Apex Unit 11 Across the Lifespan

Question 1

A patient requires an emergency cesarean section. Which of the following is the MOST likely cause for rapid arterial oxygen desaturation during intubation?

Increased residual volume
Decreased vital capacity
Increased inspiratory reserve capacity
Decreased expiratory reserve volume

Answer 1

Decreased expiratory reserve volume

By now you should know that an increased oxygen consumption relative to FRC contributes to rapid arterial desaturation in the obstetric patient.

You had to choose between several lung volumes and capacities. You probably knew that FRC declines, but quickly realized that FRC was not listed. The next course of action should have been to think about the determinants of FRC (RV + ERV). ​​

Eureka! Expiratory reserve volume is reduced, which decreases FRC and this increases the rate of desaturation during apnea.

Question 2

Which hemodynamic variables increase during pregnancy? ​ (Select 2.)

Systemic vascular resistance
Heart rate
Stroke volume
Pulmonary artery occlusion pressure

Answer 2

Heart rate
Stroke volume

You need to understand how normal physiology changes for each special population: ​ OB, peds, and the elderly. It’s a fool’s errand to attempt to memorize all of these changes without understanding why each occurs.

Stroke volume is increased as a function of increased intravascular volume, while heart rate is increased to satisfy a higher metabolic demand.

In the vascular smooth muscle, increased progesterone stimulates NO release. This reduces SVR. A dilutional anemia also contributes to the reduction in SVR.

PAOP is unchanged.

Question 3

Which factors are expected to increase during pregnancy? ​ (Select 3.)

Sensitivity to local anesthetics
Urine glucose
MAC
Lower esophageal sphincter tone
Gastric pH
Creatinine clearance

Answer 3

Creatinine clearance
Urine glucose
Sensitivity to local anesthetics

Creatinine clearance increases as a function of increased intravascular volume and cardiac output - more creatinine is delivered to the kidney per unit time. Creatinine and BUN are decreased.

Urine glucose increases as a result of increased GFR and reduced reabsorption into the peritubular capillaries.

Increased progesterone explains the increased sensitivity to local anesthetics. This also decreases MAC by 30 - 40 % and reduces lower esophageal sphincter tone.

Increased gastrin reduces gastric pH.

Question 4

Uterine blood flow is: ​ (Select 2.)

20% of the cardiac output.
reduced by phenylephrine.
not autoregulated.
700 mL/min.

Answer 4

700 mL/min
Not autoregulated

Key facts about uterine blood flow:
At term, uterine blood flow increases to 700 mL/min.
UBF is not autoregulated - it is dependent on maternal MAP, cardiac output, and uterine vascular resistance.
UBF is 10% of the cardiac output (not 20%).
UBF is not reduced by phenylephrine. Use of phenylephrine instead of ephedrine is associated with a higher fetal blood pH. Both drugs are acceptable agents to use in obstetrics.

Question 5

Which stage of labor begins with the onset of perineal pain?

Latent stage
Active stage
First stage
Second stage

Answer 5

Second stage

There are three stages of labor:
The first stage begins with cervical dilation with regular uterine contractions and ends with full cervical dilation (10 cm). It can be divided into the latent phase and the active phase.
The second stage begins with full cervical dilation and ends with delivery of the newborn.
The third stage begins with the delivery of the newborn and ends with the delivery of the placenta.

Question 6

All of the following are appropriate for pain relief during the first stage of labor EXCEPT a/an:

paravertebral sympathetic lumbar block.
pudendal block.
epidural block.
paracervical block.

Answer 6

Pudendal block

The perineum is innervated by the pudendal nerve, which derives from S2-S4. This explains why a pudendal nerve block is not useful during the first stage of labor (T10-L1).

During the second stage, the uterus is still contracting and the cervix is fully dilated. For this reason, T10-S4 will need to be anesthetized to adequately treat labor pain.

Question 7

Which local anesthetic reduces the efficacy of epidural morphine?

Levobupivacaine
Etidocaine
Ropivacaine
2-Chloroprocaine

Answer 7

2-Chloroprocaine

This is one of those questions that may sound like trivia, however it’s important stuff for boards.
​
2-Chloroprocaine antagonizes mu and kappa receptors in the spinal cord. This reduces the efficacy of epidural morphine. There are no other local anesthetics that do this.

Question 8

Fifteen minutes after a patient’s epidural was dosed, the patient becomes hypotensive and experiences respiratory arrest. What is the MOST likely etiology?

Subdural injection
Epidural catheter migration
Loss of accessory respiratory muscle strength
Eclampsia

Answer 8

Subdural injection

This patient has experienced a total spinal. Due to the time course, the most likely explanation is a subdural injection. ​

Question 9

According to the American College of Obstetrics and Gynecologists, which of the following are predictive of poor fetal status? ​ (Select 2.)

Absent baseline variability
Sinusoidal pattern
No late or variable decelerations
Bradycardia without absence of baseline variability

Answer 9

Sinusoidal pattern
Absent baseline variability

Question 10

Match each serum magnesium concentration with its expected clinical effect.

1 mg/dL ​
5 mg/dL ​
8 mg/dL ​
15 mg/dL ​

Respiratory depression
​Loss of patellar tendon reflex (deep tendon reflex)
Seizures
Drowsiness

Answer 10

1 mg/dL ​ + ​ Seizures
5 mg/dL ​ + ​ Drowsiness
8 mg/dL ​ + ​ Loss of patellar tendon reflex (deep tendon reflex)
15 mg/dL ​ + ​ Respiratory depression

Question 11

Anesthetic considerations for the use of methergine include:

IV administration.
risk of water intoxication.
administration of 0.2 mg.
tocolysis.

Answer 11

Administration of 0.2 mg

The dose of IM methergine is 0.2 mg. It should always be given IM, as IV administration can result in severe hypertension, particularly in the patient with preeclampsia.

Methergine is an uterotonic drug (it increases contractility). It is not a tocolytic (uterine relaxant).

There is a risk of water intoxication with oxytocin (not methergine).

Question 12

Anesthetic implications for cesarean section under general anesthesia include:

rapid sequence induction.
administration of a dopamine agonist.
increased MAC.
prolonged neonatal respiratory depression.

Answer 12

Rapid sequence induction

​In this patient population, mortality is 17-times higher with a general anesthetic. Avoid it whenever possible! Failure to successfully manage the airway is the most common cause of maternal death.

Question 13

An obstetric patient at 33-weeks gestation requires a laparoscopic appendectomy. Which drug should be avoided?

Ketorolac
Morphine
Succinylcholine
Propofol

Answer 13

Ketorolac

After the first trimester, NSAIDs can close the ductus arteriosus.

While no anesthetic is a proven teratogen in humans, it’s wise to stick with drugs with a long track record of safety such as: ​ propofol, opioids, neuromuscular blockers, and inhalation agents.

Question 14

Which signs are consistent with a diagnosis of preeclampsia? ​ (Select 3.)

Vasoconstriction
Increased thromboxane
Impaired platelet aggregation
Increased prostacyclin
Seizures
Proteinuria

Answer 14

Increased thromboxane
Vasoconstriction
Proteinuria

Preeclampsia is associated with increased thromboxane, vasoconstriction, and proteinuria. These patients also have enhanced platelet aggregation (not impaired) and decreased prostacyclin (not increased).

The patient with eclampsia has seizures, while the patient with preeclampsia does not - although she is at risk.

Question 15

Match each placental deformity to its description.

Placenta previa ​
Placenta accreta ​ ​
Placenta increta ​
Placenta percreta ​

Placenta invades the myometrium
Placenta extends beyond the uterus
Placenta attaches to the surface of the myometrium
Placenta covers the cervical os

Answer 15

Placenta previa ​ + ​ Placenta covers the cervical os
Placenta accreta ​ + ​ Placenta attaches to the surface of the myometrium
Placenta increta ​ + ​ Placenta invades the myometrium
Placenta percreta ​ + ​ Placenta extends beyond the uterus

Question 16

What is the MOST common cause of postpartum hemorrhage?

Retained placenta
Disseminated intravascular coagulopathy
Uterine inversion
Uterine atony

Answer 16

Uterine atony

​Uterine atony is the most common cause of postpartum hemorrhage.

Other causes of postpartum hemorrhage include: ​
Retained placenta
DIC
Uterine inversion

Question 17

Five minutes following delivery, a newborn has an irregular respiratory rate with a heart rate of 105. He is grimacing, has some flexion in the extremities, and has a pink body with blue extremities. Calculate his APGAR score.

Answer 17

6

The Apgar score is used to assess the newborn and guide resuscitative efforts. ​ Five parameters are evaluated at one and five minutes after delivery.

​The score at one minute correlates with fetal acid-base status.
The five minute score may be predictive of neurologic outcome.
​
This newborn has an Apgar score of 6 (1 + 2 + 1 + 1 + 1 = 6).

Question 18

Each vital sign is consistent with the term newborn EXCEPT:

diastolic blood pressure 40 mmHg.
heart rate 140 bpm.
respiratory rate 40 bpm.
systolic blood pressure 90 mmHg.

Answer 18

Systolic blood pressure 90 mmHg

The SBP in the newborn is ~ 70 mmHg.

A neonate with a SBP > 80 mmHg is hypertensive.

The rest of the vital signs are textbook examples of normal:
DBP = 40
HR = 140
RR = 40

Question 19

Select the statements that MOST accurately reflect the cardiovascular system in the newborn. ​ (Select 2.)

Heart rate is the primary determinant of blood pressure.
Hypotension is defined as systolic blood pressure < 70 mmHg.
Phenylephrine is a first line treatment for hypotension.
Stress is more likely to activate the parasympathetic nervous system.

Answer 19

Heart rate is the primary determinant of blood pressure
Stress is more likely to activate the parasympathetic nervous system

Heart rate is the primary determinant of both cardiac output and blood pressure. The ANS is immature, and there is a predominance of the PNS. Stress is likely to cause bradycardia, which in turn reduces cardiac output.

​In the newborn, hypotension is defined as SBP < 60 mmHg (not < 70 mmHg).

Neonates have a poorly compliant ventricle, so they are unable to significantly increase contractility to overcome an elevated afterload. This makes phenylephrine a poor choice for the treatment of hypotension. As you will see later, however, there are instances where phenylephrine is useful for the neonate.

Question 20

Which statement MOST accurately describes the infant airway? ​ (Select 3.)

Epiglottis is floppy
C shaped epiglottis
Vocal cord position at C1-C2
Right and left mainstem bronchi take off at same angle
Vocal cords have anterior slant
Glottic opening is positioned more cephalad

Answer 20

Glottic opening is more cephalad
Vocal cords have an anterior slant
Right and left mainstem bronchi take off at the same angle

Here’s why the distractors were wrong:
The vocal cord position is at C3-C4 (not C1-C2).
The epiglottis is U or omega shaped (not C).
The epiglottis is long and stiff (not floppy). Anyone who says the epiglottis is floppy has clearly never intubated a neonate!

