mucus, laryngoscope blade, suction catheter, surgical debris, or other foreign objects.

This protective reflex is mediated by the superior laryngeal nerve and manifested as

sustained closure of the glottis. Laryngospasm with complete airway obstruction can

be associated with negative pressure pulmonary edema, as patients can create a

significant amount of negative intrathoracic pressure during attempts to breathe

against an obstructed upper airway. The management consists of positive pressure

ventilation, increasing the depth of anesthesia, and occasionally a small dose of a

muscle relaxant with or without reintubation.

29. A. Tracheal intubation to facilitate mechanical ventilation is common in ICU

patients to appropriately manage failure of adequate spontaneous ventilation and/or

oxygenation. Both nasal and oral tracheal tubes are relatively safe, for at least

several weeks, while patients convalesce. When compared with prolonged oral

intubation, nasotracheal intubation may be more comfortable for the patient, more

secure (fewer occurrences of accidental self-extubations), and less likely to cause

laryngeal damage. Nasal intubation, however, has its own significant adverse events,

including significant nasal bleeding, transient bacteremia, sinusitis, and otitis media

(from obstruction of the auditory tubes).

30. C. Recognizing the anatomical differences between an adult and a pediatric airway

is important. One of the most obvious differences is the tongue itself. The pediatric

tongue is larger, in relation to the amount of free space in the oropharynx, when

compared to the adult tongue. With regards to the pediatric epiglottis, it tends to be

large and floppy with a more oblong configuration, making epiglottis control with a

laryngoscope blade more challenging. Additionally, the position of the adult larynx is

at about the level C5–C6; the pediatric larynx is more cephalad, at about the level of

the C3–C4. This is an important anatomical airway consideration, since the higher

larynx tends to be more anterior as well (Fig 16-2).

Figure 16-2.

31. A. Laryngospasm associated with airway manipulation is more likely to occur in

the presence of a URI such that surgery is typically postponed until resolution of

symptoms, typically 1 to 2 weeks. Young children, however, have frequent URIs

such that risk:benefit ratio should be considered when determining appropriateness of

proceeding versus further postponement.

32. D. Hemorrhage from a bleeding tonsillar bed in the postoperative period is a

hazardous complication. Her vitals reveal hypovolemia and as such, initial

management should be to resuscitate the patient prior to returning to the operating

room to minimize morbidity associated with anemia and hypovolemia in the setting of

repeat general anesthesia. Also assume that patient will now have a difficult airway

with a “full stomach.”

33. C. Anesthesia during laser surgery may be administered with or without an

endotracheal tube. If intubation is needed, appropriate laser-resistant endotracheal

tubes should be utilized. In this regard, remember that all PVC tubes are flammable

and can ignite when contacted by the laser beam. Using the laser intermittently,

ventilating the patient with a low concentration of combustible gases, along with

protecting adjacent tissues with saline-soaked sponges are all appropriate approaches

to minimize the fire hazards.

34. D. Airway fires are an inherent risk with laser surgery, such that a plan of action

should be considered before the case begins. The cuff of the endotracheal tube may

be filled with saline, as opposed to air, to minimize flammability should the laser

beam rupture the cuff. Inspired oxygen concentration is minimized as tolerated

(usually Fio2 of <0.50), as oxygen readily supports combustion. In the event of an

airway fire, the anesthesia circuit should be immediately disconnected to interrupt

further delivery of oxygen, followed by removal of the tube from the patient’s

airway. If the flame persists, the field should next be flooded with normal saline.

35. B. Post airway fires, it is most appropriate to leave the patient intubated for

continued observation as the presence of laryngeal and pharyngeal edema can result

in failed extubation. Therefore, this patient should be reintubated with a regular

endotracheal tube and monitored for the next 24 hours. Corticosteroids can be

considered for severe edema with absent cuff leak, but generally is not given

prophylactically.

36. B. The mixture of gases delivered into the endotracheal tube may affect the risk of

combustion during general anesthesia and laser surgery of the airway. N2O is highly

combustible and should be strictly avoided. Fio2 should be reduced to as low as

possible with an air–oxygen mixture. Helium, if available, is ideal as it is inert and

noncombustible. Though N2

is also considered safe, the mean time to ignition with

nitrogen has been found to be significantly shorter when compared to the same

concentration of helium.

