3. A. Pierre Robin is a congenital syndrome associated with enlarged tongue, small

mouth, and mandibular anomalies typically manifested as micrognathia. All of these

limit the oropharyngeal space, contributing to airway obstruction between the tongue

and posterior pharyngeal wall. When you see Pierre Robin, think PR: Posterior

Restriction behind the tongue.

4. D. Klippel–Feil is a congenital syndrome associated with the phenotypical triad of

short neck, low posterior hair line, and congenital spinal fusion causing limited neck

mobility. Fused segments of the cervical spine in patients with this syndrome

promote hypermobility at unfused spine segments, increasing the risk of neurologic

compromise during neck manipulation. When you see Klippel–Feil, think KF:

Cervical Fusion.

5. D. Airway management of patients with trisomy 21 (Down syndrome) is

complicated by several factors. These patients tend to have small mouths and large

tongue, resulting in limited oropharyngeal space. They are prone to laryngospasm.

They also have a high incidence of subglottic stenosis, such that endotracheal tubes

should be downsized by 0.5 mm from the caliber expected for a patient of the same

size without Down syndrome. Finally, they have a high incidence of cervical spine

instability. The other three syndromes share a common feature of micrognathia (small

jaw), which renders these patients a challenge for direct laryngoscopy. Turner

syndrome occurs in females who lack a complete second X chromosome

(monosomy). These women tend to have short necks and small jaws. Laryngeal

distortion (choice A) has not been described in this population. Treacher Collins is a

rare syndrome characterized by abnormal development of facial bones (e.g.,

maxillary and mandibular). A high incidence of cervical spine instability (choice B)

has not been described in this population. Goldenhar syndrome is manifested by

dysplastic growth of the face (especially the ears, eyes, and mouth) and vertebral

anomalies (e.g., scoliosis). A high incidence of subglottic stenosis (choice D),

although a common finding in patients with trisomy 21, has not been described in the

Goldenhar population.

6. A. A positive-pressure leak test provides information about the tightness of the

seal formed between an ETT and its surrounding mucosa. A leak at pressures below

25 cm H2O places the tracheal mucosa at a very low risk of ischemic injury.

Pressures above 30 cm H2O, the arteriolar-capillary perfusion pressure, can cause

mucosal ischemia, with resulting inflammation, ulceration, stridor, and later scarring

and stenosis.

7. C. When an endotracheal tube migrates from an intratracheal to an endobronchial

position while on volume-control ventilation, the first sign of migration is generally

an increase in peak inspiratory pressures. Peak inspiratory pressure results from the

resistance to flow of the large airways and the static compliance of the lung. A fixed

volume of air moving out of an endobronchial tube would encounter significantly

more large airway resistance compared to the same volume moving out of an

endotracheal tube (remember: resistance is inversely proportional to radius raised to

the fourth power). Thus, the first sign of an endobronchial intubation would be an

elevation in peak inspiratory pressures. Because the nonventilated lung has some

reserve of oxygen, passive oxygenation would delay onset of hypoxemia briefly

(choice A). Hypercapnia (choice B) would eventually develop in an endobronchially

intubated patient on controlled ventilation if the minute ventilation were kept

constant. Hypotension (choice D) might occur if the right lung is allowed to

hyperinflate, restricting venous return. However, this would not be as immediate as a

rise in peak inspiratory pressures.

8. C. Palpation of the endotracheal tube cuff palpable above the cricoid cartilage

implies that the cuff’s position is intralaryngeal. This is problematic for two reasons:

(1) an inflated cuff in the larynx may cause laryngeal injury and postoperative

respiratory compromise, and (2) such a high tube position may increase the risk of

inadvertent extubation. The cuff should be deflated and the tube advanced until the

cuff (when inflated) is palpable below the cricoid cartilage. Choice B is incorrect: a

cuff inflated to enable air leak at 20 to 25 cm H2O of positive pressure should not

cause airway injury and edema in routine circumstances. Choice D would likely

result in the tip of the endotracheal tube moving from an intralaryngeal to a

supralaryngeal position.