Question 21

During an inhalation induction, a neonate begins to desaturate shortly after removal of the facemask. Which statement BEST explains why the neonate desaturated so quickly?

Increased alveolar ventilation to FRC ratio
Oxygen consumption is 3 mL/kg/min
The patient is experiencing malignant hyperthermia
Decreased alveolar ventilation to FRC ratio

Answer 21

Increased alveolar ventilation to FRC ratio

The oxygen consumption in the neonate is nearly twice that of the adult.

Neonate ~ 6 mL/kg/min
Adult = ~ 3.5 mL/kg/min
​

Because the neonate has a higher ratio of alveolar ventilation relative to the size of her FRC, the oxygen supply contained within the FRC is quickly depleted. This makes her desaturate comparatively faster during apnea.

While an inhalation agent could theoretically precipitate MH, and this would significantly increase oxygen consumption, this is not the most likely cause of desaturation in the patient detailed in this question.

Question 22

When compared to the adult, select the true statements regarding the pulmonary system in the newborn. ​ (Select 2.)

The diaphragm has more type II than type I muscle fibers.

Neonates have the same amount of dead space on a per weight basis.

The diaphragm has more type I than type II muscle fibers.

The newborn has a higher tidal volume on a per weight basis.

Answer 22

The diaphragm has more type II than type I muscle fibers

Neonates have the same amount of dead space on a per weight basis

The diaphragm has more type II (fast twitch) fibers and less type I (slow twitch) fibers. Because of this, neonates are more likely to experience respiratory fatigue.

Neonates and adults have the same amount of dead space (2 mL/kg).

The newborn has the same tidal volume as the adult (6 mL/kg), however it has a much higher respiratory rate to support its high alveolar ventilation requirement.

Question 23

When compared to the adult, which statement presents the MOST accurate understanding of neonatal pulmonary mechanics? ​ (Select 2.)

Airflow resistance during tidal breathing is decreased.
Chest wall compliance is increased.
Closing capacity is increased.
Residual volume is decreased.

Answer 23

Closing capacity
Chest wall compliance is increased

On a per weight basis, closing capacity is increased in the neonate. When closing capacity overlaps with tidal volume, the neonate is at risk for V/Q mismatching in favor of shunting.

Chest wall compliance is increased due to a cartilaginous ribcage that provides less structural support.

Airflow resistance is increased (not decreased). Remember that, during laminar flow, resistance is inversely proportional to the radius raised to the 4th power.

Residual volume is increased (not decreased).

Question 24

Select the data set that MOST accurately depicts a normal umbilical artery blood gas.

pH = 7.40 ​ PaO2 = 90 ​ PaCO2 = 30

pH = 7.20 ​ PaO2 = 50 ​ PaCO2 = 50

pH = 7.30 ​ PaO2 = 20 ​ PaCO2 = 50

pH = 7.35 ​ PaO2 = 30 ​ PaCO2 = 40

Answer 24

pH = 7.30 ​ PaO2 = 20 ​ PaCO2 = 50

The umbilical arteries return deoxygenated blood from the fetus to the placenta, so it should make sense that this blood has a low PaO2 and an elevated PaCO2.

Know and understand the following reference ABGs:
Umbilical vein (to the fetus): ​ pH = 7.35 ​ PaO2 = 30 ​ PaCO2 = 40
Umbilical arteries (to the placenta): ​ pH = 7.30 ​ PaO2 = 20 ​ PaCO2 = 50
First 10 min of life: ​ pH = 7.20 ​ PaO2 = 50 ​ PaCO2 = 50
Mother at term: ​ pH = 7.40 ​ PaO2 = 90 ​ PaCO2 = 30
​

Before moving to the next page, where we’ll explain all of this to you, take a moment and see if you can reason it out.

Question 25

Which statement regarding fetal hemoglobin is TRUE?

It has an increased affinity for 2,3-DPG.

It has a higher P50 than the adult.

It is replaced by hemoglobin A at 9 months of age.

Erythrocytes containing hemoglobin F have a shorter lifespan.

Answer 25

Erythrocytes containing hemoglobin F have a shorter lifespan
​

Key facts regarding fetal RBCs and HgbF:
Fetal RBCs have a lifespan of 70 – 90 days, which is shorter than those with HgbA (120 days).
HgbF has a P50 value of 19 mmHg, which is lower than the adult value of 26.5 mmHg.
HgbF is unable to bind 2,3-DPG, which explains why it has a higher affinity for oxygen.
HgbF is replaced by RBCs containing Hgb A in the first two months of life.

Question 26

Potential complications of massive transfusion in the neonate include all of the following EXCEPT:

metabolic acidosis.
hypokalemia.
hypocalcemia.
metabolic alkalosis.

Answer 26

Hypokalemia

Massive transfusion is associated with hypocalcemia, metabolic acidosis, and/or metabolic alkalosis.

Neonates and children who receive erythrocyte transfusion are at risk for hyperkalemia (not hypokalemia).

Question 27

A 3-kg term neonate requires emergency exploratory laparotomy for necrotizing enterocolitis. Her preoperative hematocrit is 50%. What is the maximum allowable blood loss to maintain a hematocrit of 40%?

​

(Enter your answer as mL)

Answer 27

48 - 60 mL or 53 - 67 mL (we accepted the wider range)

The “correct” range is a function of the equation you use (there are two common ones). We like the following equation:

​

MABL = EBV x [(Hct starting - Hct target) / Hct starting]
If you used this equation, the correct range is 48 - 60 mL.
​

The other equation uses Hct average in the denominator:

​

MABL = EBV x [(Hct starting - Hct target) / Hct average]
If you used this equation, then the correct range is 53 - 67 mL.
​

For your exam, the item writers should be aware of the different equations in the texts and take this into account when determining the correct response to the question.

Question 28

The newborn’s kidney tends to:

reabsorb water.

reabsorb glucose.

reabsorb sodium.

excrete sodium.

Answer 28

Excrete sodium

The newborn’s kidney has an immature concentrating mechanism, so it tends to excrete sodium - it is an obligate sodium loser.

​

For the same reason, it partially lacks the ability to retain water and glucose

Question 29

The total body water for a premature neonate is approximately: ​

​

(Enter your answer as a percentage)

Answer 29

80 – 90%

The total body water for the premature neonate is 80 – 90%.

Question 30

Calculate the hourly maintenance rate for a child who weighs 15 kg.
​

(Enter your answer as a whole number in mL)

Answer 30

50 mL

Unless you are instructed otherwise, you should use the 4:2:1 rule for fluid calculations on the NCE.

Step1: ​ 0-10 kg ​ → ​ Begin with 4 mL/kg/hr
Step 2: ​ 10-20 kg ​ → ​ Add 2 mL/kg/hr to the previous total
Step 3: ​ > 20 kg ​ → ​ Add 1 mL/kg/hr to the previous total
​
The child in this question weights 15 kg so…
Step 1: ​ 10 kg ​ x ​ 4 mL/kg/hr ​ = ​ 40 mL
Step 2: ​ 5 kg ​ x ​ 2 ​ mL/kg/hr ​ = 10 mL
​
Answer: ​ 40 mL ​ + ​ 10 mL ​ = ​ 50 mL total

Question 31

A 2-week-old neonate will be expected to demonstrate all of the following EXCEPT a/an:

faster circulation time.
shorter duration of action for lipid soluble drugs.
increased free fraction of highly protein bound drugs.
larger volume of distribution for water soluble drugs.

Answer 31

Shorter duration of action for lipid soluble drugs

Neonates have a greater percentage of total body water and a lower percentage of fat and muscle mass.

​Drugs that require fat for redistribution and termination of effect have a longer duration of action (not shorter).

​A high TBW also means that they require higher doses of water soluble drugs to achieve a given plasma concentration.

Since they have lower concentrations of plasma proteins, there will be an increased free fraction of highly protein bound drugs.

The cardiac output in the newborn is 200 mL/kg/min. This accounts for a faster circulation time. ​ ​

Question 32

Anesthetic considerations for the administration of neuromuscular blockers in the neonate include:

avoidance of succinylcholine.

a larger dose of succinylcholine.

a longer duration of action of succinylcholine.

a larger dose of succinylcholine and nondepolarizing neuromuscular blockers.

Answer 32

A larger dose of succinylcholine

The combination of an increased ECF and normal sensitivity of succinylcholine necessitates an increased dose of 2 mg/kg. Its duration is similar between neonates and adults (not increased).

The black box warning on succinylcholine warns of hyperkalemia associated with undiagnosed muscular dystrophy in children under eight years old. Considering this, succinylcholine remains a suitable option for rapid sequence intubation, anticipated difficult airway, laryngospasm, or other airway emergencies.

The dose for nondepolarizers is the same for neonates and adults on a per kg basis.

Question 33

Which lecithin/sphingomyelin ratio suggests fetal lung maturity?

0. 5
1. 0
2. 5
3. 0

Answer 33

2.0

An L/S ratio of 2.0 or greater suggests fetal lung maturity.

​An L/S ratio less than 2.0 suggests immature fetal lungs and may place the fetus at risk for respiratory distress syndrome.

Question 34

What is a late finding in the patient with pyloric stenosis?

Metabolic acidosis

Alkaline urine

Hyponatremia

Hyperkalemia

Answer 34

Metabolic acidosis

Pyloric stenosis occurs when hypertrophy of the pyloric muscle creates a mechanical obstruction at the gastric outlet (between the stomach and the duodenum).

​

Vomiting causes the infant to lose H+ and electrolytes, so he will commonly present with:

Metabolic alkalosis
Hyponatremia
Hypokalemia
Alkaline urine
​

If vomiting persists, and dehydration is not corrected, impaired tissue perfusion increases lactic acid production (metabolic acidosis).

Question 35

What is the MOST appropriate gas mixture for the neonate with necrotizing enterocolitis?

30% oxygen ​ + ​ 70% nitrous oxide

50% oxygen ​ + ​ 50% nitrous oxide

50% oxygen ​ + ​ 50% air

100% oxygen

Answer 35

50% oxygen ​ + ​ 50% air

Necrotizing enterocolitis is necrosis of the bowel. The two most important risk factors are prematurity (< 32 weeks) and low birth weight (< 1,500 g).

​

Since many of these babies experience bowel perforation, they present to the OR for bowel resection. Nitrous oxide is contraindicated. That eliminates two of the answer choices.

​

Since they’re premature, they’re also at risk of retinopathy of prematurity. For this reason, you’ll want to decrease the FiO2 to maintain the SpO2 between 89 - 94%. This means that 50% oxygen + 50% air is the best gas mixture for this patient.

Question 36

Select the MOST significant risk factor for retinopathy of prematurity.