37. C. In 1960s, Sanders described ventilation technique using a 16-gauge jet placed

down the side arm of a rigid bronchoscope, relying on air entrapment to continue

oxygenation with an open bronchoscope. An intermittent jet of oxygen administered

from a high-pressure source (50 psi) entrains room air to maintain supranormal

oxygen concentrations in the upper airways, which creates a diffusion gradient to the

alveolar spaces. This gradient is maintained as alveolar oxygen is constantly

consumed.

38. C. Apneic oxygenation relies on mass movement oxygenation. With the onset of

apnea, a low pressure develops in the airspace of the lungs, as more oxygen is

absorbed (230 mL/min) than CO2

is released (200 mL/min). If the airways are open,

100% oxygen supplied to the upper airways will follow the pressure gradient and

flow into the lungs, replacing the oxygen consumed. The uptake of oxygen into the

blood will then remain at relatively normal levels, recognizing that the lack of

ventilation will eventually cause marked hypercapnia and acidosis.

39. D. The configuration of the flow–volume curve during spirometry testing can be

used to demonstrate abnormalities of the larger central airways (larynx, trachea, and

main stem bronchi). The FEV1

/FVC ratio can provide diagnostic value, as

disproportionate reduction in the FEV1 as compared to the FVC is the hallmark of

obstructive lung diseases. Concern should be made regarding airway collapse

following sedation or induction of anesthesia when extrathoracic lesions are present.

If long-standing, tracheomalacia may leave the trachea weak and collapsible

postoperatively (Fig 16-3).

Figure 16-3.

40. A. Anesthesia of the nasal mucosa and nasopharynx is achieved via blockade of

trigeminal branches, particularly the sphenopalatine ganglion and ethmoid nerves.

Blockade of the glossopharyngeal and superior laryngeal nerves provide anesthesia

to the mouth, oropharynx, and base of the tongue. The hypopharynx, larynx, and

trachea are innervated via a branch of the vagus nerve (CN X), specifically the

recurrent laryngeal nerve, which can be blocked via a transtracheal approach. On the

other hand, blockade of the hypoglossal nerve (CN XII) will only serve to paralyze

the intrinsic muscles of the tongue without adding to anesthesia of the airway (Fig 16-

4).

Figure 16-4.

41. A. Inspection of the neck is generally considered the first step, as it may reveal a

life-threatening and reversible cause of airway obstruction such as a compressing

hematoma. Direct visualization of vocal cords may point toward recurrent laryngeal

nerve damage contributing to dyspnea. Though hypocalcemia due to removal of the

parathyroid glands can occur, signs and symptoms will usually present much later in

the perioperative course (24–96 hours), and unlikely to be contributing to dyspnea in

the PACU. Inhaled racemic epinephrine is commonly used when stridor is present

after extubation.

42. B. The recurrent laryngeal nerves provide motor innervation to all the intrinsic

muscles of the larynx, except the cricothyroid muscle, which is innervated by the

superior laryngeal nerve. Damage to bilateral recurrent laryngeal nerves will affect

abduction and adduction of the cords, resulting in both vocal cords adopting an

intermediate, or paramedian, position. Patient would also have associated aphonia

with risk of airway obstruction with inspiration as the cords flap together. Unilateral

damage will present with hoarseness.

43. B. In the case of lesions to the SLNs, adduction and abduction of the vocal cords

remain intact. SLN lesions instead lead to weak tensor strength (cricothyroid muscle),

leaving the voice hoarse, weak, breathy, and with the inability to scream or shout.

Other associated findings would be loss of sensation above the cords, leaving patient

vulnerable to inhalation of any material present in the pharynx.