9. D. The scenario describes extubation of a child during a “light” plane of anesthesia

when laryngeal reflexes are hypersensitive. Return of a gag reflex is a characteristic

of this lighter, hyperexcitable stage. If a patient is extubated while lightly

anesthetized, there is an increased risk of laryngospasm. Stimulation of the laryngeal

mucosa by secretions or a foreign body (e.g., the endotracheal tube or an oral

airway) can result in laryngospasm during the excitation stage of anesthesia or

sometimes even during awake states.

Laryngospasm and other causes of upper airway obstruction (e.g., tongue

collapsed against the posterior pharyngeal wall) may not be immediately

distinguishable. However, the initial treatment is identical: anterior displacement of

the mandible using a chin lift or jaw thrust combined with positive-pressure

ventilation. If these measures fail to relieve the laryngospasm and hypoxemia

develops, pharmacologic therapy should be initiated emergently. In a patient with no

contraindications, a small dose of succinylcholine (0.25–0.5 mg/kg) or deepening of

the anesthetic (e.g., with propofol or another general anesthetic) should break the

laryngospasm.

10. C. Left untreated, upper airway obstruction in a spontaneously breathing patient

can result in the development of negative-pressure pulmonary edema (also called

postobstructive pulmonary edema). Forceful inspiration against a closed upper

airway generates a large negative intrathoracic pressure which can result in

pulmonary edema by increasing capillary transmural pressure and/or by acutely

elevating left ventricular end-diastolic pressure. Aspiration (choice A) would be

impossible during laryngospasm. Bronchospasm (choice B) would not be expected as

a direct consequence of prolonged laryngospasm. Croup or laryngotracheal bronchitis

(choice D) is a form of upper airway obstruction that typically occurs in response to

a viral or bacterial upper respiratory tract infection in children between the ages of 6

months and 6 years. This clinical scenario is not suggestive of an infectious etiology

for the upper airway obstruction.

11. B. A commonly used formula for estimating the internal diameter of an uncuf ed

endotracheal tube in children is

Internal diameter (in mm) = (Age + 16)/4

The resulting value should be reduced by 0.5 mm when using a cuf ed endotracheal

tube to allow space in the tracheal lumen for cuff inflation. Since this child appears

to have a height and weight appropriate for her age, the formula would be reasonable

to use. For the patient in this question, the internal diameter is (2 + 16)/4 = 4.5 mm

for an uncuffed tube, which is reduced to 4.0 mm for a cuffed tube.

12. C. The vagus nerve provides sensory innervation to the structures of the airway

beginning with the epiglottis and moving caudally. It has two major branches that

innervate distinct parts of the airway: the superior laryngeal nerve (SLN) and

recurrent laryngeal nerve (RLN). Above the vocal cords, the sensory innervation of

the larynx is via the SLN. Below the vocal folds, sensory innervation of the airway is

provided by branches of the recurrent RLN. The vocal cords themselves receive dual

innervation from both nerves. The SLN has two branches: internal and external. The

internal SLN branch (choice C) is exclusively a sensory nerve that innervates both

the superior and inferior surfaces of the epiglottis. The external branch of the SLN is

a motor nerve that innervates the cricothyroid muscle (Fig. 2-2). The RLN (choice B)

is a mixed motor and sensory nerve. The motor branch innervates all of the laryngeal

muscles, except the cricothyroid muscle, while the sensory branch innervates the

subglottic mucosa of the airway. The hypoglossal nerve (choice A) is a purely motor

nerve that innervates the muscles of the tongue.

Figure 2-2. Subdivisions of the superior laryngeal nerve in the sagittal view.