Sepsis

Hypoxemia

Intraventricular hemorrhage

Prematurity

Answer 36

Prematurity

​

Explanation:

​

Retinopathy of prematurity causes abnormal vascular development in the retina. The immature retinal blood vessels are at risk for vasoconstriction and hemorrhage. Dysfunctional healing creates scars. As the scars retract, they pull on the retina, causing retinal detachment and blindness.

​

Vasculogenesis occurs 16 - 44 weeks after conception. It’s during this time that the patient is at risk for ROP. Prematurity and hyperoxia are the two most significant risk factors.

Question 37

Based on experimental animal data, which anesthetic agents are MOST likely to cause apoptosis? ​ (Select 2.)

Midazolam

Dexmedetomidine

Fentanyl

Ketamine

Answer 37

Ketamine

Midazolam

​

Explanation:

​

In experimental animal models, drugs that antagonize the NMDA receptor, stimulate GABA, or both may cause apoptosis.

​

Examples include:

​

Halogenated anesthetics
Nitrous oxide
Propofol
Ketamine
Etomidate
Barbiturates
Benzodiazepines

Question 38

Match each shunt with its location within the fetal circulation.

Answer 38

Ductus venosus ​ + ​ Umbilical vein → inferior vena cava

Foramen ovale ​ + ​ Right atrium → left atrium

Ductus arteriosus ​ + ​ Pulmonary artery → proximal descending aorta

The fetal circulation differs from the adult circulation in several ways. In the fetus, gas exchange occurs in the placenta (not the lungs). Also, the circulation is organized in such a way that the blood with the highest oxygen content is preferentially delivered to the heart and brain. This arrangement is dependent on the function of 3 shunts.

Ductus venosus:
Umbilical vein → inferior vena cava
Oxygen rich blood from the placenta bypasses the liver
​
Foramen ovale:
Right atrium → left atrium
Oxygen rich blood bypasses the lungs and is preferentially delivered to the heart and developing brain

Ductus arteriosus: 
Pulmonary artery (or RV) → proximal descending aorta 
Lower oxygen blood bypasses the lungs and is delivered to the lower body

Question 39

Which conditions increase pulmonary vascular resistance? ​ (Select 3.)

Light anesthesia

Hypercarbia

Anemia

Nitric oxide

Alkalosis

Trendelenburg position

Answer 39

Hypercarbia
Trendelenburg position
Light anesthesia

The balance between PVR and SVR is important in the patient with congenital heart disease, and understanding this concept will help you answer a variety of questions about this patient population.

This question asked you about conditions that increase PVR. Notice that each of the examples below decrease vessel diameter, increase pulmonary blood volume, or both.

Conditions that increase PVR:
Hypercarbia
Hypoxemia
Acidosis
Atelectasis
Trendelenburg position
Hypothermia
Vasoconstrictors
Light anesthesia
Pain

Question 40

Which congenital defects are MOST likely to cause hypoxemia? ​ (Select 3.)

Ebstein’s anomaly
Patent ductus arteriosus
Tetralogy of Fallot
Eisenmenger’s syndrome
Coarctation of the aorta
Ventricular septal defect

Answer 40

Tetralogy of Fallot
Eisenmenger’s syndrome
Ebstein’s anomaly

Shunting occurs when there is an abnormal communication between the pulmonary and systemic circulations.

Cyanotic Shunt (R → L):
A right-to-left shunt allows blood to bypass the pulmonary circulation and enter the systemic circulation. Examples include:
Tetralogy of Fallot
Transposition of the great arteries
Tricuspid valve abnormality (Ebstein’s anomaly)
Truncus arteriosus
Total anomalous pulmonary venous connection

Acyanotic shunt (L → R):
A left-to-right shunt causes oxygenated pulmonary venous blood to return directly to the lungs instead of being pumped to the body. Examples include:
Ventricular septal defect (most common)
Atrial septal defect
Patent ductus arteriosus
Coarctation of the aorta

Question 41

During surgical repair of tetralogy of Fallot, the patient’s blood pressure declines by 25% and the SpO2 decreases by 10%. What are the MOST likely explanations for these findings? ​ (Select 2.)

Pulmonary vascular resistance decreased
Systemic vascular resistance decreased
Preload increased
Myocardial contractility increased

Answer 41

SVR decreased
Myocardial contractility increased

Tetralogy of Fallot is characterized by four defects:
Ventricular septal defect
Aorta that overrides the RV and LV
Pulmonic stenosis (obstruction to RV ejection)
RV hypertrophy
​
Your job is to minimize the R-to-L shunt by satisfying the following goals.

Increase SVR
Decrease PVR
Maintain Contractility and HR
Increase Preload

Question 42

Failure of the fossa ovalis to close results in what type of atrial septal defect?

Perimembranous
Sinus venosus
Secundum
Primum

Answer 42

Secundum

There are three types of atrial septal defects:
Secundum ASDs occur in the middle of the atrial septum and result when the fossa ovalis fails to close. This type of ASD represents ~ 80% of all ASDs.

Primum ASDs occur in the lower region of the atrial septum, just above the tricuspid valve.

Sinus venosus ASDs are located just below the IVC or less commonly just above the IVC.

The most common type of ventricular septal defect is the perimembranous VSD. It is located in the middle of the ventricular septum, just below the septal leaflet of the tricuspid valve.

Question 43

A patient is undergoing surgical repair for coarctation of the aorta. Select the BEST site to monitor the arterial blood pressure.

Right arm
Right leg
Left arm
Left leg

Answer 43

Right arm

Coarctation of the aorta occurs when the aorta narrows in the area of the ductus arteriosus.

Since the aorta is narrowed, the LV must generate a higher pressure to overcome the increased aortic resistance. Severe narrowing can limit the amount of blood delivered to the lower half of the body.

Although rare, coarctation may occur proximal to the left subclavian artery, reducing perfusion to the left upper extremity. For this reason, the right upper extremity is the best site to measure blood pressure.

Question 44

The patient scheduled for a Fontan procedure MOST likely has a diagnosis of:

transposition of the great arteries.
Ebstein’s anomaly.
hypoplastic left heart syndrome.
truncus arteriosus.

Answer 44

Hypoplastic left heart syndrome

​All patients with a single ventricle require surgical correction with the Fontan procedure.

Hypoplastic left heart syndrome is the most common single ventricle lesion.

Question 45

Compared to epiglottitis, which findings are MORE likely to occur with laryngotracheobronchitis? ​ (Select 3.)

Age affected < 2 years
Onset between 24 - 72 hours
High fever
Steeple sign
Tripod position
More likely to require anesthesia for urgent airway control

Answer 45

Age affected < 2 years
Onset between 24 - 72 hours
Steeple sign

It is essential that you understand the similarities and differences between epiglottitis and croup.

Question 46

When diluted into 2.5 mL of 0.9% sodium chloride, what is the MOST appropriate dose of racemic epinephrine to administer to the child with postintubation croup?

0.5 mL of a 0.25% solution
0.5 mL of a 2.25% solution
5 mL of a 0.25% solution
5 mL of a 2.25% solution

Answer 46

0.5 mL of a 2.25% solution

Racemic epinephrine and dexamethasone serve as the cornerstone in the treatment of postintubation croup.

Racemic epinephrine = 0.5 mL of 2.25% solution diluted in 2.5 mL of 0.9% NaCl
Dexamethasone = 0.25 - 0.5 mg/kg IV

Question 47

A five-year-old child presents for surgery with clear rhinorrhea, but she is afebrile and appears active. Rank the following airway techniques from most to least favorable.

(One is the most favorable and three is the least favorable)

Answer 47

Facemask ​ + ​ 1
LMA ​ + ​ 2
Endotracheal tube ​ + ​ 3

Although this child can reasonably proceed to surgery, you should recognize that she is at a higher risk of pulmonary complications.​

Since mechanical stimulation of the airway increases the risk of bronchospasm 10-fold, you should select the least stimulating airway to satisfy the demands of the surgical procedure.

Facemask > LMA >>> Endotracheal tube
​
Having said this, if the child requires a secure airway, you are going to provide a secure airway.

Question 48

A three-year-old child aspirated a peanut and presents for rigid bronchoscopy. What is the MOST important anesthetic consideration for this patient?

Positive pressure ventilation
Rocuronium
Observing NPO guidelines
Inhalation induction

Answer 48

Inhalation induction

Foreign body aspiration in a child presents a precarious situation. The primary goals include preventing complete airway obstruction as well as preventing the foreign body from migrating distally in the airway.

Positive pressure ventilation can push the foreign body deeper into the bronchial tree, increasing the difficulty of its retrieval. Therefore, a sevoflurane induction that preserves spontaneous ventilation is usually the best approach.

Observation of NPO guidelines must be weighed against the risk of airway compromise.

Question 49

Which congenital condition is associated with macroglossia?

Trisomy 21
Treacher Collins
Glucose-6-dehydrogenase deficiency
Klippel-Feil

Answer 49

Trisomy 21

Trisomy 21 (Down syndrome) presents with macroglossia (large tongue). This finding increases the risk of upper airway obstruction.

Question 50

What is the MOST common cardiac anomaly associated with Down syndrome?

First degree heart block
Bicuspid aortic valve
Atrioventricular septal defect
Single ventricle

Answer 50

Atrioventricular septal defect

Approximately 50% of infants with Down syndrome have coexisting cardiac disease:

Most common ​ = ​ Atrioventricular septal defect
Second most common ​ = ​ Ventricular septal defect

Question 51

Match each congenital condition with is MOST likely presentation.

VACTERL association ​ ​
CHARGE association ​ ​
CATCH 22 syndrome ​

Choanal atresia
Hypocalcemia
Renal dysplasia

Answer 51

VACTERL association ​ + ​ Renal dysplasia
CHARGE association ​ + ​ Choanal atresia
CATCH 22 syndrome ​ + ​ Hypocalcemia

Question 52

A 70-kg patient can walk up two flights of stairs without stopping. How much oxygen is consumed per minute during this activity?

250 mL
500 mL
1,000 mL
1,500 mL

Answer 52

1,000 mL

One metabolic equivalent (MET) corresponds to an oxygen consumption of 3.5 mL/kg/min.

Walking up two flights of stairs without stopping is equal to 4 METs and consumes ~ 1,000 mL O2/min.
Inability to achieve 4 METs is associated with increased perioperative risk.

Question 53

Which factor increases in the elderly?

PaO2
Lung elasticity
Dead space
Chest wall compliance

Answer 53

Dead space

Increased dead space necessitates an increased minute ventilation to maintain a normal PaCO2.

​Aging is associated with a reduction in PaO2, lung elasticity, and chest wall compliance.

Taken together, these changes reduce pulmonary reserve and increase the risk of respiratory failure.

Question 54

Which volumes and capacities are increased in the 70-year-old patient? ​ (Select 3.)

