEA vs CIE • Consultants and ASA members agree: o PCEA vs CIE improves analgesia + reduces need for anesthetic interventions o PCEA improves maternal satisfaction (Chestnut Ch 23 Pg 475) • Compared with intermittent boluses, a constant infusion results in greater drug use, higher degree of motor blockade, and higher incidence of instrumental vaginal delivery • Intermittent manual bolus administration by the anesthesia provider results in more breakthrough pain, less patient satisfaction, and more work for the anesthesia provider • PCEA overcomes these disadvantages and many studies consistently find analgesia with PCA is comparable to that of continuous infusion techniques • Van der Vyver et al: PCEA (no background infusion) vs continuous infusion - fewer anesthetic interventions, lower total bupivacaine dose, lower incidence of motor blockade o No difference in pain scores, patient satisfaction, and maternal and neonatal outcomes

28. Patient with PCEA for delivery: [2008] a) More frequent instrumental delivery b) No difference in the patient satisfaction c) Diminution of total dose given d) ?

ANSWER: D Regarding B + C: (Chestnut Ch 6 Pg 102) Persistent fetal tachycardia (defined as FHR > 160 bpm) may be associated with fetal hypoxia, maternal fever, chorioamnionitis (intrauterine infection), administration of an anticholinergic or beta-adrenergic receptor agonist, fetal anemia, or tachyarrhythmia. Regarding A: (Chestnut Ch 8 Pg 151) After prolonged hypoxemia, the fetus may experience tachycardia as a result of catecholamine secretion and sympathetic nervous system activity. Changes in baseline FHR may also be caused by fetal anatomic or functional heart pathology, maternal fever and/or intrauterine infections, or maternally administered medications (such as beta-adrenergic receptor agonists or atropine).

29. All EXCEPT ONE of the following may lead to fetal tachycardia: [2008] a) Prolonged fetal hypoxemia b) Maternal fever c) Maternal infection d) Maternal anxiety

Answer D Baricity of local • Quotes (Miller/Barash) o Key point (section beginning of chapter) - Cerebrospinal fluid volume and local anesthetic baricity are the most important determinants for the spread (i.e. block height) of spinal anesthesia (Miller Chapter 56 pg 1684) o Of those factors that do exert significant influence on local anesthetic spread, the baricity of the local anesthetic solution relative to patient position is probably the most important (Barash page 916) • Tables from Miller/ Barash of factors that affect block height -dose -baricity -CSF volume -advanced age -pregnancy -pt position -epidural injection post spinal Recall that baricity is the ratio of density of local anesthetic solution to the density of CSF. • Isobaric = local anesthetic that have same density as CSF • Hyperbaric = local anesthetic that has higher density than CSF • Hypobaric = local anesthetic has lower density than CSF • Hyperbaric solutions will preferentially spread to the dependent region sof the spinal canal whereas hypobaric solutions will spread to nondependent regions Regarding A • Within the range of "normal sized" adults, patient height does not seems to affect the spread of spinal anesthesia (Miller chapter 56 pg 1694) Regarding B and C • Not as important as baricity • The dose volume and concentration are inextricably linked (volume x concentration = dose) but does is the most reliable determinant of local anesthetic spread (and thus block height) when compared with either volume or concentration for isobaric and hypobaric local anesthetic solutions.

3. The most important factor in determining the height of a spinal block is: [2010] a) Pt height b) Volume of local c) Concentration of local d) Baricity of local

ANSWER: C The question options are dumb Regarding A: Cesarean delivery is listed as associated with uterine atony in box below. If patient has previa, she will need a C/S (Chestnut Ch 38 Pg 889) Regarding B: prior uterine surgery is listed as associated with uterine rupture (Chestnut Ch 38 Pg 887) Regarding C: (Chestnut Ch 38 Pg 894) Placenta percreta is invasion through the myometrium into serosa and sometimes into adjacent organs (most often bladder). The combination of placenta previa with a previous C/S synergistically increases the risk for coexisting placenta accreta, particularly if the placenta is anterior and overlies the uterine scar. There is no specific discussion of increased risk of percreta - I'm not sure if you can make the leap that because there is increased risk of accreta you would get increased risk of percreta. Regarding D: Nothing in Chestnut to support this. It would make sense to have more anemia if you are bleeding, but not all previas bleed... May increase atony at fibrous implantation site, but not at fundus (?remembered wrong) May have increased anemia or PPH because are at increased risk of vaginal 2nd and 3rd trimester bleeding and increased risk of intraoperative bleeding Unsure if will be allowed to labor vs C/S (?marginal vs complete previa)

30. Placenta Previa term, previous c-section, has increased risk of all EXCEPT: [2008] a) Uterine atony (?at fundus) b) Uterine rupture c) Placenta percreta d) 3rd trimester anemia

Answer C • I think this question may have come from Barash 6th edition mentions a study of 10 preeclamptic women where the above variables were measured initially than were given volume expansion o Initial measurements revealed a low pulmonary capillary wedge pressure (PCWP), a low cardiac index, a high SVR and an increased HR indicated the existence of a low ouput state in untreated pre eclampic women. • Barash 7th edition does not help and does not quote this study • Chapter 36, Hypertensive disorders, in Chestnut discusses Preeclampsia. • Under the clinical presentation and cardiac system discusses an elevated SVR and BP as a result of severe vasospasm. No mention of PCWP, HR or CI (Increased CO is mentioned, but nothing specifically about which one increases first.) o Women with preeclampsia have increased vascular tone and increased sensitivity to vasoconstrictor influences which result in the clinical manifestations of hypertension, vasospasm and end organ ischemia. Pre eclampsia is characterized by severe vasospasm as well as exaggerated hemodynamic responses to circulating catecholamines. Characteristically, blood pressure and SVR are elevated. o Severe preexlampsia is usually a hyperdynamic state.... Overall studies have found that the majority of affected women exhibit increased cardiac output, hyperdynamic left ventricular function and mild to moderately increased SVR (Chestnut page 834). • Miller does not help much with the choices. • The only quote I could find regarding the above variables o Pregnant women who develop preeclampsia before 34 weeks gestation have lower cardiac output and higher vascular resistance than those who develop less severe disease when measured at 20 weeks gestation before the onset of signs (Miller chapter 77 pg 2348)