44. A. Blunt-neck trauma is most commonly a result of a motor vehicle collision

associated with rapid acceleration or deceleration injuries, which may include

crushing injuries of the trachea, esophagus, vascular structures, and cervical spine. A

laryngeal fracture can lead to life-threatening airway obstruction and as such should

be treated in an emergent manner. Signs and symptoms of dyspnea, emphysema, and

inability to lie flat reflect a fragile airway. Definitive airway management following

airway trauma is a surgical airway, most commonly a tracheostomy.

Cricothyroidotomy is not recommended following laryngotracheal injuries, as the

landmarks are usually difficult to assess, since the cricoid is often the level of the

injury.

45. B. The neck is divided into three zones: zone I, including the thoracic inlet, up to

the level of the cricothyroid membrane, is treated as an upper thoracic injury. Zone

III, above the angle of the mandible, is treated as a head injury. In this case, fracture

of the thyroid cartilage represents an injury of the neck in zone II. For ease of

memory, consider that the cricoid cartilage demarcates the border between zones I

and II and the angle of the mandible separates zone II from zone III (Fig 16-5).

Figure 16-5.

46. D. Increasing EtCO2 and temperature may reveal possible malignant hyperthermia.

With onset of cardiac arrhythmias, and the increasing likelihood of the development

of malignant hyperthermia with rapidly climbing EtCO2 and hyperthermia, treatment

with dantrolene should be considered and pursued. Other signs that can strengthen the

diagnosis are muscle rigidity and myoglobinuria.

47. A. More than 30 different mutations are linked to malignant hyperthermia

susceptibility. Genetic testing is available to establish a diagnosis, but the CHCT

remains the criterion standard.

Obstetric Anesthesia

Thoha Pham

1. Beyond midgestation, pregnant women are at increased risk of gastroesophageal

reflux and aspiration of gastric contents for all these reasons, except

A. Decreased competence of the lower esophageal sphincter

B. Delayed gastric emptying associated with the onset of labor

C. Delayed gastric emptying due to opioid administration

D. Increased incidence of constipation

2. Changes in the cardiovascular system associated with pregnancy include

A. Increase in central venous pressure

B. Increase in cardiac output

C. Increase in systemic vascular resistance

D. Increase in blood pressure

3. During pregnancy, the disproportionate increase in plasma volume versus

erythrocyte volume accounts for

A. Increase in the mean arterial pressure

B. Increase in stroke volume

C. Increase in cardiac output

D. Relative anemia of pregnancy

4. By the third trimester of pregnancy, cardiac output increases to nearly 50% due to

which of these alterations?

A. Increase in stroke volume and increase in heart rate

B. Decrease in stroke volume and increase in heart rate

C. Increase in stroke volume and decrease in heart rate

D. Decrease in stroke volume and decrease in heart rate

5. The largest increase in cardiac output is seen during this peripartum period:

A. During induction of anesthesia

B. During the start of labor

C. Immediately after delivery

D. At conception

6. A 20-year-old G1P0

female at 42

5 weeks of gestation presents to labor and delivery

floor with rupture of membranes and onset of early labor. She appears uncomfortable

and becomes extremely anxious with peripheral IV placement, and begins to

hyperventilate. If allowed to continue hyperventilation, it will cause

A. Increased placental perfusion

B. Decreased maternal arterial pH

C. Increased fetal arterial pH

D. Decreased maternal uterine artery flow

7. In the above patient, labor is nonprogressive with signs of fetal distress on heart rate

monitoring. Spinal anesthesia with 2-chloroprocaine 3% (2 mL) is provided for

emergent cesarean section. On postpartum day 2, she complains of leg numbness,

which quickly progressed to flaccid paralysis. On examination, inability to move her

lower extremities with complete loss of pain and temperature sensation below T4

with normal sensation to light touch was noted. The most likely cause of this

complication is

A. 2-Chloroprocaine neurotoxicity

B. Inadvertent subdural injection

C. Anterior spinal artery syndrome

D. Brown-Séquard syndrome

Questions 8 to 9

A 23-year-old female, in early labor, was transferred from an outside hospital at 37 weeks’

gestation with a history of a congenital bicuspid aortic valve. The patient reports dyspnea

throughout her pregnancy, and had a recent syncopal event. Subsequently, transthoracic

echocardiogram revealed a mean aortic valve gradient of 45 mm Hg and an aortic valve

area of 1.2 cm2

.