Expiratory reserve volume
Total lung capacity
Functional residual capacity
Residual volume
Closing capacity
Vital capacity

Answer 54

Residual volume
Functional residual capacity
Closing capacity

Aging produces the following changes:
Increased: ​ RV, FRC, and CC
Decreased: ​ VC and ERV
Unchanged: ​ TLC

Question 55

All of the following changes occur in the cardiovascular system in response to aging EXCEPT:

fibrosis of the cardiac conduction system.
increased venous capacitance.
loss of elastin in arterial wall.
diastolic dysfunction.

Answer 55

Increased venous capacitance

Our veins become stiffer as we age, and this reduces venous capacitance (the volume of blood the veins can hold).

In the OR, this manifests as greater blood pressure lability with anesthetic induction or during acute blood loss.

Question 56

Which factor remains unchanged in the healthy geriatric patient?

Systolic function

Systemic vascular resistance

Lusitropy

Pulse pressure

Answer 56

Systolic function

Systolic function is usually preserved in the healthy geriatric patient.

Why are the other answers wrong?

The arterial tree becomes stiffer over time, signifying a reduction in compliance. This increases SVR and SBP.
The pulse pressure widens, because SBP increases to a much greater degree than DBP.
The aged heart is slower to return Ca+2 into the sarcoplasmic reticulum during diastole, and this slows the rate of myocardial relaxation (decreased lusitropy).

Question 57

Which factor decreases as a result of the aging process?

Incidence of orthostatic hypotension
Baroreceptor sensitivity
Sympathetic tone
Plasma norepinephrine concentration

Answer 57

Baroreceptor sensitivity

​Aging is associated with a decline in baroreceptor sensitivity. This increases the incidence of orthostatic hypotension and contributes to the greater degree of hemodynamic compromise following sympathectomy associated with neuraxial anesthesia.

Aging is associated with an increased sympathetic tone and increased plasma norepinephrine concentration. Despite this, end organs are less responsive to adrenergic stimulation.

Question 58

By what percentage does MAC decrease for each decade of life after 40 years of age? ​

(Enter your answer as a percentage)

Answer 58

6% per decade

MAC decreases by 6% for each decade of life after 40 years of age. In the 80-year old-patient, MAC is reduced by approximately 25%.

Question 59

Identify the statement that MOST accurately describes neuraxial anesthesia in the elderly patient. ​ (Select 2.)

Spinal anesthesia is associated with a lesser spread of local anesthetic.
Epinephrine test dose has a higher rate of false negative results.
Epidural anesthesia is associated with a greater spread of local anesthetic.
CSF volume is increased.

Answer 59

Epinephrine test dose has a higher rate of false negative result

Epidural anesthesia is associated with a greater spread of local anesthetic

Decreased beta receptor sensitivity in the myocardium reduces the efficacy of an epinephrine test dose (higher rate of false negative results).

​Epidural anesthesia is associated with greater spread of LA because of a reduction in epidural space volume.

Spinal anesthesia is associated with greater spread of LA because of a reduction in CSF volume.

Question 60

Which factor is unchanged in the geriatric patient?

Aldosterone
Creatinine clearance
Serum creatinine
Glomerular filtration rate

Answer 60

Serum creatinine

Serum creatinine remains stable as we age. On the one hand, muscle mass is reduced, so the body produces less creatinine. On the other hand, GFR is reduced so we excrete less creatinine. These changes cancel each other out, leaving the serum creatinine unchanged.

Why are the other answers wrong?
GFR decreases by 1 mL/min/year after age 40.
Age is included in the creatinine clearance formula. This should tip you off that it changes as a function of age.
Decreased aldosterone sensitivity impairs the ability to conserve sodium.

Question 61

All of the following decrease as a normal response to aging EXCEPT:

hepatic blood flow.
alpha1-acid glycoprotein.
pseudocholinesterase.
albumin.

Answer 61

Alpha 1-acid glycoprotein

Alpha 1-acid glycoprotein binds basic drugs. Its production is increased.

Albumin binds acidic drugs. Its production is reduced, particularly in those with poor nutrition.

Pseudocholinesterase production is reduced. This can prolong the duration of succinylcholine, especially in men.

Hepatic blood flow is decreased. In consequence, less drug is delivered to the liver per unit time. This can prolong elimination of drugs with a high hepatic extraction ratio (fentanyl, lidocaine, metoprolol).

Question 62

How does aging affect the pharmacokinetics of anesthetic drugs? ​ (Select 2.)

Increased volume of distribution of propofol
Increased volume of distribution of rocuronium
Faster induction with thiopental
Faster induction with sevoflurane

Answer 62

Increased volume of distribution of propofol
Faster induction with sevoflurane

Total body fat is increased. This accounts for the larger Vd for lipophilic drugs (propofol).

Total body water and blood volume are decreased. This accounts for the smaller Vd for hydrophilic drugs (rocuronium).

Decreased cardiac output prolongs circulation time. This causes a faster inhalation induction and a slower IV induction.

Question 63

Cardiovascular changes that accompany a normal pregnancy include an increased: ​ (Select 3.)

plasma volume.
diastolic blood pressure.
systemic vascular resistance.
systolic blood pressure.
stroke volume.
heart rate.

Answer 63

Heart rate
Stroke volume
Plasma volume

During pregnancy, the cardiovascular system must adapt to support a growing mother and fetus.

You will most likely be asked about these changes on boards. Don’t freak out when you see that something increases by 40% in one book and that same variable increases by 50 percent in another book. Know the trends! Trust me, I know this is difficult for you type-A folks (I’m one of them). Rant over …

Several weeks after conception, SVR decreases with a compensatory rise in cardiac output and RAAS activity (sodium retention → increased plasma volume).

Diastolic BP decreases due to a reduction in SVR.
Systolic BP is unchanged.

Key Cardiovascular Changes During Pregnancy:
Cardiac output ​ (↑ 40 - 50%)
Stroke volume ​ (↑ 30%)
Heart rate ​ (↑ 15%)

Peripheral circulation
SBP ​ (no change)
DBP ​ (↓ 15%)
SVR ​ (↓ 15%)
​
Intravascular fluid volume ​ (↑ 35%)
Plasma volume ​ (↑ 45%)
Erythrocyte volume ​ (↑ 20%)

Question 64

A pregnant mother has a history of mitral stenosis. When is she at GREATEST risk of hemodynamic compromise?

Second trimester
Third trimester
Second stage of labor
Third stage of labor

Answer 64

Third stage of labor

You must know how cardiac output changes throughout pregnancy AND during labor and delivery.

Cardiac output changes during pregnancy:
First trimester ​ = ​ 35% over baseline
Second trimester ​ = ​ 50% over baseline
Third trimester ​ = ​ 50% over baseline
​Cardiac output changes during labor (uterine contraction → autotransfusion)

First stage of labor ​ = ​ 10 – 25% over prelabor value
Second stage of labor ​ = ​ 40% over prelabor value
Third stage of labor (after delivery) ​ = ​ 80 – 100% over prelabor value

Patients with a history of valvular stenosis or pulmonary hypertension are at greatest risk of hemodynamic compromise when cardiac output is the highest (third stage of labor).

Question 65

P50:

decreases in the mother and increases in the fetus.
increases in the mother and decreases in the fetus.
remains constant in the mother and decreases in the fetus.
remains constant in the mother and increases in the fetus.

Answer 65

Increases in the mother and decreases in the fetus

The oxyhemoglobin dissociation curve tells us the tendency of hgb to bind oxygen, and the P50 is the PaO2 where hgb is 50% saturated by oxygen (normal = 26.5 mmHg).

A higher P50 reflects a right shift ​ (right = release)
A lower P50 reflects a left shift ​ (left = love)
​
To ensure fetal oxygenation, there has to be an oxygen concentration gradient from mother to fetus. This is accomplished by changes in the P50.

Maternal P50 is higher = 30 mmHg ​ (↑ 2,3-DPG)
Fetal P50 is lower = 19 mmHg ​ (does not respond to 2,3-DPG)
​
The higher P50 in the mother and the lower P50 in the fetus ensures O2 offloading across the placenta.

Question 66

Which arterial blood gas is MOST likely to occur in a pregnant patient’s first trimester?

7. 45 / 31 / 85 / 19
8. 33 / 44 / 96 / 19
9. 36 / 36 / 97 / 22
10. 42 / 30 / 101 / 20

Answer 66

7.42 / 30 / 101 / 20

Progesterone is a respiratory stimulant, increasing minute ventilation up to 50 percent (↑ Vt > ​ ↑ RR).

Primary event ​ = ​ PaCO2 decreases to ~ 30 mmHg (respiratory alkalosis)
Renal compensation ​ = ​ HCO3- decreases to ~ 20 mEq/L (metabolic acidosis)
pH is unchanged or very slightly increased
​
A small reduction in physiologic shunt explains the mild increase in PaO2 (~ 100 mmHg). This increases the driving pressure of oxygen across the placenta and improves fetal oxygenation.

Question 67

All of the following increase the risk of pulmonary aspiration before the onset of labor EXCEPT:

decreased gastric emptying.
decreased gastroesophageal barrier pressure.
increased gastrin secretion.
increased progesterone production.

Answer 67

Decreased gastric emptying

After 20 weeks gestation, the pregnant patient is a higher risk of gastroesophageal reflux, which augments the risk of pulmonary aspiration. In short, this is caused by increased gastric acid production and a decreased esophageal barrier pressure.

Gastric acid production is increased by:
↑ Gastrin production by the placenta

Lower esophageal sphincter tone is decreased by: ​
↑ Progesterone
↑ Estrogen
Cephalad movement of uterus (alters gastroesophageal geometry)
Gastric emptying does NOT change during pregnancy. During labor, however, gastric emptying slows as a function of pain, anxiety, SNS stimulation, and opioids (IV and neuraxial).

Question 68

Physiologic effects of progesterone during pregnancy include: ​ (Select 3.)

decreased MAC.
decreased PaCO2.
decreased renin.
increased sensitivity to local anesthetics.
increased systemic vascular resistance.
increased lower esophageal sphincter tone.

Answer 68

Decreased MAC
Decreased PaCO2
Increased sensitivity to local anesthetics

The old adage says that when you’re in doubt, go with progesterone as the cause of the physiologic changes in pregnancy. While that may work if you’re given a list of hormones, it falls flat on its face when you’re asked a question specific to progesterone.

Progesterone Increases:
Minute ventilation (↓ PaCO2 & ↑ HCO3- excretion)
RAAS activity ​ (↑ blood volume ​ → ​ ↑ cardiac output)
Vascular muscle relaxation (↓ SVR & ↓ PVR)
Sensitivity to local anesthetics
​Progesterone Decreases:

Airway resistance (↑ bronchodilation)
MAC
Lower esophageal sphincter tone

Question 69

Which drugs undergo the GREATEST amount of uteroplacental transfer? ​ (Select 3.)

