CHAPTER 41 | Obstetric Anesthesia

Question 1

Which of the following is INACCURATE during term pregnancy:

A. gastric emptying is not delayed during pregnancy or early labor

B. BP should be monitored frequently (every 2 to 3 minutes) after the induction of neuraxial
anesthesia

C. Cardiac output is highest immediately post partum

D. Flow volume loop is decreased

E. Arterial CO2 tension is increased

Answer 1

E. Arterial CO2 tension is increased

Question 2

Hypotension after spinal anesthesia is common due to sympathetic blockade. Which of the following agents results in LESS fetal acidosis:

A. Phenylephrine
B. Ephedrine
C. Norepinephrine
D. Epinephrine

Answer 2

A. Phenylephrine

Phenylephrine is equally efficacious to ephedrine for treating maternal hypotension and results in less fetal acidosis; thus, phenylephrine is
preferred for the prevention and treatment of neuraxial anesthesia-induced
hypotension in pregnancy.

Question 3

Can you give Norepinephrine as a bolus in spinal anesthesia-induced hypotension?

If yes, what is the suggested bolus dose according to BARASH?

Answer 3

YES. The suggested dose is 6ug

Because phenylephrine may result in reflex bradycardia and decreased CO, some experts have proposed using norepinephrine to prevent and treat hypotension due to its β-adrenergic agonist effects.

The relative potency of norepinephrine to phenylephrine is approximately 11:1, and thus the
suggested dose of IV bolus norepinephrine for this indication is 6 μg.

Question 4

What is the underlying cause of this CTG tracing?

A. Head compression

B. Uteroplacental insufficiency

C. Cord compression

D. Fetal acidosis

Answer 4

A. Head compression

This shows EARLY DECELERATIONS

Early Deceleration > Head compression

Variable Deceleration > Cord Compression

Late Deceleration > Uteroplacental insufficiency

Question 5

What is the underlying cause of this CTG tracing?

A. Head compression

B. Uteroplacental insufficiency

C. Cord compression

D. Fetal acidosis

Answer 5

B. Uteroplacental insufficiency

This shows LATE DECELERATIONS

Early Deceleration > Head compression

Variable Deceleration > Cord Compression

Late Deceleration > Uteroplacental Insufficiency

Question 6

A category I fetal heart rate has:

A. Minimal variability +/- early decelerations

B. Moderate variability +/- early decelerations

Answer 6

B. moderate variability ± early decelerations

NORMAL ACID BASE status

Question 7

Peak effect of Betamethasone:

A. 24 hrs

B. 48 hrs

C. 12 hrs

Answer 7

B. 48 hrs

Question 8

TRUE or FALSE

Continuous epidural infusion of lidocaine is associated with a higher incidence of ‘Tachyphylaxis.’

Answer 8

TRUE

Question 9

TRUE or FALSE

Being pregnant doesn’t increase the risk of developing PDPH.

Answer 9

FALSE

Pregnant is PDPH risk!

By virtue of age and sex, pregnant patients are at HIGHER risk for developing PDPH

In addition, after delivery, reduced pressure in the epidural space may increase the risk of cerebrospinal fluid leakage through a dural puncture, and estrogen withdrawal after delivery of
the placenta may exacerbate vascular headaches.

Question 10

Meningitis is a rare complication after spinal or epidural anesthesia. If clinically suspected, the most common pathogen is:

A. staph. aureus

B. strep. viridans

C. staph. epidermidis

Answer 10

B. strep. viridans

Infections are rare; epidural abscess is usually
caused by skin contaminants and meningitis by contamination of drugs or needles with clinicians’ nasopharyngeal flora (streptococcus viridans).

Question 11

At the ER, you called a code blue on a full term G2P1001. The resuscitation measures failed after several attempts and the OB decided to do a perimortem cesarean section. When is the golden period to perform perimortem CS?

A. within 5 minutes of the cardiac arrest

B. within 2 minutes of the cardiac arrest

C. CS hysterectomy should be done within 30 mins after the arrest

Answer 11

A. within 5 minutes of the cardiac arrest

In the event of maternal cardiac arrest, cardiopulmonary resuscitation should be initiated immediately.