8. Two hours later, she endorses abdominal pain (8/10) and is requesting analgesia.

The most appropriate option for her pain management during labor and delivery is

A. Spinal anesthetic with bupivacaine

B. Epidural anesthesia with adequate volume preloading

C. Inhaled nitrous oxide

D. Oral analgesics

9. Despite an appropriate increase in her cardiac output and plasma volume, her

systemic blood pressure does not increase during the course of her pregnancy

because of

A. Decrease in systemic vascular resistance

B. Compression of the vena cava

C. Decrease in venous capacitance

D. Decrease in heart rate

10. Iatrogenic contributions to maternal supine hypotension syndrome can be minimized

by

A. Left hip elevation

B. Left-uterine displacement

C. Regional anesthesia

D. General anesthesia

11. The most significant change in maternal lung volume that occurs in the third

trimester of pregnancy includes

A. Decrease in vital capacity

B. Increase in residual volume

C. Decrease in functional residual capacity (FRC)

D. Decrease in closing capacity (CC)

12. Which of the following is not associated with oxytocin administration?

A. Myocardial ischemia

B. Respiratory depression

C. Hypotension

D. Tachycardia

13. During maintenance of a general inhaled anesthetic for an urgent nonobstetric

surgery, one would expect this difference in the pregnant patient versus a

nonpregnant patient:

A. Slower emergence from anesthesia

B. Minimal changes in depth of anesthesia

C. There is to be no difference

D. Faster induction of anesthesia

14. When providing general anesthesia during pregnancy, minimum alveolar

concentration (MAC) is

A. Increased

B. Decreased

C. Unchanged

D. Unclear

15. The speed of time to hypoxia following apnea is faster in the late-trimester parturient

due to all of the following factors, except

A. Reduced functional residual capacity

B. Increased minute ventilation

C. Preoxygenation

D. Increased oxygen consumption

16. The correct respiratory physiologic change associated with pregnancy is

A. Increase in arterial pH

B. Increase in HCO3

C. Increase in PaCO2

D. Increase in tidal volume

17. The P50

for maternal hemoglobin

A. Increases due to elevated levels of 2,3-diphosphoglycerate (DPG)

B. Remains unchanged

C. Increases to maintain pH

D. Decreases to enhance oxygen delivery to tissues

18. At sea level, the most likely arterial blood gas (ABG) sample of a parturient at 35

weeks’ gestation when she rests in the supine position breathing room air is

A. pH = 7.35, PaO2 = 90, PaCO2 = 45, HCO3 = 20

B. pH = 7.40, PaO2 = 100, PaCO2 = 40, HCO3 = 24

C. pH = 7.44, PaO2 = 90, PaCO2 = 30, HCO3 = 20

D. pH = 7.50, PaO2 = 105, PaCO2 = 30, HCO3 = 20

19. A 27-year-old G2P1 at 39

2 weeks’ gestation is electing to have spinal anesthesia for

a repeat cesarean section. Five minutes after bupivacaine spinal injection, the patient

becomes hypotensive and is complaining of tingling in her fingers with subjective

difficulty breathing. Her oxygen saturation remains 100% and blood pressure is

95/55. The most likely etiology is

A. Engorgement of epidural veins contributed to inadvertent intravascular injection

of the local anesthetics

B. Decrease in volume of CSF in the subarachnoid space facilitated higher spread

of local anesthetics

C. Severe patient anxiety

D. Increased peripheral nerve sensitization to local anesthetics

20. During pregnancy, hepatic changes contribute to

A. Decreased albumin levels contributing to higher free blood levels of highly

protein-bound drugs

B. Decreased liver function tests due to decreased blood flow

C. Decreased concentration levels of coagulation factors leading to easy

bruisability

D. Decreased activity of plasma cholinesterase resulting in significantly longer

duration of action of succinylcholine

Questions 21 to 23

After 18 hours of laboring and adherence to a strict nonpharmacologic natural birth plan,

the patient experiences late decelerations and fetal distress, requiring emergent cesarean

section.