Glycopyrrolate
Rocuronium
Lidocaine
Magnesium
Heparin
Desflurane

Answer 69

Desflurane
Lidocaine
Magnesium

Diffusion is the primary mechanism by which a drug passes from the maternal circulation to the fetus. As a general rule, if a drug diffuses across the blood-brain-barrier, then it will also diffuse across the placenta.

Factors that determine the maternal-fetal gradient:
Maternal plasma concentration
Maternal plasma protein binding
Drug ionization
Drug lipid solubility
Drug molecular weight
​
Tell me more about molecular weight…
A drug with a MW < 500 Daltons will easily diffuse across the placenta unless it is highly ionized.
A drug that is > 1000 Daltons usually won’t cross the placenta.
​
Drugs with poor placental transfer tend to be highly ionized:
Succinylcholine ​
Nondepolarizing neuromuscular blockers
Heparin
Glycopyrrolate
Insulin
​
Drugs with significant placental transfer tend to be lipophilic:
Benzodiazepines
Opioids
Volatile anesthetics
IV anesthetics (usually not a problem)
Local anesthetics (except chloroprocaine d/t rapid metabolism)
Atropine
Beta-blockers

Magnesium isn’t lipophilic but it’s small, so it can easily diffuse across the placenta. Fetal hypermagnesemia can contribute to skeletal muscle weakness after delivery.

Remember that fetal pH is slightly more acidic than the mother’s, so weak bases in the fetal circulation will ionize to a greater degree. This is the basis of fetal ion trapping, and is most likely to occur when increasing maternal alkalosis and increasing fetal acidosis.

Question 70

Side effects of beta agonist therapy for preterm labor include:

maternal hypoglycemia.
maternal hypokalemia.
fetal hyperglycemia.
fetal bradycardia.

Answer 70

Maternal hypokalemia

Beta-2 agonists (ritodrine and terbutaline) are tocolytic agents that stop or slow preterm labor. These drugs reduce uterine tone by increasing intracellular cAMP and progesterone release.

While you’ll likely never encounter these drugs in practice (ritodrine and terbutaline), we included them for historical context along with the fact that learning about them helps solidify the connection between pharmacology and physiology.

Maternal side effects:
Hyperglycemia results from glycogenolysis in the liver.
Hypokalemia results from an intracellular potassium shift.
Tachycardia
Fetal side effects:

The newborn of a hyperglycemic mother is a risk of post-delivery hypoglycemia. The mother’s glucose supply is gone, but the insulin in the neonatal circulation remains.
Beta-2 agonists cross the placenta and may increase FHR (Beta-1 crossover effect).

Question 71

Which local anesthetic is LEAST likely to undergo fetal ion-trapping?

Chloroprocaine
Mepivacaine
Lidocaine
Bupivacaine

Answer 71

Chloroprocaine

To answer this question, we have to know how much of the local anesthetic is available to reach the fetus.

Chloroprocaine is an ester-type local anesthetic. Because it is metabolized by pseudocholinesterase in the plasma, very little of chloroprocaine (if any) reaches the fetus. Therefore, fetal ion-trapping is not a significant concern when chloroprocaine is used.

Lidocaine, bupivacaine, and mepivacaine are amide-type local anesthetics. They have much longer half-lives, so more of the drug is delivered to the placenta over time.

Question 72

A mother in labor complains of dull and diffuse pain in her abdomen. Choose the statements that BEST describe her pain. ​ (Select 2.)

A pudendal nerve block will treat the pain.
Afferent pain travels through the hypogastric plexus.
Pain is transmitted to the T10-L1 segments of the spinal cord.
The cervix is fully dilated.

Answer 72

Afferent pain travels through the hypogastric plexus

Pain is transmitted to the T10 – L1 segments of the spinal cord

You must be able to differentiate between pain related to the 1st and 2nd stages of labor.

Pain specific to the first stage of labor:
Afferent pathway = somatic C-fibers → hypogastric plexus
Spinal segments = T10-L1 (posterior nerve roots)
Quality of pain = diffuse, cramping & dull
Specific neuraxial techniques = paracervical block, paravertebral lumbar sympathetic block
​Pain specific to the second stage of labor:

Afferent pathway = pudendal n.
Spinal segments = S2-S4 (posterior nerve roots)
Quality of pain = well localized & sharp
Specific neuraxial technique = pudendal n. block
​
A spinal, epidural, or CSE will provide analgesia for uterine, cervical, and/or perineal pain.

A technique that provides analgesia to T10-L1 during the first stage of labor must be extended to cover T10-S4 during the second stage of labor.

Question 73

Which analgesic technique is associated with the HIGHEST incidence of fetal bradycardia?

Combined spinal/epidural
Paravertebral lumbar sympathetic block
Paracervical block
Pudendal block

Answer 73

Paracervical block

Fetal bradycardia is a common complication of a paracervical block, especially if bupivacaine is used.

​

Question 74

A patient requires a forceps delivery. She is receiving a continuous epidural infusion of 0.125 percent bupivacaine for labor pain. What are the BEST analgesic options for this procedure? ​ (Select 2.)

Bolus 3 percent chloroprocaine in the epidural

Paracervical nerve block
Continue the current epidural infusion
Pudendal nerve block

Answer 74

Bolus 3 percent chloroprocaine in the epidural
Pudendal nerve block

The dose of a laboring epidural by itself does not provide sufficient analgesia during a forceps delivery.

Analgesic options include:
Bolusing the epidural with a higher concentration of a rapidly acting local anesthetic, such as 1-2 percent lidocaine or 2-3 percent chloroprocaine.
If you were unable to bolus the epidural or if there is no epidural in place, then you could perform a “second-stage” spinal or pudendal nerve block.

Question 75

An OB/GYN physician requests an inhalation technique to provide analgesia for her patient’s labor pain. Which technique is MOST appropriate to use on the labor and delivery floor?

50% nitrous oxide + 50% oxygen administered by the labor and delivery RN
0.5% sevoflurane + 100% oxygen administered by the labor and delivery RN
50% nitrous oxide + 50% oxygen self-administered by the patient
An anesthesia provider must be present to provide an inhalation agent

Answer 75

50% nitrous oxide + 50% oxygen administered by the patient

Inhaled nitrous oxide is making a resurgence as a non-invasive alternative for labor analgesia. A common (and safe) approach is 50% nitrous oxide + 50% oxygen self-administered by the patient via facemask.

When administered alone (not with opioids), a 50/50 N2O/O2 mixture is not associated with hypoxia, loss of airway reflexes, or unconsciousness. Additionally, it preserves uterine contractility, and it does not cause neonatal depression

Halogenated agents are not used for labor analgesia.

Question 76

A healthy, 40-week parturient requests an epidural for labor pain. She is concerned she won’t be able to eat or drink. According to the ASA Practice Guidelines for Obstetric Anesthesia, this patient:

may eat solid food before the epidural is placed.
must stop clear liquids after the epidural is inserted.
can continue to eat and drink until she enters the second stage of labor.
should abstain from eating or drinking until the baby is delivered.

Answer 76

May eat solid food before the epidural is placed
​
Having a baby is serious work! The laboring mother requires adequate nutrition and hydration to support her and the baby during labor.

It doesn’t matter when mom last ate or drank - she is always considered a full stomach! According to the ASA Practice Guidelines for Obstetric Analgesia, the laboring mother who is healthy may:

Drink a moderate amount of clear liquids throughout labor.
Eat solid food up to the point a neuraxial block is placed.
​
If there is a high probability of a surgical intervention requiring a general anesthetic, the patient should remain NPO.

Question 77

A healthy patient is entering the latent phase of labor and requests an epidural. What is the MOST appropriate action at this time?

Wait until the patient has been NPO > 2 hours.
Obtain a platelet count, then proceed if > 75,000/uL.
Approve the request with the consent of the obstetrician.
Wait until the cervix has dilated to 5 cm.

Answer 77

Approve the request with the consent of the obstetrician

The American College of Obstetricians and Gynecologists (ACOG) Guidelines for Assessment of the Obstetric Patient provide direction for the safe management of obstetric patients. They recommend that the timing of epidural placement should be individualized to each patient, and a patient should not have to wait until she achieves 4 – 5 cm cervical dilation before she can receive analgesia. Therefore, after it is approved by the obstetrician, it is ok to proceed with the epidural placement.

Clear liquids may be administered before and after epidural placement.

A routine platelet count is unnecessary in healthy patients without a history of abnormal bleeding

Question 78

Compared to a single-shot intrathecal anesthetic, the epidural volume extension technique:

is more likely to cause hypotension.
uses a smaller initial dose of local anesthetic.
is associated with a slower onset.
enhances caudal spread of the local anesthetic.

Answer 78

Uses a smaller initial dose of local anesthetic

The combined spinal-epidural anesthesia (CSE) technique provides the dual benefit of a rapid onset of spinal anesthesia and the ability to prolong the duration of anesthesia with an indwelling epidural catheter. This technique is particularly useful in labor and delivery.

The epidural volume extension (EVE) technique involves injection of saline into the epidural space immediately after the local anesthetic is administered into the subarachnoid space. Adding volume to the epidural space compresses the subarachnoid space, and this enhances the rostral spread of the local anesthetic. Said another way, this technique pushes the LA towards the brain to achieve a higher level for a given dose.

Administering a smaller dose of local anesthetic in the subarachnoid space provides a more stable hemodynamic profile as well as a faster recovery.

The epidural may be dosed if additional anesthesia is required.

Question 79

All of the following are consistent with subdural placement of an epidural catheter EXCEPT a/an:

negative test dose for intravascular injection.
rapid onset of anesthetic action.
higher than expected spread of local anesthetic.
negative test dose for intrathecal injection.

Answer 79

Rapid onset of anesthetic action

Although it’s a rare event, it’s possible to accidentally place the epidural catheter in the subdural space (in-between the dura and the arachnoid).

Can a test dose rule out subdural catheter placement?

No! The test dose will be negative for both intrathecal and intravascular placement.
​
How does a subdural injection present?
After a 10 - 25 minute delay (no apparent clinical effect), the patient will develop a high block very rapidly.
Because the subdural space is a potential space, its volume is small, so even a small dose of local anesthetic has the potential to create a high block.
Respiratory compromise as well as a total spinal are possible.
Treatment is supportive (airway control and hemodynamic support) until the block recedes.
​
A subdural injection is also a possible cause of a failed spinal. Since the dose for a subarachnoid block is comparatively much smaller than an epidural, the clinical effect will be negligible.

Question 80

A 32-week parturient presents with painless vaginal bleeding. The MOST likely diagnosis is:

uterine atony.
uterine rupture.
placenta previa.
abruptio placentae.