31. In a parturient with severe preeclampsia what is the first hemodynamic change seen? [2012] a) Increased PCWP b) Decreased HR c) Increased SVR d) Increased CI

Answer A and B Maybe the questions should have been which of the following is NOT true?? Answer A Placenta previa often presents with painless 2nd trimester bleeding • The classic sign of placenta previa is painless vaginal bleeding during the second or third trimester. The first episode of bleeding typically occurs preterm and is not related to any particular inciting event. The lack of abnormal pain and/ or absence of abnormal uterine tone helps distinguish this even from placenta abruption (Chestnut page 882) Answer B Change in fetal heart rate is a sensitive indicator of uterine rupture • Hard to diagnose but FHR and abdominal pain are the most common signs o The variable presentation of uterine rupture may cause diagnostic difficulty. o Abnormal pain and an abnormal FHR pater are the two most common presenting signs of uterine rupture, but neither is 100% sensitive. o One retrospective study reported the occurrence of abdominal pain in 17% of patients; a FHR abnormality was the first sign of uterine rupture in 87% of patients. (Chestnut page 887) Regarding D Can have greater hemodynamic consequences for the mother, than for the fetus • This statement if false o The greatest threat of antepartum hemorrhage is not to the mother but to her fetus o Several decades ago, vaginal bleeding during the second and third trimesters was associated with perinatal rates as high as 80% o More recent data suggest antepartum bleeding secondary to placenta previa and placental abruption is responsible for perinatal mortality rates of 2.3 and 12 % respectively (Chestnut page 882)

32. A 25 yr old primigravid, with antepartum hemorrhage; which is true? [2012] a) Placenta previa often presents with painless 2nd trimester bleeding b) Change in fetal heart rate is a sensitive indicator of uterine rupture (? reliable instead of sensitive) c) ? [3 might have been the answer I chose, but I can't for the life of me remember what it was!!!V d) Can have greater hemodynamic consequences for the mother, than for the fetus

Answer A IV nitroglycerine Anesthesia for vaginal breech delivery (Chestnut page 815) • Greatest fear is risk for fetal head entrapment • Entrapment of fetal head behind partially dilated cervix or may be trapped by perineum • More likely < 32 weeks gestation because before this time the fetal head is larger than the wedge formed by fetal buttocks and thighs • The lower extremities buttocks and abdomen may deliver before the cervix is fully dilated and the cervix may then entrap the head • OB has three options o 1) performance of Duhrssen incisions in the cervix o ♣ two or three radial incisions in the cervix at the 2, 6, 10 oclock positions but is associated with high risk maternal morbidity (GU trauma, hemorrhage) o 2)relaxation of skeletal and cervical smooth muscle - most often ♣ Past technique RSI GA followed by high concentration of volatile halogenated agent 2-3 MAC, uterine cervical relaxation in 2 to 3 minutes, if head entrapment results form perineal obstruction delivery after sux. However, increases risk of uterine atony and hemorrhage after delivery ♣ Modern technique, intravenous or sublingual administration of NTG. Transient hypotension is common. Case reports IV NTG 50-1500 ug. Sublingual 400-800 ug. May get headache and need vasopressors o 3) csection Regarding B ritrodrine and D magnesium • No mention of this for fetal head entrapment • Ritodrine is a B2 recpetor agonist to stop premature labour no longer in use in the US because other tocolytics like nifedipine and oxytocin antagonists are equally efficacious with fewer side effects Regarding C epidural bupivacaine • No mention of use for acute fetal head entrapment but in general the use of epidural has lowered the incidence of fetal head entrapment (inhibits early pushing during first stage of labour and provides effective pain relief and skeletal muscle relaxation)

33. What drug indicated for fetal head entrapment during vaginal delivery? [2012] a) IV nitroglycerin b) Ritodrine c) Epidural bupivacaine d) Magnesium

Answer D There will be decreased vascular smooth muscle tone • This is true. Chestnut describes the mechanism of magnesium competitively antagonizes calcium o Extracellular magnesium functions as a competitive antagonists of calcium either at the motor end plate or cell membrane, thus reducing calcium influx into the myocyte. It also completes with calcium for low affinity calcium binding sites on the outside of the SR membrane and prevents rise in free intracellular calcium concentration. Hypermagnesmia results in abnormal neuromuscular function (Chestnut page 34) o In reference to asthma, magnesium causes bronchodilation via inhibition of calcium mediated smooth muscle contraction (P&P pdf 773) Regarding A Uterine tone will be increased • False, uterine tone will be relaxed as above statement reducing calcium influx to myocyte. Also if question is referring to uterine vessel tone it causes vasodilation as quote below from P&P o Magnesium appears to improve the clinical symptoms of preeclampsia by causing systemic, vertebral and uterine vasodilation via direct effects on vessels as well by increasing concentrations of endogenous vasodilators (endothelium derived relaxing factor and calcitonin gene-related peptide) and attenuating endogenous vasoconstrictors (endothelin-1) (P&P pdf 772) Regarding B there will be decreased sensitivity to non depolarizing muscle relaxants • The drug potentiates the action of both depolarizing and nondepolarizing muscle relaxants (Chestnut page 34) Regarding C there will be an increased compensatory release of presynaptic acetylcholine • Magnesium also decreases the release of ach at the neuromuscular junction and the sensitivity of the end plate to ach (Chestnut page 34)