13. A. The tongue has innervation for both gustatory (aka “taste”) and tactile (general

sensory) input. Gustatory (taste) sensation for the anterior two-thirds of the tongue is

provided by the facial nerve (CN VII), and for the posterior third of the tongue by the

glossopharyngeal nerve (CN IX). Tactile sensation for the anterior two-thirds of the

tongue is provided by the trigeminal nerve (CN V), and for the posterior one-third of

the tongue by the glossopharyngeal nerve (CN IX). In addition, a small portion of

sensory innervation of the posterior tongue is provided by fibers of the superior

laryngeal nerve’s internal branch (“spillover fibers” from that nerve’s innervation of

the epiglottis) (Fig. 2-3). The hypoglossal nerve (choice D) is a purely motor nerve

that innervates the muscles of the tongue.

Figure 2-3. General sensory innervation of tongue.

14. C. The glossopharyngeal nerve (CN IX) is a mixed motor and sensory nerve. Its

sensory fibers carry information about general sensation and taste from the posterior

third of the tongue (Fig. 2-3). Of note, the glossopharyngeal nerve does not provide

sensory innervation to the epiglottis; it is provided by the superior laryngeal nerve.

The trigeminal nerve (CN V) (choice A) carries general sensory information from the

anterior two-thirds of the tongue. The facial nerve (CN VII) (choice B) is a mixed

motor and sensory nerve. It carries taste sensation from the anterior two-thirds of the

tongue and oral cavity. The hypoglossal nerve (CN XII) (choice D) is a purely motor

nerve that innervates the muscles of the tongue.

15. B. The superior laryngeal nerve (SLN) is a mixed motor and sensory nerve that

receives sensory information from the supraglottic larynx and provides motor

innervation to the cricothyroid muscle. The cricothyroid muscle tenses and adducts

the vocal cords. This action raises the pitch of speech and enables singing. Acute,

bilateral denervation of the external branch of the SLN may cause hoarseness and

other subtle voice findings. However, the ability to adduct and abduct the vocal

cords would remain intact.

16. C. Sensory innervation of the larynx above the vocal cords is carried by fibers of

the superior laryngeal nerve (SLN). The internal branch of the SLN provides sensory

innervation to the supraglottic portion of the larynx, including all of the epiglottis and

the supraglottic mucosa. The external branch of the SLN is primarily a motor nerve

that innervates the cricothyroid muscle. The SLN can be blocked as it descends

between the greater cornu of the hyoid bone and the superior cornu of the thyroid

cartilage. As shown in Figure 2-4, “SLN block” is likely to block the internal branch

of the SLN, but not the external “motor” branch. Choice A describes a

glossopharyngeal block. Choice B does not describe a clinically relevant procedure

(i.e., the injection would be too medial to reliably block the SLN). Choice D

describes a transtracheal topicalization of RLN fibers.

17. C. The efferent limb of the glottic closure reflex involved in laryngospasm is

primarily mediated by the recurrent laryngeal nerve (RLN), while the afferent limb is

mediated by the superior laryngeal nerve (SLN). The RLN innervates all of the

muscles of the larynx except the cricothyroid muscle. The external branch of the SLN

(not one of the listed options) is a motor nerve that innervates the cricothyroid

muscle. The cricothyroid muscle contributes to laryngospasm by lengthening, and

thus tensing the vocal cords.

18. B. The presentation of acute aphonia and respiratory distress immediately after

thyroidectomy are suggestive of bilateral injury to the recurrent laryngeal nerve

(RLN), a recognized complication of this surgery. Bilateral RLN injury leaves the

vocal cords tensed and closed due to the unopposed action of the cricothyroid

muscles. The cricothyroid muscle is innervated by the external (motor) branch of the

superior laryngeal nerve (SLN). Blockade of the motor branch of the SLN should

improve the patient’s respiratory distress by relaxing the vocal cords but would have

no impact on the aphonia. Practically speaking, a typical “SLN block” (i.e., injection

of ∼2 mL of local anesthetic between the greater cornu of the hyoid cartilage and the

superior cornu of the thyroid cartilage) is likely to only block the internal (sensory)

branch of this nerve as opposed to the motor branch (Fig. 2-4).