Answer 80

Placenta previa

Placenta previa, abruptio placenta, uterine rupture, and uterine atony increase the risk of obstetric bleeding. Remember that the placenta receives 500 - 700 mL/min or 10% of the cardiac output, so uterine bleeding can become a true emergency.

Placenta previa occurs when the placenta covers all or part of the cervical os.

The hallmark presentation is painless vaginal bleeding ~ 32 weeks gestation.
Risk factors include: ​ previous c-section, advanced maternal age, and multiple parity.
​
Abruptio placentae occurs when the placenta prematurely separates from the endometrium.

This always presents with abdominal pain.
This may present with or without vaginal bleeding (bleeding may occur behind the placenta).

Risk factors: ​ cocaine, methamphetamines, alcohol, hypertension, and multiparity.
There is a high risk of DIC.
​
Uterine rupture can range from incomplete to total rupture.

This always presents with severe abdominal pain.
Referred shoulder pain is the result of diaphragmatic irritation secondary to intraabdominal blood.
Uterine rupture can be masked by an existing epidural.
Any patient with an existing epidural who develops new onset abdominal pain should be evaluated for uterine rupture.
​
Uterine atony only presents a bleeding problem after delivery.

Question 81

What is the MOST common cause of postpartum hemorrhage?

Uterine inversion
Cervical laceration
Uterine atony
Placental retention

Answer 81

Uterine atony

Hemorrhage is the most common serious obstetric complication, and uterine atony is the most common cause of postpartum hemorrhage. Other causes include:

Anatomic abnormalities
Uterine inversion
Lacerations
Disordered coagulation
Retained placenta
​
Oxytocin, methergine, prostaglandin, and/or an intrauterine balloon (to tamponade bleeding) are treatments for uterine atony.

If the uterine atony is caused by retained placenta, then nitroglycerine is the treatment of choice. It relaxes the uterus and facilitates its manual removal. Because nitroglycerine also relaxes the vasculature (mostly venous), you must take the patient’s volume status into account.

Question 82

A patient with preeclampsia is receiving a magnesium sulfate infusion. She appears lethargic with shallow respirations and has an irregular pulse. What are the BEST treatments at this time? ​ (Select 2.)

Furosemide
Activated charcoal
Calcium gluconate
Potassium chloride

Answer 82

Calcium gluconate
Furosemide

This patient is suffering from hypermagnesemia. The most common etiology of this complication is overdose during magnesium therapy.

The first sign of magnesium toxicity is loss of deep tendon reflexes (4 - 6.5 mEq/L or 10 - 12 mg/dL…watch your units!)
​
Hypermagnesemia is treated with calcium gluconate 10 - 15 mg/kg IV and diuresis and/or dialysis. Cardiopulmonary support may be required as well.

Question 83

All of the following are appropriate during a cesarean section under general anesthesia EXCEPT a/an:

Datta handle.
6.0 endotracheal tube.
nasal airway.
rapid sequence induction.

Answer 83

Nasal airway

The parturient is at higher risk of difficult mask ventilation, difficult laryngoscopy, and difficult intubation.

Increased progesterone, estrogen, and relaxin cause vascular engorgement and hyperemia. Combined with an increased extracellular fluid volume, this leads to upper airway swelling, affecting the nasal passages, oropharynx, epiglottis, larynx, and trachea. Epistaxis and airway narrowing can also occur. ​ Your anesthetic plan must take these changes into account:
Mallampati score increases during pregnancy.
Difficult and failed intubation is 8 times higher in full term patients.
The glottic opening is narrowed; a downsized (6.0 – 7.0) endotracheal tube should be used.
A short handled laryngoscope (Datta handle) is useful for women with large breasts.
Airway manipulation may cause tissue trauma and bleeding. The tissue in the nasopharynx is particularly friable, so insertion of an artificial airway into the nasopharynx should be avoided. ​ ​
Airway edema is made worse by pre-eclampsia, tocolytics, and prolonged Trendelenburg position.

Question 84

During an emergency cesarean section, the surgeon should make incision immediately after:

mask ventilation is established.
the prep solution is completely dry.
confirmation of end-tidal carbon dioxide.
the patient loses consciousness.

Answer 84

Confirmation of end-tidal carbon dioxide

The goals of anesthetic induction for an emergency C-section include securing the airway and delivering the baby as soon as possible.

Before induction:
The patient is prepped.
The entire surgical team is ready.

During induction:
Rapid sequence induction with cricoid pressure (do NOT mask ventilate).
If hemodynamically stable, then propofol 2.0-2.5 mg/kg IV.
If NOT hemodynamically stable, then ketamine 1 mg/kg IV or etomidate 0.3 mg/kg IV.
After confirmation of successful endotracheal intubation (+EtCO2):

Surgery should begin promptly to minimize neonatal depression.

Question 85

When is the BEST time to perform non-obstetric surgery on the parturient?

First trimester
Second trimester
Third trimester
The timing of surgery does not affect fetal outcome.

Answer 85

Second trimester

In an ideal world, elective surgery is delayed until 2 - 6 weeks postpartum.

From time to time, however, non-obstetric surgery must be performed in the pregnant patient. If possible, it should be performed during the second trimester.

First trimester: ​ Increased risk to fetal organ development (organogenesis)
Second trimester: ​ This is the best time
Third trimester: ​ Increased risk of premature delivery
​
GI prophylaxis should be administered to all pregnant patients and left uterine displacement should be used for those in the second and third trimesters.

A note on teratogenicity …
There is concern that benzodiazepines administered during the first trimester contribute to cleft palate. While there is some truth to this in mothers receiving high-dose diazepam, Hines says that there is no data to justify this concern when midazolam is used for preoperative sedation.

Question 86

Cardiovascular complications of chronic maternal cocaine abuse include all of the following EXCEPT:

ephedrine resistant hypotension.
thrombocytopenia.
myocardial ischemia.
anemia.

Answer 86

Anemia

Cocaine is an ester-type local anesthetic that inhibits NE reuptake in the presynaptic SNS neuron. Flooding the synaptic cleft with NE increases SNS tone.

Chronic cocaine abuse is associated with thrombocytopenia (check platelet count before neuraxial anesthesia). Other risks include tachycardia, dysrhythmias, and myocardial ischemia.

Hypotension may not respond to ephedrine in chronic cocaine abusers (d/t catecholamine depletion). Phenylephrine is the best option.

Question 87

The fetal heart rate monitor shows bradycardia that parallels the rise in intrauterine pressure. This finding is MOST likely the result of:

umbilical cord compression.
maternal hypertension.
fetal head compression.
fetal acidosis.

Answer 87

Fetal head compression

Fetal heart rate monitoring provides an indirect method to assess for fetal hypoxia. Fetal oxygenation is a function of uterine and placental blood flow. ​ The fetus responds to stress with peripheral vasoconstriction, hypertension, and a baroreceptor mediated reduction in heart rate.

There are three patterns of fetal decelerations: ​ early, late, and variable.

Early:
Uterine contraction compresses the fetal head.
Head compression increases vagal tone to reduce HR.
Occurs with each uterine contraction.
Onset and offset parallels uterine contraction.

Late:
Related to decreased uteroplacental perfusion.
FHR decreases after peak uterine contraction then returns to baseline after completion of the contraction.
Caused by maternal hypotension, hypovolemia, acidosis, preeclampsia.
Requires urgent assessment of fetal status.
​
Variable:
FHR shows no consistent pattern with uterine contraction.
Umbilical cord compression causes a baroreceptor mediated ↓HR.
Decelerations are typically self-limiting.
Fetal compromise will prolong the FHR recovery time.
Persistent decelerations require urgent assessment of fetal status.

Question 88

Congenital defects associated with Tetralogy of Fallot include all of the following EXCEPT:

right ventricular outflow tract obstruction.
atrial septal defect.
right ventricular hypertrophy.
aorta that overrides the pulmonary artery.

Answer 88

Atrial septal defect

Tetralogy of Fallot is the most common cyanotic congenital heart defect.

There are four abnormalities associated with this disease:
Right ventricular outflow tract obstruction - due to a narrowed or stenotic pulmonic valve
Right ventricular hypertrophy - due to pressure overload from the RV obstruction
Ventricular septal defect - due to septal malalignment
An overriding aorta that receives blood from both ventricles
​
Because there is a resistance at the PA outflow tract, blood is shunted across the VSD. This creates a R → L shunt (cyanotic). Since blood bypasses the lungs, arterial hypoxemia ensues.

The shunt is made worse by conditions that:
Increase PVR (hypercarbia, acidosis, hypoxemia, PEEP)
Decrease SVR ​ (volatile agents, histamine release)
Increase myocardial contractility
​
A R → L shunt speeds the onset of action of IV drugs.

A R → L shunt slows the onset of volatile agents (more so with less soluble agents).

Ketamine is great for these patients, because it preserves SVR. While it can increase contractility and PVR, these effects are not clinically significant in this context.

Question 89

Which congenital heart defects are associated with ventricular outflow tract obstruction? ​ (Select 2.)

Patent ductus arteriosus
Pulmonary stenosis with atrial septal defect
Tetralogy of Fallot
Atrioventricular canal defect

Answer 89

Pulmonary stenosis with atrial septal defect
Tetralogy of Fallot

An outflow tract obstruction occurs when there is a resistance to ejection of ventricular blood.

Shunt lesions with outflow tract obstruction include:

Tetralogy of Fallot
Ebstein’s anomaly
Pulmonary stenosis with atrial or ventricular septal defect
Eisenmenger’s syndrome
Shunt lesions without outflow tract obstruction include:

Atrial septal defect
Ventricular septal defect
AV canal defect
Patent ductus arteriosus
Aortopulmonary window
​

Question 90

What is the MOST common congenital heart defect in the neonate?

Coarctation of the aorta
Atrial septal defect
Ventricular septal defect
Tetralogy of Fallot

Answer 90

Ventricular septal defect

VSD is the most common congenital defect in the neonate. This can be diagnosed by echocardiography with Doppler or cardiac catheterization with angiography.

The direction of blood flow across the ventricular septum is a function of SVR and PVR.

If SVR is higher, then there will be a L → R shunt (non-cyanotic).
If PVR is higher, then there will be a R → L shunt (cyanotic).

Remember that a L → R shunt increases RV volume and workload. Over time, the increased pulmonary blood flow increases PVR, and if left untreated, PVR can become higher than the SVR leading to a R → L (cyanotic) shunt.
If you are presented with a question about the most common congenital defect with a certain disease (and you are unsure of the correct answer) VSD is a smart choice. Examples might include Treacher Collins syndrome or Tetralogy of Fallot.

Question 91

All of the following are indicated in the premature neonate with respiratory distress syndrome EXCEPT:

intubation.
resuscitation with 0.9% NaCl.
exogenous surfactant.
nasal CPAP

Answer 91

Resuscitation with 0.9 percent NaCl

Fetal lungs don’t mature until 35 weeks gestation, so neonates born before this time are at risk of inadequate surfactant production and the development of respiratory distress syndrome.