35. You are performing a cesarean section under general anesthesia in a parturient with preeclampsia. The patient has been receiving magnesium sulfate. Which of the following regarding prolonged infusions of magnesium is TRUE? [2012] a) Uterine tone will be increased b) There will be a decreased sensitivity to non-depolarizing muscle relaxants c) There will be an increased compensatory release of presynaptic acetylcholine d) There will be decreased vascular smooth muscle tone

Answer C Regarding C, goals for those with mitral stenosis in delivery are: 1)maintain low-normal HR; 2)maintain sinus rhythm; 3)aggressively treat AFib if present; 4)avoid aortocaval compression; 5)maintain venous return; 6)maintain SVR; 7)prevent pain, hypoxemia, hypercarbia, acidosis, hypothermia which will increase PVR. Electrical cardioversion can be safely performed during pregnancy without adverse effects on the fetus. AFib may cause significant hemodynamic disturbance in pregnant women with stenotic lesions and HCM due to loss of atrial kick contributing to ventricular filling. Those with AFib (non-pregnant, without stenotic lesions) do not benefit from rhythm control any more than from rate control, but in the pregnant patient (with or without stenotic lesion), it is reasonable to both control HR and maintain sinus rhythm. Chestnut p.980,985 Regarding D, those with mitral stenosis are predisposed to atrial arrhythmias (fib/flutter) which increased the risk of thromboembolic events. Additionally the hypercoagulable state of pregnancy increases thromboembolic risk. Anticoagulation is recommended for the duration of pregnancy and postpartum. Anticoagulation is additionally recommended for any parturients with atrial fibrillation (without valve lesions). Patients should be anticoagulated simply by virtue of having mitral stenosis, not specifically due to the AFib. Chestnut p.979,985. Regarding A, valvuloplasty (ideally preconception, but otherwise after 12-14 weeks to avoid radiation exposure from the procedure during organogenesis; if the patient can be medically managed, delaying until 26-30 weeks is ideal) is recommended only for those with NYHA 3 or 4 status. Percutaneous valvuloplasty is recommended over open valve surgery as the latter results in increased fetal loss (Chestnut p.985) Regarding B, ventricular rate can be controlled with digoxin, beta-blockers, or CCBs. Digoxin freely crosses the placenta but has not been shown to have any adverse fetal effects. There is no evidence that BB's are teratogenic, though prolonged use of high doses may lead to IUGR. In this case with a stenotic lesion and class II heart failure it seems that maintaining sinus rhythm should be attempted rather than just rate control. Chestnut p.966-967, 979-980.

36. 25 yo primigravida with mitral stenosis NYHA 2 with new onset of A fib. Best management: [2012] a) Balloon valvuloplasty b) Dig + beta-blockers c) Synchronized cardioversion d) Anticoagulation

Answer C No mention of umbilical artery in discussion of AFE. Current thinking is that fetal material in maternal circulation alone is quite common and is not specifically a cause of AFE. The condition of AFE is felt to be due to an idiosyncratic allergic reaction to fetal material (either an uncommon antigen, or a common antigen presenting in an uncommon way) which then triggers a massive inflammatory cascade. Passage of fetal material including squamous cells, lanugo hair, and mucin into the maternal circulation is a common occurrence at term. Regarding A, B, and D, risk factors for AFE include advanced maternal age, abnormal placentation, placental abruption, eclampsia, multiple gestation, induction of labour, and operative delivery. AFE can present after abdominal trauma, or after 1st trimester abortion. The portal of entry is felt to be via ruptured membranes, or ruptured uterine or cervical vessels down a pressure gradient into the venous system. Small tears in the lower uterine segment and endocervix are thought to be the most common point of entry.

39. Which of the following are associated with amniotic fluid embolism, EXCEPT: [2012] a) Uterine trauma b) Pericervical veins c) Umbilical artery d) Placenta

Answer B • Several studies have assessed gastric emptying in pregnant and postpartum women. In summary, the preponderance of evidence suggests that 1) administration of an opioid during labor increases the likelihood of delayed gastric emptying during the early postpartum period 2) gastric emptying of solids is delayed in all parturients, and 3) gastric emptying of clear liquids is probably not delayed unless parenteral opioids were administered (chestnut 5th edition pg 536) Regarding Nitrous • Nothing in Chestnut, Miller about gastric emptying Regarding C Epidural with LA only • Epidural analgesia using local anesthetics alone does not further delay gastric emptying (Miller Chapter 77 page 2333) Regarding D Epidural with LA and opioid • LA and opioid do not appear to delay gastric emptying in one part of text. Another part of text says not until fentanyl exceeds 100ug in chestnut • Confirmed in Miller epidural with LA doesn't but boluses of epidural fentanyl does. o Systemic absorption of an opioid occurs after epidural administration. However, published studies have provided conflicting results about the effect of epidural opioid administration on gastric emptying. ...however Kelly et. Al found that intrathecal but not epidural, administration of fentanyl delayed gastric emptying. (Chestnut pg 533-534) o Parenteral opioids cause a significant delay in gastric emptying, as do bolus doses of epidural and intrathecal opioids. Continuous epidural infusion of low dose local anesthetic with fentanyl does not appear to delay gastric emptying until the total dose of fentanyl exceeds 100 ug (chestnut pg 669) o Epidural boluses of fentanyl do delay gastric emptying (Miller page 2333)

4. For a labouring woman, gastric emptying is most delayed with which form of pain management? [2010] a) Nitrous b) IV PCA opioid c) Epidural with LA only d) Epidural with LA and opioid

Answer D Minute ventilation is increased by ~45% in pregnancy. Regarding A, FRC decreases by 20% Regarding B, fibrinogen is increased in pregnancy. Regarding C, blood volume increases by 45%.