If return of spontaneous circulation is not achieved with the usual resuscitation measures, perimortem
cesarean delivery should be performed, ideally within 5 minutes of the cardiac arrest.

The patient should not be moved to an operating room to perform the hysterotomy, as this wastes valuable time. Rather, the delivery should be performed at the site of the arrest.

Question 12

Advanced maternal age is defined as:

Answer 12

> 35 year old at the time of delivery

Question 13

Which of the following drugs does NOT pass the placenta easily?

A. Etomidate
B. Ephedrine
C. Atropine
D. Glycopyrrolate

Answer 13

D. Glycopyrrolate

Question 14

Magnesium sulfate (MgSO4 ) is used as an anticonvulsant in patients with preeclampsia and for fetal neuroprotection and sometimes for short-term tocolysis. MgSO4 may produce any of the following effects EXCEPT:

A. Sedation
B. Respiratory paralysis
C. Inhibition of acetylcholine (ACh) release at the myoneural
junction
D. Hypertension when used with nifedipine

Answer 14

D. Hypertension when used with nifedipine - FALSE NOTION

Because magnesium antagonizes the effects of α-adrenergic agonists, ephedrine is usually preferred over phenylephrine if a vasopressor is needed to restore blood pressure, along with fluids, after a neuraxial blockade. When a calcium channel blocker, such as nifedipine, is administered along with magnesium, greater hypotension has resulted.

Question 15

Cardiac output increases dramatically during pregnancy and delivery. The
cardiac output returns to nonpregnant values by how long postpartum?

A. 12 hours
B. 1 day
C. 2 weeks
D. 6 months

Answer 15

C. 2 weeks

Question 16

Each uterine contraction increases the cardiac output by about:

A. 10 -25%

B. 5%

C. 30 - 40%

Answer 16

A. 10 -25%

Question 17

What is therapeutic range of Magnesium Sulfate:

A. 4 to 8 mEq/L

B. 10 mEq/L

C. 2 - 3 mEq/L

D. 15 - 20 mEq/L

Answer 17

A. 4 to 8 mEq/L

With increasing serum levels, loss of deep tendon reflexes occurs at 10 mEq/L (12 mg/dL),
respiratory paralysis occurs at 15 mEq/L (18 mg/dL), and cardiac arrest at greater than 25 mEq/L (> 30 mg/dL) can occur.

Magnesium decreases the release of ACh at the myoneural junction and decreases the sensitivity of the motor endplate to ACh. This can produce marked potentiation of nondepolarizing muscle relaxants.

Question 18

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; 5 minutes later, the blood pressure is noted to be 80/40 mm Hg and the heart rate is 110 beats/min.
The BEST treatment (best fetal pH) after ensuring that adequate left uterine displacement is performed would be:

A. Phenylephrine
B. Ephedrine
C. Epinephrine
D. 1000 mL 5% dextrose in lactated Ringer solution

Answer 18

A. Phenylephrine

In this patient who has left uterine displacement, adequate IV hydration, and a heart rate of 110
beats/min, phenylephrine would be the preferred vasopressor. If the mother has hypotension with bradycardia, ephedrine might be a better choice.

Epinephrine is rarely needed but should be available and used when there is severe hypotension that is not responsive to phenylephrine or ephedrine, especially when there is associated fetal bradycardia.

Question 19

What is the P50 of fetal hemoglobin at term?

A. 12 mm Hg
B. 18 mm Hg
C. 24 mm Hg
D. 30 mm Hg

Question 20

A 32-year-old parturient with a history of spinal fusion, severe asthma, and hypertension (blood pressure 180/110) is brought to the operating room wheezing. She needs an emergency cesarean section under general anesthesia
for a prolapsed umbilical cord.

Which of the following induction agents would be MOST appropriate for her induction?

A. Sevoflurane
B. Midazolam
C. Ketamine
D. Propofol

Answer 20

D. Propofol

When inducing general anesthesia 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 asthma, IV induction will work with ketamine or propofol

Ketamine is considered by many as the induction
agent of choice due to its mild bronchodilator properties, but because propofol (also a good induction agent in asthmatic patients) does not
stimulate the cardiovascular system as ketamine does, propofol would be preferred in this patient with hypertensive disorders of pregnancy.