Type II pneumocytes produce surfactant. It increases lung compliance by reducing alveolar surface tension (law of Laplace). Without surfactant, alveolar collapse reduces FRC and RV. This leads to V/Q mismatch, hypoxemia, and metabolic acidosis.

Therapy for RDS begins with nasal CPAP. Although this modality often eliminates the need for more invasive maneuvers, continued respiratory distress warrants tracheal intubation and exogenous surfactant.
Since oxygen delivery is the name of the game, Hct should be maintained above 40 percent. Crystalloid resuscitation causes a dilutional anemia, which reduces DO2. Albumin 5 percent is a better choice (10-20 mL/kg at a time), because a smaller volume can achieve a similar expansion of the intravascular space.

Complications that often accompany RDS include: pneumothorax, acidosis, and sudden CV decompensation.

A preductal a-line is preferred.

Question 92

Acute treatment for postintubation laryngeal edema includes all of the following EXCEPT:

nebulized racemic epinephrine 0.5 mL of 2.25% solution diluted in 2.5 mL of 0.9% NaCl
cool and humidified oxygen.
dexamethasone 0.5 mg/kg IV.
heliox.

Answer 92

Dexamethasone 0.5 mg/kg IV

Postintubation laryngeal edema (postintubation croup) typically presents within 30 - 60 minutes following extubation.

The child experiences hoarseness, a barky cough, and stridor.

Treatment includes
Cool and humidified oxygen
0.5 mL of 2.25% solution diluted in 2.5 mL of 0.9% NaCl
Heliox (helium + oxygen mixture)
Dexamethasone 0.25 - 0.5 mg/kg IV

Dexamethasone does not provide acute treatment, because it requires 4 - 6 hours to achieve peak effect.

Question 93

Risk factors for postintubation laryngeal edema include all of the following EXCEPT:

multiple intubation attempts.
laryngeal mask airway.
age < 4 years.
endotracheal cuff leak absent at 30 cm H2O pressure.

Answer 93

Laryngeal mask airway

Risk factors for the development of postintubation laryngeal edema include:
Age < 4 years
Endotracheal tube cuff leak absent above 25 cm H2O pressure (a monometer is useful to intermittently measure cuff pressure)
Traumatic or multiple intubation attempts
Prolonged intubation
Head or neck surgery
Head repositioning during surgery
History of infectious or postintubation croup
Upper respiratory tract infection
Trisomy 21
​
Remember that nitrous oxide can easily diffuse into the ETT cuff. This can increase the cuff pressure during intubation, impairing perfusion of the tracheal mucosa.

Question 94

Which statements regarding airway management in the patient with a cleft lip and palate are true? ​ (Select 2.)

Risk of aspiration is increased.
A nasopharyngeal airway is contraindicated.
An LMA is contraindicated.
There is an increased risk of difficult intubation.

Answer 94

There is an increased risk of difficult intubation
Risk of aspiration is increased

Commonly associated with other genetic disorders. Airway specific risk include:

Airway obstruction
Difficult laryngoscopy
Difficult mask ventilation if there are additional craniofacial abnormalities
Aspiration

The Dingman-Dott mouth retractor can reduce venous drainage and cause tongue engorgement. This increases the risk of post-extubation airway obstruction.

Question 95

What is the youngest post conceptual age that is appropriate for same day surgery?

(Enter your answer in weeks)

Answer 95

60 weeks (we also accepted 52 weeks)

Neonates are at risk of apnea following surgery and anesthesia. Patients less than 60 weeks post conceptual age should be admitted for 24 hour observation with an apnea monitor.

Hines states 52-60 weeks is the cutoff, but Miller and Barash say 60 weeks. While we accepted both answers, if you see a question similar to this on the NCE, 60 weeks is your best bet. ​ ​

Question 96

Calculate the fluid requirement for an 18-kg patient undergoing minor surgery lasting three hours. The patient has been NPO for 4 hours and evaporative loss is 2 mL/kg/hr.

​
(Enter your answer as total mL)

Answer 96

464 mL

Classic resuscitation guidelines recommend replacing the NPO deficit, evaporative loss, blood loss, as well as providing a maintenance rate. Since there was no blood loss noted in the stem, assume there wasn’t any. Don’t read into the question!

Maintenance = (10 kg x 4 mL/kg) ​ + ​ (8 kg x 2 mL/kg) ​ = ​ 56 mL ​ x ​ 3 hrs ​ = ​ 168 mL

NPO = 56 mL ​ x ​ 4 hr ​ = ​ 224 mL

Evaporative loss = 2 mL/kg ​ x ​ 2 hrs ​ = ​ 72 mL (don’t include the 1st hour)

Total fluid administration ​ = ​ 464 mL

Question 97

Calculate the hourly fluid maintenance rate for a 16-kg child.

​

(Enter your answer in mL/hr)

Answer 97

52 mL/hr

Unless you’re told otherwise, you should use the Holliday-Segar formula (4:2:1 rule) on the NCE. The hourly maintenance rate is calculated as the sum of:

The 1st 10 kg ​ = ​ 4 mL/kg/hr
The next 10 kg ​ = ​ 2 mL/kg/hr
Each additional kg over 20 kg ​ = ​ 1 mL/kg/hr
​
This patient weighs 16 kg, so…
(10 kg x 4 mL/hr) ​ + ​ (6 kg x 2 mL/hr) ​ = ​ 52 mL/hr

Question 98

Consequences of untreated pain in the neonate include: ​ (Select 2.)

intracerebral hemorrhage.
tachycardia.
hypotension.
hypoglycemia.

Answer 98

Tachycardia
Intracerebral hemorrhage

The fetus can experience pain as early as seven weeks gestation.

Even though the neonate has an immature sympathetic nervous system (an increased PNS tone), pain activates the SNS manifesting as tachycardia and hypertension. In fact, the combination of hypertension, an immature cerebral autoregulatory response, and a fragile cerebral vasculature predispose the neonate to intracerebral hemorrhage.

Other causes of intracerebral hemorrhage include: ​ hypoxia, hypercarbia, hyperglycemia, hypoglycemia, hypernatremia, and wide swings in blood pressure.

Question 99

What is the MOST significant risk factor for retinopathy of prematurity?

Prematurity
Sepsis
Congenital heart defect
Hyperoxia

Answer 99

Prematurity

Retinal maturation begins at 16 weeks gestation and is complete between term and 44 weeks gestation.

Vasculogenesis begins at the macula then continues outwards towards the edges of the developing retina. In the preterm neonate, retinal maturation continues for a longer period during extrauterine life.

The immature retinal blood vessels are at risk vasoconstriction and hemorrhage. Dysfunctional healing leads to scar formation and ultimately retinal detachment.

The risk of ROP varies inversely with gestational age and birth weight.

If you have to pick the most significant risk factor for ROP, then we suggest prematurity.
If the question asks about modifiable factors, then hyperoxia would be the correct choice (since you can’t control when the baby is delivered, but you can control how much O2 you administer).

Question 100

Causes of kernicterus include: ​ (Select 2.)

hyperbilirubinemia.
anemia.
inhibition of glucuronyl transferase.
insufficient glycogen storage.

Answer 100

Inhibition of glucuronyl transferase
Hyperbilirubinemia

Bilirubin is a byproduct of RBC breakdown. Any condition that increases serum bilirubin can cause kernicterus (fetal encephalopathy).

Glucuronyl transferase (phase II rxn) metabolizes bilirubin. 
This pathway is not mature at term. leaving the newborn vulnerable during the first few days of life. 
Risk factors: ​ prematurity, low plasma protein concentration, and acidosis. 
Treatment of hyperbilirubinemia includes phototherapy and exchange transfusion (rarely needed).

Question 101

What is the MOST common metabolic disturbance in the newborn?

Hyperkalemia
Hypocalcemia
Hypokalemia
Hypoglycemia

Answer 101

Hypoglycemia

Newborns have a limited supply of glycogen, and this small supply can quickly exhaust during acute stress.

Risk factors for hypoglycemia include < 48 hours of age, small for gestational age, and being born to a diabetic mother. The risk of hypoglycemia becomes less of an issue after the 1st week of life. Hypoglycemia in children older than one week should raise suspicion of an underlying disorder, such as hyperinsulinism.

Signs of hypoglycemia typically manifest when serum glucose falls below 30 – 40 mg/dL in newborns < 72 hours old and 40 mg/dL in those older than 72 hours. A good number to keep in your head is 40 mg/dL. General anesthesia masks these signs.
Treatment consists of IV 10% dextrose (2 mL/kg). If seizures are present, then dose is doubled (4 mL/kg) in order to provide adequate substrate to the brain. After the bolus, a D10 infusion at 8 mg/kg/min is titrated to maintain serum glucose > 40 mg/dL. ​

Glycosuria leads to osmotic diuresis, dehydration and increased serum osmolarity that can ultimately lead to intracerebral hemorrhage.

Question 102

Neonates are obligate:

potassium excreters.
sodium excreters.
glucose reabsorbers.
sodium reabsorbers.

Answer 102

Sodium excreters

At birth, GFR and tubular function are far from mature, and the ability to handle free water and excess solute is diminished.

A consequence of this is that newborns have a high fluid turnover. Since they are unable to reduce their urine output below 1 mL/kg/hour during the first week of life, fluid requirements can be as high as 150 mL/kg/day.

Neonates are obligate sodium excreters. The renin-angiotensin-aldosterone system attempts to conserve sodium, however the immature distal tubules fail to fully respond to aldosterone. The response to antidiuretic hormone is diminished as well. ​ ​

Nagelhout says GFR matures by 6 – 12 months, however there are other sources that say it can be as late as 2 years. Tubular function matures by 2 years.

Question 103

What is the MOST common indication for liver transplantation in children less than 2 years of age?

Alpha-1 antitrypsin deficiency
Alagille syndrome
Biliary atresia
Cystic fibrosis

Answer 103

Biliary atresia

Biliary atresia is the result of a defect in the extrahepatic bile duct system that impairs bile flow.

It presents within weeks of birth. Signs include:
Persistent jaundice (> 14 days)
Dark urine
Acholic stool (pale or clay colored)
Hepatomegaly
Splenomegaly (late sign)

Surgical correction includes:
Kasai’s operation (portoenterostomy)
Liver transplantation
Indeed, biliary atresia is the most common indication for liver transplantation in children less than two years of age.

​

Question 104

Gastroschisis:

requires earlier surgery compared to omphalocele.
presents with a hernia sac that covers the abdominal viscera.
is more common than omphalocele.
is associated with a midline umbilical cord.

Answer 104

Requires earlier surgery compared to omphalocele

Gastroschisis and omphalmocele are congenital defects of the abdominal wall which permit externalization of the abdominal viscera.