40. The right physiologic change in pregnancy [2012] a) FRC goes down by 50% b) Fibrinogen is low c) Blood volume goes up by 25% d) Minute ventilation goes up by 50%

Answer A Pre-eclampsia is not mentioned as a specific cause of uterine atony. The umbrella of hypertensive disease is a risk factor, but not specifically preeclampsia. Multiple gestation, augmented labour, and tocolytics are all explicitly associated with uterine atony.

41. All the following cause uterine atony except: [2013] a) Pre-eclampsia b) Multiple gestation c) Oxytocin augmentation d) Tocolytics

ANSWER: A A: Fetal Pao2 never exceeds 60 mm Hg, even when maternal Pao2 increases to 600 mm Hg, because of a large maternal-fetal oxygen tension gradient. Thus, intrauterine retrolental fibroplasia (retinopathy of prematurity) and premature closure of the ductus arteriosus cannot result from high levels of maternal Pao2. B: Teratogenicity has been defined as any significant postnatal change in function or form in an offspring after prenatal treatment. Although only 20 to 30 commonly used drugs are known teratogens, 7% of all the medications that are listed in the Physicians' Desk Reference are classified as Category X. Although nitrous oxide is known to be a weak teratogen in rats, these studies used high doses (>50%) for an exposure period of >24 hours. There is no evidence of nitrous oxide teratogenicity in human studies. Evidence does not suggest that anesthesia during pregnancy results in an overall increase in congenital abnormalities, and there is no evidence of a relationship between outcome and type of anesthesia. C: Most epidemiologic studies of nonobstetric surgery during pregnancy have reported a higher incidence of abortion and preterm delivery. It is unclear whether the surgery, manipulation of the uterus, or the underlying condition is responsible. Although the volatile agents depress myometrial irritability and thus are theoretically advantageous for abdominal procedures, evidence does not show that any one anesthetic agent or technique positively or negatively influences the risk for preterm labor. D: Compression of the inferior vena cava occurs as early as 13 to 16 weeks' gestation.

42. A 28 year old female, pregnant at 24 weeks GA, requires an urgent open cholecystectomy. Which is true? [2013] a) Increased maternal FiO2 will not cause in-utero retrolental fibroplasia (AKA retinopathy of prematurity) b) Nitrous oxide is a teratogen and should be avoided. c) Volatile anesthetics will decrease the chance of premature labor. d) IVC compression does not happen until 3rd trimester.

ANSWER: C Hemodynamic Goals of mitral stenosis: Heart rate: low-normal Rhythm: sinus critical Contractility: maintain Preload: maintain Afterload: maintain Avoid increases in PVR A: Valsalva maneuver during the second stage of labor may result in a sudden increase in central venous pressure. Similar to IV bolus, rapid increase in preload can cause volume overload and pulmonary edema. B: Increases in preload are not well tolerated and can precipitate CHF. C: Fixed cardiac output lesions benefit from heart rate control to allow time for diastolic filling. D: Maintenance of SVR in mitral stenosis is important for arterial perfusion pressure since compensation of perfusion is not possible via increasing cardiac output. Hypotension should be treated with a direct-acting vasoconstrictor (phenylephrine). References: Chestnut chapter 42 p. 985

44. Which one helps a mitral stenosis pregnant woman in labor? [2013] a) Valsalva b) Rapid bolus c) Decrease HR d) Decrease SVR

Answer: A - No IV anesthetic drugs have been shown to be teratogenic Chestnut Pg. 361-362, 375, 21 No IV anesthetic drugs have been shown to be teratogenic - TRUE: a direct quote from Chestnut "the list of agents or factors that are proven human teratogens does not include anesthetic agents (which are listed as "unlikely teratogens") or any drug routinely used during the course of anesthesia." Surgery increases risk of miscarriage 3x - FALSE? - Chestnut quotes a study that found 22% of women who underwent appendectomy during weeks 24-36 of pregnancy delivered within the first week after surgery. Beyond one week, there was no further increase in preterm labour. The database used in this study was unsuitable for determining the incidence of preterm delivery in women who had surgery prior to 24 weeks gestational age (though it appeared to show a similar incidence of preterm labour in this group). Second trimester procedures (particularly those which do not involve manipulation of the uterus) carry the lowest risk. TIVA is anesthetic of choice - FALSE: no studies have shown any association between a particular anesthetic technique and improved fetal outcome. There was one retrospective study that found the use of GA was associated with lower birth weight despite similar gestational age at delivery. Local or regional anesthesia is preferred when possible, as it involves the use of drugs with no laboratory or clinical evidence of teratogenesis (this somewhat contradicts answer option A), and are associated with fewer instances of maternal respiratory complications. Moderate maternal hyperventilation is desirable - FALSE: "Hyperventilation should be avoided; rather, end-tidal CO2 should be maintained in the normal range for pregnancy." This is a bit of an annoying option, as maintenance of a normal range for pregnancy would involve hyperventilation to a pCO2 of 30.