Figure 2-4. Gross anatomic distribution of the SLN and RLN.

19. A. A cough occurs through the stimulation of a complex reflex arc. This is initiated

by the irritation of cough receptors, which are found in the pharynx, larynx, trachea,

carina, branching points of large airways, and more distal smaller airways. When

triggered, impulses travel via the internal branch of the superior laryngeal nerve and

the recurrent laryngeal nerve, which stem from the vagus nerve, to the medulla of the

brain. This is the afferent neural pathway. The efferent neural pathway then follows,

with relevant signals transmitted back from the cerebral cortex and medulla via the

vagus and superior laryngeal nerves to the glottis, external intercostals, diaphragm,

and other major inspiratory and expiratory muscles.

20. B. Acute, bilateral injury to the vagus nerve (CN X) terminates all of the motor

innervation to the larynx. This leaves the vocal cords in a fully open or abducted

position. In contrast, bilateral injury to the recurrent laryngeal nerve (a branch of the

vagus) would leave the cords paralyzed in a partially adducted position because of

unopposed action of the cricothyroid muscle. This adducted position may cause

stridor and respiratory distress, especially if the patient has any concurrent laryngeal

edema. Choice A would be observed during laryngospasm. Choice D would be

observed in a patient with a normal larynx who is alternating between breathing and

phonating.

21. C. Postoperative hoarseness can result from injury to the motor nerves which

innervate the larynx. The left recurrent laryngeal nerve (RLN) is particularly

vulnerable to injury during cardiothoracic surgeries and many neck surgeries due to

its anatomic location. After branching off the left vagus nerve in the chest, the left

RLN passes between the left pulmonary artery and the arch of the aorta above before

ascending alongside the trachea to the larynx. The right RLN, in contrast, branches

off the right vagus nerve in the lower neck where it passes under the root of the right

subclavian artery before ascending alongside the trachea to the larynx. An aortic arch

repair that spares the arch vessels would be more likely to damage the left RLN than

the right RLN.

Acute injury to the left RLN would leave the left vocal cord subject to the

unopposed action of the cricothyroid muscle (the only laryngeal muscle NOT

innervated by the RLN). This muscle stretches and tenses the vocal cords, an action

that shifts the vocal cords toward midline (adduction). During inspiration, both vocal

cords normally abduct, maximizing the glottic opening for air movement. During

inspiration, a patient with acute left RLN palsy would be expected to have an

adducted left vocal cord and an abducted right vocal cord.

22. D. Above the vocal cords, the sensory innervation of the larynx is via the superior

laryngeal nerve. Below the vocal cords, sensory innervation is via branches of the

recurrent laryngeal nerve (RLN). The vocal cords themselves receive dual

innervation from both nerves. The trigeminal nerve (choice A) provides tactile

sensation, among other things, to the anterior two-thirds of the tongue and the nasal

passages. The glossopharyngeal nerve (choice B) provides tactile and gustatory

sensation to the posterior one-third of the tongue. None of the choices except for the

RLN would be stimulated during an awake tracheostomy.

23. B. The ophthalmic (V1) and maxillary (V2) divisions of the trigeminal nerve (CN

V) convey sensory information from the nasal mucosa. Blockade of these nerves

would facilitate awake nasotracheal intubation. The gag reflex is elicited primarily

by tactile stimulation of the posterior one-third of the tongue. The afferent limb of

this reflex is carried by the glossopharyngeal nerve (CN IX), not the recurrent

laryngeal nerve (choice A) or the hypoglossal nerve (choice D). The superior surface

of the epiglottis is innervated by the superior laryngeal nerve (SLN), not the

glossopharyngeal (choice C). In general, the SLN provides sensory innervation to all

structures of the larynx above the vocal cords, including the epiglottis.