​Most cases are diagnosed by prenatal ultrasound.

Compared to omphalocele, gastroschisis:
Is associated with a periumbilical cord (usually the right).
Is usually a smaller defect in the abdominal wall.
Does not have a hernia sac covering the abdominal viscera.
Requires earlier surgery (usually within 24 hours of birth)
Is less common.
Is more commonly associated with premature birth.

Question 105

Requires earlier surgery compared to omphalocele

Gastroschisis and omphalmocele are congenital defects of the abdominal wall which permit externalization of the abdominal viscera.

​Most cases are diagnosed by prenatal ultrasound.

Compared to omphalocele, gastroschisis:
Is associated with a periumbilical cord (usually the right).
Is usually a smaller defect in the abdominal wall.
Does not have a hernia sac covering the abdominal viscera.
Requires earlier surgery (usually within 24 hours of birth)
Is less common.
Is more commonly associated with premature birth.

Answer 105

Radiation ​ + ​ Cover head with plastic
Conduction ​ + ​ Place a foam pad on the OR table
Evaporation ​ + ​ Humidify anesthetic gases

Neonates are particularly susceptible to heat loss as a result of a large surface area to body mass ratio, limited fat stores, thin skin, and inability to shiver. Up to 60 percent of the heat is lost via the head. ​

Nonshivering thermogenesis (metabolism of brown fat) is a mechanism by which the neonate maintains its body temperature. This process is mediated by the SNS (beta-3). Brown fat is stored in the scapulae, axillae, mediastinum, and retroperitoneal space. Preterm babies have a smaller reserve of brown fat. Anesthetic agents impair NST. ​

Question 106

Which age is associated with the HIGHEST isoflurane requirement?

1 month
3 months
6 months
12 months

Answer 106

Three months

Minimum alveolar concentration (MAC) varies with age.

Infant 1 - 6 months: ​ MAC is higher than the adult
Infant 2 - 3 months: ​ MAC peaks at its highest level
Neonate (0 - 30 days): ​ MAC is lower than the infant
Premature: ​ MAC is lower than neonate
​
The MAC requirement pattern for sevoflurane is different.

0 days to 6 months: ​ MAC = 3.2 percent
6 months to 12 years: ​ MAC = 2.5 percent

Question 107

In the neonate, what are the MOST reliable indicators of recovery from neuromuscular blockade? ​ (Select 2.)

A maximum inspiratory force better than -25 cm H2O
Head lift > 10 seconds
TOF ratio of 80 percent
Flexion of the knees to the chest

Answer 107

A maximum inspiratory force better than – 25 cm H2O
Flexion of the knees to the chest

The neonate isn’t going to follow commands prior to extubation, so we must rely on other measures that do not require cooperation.

Although it doesn’t provide an objective measure, many practitioners rely on visual inspection. Grimacing, elbow and hip flexion, and bringing the knees to the chest seem to correlate with adequate recovery. Although a head lift > 5 seconds is appropriate for an adult, a neonate does not have the muscle strength to raise his head.

A TOF ratio > 90 percent suggests a full recovery.

A maximum inspiratory force (MIF) less than -25 cm H2O predicts adequate recovery from neuromuscular blockade. Since this is a negative number, a MIF of -30 is better than a MIF of -25

Question 108

A neonate is experiencing succinylcholine induced hyperkalemia. Which drug(s) should be administered first?

Sodium bicarbonate
Calcium gluconate
Glucose + insulin
Albuterol

Answer 108

Calcium gluconate

The initial treatment for hyperkalemia is to antagonize the membrane effect of potassium.

Hyperkalemia brings resting membrane potential closer to threshold potential. The myocyte is more easily depolarized, and this increases the risk of lethal arrhythmias.

Calcium chloride or calcium gluconate raises the threshold potential, and this restores the distance between resting membrane potential and threshold potential.

Other treatments for severe hyperkalemia include:
​Transcellular shift:
Sodium bicarbonate 1 - 2 mmol/kg per dose
Glucose 0.3 - 0.5 g/kg as 10% glucose solution + insulin 1 unit per 4 - 5 g glucose IV
Albuterol
Hyperventilation

Potassium excretion:
Kayexalate 1 g/kg per dose (PO or enema)
Furosemide 1mg/kg per dose IV
Dialysis
Hemofiltration
​

Question 109

At what age does closing capacity exceed FRC while laying supine?

45 years
55 years
65 years
75 years

Answer 109

45 years

Closing volume is the point at which dynamic compression of the airways begin. Said another way, it is the volume above residual volume where the small airways begin to close during expiration. Things that increase closing volume include: ​ CLOSE-P

COPD
LV failure
Obesity
Supine position
Extreme age
Pregnancy
​
Closing capacity = Closing volume ​ + ​ Residual volume
In the supine patient, CC exceeds FRC at ~ 45 years of age, and in the standing position this occurs at ~ 66 years of age. ​

Question 110

What is the MOST significant risk factor for developing cancer?

Age
Obesity
Family history
Smoking

Answer 110

Age

This one shocked us a little bit too! Age is the most significant risk factor for cancer. The incidence of cancer is below 2% in the teen years and increases to 25% after age 65.

Question 111

Which statements BEST describe postoperative cognitive dysfunction? ​ (Select 2.)

It is common following cardiac surgery.
Treatment targets the underlying medical cause.
Symptoms begin within 2 - 4 days after the surgical procedure. ​ ​
The most significant risk factor is increasing age.

Answer 111

The most significant risk factor is increasing age
It is common following cardiac surgery

Postoperative cognitive dysfunction (POCD) presents insidiously over a period of weeks to months (delirium usually occurs early in the postop period). Patients complain of impaired concentration, psychomotor skills, and comprehension, and this can lead to chronic alteration in activities of daily living. Diagnosis consists of postoperative neuropsychological testing.

The cause is unknown, but it may be related to cerebral hypoperfusion, inflammation, and general anesthesia.
Advanced age is probably the most significant risk factor for developing POCD.

Other risk factors include: cardiac surgery, low level of education, high ASA status, pre-existing cognitive deficit, major surgery, long duration of surgery, and postoperative infection. Nagelhout says that inhalation anesthetics are preferred over IV agents. Hines disagrees, and says that due to the dearth of evidence, there is no reason to avoid specific agents.

There is no treatment for POCD, but luckily most cases are mild and tend to resolve after ~ 3 months. ​

Question 112

Postoperative delirium: ​ (Select 2.)

can be precipitated by urinary retention.
is treated by fixing the underlying medical cause.
has a delayed onset.
occurs more frequently in women.

Answer 112

Can be precipitated by urinary retention

Is treated by fixing the underlying medical cause and is the most common postoperative CNS complication in the elderly
​
In the elderly, delirium is the most common CNS complication postoperatively and can be seen as frequently as 60 percent in some procedures (femoral fractures). Delirium presents early in the postoperative period and can last from days to weeks. Causes of DELIRIUM include:

Drug use (what new drugs have been introduced)
Electrolyte imbalance
Lack of drugs (Withdrawal)
Infection (UTI and respiratory)
Reduced sensory input
Intracranial dysfunction
Urinary retention and fecal impaction
Myocardial event, male gender

Question 113

Which cardiovascular factors are increased in the geriatric patient? ​ (Select 2.)

Heart rate
Left ventricular lusitropy
Plasma norepinephrine concentration
Pulse pressure

Answer 113

Pulse pressure
Plasma norepinephrine concentration

Vascular elasticity is reduced in the elderly. This makes the vessels “stiffer” so we can say that their compliance is decreased. Arterial stiffness increases SBP to a greater degree than it does DBP, so pulse pressure becomes wider.

The plasma NE concentration is increased, however this causes adrenergic receptor downregulation - there is a resistance to adrenergic stimulation.

Lusitropy is the process of myocardial relaxation. Impaired ventricular Ca+2 homeostasis and a hypertrophied myocardium result in a slower rate of ventricular relaxation. These factors contribute to the diastolic dysfunction that is common in the elderly.

Heart rate decreases as a function of age (max HR = 220 - age). This population is less able to increase HR in response to hypoxia, hypotension, and hypovolemia.

Question 114

In the PACU, a patient with Parkinson’s disease is experiencing an exacerbation of extrapyramidal symptoms. What is the MOST appropriate drug to administer at this time?

Chlorpromazine
Droperidol
Diphenhydramine
Metoclopramide

Answer 114

Diphenhydramine

Parkinson’s disease is associated with a loss of dopaminergic neurons in the substantia nigra in the basal ganglia. DA inhibits the firing rate of extrapyramidal neurons. Loss of dopaminergic fibers creates a relative increase in acetylcholine activity in the extrapyramidal neurons. The patient exhibits signs of motor excitation, such as resting tremor and rigidity. Bradykinesia is one of the cardinal signs of Parkinson’s disease. ​

Knowing the pathophysiology makes the treatment obvious. There are 2 pharmacologic broad options: ​ 1.) ​ reduce Ach with an anticholinergic such as benztropine or diphenhydramine and/or 2.) increase DA with levodopa or selegiline. If a patient experiences an exacerbation of Parkinsonian signs during the perioperative period, the most appropriate choice is a drug with anticholinergic properties.

​Drugs that exacerbate Parkinsonian signs include: ​ droperidol, metoclopramide, and chlorpromazine.

Increasing age is the most common cause of Parkinson’s disease, however additional contributing factors include: ​ manganese exposure in welders and genetic predisposition.

Question 115

Aging is associated with an increased: ​ (Select 3.)

closing capacity.
lung compliance.
minute ventilation.
inspiratory reserve capacity.
vital capacity.
expiratory reserve volume.

Answer 115

Minute ventilation
Lung compliance
Closing capacity

Respiratory parameters that increase with age include:
Lung compliance
Closing capacity
Minute volume
Residual volume
FRC
Respiratory parameters that decrease with age include:

Vital capacity, forced VC
Expiratory reserve volume
Inspiratory reserve capacity
Elasticity of the lung
Chest wall compliance
Lung mass
​

Question 116

The ability to perform at least 4 METs is demonstrated by: ​ (Select 2.)

getting dressed.
walking one block slowly.
gardening.
Walking up two flights of steps without stopping

Answer 116

Gardening
Walking up a flight of steps without stopping

One metabolic equivalent is equal to the oxygen consumption by an awake patient while sitting. By convention, one MET is equal to an oxygen consumption of 3.5 mL/kg/min. Two METs equals 7 mL/kg/min, three METs equals 10.5 mL/kg/min and so on.

We can estimate the functional status of the cardiopulmonary system by determining how many metabolic equivalents a patient can perform. Mortality drops by 11 percent for each additional MET a patient can do. Assuming that cardiac status is optimized, patients who can achieve at least 4 METs can be cleared for surgery.