48. For non-OB surgery in the 1st trimester. Which is true? [2014] a) No IV anesthetic drugs have been shown to be teratogenic b) Surgery increases risk of miscarriage 3X c) TIVA is anesthetic of choice d) Moderate maternal hyperventilation is desirable

Answer: A Last group thought D, but several studies of prostaglandin E2 being used to severe obstetric hemorrhage Chestnut Pg. 890-891 Prostaglandin E2 - true : also known as cervidil or dinoprostone. Used for cervical ripening/to induce labour, not a uterotonic agent (or at least not mentioned as a uterotonic agent in any of our textbooks). Misoprostol, a PGE1 analogue can be considered for use in uterine atony, though it is of questionable benefit when other agents have failed. Misoprostol is sqecifically mentioned as having a more favorable side effect profile than methylergonovine or hemabate in patients with hypertension or reactive airway disease. PGE2 (dinoprostone) is listed on Barash table for uterine atony treatments. ?PGI2 which is useful in pulmonary HTN but unsure of use in uterine atony. Miller states that PGE1 is devoid of cardiac effects, but may cause mild hyperthermia. Hemabate - FALSE: Chemical Name is 15-methyl prostaglandin F2alpha or carboprost. Potential risks include the development of bronchospasm, abnormal V-Q ratio, increased intrapulmonary shunt fraction, and hypoxemia. All would be factors to avoid in someone with pulmonary hypertension. Methylergonovine - FALSE: a drug from the ergot alkaloid category. Produces a rapid tetanic contraction of the uterus. Mechanism is not known, but thought to be related to alpha receptor agonism. Potential risks/side effects of administration include nausea and vomiting, vasoconstriction, hypertension, myocardial ischemia/infarction due to coronary vasospasm, stroke, seizures and death. As a result, relative contraindications include hypertension, preeclampsia, peripheral vascular disease, and ischemic heart disease. Side effect profile again suggests no particular advantage for use in pulmonary hypertension. Oxytocin - TRUE?: Oxytocin is the first line drug for prophylaxis and treatment of uterine atony after delivery of a third trimester pregnancy (alternate uterotonic agents are more effective in the first and second trimester, as the receptors for oxytocin have not yet been upregulated). Side effects of synthetic oxytocin (Syntocinon/Pitocin) include tachcardia, hypotension, myocardial ischemia, and potentially death in hypovolemic or hemodynamically compromised women; hemodynamic consequences are not usually evident with infusion rates below 1IU/min, if bolus dosing is avoided. No drug is specifically advocated for this particular scenario of pulmonary hypertension and uterine atony, but by a process of elimination, oxytocin is the only option that doesn't bring about changes that would be deleterious in pHTN.

49. In a pregnant patient with pulmonary hypertension, what is the best option to treat uterine atony? [2014] a) Prostaglandin E2 b) Hemabate c) Methylergonovine d) Oxytocin

Answer C

5. All of the following are respiratory changes of pregnancy EXCEPT: [2010] a) pH b) PaO2 c) PaCO2 d) HCO3-

Answer: D - DIC Chestnut Pg. 882-887, 1045-1046 For the sake of definitions, a total placenta previa covers the entire cervical os, a partial previa partially covers the os, and with a marginal previa, the placenta lies within 2cm of the os, but does not cover it. Women may be offered the chance to labour if the placenta lies greater than 1 cm from the cervical os, as risk of antepartum hemorrhage is low. Conditions associated with a placenta previa include multiparity, advanced maternal age, smoking, male fetus, previous cesarean section/uterine surgery, and a history of a previous placenta previa. Postpartum Anemia - TRUE: The classic sign of placenta previa is painless vaginal bleeding during the second or third trimester. The first episode of bleeding usually stops spontaneously, and is rarely associated with maternal shock or fetal compromise. In addition, there is a higher incidence of first trimester bleeding in women with a placenta previa. One of the primary anesthetic considerations for a placenta previa is the expectation of significant blood loss with delivery, even in the absence of active pre-operative bleeding. Blood loss stems from the potential for injury to an anterior placenta during uterine incision by the obstetrician, a poorly contracting lower uterine segment implantation site (the muscular fundus is the usual implantation site, and contracts better than the lower uterine segment), and the increased risk of a placenta accreta (which carries even higher risk for massive blood loss). Standard practices dictate that at least one IV be maintained in patients admitted due to the presence of a previa, and that blood typing be performed as frequently as every 3 days to ensure an up to date blood sample is available, and that the development of new alloantibodies is detected. The increased risk of antenatal and intrapartum bleeding would translate into risk of postpartum anemia. Placenta accreta - TRUE: A patient with a placenta previa is at increased risk of developing placenta accreta, especially with a history of previous cesarean section. Uterine rupture - TRUE: Uterine rupture shares some risk factors with placenta previa, but having a previa is not a known risk factor for developing uterine rupture. This patient has had a previous cesarean section, and as a result would be at increased risk for uterine rupture. Previous uterine surgery (cesarean section or myomectomy) increase the risk of a uterine rupture, with an incidence of <1% after cesarean section. Rupture can happen in primigravid women with no risk factors, though this is extremely uncommon. In addition, patients with a previous uterine scar can have a uterine rupture develop in the absence of labour (~22% of ruptures in one study; but 1.6/1000 in another larger study). Risk for uterine rupture after a prior cesarean section were found to be 1.6/1000 in non-laboring women, 5.2/1000 with spontaneous labor, 7.7/1000 with induction of labour, and 24.5/1000 with prostaglandin induction of labor. Post term gestation (>42 weeks), attempted VBAC, birth weight >4000g, advanced maternal age (>35 years) and maternal height >164cm. DIC - FALSE: DIC results from abnormal activation of the coagulation system, resulting in formation of large amounts of thrombin, activation of the fibrinolytic system, depletion of coagulation factors and hemorrhage. The most frequent causes of DIC are preeclampsia, placental abruption, sepsis, retained dead fetus syndrome, postpartum hemorrhage, acute fatty liver of pregnancy, and amniotic fluid embolism. Strictly speaking, a placenta previa would put you at risk primarily for intrapartum hemorrhage, not post-partum hemorrhage.