24. C. Both nasotracheal intubation and nasal trumpet insertion are contraindicated in

patients with facial or skull injuries (choice A), with coagulopathy (choice B), and

those on anticoagulation (choice D). In choice A, the patient’s mechanism of injury

and findings of periorbital bruising suggest an underlying skull fracture. In addition to

periorbital ecchymoses, other classic signs of a basilar skull fracture include leakage

of blood or cerebrospinal fluid from the nares, ecchymoses on the skin overlying the

mastoid process, and hemotympanum or bleeding from the ears. For a patient with

temporomandibular joint dysfunction who has none of the above contraindications

(choice C), the nasal trumpet would be a reasonable way to bypass the patient’s

limited mouth opening and relieve upper airway obstruction.

25. D. This patient has multiple risk factors for difficult intubation, including

Mallampati class > 2, thyromental distance < 3 fingerbreadths, mouth opening < 3

fingerbreadths, and total atlanto-occipital range-of-motion < 80 degrees. Patients with

inflammatory rheumatoid arthritis (RA) have an increased incidence of

temporomandibular joint disease (and associated limited mouth opening) and

immobile cervical vertebra (associated with limited neck range-of-motion).

Additionally, patients with RA can have occult airway abnormalities not apparent on

physical exam, such as laryngeal rotation, cricoarytenoid arthritis, and cervical spine

instability. The patient’s thyroid malignancy may result in other airway abnormalities

including tracheal deviation and/or compression. Were such a patient to be induced

and mask ventilation turn out to unsuccessful, there would be no reliable backup

method of airway management. The safest way to secure this patient’s airway would

be an awake fiberoptic intubation. Since the patient has refused this option and the

case is not urgent, the anesthesiologist should cancel the operation and discuss the

options for airway management with the patient so that a mutually acceptable plan

can be reached.

26. B. The “cannot intubate, cannot ventilate” scenario is an emergency and

necessitates immediate invasive airway access to prevent anoxic injury. Two options

include transtracheal jet ventilation and surgical cricothyrotomy. Transtracheal jet

ventilation requires that the airway be cannulated in some way. In emergent

circumstances, this may be accomplished by cannulating the cricothyroid membrane

with an intravenous catheter (e.g., 14/16G) and then attaching the end of the catheter

to a jet ventilator. Jet ventilation requires a pathway for expired air to egress out of

the lungs. Thus, when using transtracheal ventilation, laryngospasm (choice C), or

another cause of upper airway obstruction (choice A), would rapidly cause

pulmonary overinflation and barotrauma. In contrast, a surgical cricothyrotomy

permits both inhalation and exhalation through the lumen of inserted tube (choice B)

and so is not dependent on upper airway patency in order to function safely.

Transtracheal jet ventilation is a temporary way to provide oxygenation until a

definitive airway can be established. With prolonged jet ventilation, the delivered

high pressures can expel the catheter out of the trachea. When the catheter migrates

into the anterior cervical soft tissues, catastrophic subcutaneous emphysema can

rapidly develop rendering other attempts at invasive airway access impossible.

Surgical cricothyrotomy, on the other hand, is a definitive method of securing the

airway that can be used for up to 72 hours.

27. A. The ASA Difficult Airway Algorithm recommends use of supraglottic devices

such as the laryngeal mask airway (LMA) as rescue tools when laryngoscopy and

mask ventilation are unsuccessful. Although the patient in choice A ideally would be

treated with “full stomach” precautions, if a rapid sequence induction and intubation

are unsuccessful, an LMA may be a life-saving tool to oxygenate and ventilate the

patient. Aside from its use as a rescue device, the LMA can be used as a

supraglottic airway for elective surgery. Relative contraindications to the elective

use of the LMA include low airway compliance (choices B and C), incompetence of

the gastroesophageal sphincter (choice C), and in patients with a full stomach (choice

D).