50. A pregnant woman with previous history of C-section presents with placenta previa, she is at increased risk of all of the following EXCEPT ONE: [2014] a) Postpartum anemia b) Placenta accreta c) Uterine rupture d) DIC

Answer: A - Magnesium Chestnut Pg. 838-839, 850-852 Magnesium - TRUE: used as both treatment for women with recurrent eclamptic seizures, as well as prophylactically for women with severe pre-eclampsia. The anticonvulsant mechanism of magnesium is not known. Eclamptic seizures were thought to be the result of cerebral vasospasm, and that the cerebral vasodilating properties of magnesium relieved cerebral vasospasm and prevented/treated the seizure. More recent studies suggest that the sudden and sustained spikes in blood pressure associated with pre-eclampsia overwhelm the autoregulatory mechanisms in the brain and cause forced dilation of the cerebral vessels, hyperperfusion, and cerebral edema. If this mechanism were true, then magnesium would be expected to worsen the hyperperfused state by promoting cerebral vasodilation. Further studies suggested that magnesium preferentially vasodilates the peripheral vessels over the cerebral vessels, thereby preventing/treating seizures by promoting peripheral vasodilation. Other proposed mechanisms include "protection" of the blood brain barrier, decreasing cerebral edema, or acting on the NMDA receptors to raise the seizure threshold. There is no consensus on when to start treatment with Magnesium, what the ideal loading/maintenance doses are, and how long to treat for. Common options include a 4-6g bolus over 20-30 minutes, once the decision to deliver the baby is made, followed by an infusion of 1-2g/hr that runs until 24 hours post-partum. Expert opinion suggests Magnesium should be given at least 2 hrs prior to cesarean delivery, and maintained for 12 hrs postpartum. Diazepam - FALSE: associated with fetal hypotonia, hypothermia, and respiratory depression. This is an eclamptic seizure, and should be treated with magnesium, not benzodiazepines. ?Also has potential for cleft lip if given early in pregnancy? Propofol - Not a first line choice, but may be considered. Eclamptic seizures are often associated with in increased ICP. If there is the need for immediate delivery of a woman with eclamptic seizures, a neuroanesthetic technique should be considered. Propofol or thiopental will reduce CMRO2 and cerebral blood flow, decreasing cerebral blood volume and ICP. Both agents may be useful in termination of seizures. Etomidate - FALSE: no mention of its use in seizure control or induction of an eclamptic patient.

51. A woman with severe preeclampsia has a seizure. What is the drug of choice to manage her seizure? [2014] a) Magnesium b) Diazepam c) Propofol d) Etomidate

ANSWER: D Severe renal impairment based on very high creatinine for pregnant patient (normal should be around 50) and oliguria. See points from Chestnut below. (Chestnut Ch 36 Pg 834-35) Renal manifestations of preeclampsia include persistent proteinuria, changes in the GFR, and hyperuricemia. The presence of proteinuria is a defining element of preeclampsia. During normal pregnancy, the GFR increases by 40-60% during the first trimester, resulting in decrease in BUN, Creatinine, uric acid. In preeclampsia, this increase in GFR is blunted compared with normal pregnancy. Oliguria is a possible late manifestation of severe preeclampsia and parallels the severity of disease. (Chestnut Ch 2 Pg 27) Creatinine clearance is increased to 150 to 200 mL/min from the normal baseline vales of 120 mL/min. The increase occurs early in pregnancy, reaches a maximum by the end of the first trimester, decreases slightly near term, and returns to the prepregnancy level by 8 to 12 weeks postpartum. The increased GFR results in reduced blood concentrations of nitrogenous metabolites. The blood urea nitrogen concentration decreases to 8 to 9 mg/dL by the end of the first trimester and remains at that level until term. The serum creatinine concentration decreases progressively to 0.5 to 0.6 mg/dL by the end of pregnancy (production of creatinine is constant, but GFR is increased). (According to table below, 0.5 mg/dL should be around 50 µmol/L.) Normal Values: (http://www.ccpe-cfpc.com/en/pdf_files/drug_lists/normal_values.pdf) SI Units (Canada) US Creatinine (serum) Male 70 - 120 µmol/L 0.8 - 1.4 mg/dL Female 50 - 90 µmol/L 0.56 - 1.0 mg/dL Creatinine Clearance 75 - 125 mL/min 75 - 125 mL/min BUN 2.5 - 8.0 mmol/L 7 - 22.4 mg/dL Regarding A: (some schools in consensus document picked A) Probably less likely given how high the creatinine is and that she is oliguric. Regarding B: Creatinine too high for normal pregnancy. Regarding C: Chestnut does not say how much preeclampsia blunts the GFR increase. In Chestnut Box 36-2, creatinine > 1.1 mg/dL or > 2 times baseline serum creatinine concentration suggests severe preeclampsia. Based on normal values table above, a creatinine of 120 mol is equivalent to 1.4 mg/dL. This amount is more a feature of severe preeclampsia than all preeclampsia.

52. A patient with pre-eclampsia presents to L&D with oliguria. Lab work reveals a creatinine of 120, and BUN 10. This represents: [2014] a) Mild renal impairment b) Normal values for a pregnant patient c) Normal values for a patient with pre-eclampsia d) Severe renal impairment

ANSWER: B (Chestnut Ch 8 Pg 153) Early decelerations occur simultaneously with uterine contractions and usually are less than 20 bpm below baseline. The onset and offset of each deceleration coincides with the onset and offset of the uterine contraction. In humans, early decelerations are believed to result from reflex vagal activity secondary to mild hypoxia. Early decelerations are not ominous. Regarding A: The differential diagnosis of decreased variability includes fetal hypoxia, fetal sleep state, fetal neurologic abnormality, and decreased CNS activity that results from exposure to drugs such as opioids. Regarding C: Late decelerations begin 10 to 30 seconds after the beginning of uterine contractions and end 10 to 30 seconds after the end of uterine contractions. Late decelerations are smooth and repetitive (i.e. occur with each contraction). Animal studies suggest late decelerations represent a response to hypoxemia (reflects time needed for chemoreceptors to detect decreased oxygen tension and mediate the change in FHR by the vagus nerve). They may also result from decompensation of the myocardial circulation and myocardial failure. Late decelerations may be an oversensitive indication of fetal asphyxia. Regarding D: Variable decelerations vary in depth, shape, and duration. They often are abrupt in onset and offset. Variable decelerations result from baroreceptor- or chemoreceptor-mediated vagal activity. Potential causes include: umbilical cord occlusion (partial or complete), compression of fetal head during second stage of labour. The healthy fetus can typically tolerate mild to moderate variable decelerations (now below 80 bpm) without decompensation. Regarding E: Sinusoidal and saltatory patterns are two unusual FHR tracing results that may indicate fetal compromise. The sinusoidal FHR pattern is a regular, smooth, wave-like pattern that may signal fetal anemia. Occasionally, maternal administration of an opioid can lead to a sinusoidal FHR pattern. The saltatory pattern consists of excessive alterations in variability (>25 bpm) and may signal acute fetal hypoxia. There is a weak association between this pattern and low Apgar scores.

54. All of the following can be associated with fetal distress except: [2014] a) Loss of FHR variability b) Early decelerations c) Late decelerations d) Variable decelerations e) Sinusoidal pattern

ANSWER: A According to Chestnut, 18 hours. (Chestnut Ch2 Pg 26) Gastric emptying is delayed during the early postpartum period but returns to prepregnancy levels by 18 hours postpartum. Gastric volume and pH values are similar in fasting women more than 18 hours after delivery and in nonpregnant individuals who have fasted before surgery.

55. In pregnancy patients after delivery, when to gastric volume, pH, and emptying return to normal? [2014] a) 1-3 days b) 7-10 days c) 3-6 weeks d) >6 weeks

ANSWER: B (Chestnut Ch 19, Pg 403) Contraindications to planned TOLAC (Trial of Labour After Cesarean) include: • Previous classic or T-shaped incision or extensive transfundal uterine surgery • Previous uterine rupture • Medical or obstetrical complication that precludes labour and vaginal delivery • Inability to perform emergency cesarean delivery because of unavailable surgeons, anesthesia provider, or operating room staff Regarding A: (Chestnut Ch 19 Pg 401-2) A large multicenter study found no increased risk for uterine rupture (0.9% vs 0.7%) in women with more than one previous caesarean delivery, when compared with women with only one previous caesarean delivery. A second large study observed that risk for uterine rupture increased from 0.9% to 1.8% in women with two previous caesarean deliveries. The ACOG concluded it is reasonable to consider TOLAC for women with two previous low-transverse caesarean deliveries. Data regarding the risk of TOLAC in women with more than 2 previous caesarean deliveries are limited. Regarding C: (Chestnut Ch 19 Pg 408 Summary statement) "Epidural analgesia does not delay the diagnosis of uterine rupture or decrease the likelihood of successful VBAC" Summary of reasons (7) why TOLAC should NOT preclude use of neuraxial analgesia: • Pain, uterine tenderness, and tachycardia have low sensitivity as diagnostic symptoms and signs of lower uterine segment scar dehiscence or rupture (some scars separate painlessly) o FHR abnormalities represented the most common sign of uterine rupture among patients who did and did not receive epidural analgesia o None of studies observed that epidural analgesia delayed the diagnosis of uterine rupture • Pain, uterine tenderness, and tachycardia have low specificity as diagnostic symptoms of lower uterine segment scar dehiscence o There is evidence that epidural dose escalation immediately before uterine rupture in women who attempted VBAC when compared with women without a uterine rupture ♣ Epidurals may improve specificity of abdominal pain as a symptom of rupture • Most cases of lower uterine segment scar dehiscence do not lead to severe hemorrhage o If significant bleeding should occur, epidural anesthesia may attenuate the maternal compensatory response to hemorrhage • Several published series have reported successful use of epidural analgesia in women undergoing TOLAC o Little evidence that epidural analgesia decreases likelihood of vaginal delivery or adversely affects maternal or neonatal outcome in women with uterine scar separation or rupture • Some obstetricians favour the use of epidural analgesia because it facilitates postpartum uterine exploration to assess the integrity of the uterine scar o i.e. postpartum palpation of the uterine scar (however literature says this is unnecessary routinely after successful VBAC) • Epidural analgesia provides rapid access to safe, surgical anesthesia if cesarean delivery or postpartum laparotomy should be required • It is inhumane to deny effective analgesia to women who undergo TOLAC o ACOG has concluded hat adequate pain relief may encourage more women to chose TOLAC Regarding D: TOLAC results in successful VBAC in 60 to 80% of women in whom a low-transverse uterine incision was made for a previous cesarean delivery.