28. D. “Deep extubation” refers to the technique of removing the endotracheal tube in

a patient breathing spontaneously who remains anesthetized such that his or her

protective airway reflexes are still abolished. This technique decreases the chance of

a patient coughing during emergence in response to the presence of an endotracheal

tube. Deep extubation may be performed because of potential benefit related to a

patient’s medical comorbidities or for surgical reasons. For example, a patient with

coronary artery disease or heart failure may benefit from deep extubation to avoid

the sympathetic surge associated with awake extubation and a patient undergoing

abdominal hernia repair may benefit from deep extubation to avoid the increased

intra-abdominal pressure associated with coughing. However, deep extubation should

not be attempted in patients with contraindications to this technique. These include

patients with a full stomach (choices A and B) and in patients who may be

challenging to mask ventilate or reintubate. Choice C would fall into this latter

category because of the potential for airway edema from prolonged prone

positioning.

29. D. Mask ventilation can be made difficult by anything that prevents the face mask

from forming an adequate seal with the patient’s face (e.g., a beard) or increases the

resistance to airflow between the mouth and larynx. Edentulousness, a history of

snoring, history of neck radiation, multiple attempts at laryngoscopy, male gender,

obesity, and Mallampati status ≥3 are all factors associated with difficult mask

ventilation. Choices A, B, and C represent risk factors for difficult intubation. In

general, factors that make it difficult to align the oral axis with the laryngeal axis

result in difficult intubation. These factors include prominent maxillary teeth, a highly

arched or very narrow palate, and an acute angle between the mouth and larynx.

30. B. Flow–volume loops can help differentiate fixed vs. dynamic causes of airway

obstruction. They can also help to distinguish extrathoracic vs. intrathoracic sources

of the obstruction. During the inspiratory phase of spontaneous ventilation, an

extrathoracic obstruction is drawn into the pathway of air movement by

subatmospheric intraluminal pressures. In contrast, an intrathoracic obstruction is

stented open during inspiration by the negative extraluminal intrathoracic pressure.

During expiration in a spontaneously breathing patient, an extrathoracic obstruction is

stented open by supra-atmospheric intraluminal pressure. In contrast, an intrathoracic

obstruction is exacerbated during expiration, since the extraluminal intrathoracic

pressure exceeds the intraluminal pressure. Choice A represents a normal flow–

volume loop. Choice C represents a fixed obstruction, that is, one present during both

inspiration and expiration. Choice D represents a dynamic intrathoracic obstruction,

which would be expected in a patient with asthma or chronic obstructive pulmonary

disease.

Anesthesia Machine

Paul Sikka

1. Pipeline gases are supplied at pressures of about ______ psi:

A. 25

B. 40

C. 50

D. 75

2. Which of the following prevents delivery of hypoxic gas mixture once the oxygen

pressure falls below 25 psi?

A. Diameter index safety system

B. Pin index safety system

C. Inspiratory check valve

D. Fail-safe valve

3. The oxygen-flush valve provides which of the following oxygen flows (L/min) to the

common gas outlet?

A. 10

B. 25

C. 50

D. 90

4. Gas flowmeters

A. Are gas-specific

B. Have a gas flow rate which depends on viscosity at high turbulent flows

C. Have a gas flow rate which depends on density at low laminar flows

D. Are cylindrical in shape

5. Which of the following flowmeters is situated nearest to the gas outlet?

A. Nitrous oxide

B. Oxygen

C. Air

D. None of the above

6. Modern vaporizers are

A. Agent-specific

B. Temperature-compensated

C. Pressure-compensated

D. Both A and B

7. The Tec 6 desflurane vaporizer

A. Is electrically heated to 39°C

B. Is pressurized to 3 atm

C. Is pressure-compensated

D. All of the above

8. Variable bypass vaporizers should be located

A. Between the common gas outlet (upstream) and the flowmeters (downstream)

B. Between the flowmeters (upstream) and the common gas outlet (downstream)

C. Between the gas pipeline and the flowmeters

D. Inside the circle system

9. A standing or ascending bellow is preferred for anesthesia ventilators, as

disconnection is indicated by

A. Collapse

B. Filling by gravity

C. Disconnection alarm

D. Stoppage of flowmeter gas

10. The National Institute for Occupational Safety and Health (NIOSH) recommends

limiting operating-room concentration of nitrous oxide to ______ ppm:

A. 10

B. 25

C. 50

D. 100

11. The National Institute for Occupational Safety and Health (NIOSH) recommends

limiting operating-room concentration of volatile inhalational agents to ______ ppm:

A. 0.2

B. 0.5

C. 1

D. 2

12. Capacity of an oxygen “E” cylinder is approximately ______ L:

A. 500

B. 600

C. 650

D. 750

13. If pressure in a full nitrous oxide “E” cylinder is 745 psi at 20°C, the pressure in a

half-full cylinder will be about ______ psi:

A. 186

B. 248

C. 372

D. 745

14. Which of the following system prevents the wrong gas cylinder being attached to the

anesthesia machine?

A. Diameter index safety system

B. Pin index safety system

C. Hanger yoke assembly system

D. Gauge-safety system

15. A line-isolation monitor

A. Warns that an electrical shock is imminent

B. Warns of a fault between the power line and the ground

C. Warns of the presence of two faults

D. Trips the ground leakage circuit breaker

16. The highest content of soda lime is

A. Calcium hydroxide

B. Potassium hydroxide

C. Sodium hydroxide

D. Silica

17. End products of the reaction in a soda lime CO2 canister are

A. Carbonates, water, heat

B. Carbonates, heat, sodium hydroxide

C. Sodium hydroxide, water, heat

D. Carbonates, sodium hydroxide, water, heat

1. CO2 + H2O → H2CO3

2. H2CO3 + 2 NaOH (or KOH) → Na2CO3

(or K2CO3

) + 2 H2O + Energy

3. Na2CO3

(or K2CO3

) + Ca(OH)2 → CaCO3 + 2 NaOH (or KOH)

18. If you notice that the CO2 absorbent is exhausted during the surgical procedure,

which of the following minimal fresh gas flows (L/min) will make the CO2 absorbent

unnecessary?

A. 3

B. 5

C. 7

D. 10

19. Compared to the Mapleson A system, the circle system

A. Is less bulky

B. Has a decreased risk of disconnection

C. Has decreased resistance to patient breathing

D. Better conserves humidity

20. Incorrect statement regarding the mechanisms of an Ambu bag is

A. It contains a nonrebreathing valve, same as the circle system

B. It is capable of delivery of nearly a 100% O2 concentration

C. It allows for positive-pressure ventilation

D. Patient valve has low resistance to both inspiration and expiration

21. You are preparing to set up for anesthesia in an off-floor location in the

interventional radiology suite. The radiography equipment is consuming the limited

space that is available in the suite, and therefore, the decision is made to double the

extension tube length from the ventilator to the patient table. What is the impact on

the dead-space ventilation that would have occurred secondary to doubling the

extension tubing length?

A. It would double as well

B. It has been decreased to half the original volume

C. It would have increased by 4-fold

D. It would have not changed

22. Malfunction of which of the following valves within a circle system may cause

rebreathing of carbon dioxide and could potentially result in hypercapnia?

A. Inspiratory valve

B. Expiratory valve

C. Both A and B

D. None of the above

23. Since fresh gas flow equal to minute ventilation is sufficient to prevent rebreathing,

which of the following Mapleson circuit breathing/ventilation systems is the most

efficient for spontaneous ventilation of the patient?

A. Mapleson A

B. Mapleson B

C. Mapleson C

D. Mapleson D

24. Different semi closed anesthetic ventilation/breathing systems (classically referred

to as Mapleson systems and designated A to F) are pictured below. While setting up

for anesthesia delivery in an “off-floor” location and planning for controlled

ventilation of an asthmatic patient, which of the Mapleson systems provides for the

best efficacy?

Figure 3-1.

A. D > B > C > A

B. A > B > C > D

C. D > C > B > A

D. C > A > D > B

25. Degradation of sevoflurane by soda lime results in the production of

A. Compound A

B. Compound B

C. Compound C

D. Compound D

26. In a CO2