56. Which of the following is true with respect to a trial of vaginal birth after C-section (VBAC)? [2014] a) Contraindicated if history of ≥2 previous lower segment C-sections b) Contraindicated if history of classic uterine incision c) Epidural anesthesia will make it less likely to recognize uterine rupture d) Associated with successful vaginal delivery 90% of the time

ANSWER: D (Chestnut Ch 36 Pg 841) HELLP syndrome is characterized by hemolysis, elevated levels of liver enzymes, and a low platelet count. It may be a variant of severe preeclampsia, but this is controversial because a substantial fraction of HELLP syndrome patients to not have hypertension or proteinuria.

57. Which of the following is not a feature of HELLP syndrome? [2014] a) Hemolysis b) Low platelets c) Elevated liver enzymes d) Severe proteinuria

Answer C • No mention of thiopental placental metabolism, but the other choices are discussed. • Thiopental rapidly crosses the placenta (Chestnut Pg 575) • Thiobarbituates are metabolized in hepatocytes and to a small extent in extra hepatic sites such as kidneys and possibly the CNS (P&P pdf 342) Regarding A, B, and D The following theories have been proposed to explain the clinical occurrence of an unconscious mother but an awake neonate 1) Preferential uptake of thiopental by the fetal liver, which is the first organ perfused by blood coming from the umbilical vein (Answer choice A) 2) The higher relative water content of the fetal brain 3) Rapid redistribution of the drug into the maternal tissues, which causes rapid reduction in the maternal to fetal concentration gradient 4) Nonhomogeneity of blood flow in the interviollous space (Answer choice D) 5) Progressive dilution by admixture with the various components of the fetal circulation (Answer choice B) (Chestnut page 575)

6. A term pregnant patient receives thiopentone bolus 4mg/kg for induction of GA. The reason the fetal brain levels remain low for all of the following reasons except one. Indicate the exception: [2010] a) Metabolism of thiopentone by the fetal liver. b) Dilution of thiopentone in the fetal blood volume. c) Placental metabolism of thiopentone. d) Inconsistencies in intervillous exchange surfaces at the placenta.

Answer ?A I think an outdated question that comes this table from Chestnut 4th ed.

7. All EXCEPT ONE of the following are risk factors for post partum hemorrhage. Indicate the exception: [2010] a) Preeclampsia b) Macrosomia c) Prolonged labor d) Stimulated labor

Answer C MAC values are decreased by 25-40% in pregnancy. MAC of isoflurane is 1.28%; Nitrous 104% (not adjusted for pregnancy). This results in 0.58MAC of isoflurane and 0.48MAC of nitrous. Unadjusted for pregnancy this would give a MAC of 1.06 (1.4-1.76MAC if taking into account pregnancy). MAC for awareness is 0.4-0.5. Chestnut additionally references a study done using 0.5MAC of sevo with 50% nitrous, where no patients experienced awareness. Miller p.640 Chestnut p.579 Barash p.458 Regarding B and D, as per Chestnut p.576, neonatal depression may occur with volatiles. This is typically not a clinical issue, especially for emergency C/S, as the baby is delivered before much of the volatile crosses the placenta. P.579 mentions that increasing depth of maternal anesthesia with volatile (no specific MAC value given) tends to result in lower APGARs when incision to delivery time exceeds 8 minutes. Regarding nitrous at 50%, neonates exposed to nitrous required more resuscitation, though no significant differences in APGAR scores. Chestnut p.576. Regarding A and E, Chestnut p.1200 recommends maintenance anesthesia in C/S using volatile (limiting MAC to 0.5-0.8 to prevent uterine atony) and nitrous (up to 67%). This is in relation to those chronically using alcohol who may require a higher MAC value, but the principles still stand for limiting uterine atony secondary to volatiles.

8. In a parturient is given 0.75% Isoflurane with 50% N2O and 50% O2 for C-section which is true? [2011] a) Increase of surgical blood loss b) Increase of neonatal depression c) Decrease maternal awareness d) Increase of neonatal APGAR score < 7 at one minute e) Increase in uterine atony

Answer:D This question is somewhat confusing (maybe there was more to it?) as we don't know the status of the infant. For any neonate, we dry off and wrap in blankets to keep warm. If the infant is not vigourous and born at term, we follow the NRP algorithm as detailed above. Given that all answers here involve a degree of mechanical ventilation, we can assume that the infant is apneic/hypopneic. From the stem about a narcotic addicted mother the most likely cause of neonatal respiratory depression is fetal exposure to opioids. In this case, stimulate, warm, and PPV is the appropriate initial management. If there is anticipated need for prolonged PPV, an ETT should be placed. This is likely the case in this question as we do not know the dose/half-life of what the fetus was exposed to. Although the NRP book says that naloxone can be given if opioid exposure is felt to be the cause of respiratory depression (it can be of diagnostic value), it does nothing to correct the underlying problem. Chestnut explicitly states that naloxone should not be given because it can worsen neurologic damage caused by asphyxia, precipitate neonatal opioid withdrawal including seizures. Chestnut recommends assisted ventilation continue until resolution of the opioids effect. Chestnut p.176-177 NRP book p.247-248

9. Narcotic addict mom what should you do to resuscitate the baby? [2011] a) O2 and BMV b) Stimulate, warm and BMV c) Stimulate, warm, ETT and give naloxone d) Stimulate, warm, ETT but avoid naloxone