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9/3/23

 


-absorbent canister, the greatest amount of carbon monoxide is produced by

which of the following volatile agents?

A. Sevoflurane

B. Halothane

C. Isoflurane

D. Desflurane

CHAPTER 3 ANSWERS

1. C. Pipeline gases are supplied at pressures between 45 and 55 psi. This is in

contrast to cylinder gas pressures, which are much higher, and are reduced by

pressure regulators to less than 50 psi.

2. D. The fail-safe valve automatically closes nitrous oxide (and other gases) to

prevent delivery of hypoxic gas mixture to the patient. The fail-safe valve is

designed to be activated when oxygen pressure falls below 25 psi.

3. C. The oxygen-flush valve provides gas flow at pipeline pressures of about 45 to

55 psi at 35 to 75 L/min. The high flow of oxygen is provided directly to the common

gas outlet, bypassing the flowmeters and vaporizers. One should be careful when

using the oxygen-flush valve, as high gas flows at high pressures can cause lung

barotrauma in the patient.

4. A. Gas flowmeters are calibrated for a particular gas. Gas flow rate depends on its

viscosity at low laminar flows, and its density at high turbulent flows. Flowmeters

are tapered in shape, with the diameter the smallest near the bottom of the tube.

5. B. The oxygen flowmeter is situated nearest to the gas outlet. This is because, if a

leak develops in the flowmeter tubes, a hypoxic gas mixture can be delivered to the

patient. To minimize this, the oxygen flowmeter is positioned downstream and

nearest to the gas outlet.

6. D. Modern vaporizers are agent-specific and temperature-compensated. Also,

specific fillers are available for each volatile agent, which prevent filling on the

wrong agent. A constant concentration of agent is delivered, unaffected by

temperature or flow rates. Temperature compensation is achieved by a metallic strip

composed of two different metals, which expands/contracts to deliver a constant

concentration of vapor.

7. A. The Tec 6 desflurane vaporizer is electrically heated to 39°C and pressurized to

2 atm. This is done because desflurane boils at room temperature at sea level (1

atm). The heating and pressurization optimizes the delivery of desflurane.

8. B. Vaporizers are located between the flowmeters (upstream) and the common gas

outlet (downstream). In other words, vaporizers are located outside the circle system.

This decreases the likelihood of delivery of high vapor concentrations when using the

oxygen-flush valve.

9. A. An ascending bellow collapses when disconnection occurs. A descending

bellow, however, continues to fill by gravity when disconnection occurs. Therefore,

ascending bellows are preferred for anesthesia ventilators.

10. B. NIOSH recommends limiting operating-room concentration of nitrous oxide to

25 ppm. Minimizing operating-room pollution is important to prevent health-related

effects in health-care providers. Waste-scavenging systems are utilized to decrease

operating-room pollution.

11. D. NIOSH recommends limiting operating-room concentration of volatile agents to

2 ppm. Minimizing operating-room pollution is important to prevent health-related

effects in health-care providers. Waste-scavenging systems are utilized to decrease

operating-room pollution.

12. C. The capacity of an “E” cylinder of oxygen is about 625 to 700 L. The pressure

in a full cylinder is about 1,800 psi at 20°C. Cylinders are color-coded, with oxygen

being green, nitrous oxide being blue, and air being yellow.

13. D. Pressure in a half-full “E” cylinder of nitrous oxide will still be 745 psi. Nitrous

oxide is present in the cylinder as a liquid, and therefore, the volume remaining in the

cylinder does not reflect the pressure in the cylinder. Capacity of an “E cylinder” of

nitrous is about 1590 L. It is not until three-fourth of the gas is consumed (about 400

L remaining) that the pressure in the cylinder begins to fall. Therefore, the reliable

way to determine the remaining nitrous oxide in the cylinder is to weigh the cylinder.

The empty weight of the cylinder is stamped on the cylinder.

14. B. Cylinder manufactures have adopted the pin index safety system, which

prevents attachment of wrong gas cylinder to the anesthesia machine. The diameter

index safety system prevents attachment of the wrong gas hose from the wall supply.

Hanger yoke assembly is the method of attachment of gas cylinders to the anesthesia

machine.

15. B. A line-isolation monitor, when alarming, indicates that a single fault has

occurred between the power line and the ground. As soon as the alarm is triggered,

the equipment should be checked, especially the last equipment that was plugged in.

A single fault does not cause an electrical shock, as two faults are required to

produce a shock.

16. A. The highest content of soda lime is calcium hydroxide (75%). Other constituents

include sodium (3%) and potassium hydroxide (1%), water (20%), and silica, which

is added to produce hardness. An indicator dye, such as ethyl violet, is added to

indicate the degree of exhaustion.

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

carbonates, sodium hydroxide (regeneration), water, and heat. Following are the

reactions:

18. B. Advantages of a circle system include the use of low fresh gas flow rates

because of the presence of a CO2

-absorbent canister. However, if the CO2 absorbent

is exhausted during a surgical procedure, the fresh gas flow rate has to be increased.

A minimum fresh gas flow rate of 5 L/min will make the use of the absorbent

unnecessary. Newer anesthesia machines allow changing the CO2

-absorbent canister

during the surgical procedure, if necessary.

19. D. Advantages of the circle system include economy (low fresh gas flow rates,

decreased use of volatile agents), conservation of heat and humidity, and decreased

operating-room pollution. Disadvantages of circle system include greater size,

decreased portability, increased risk of disconnection, and increased resistance to

patient breathing.

20. A. While resuscitation devices such as Ambu bags or bag-mask units have

nonrebreathing valves, neither the Mapleson (only has adjustable pressure-limiting

valve) nor the circle system (only has unidirectional valves and does allow

rebreathing) has this component. Ambu resuscitation bags do allow for positivepressure ventilation as the intake valve closes during bag compression. The patient

valve has low resistance, but can become obstructed by exhaled moisture. Ambu

bags have a reservoir system to prevent room air entrapment and are able to deliver

nearly 100% oxygen.

21. D. One advantage of the circle system ventilation when compared to the Mapleson

system is the presence of unidirectional valves (inspiratory and expiratory valves).

With the use of such valves, the volume of dead-space ventilation is limited only to

that volume distal to Y-piece (including the endotracheal tube), where inspiratory and

expiratory gases mix and converge, regardless of the length of tubing proximal to the

Y-piece (to the anesthesia machine).

22. C. Malfunction in either of the unidirectional valves within a circle system could

result in the accumulation and eventual CO2

rebreathing that may result in

hypercapnia.

23. A. During spontaneous ventilation/breathing of the patient, the Mapleson circuit

providing for the most efficacy ranges from A > D > C > B (in the order of

decreasing efficiency).

24. A. The efficiency of Mapleson systems drops from D > B > C > A for controlled

ventilation. The Mapleson D circuit is most efficient during controlled ventilation, as

its fresh gas flow drives expired air away from the patient and toward the

expiratory/exhaust valve.

25. A. Sevoflurane is degraded by soda lime, resulting in the production of a

potentially nephrotoxic compound A. Compound A production is increased by using

low fresh gas flow rates, using high concentrations of sevoflurane, and for long hours

(>6 hours).

26. D. Desflurane produces the highest amount of carbon monoxide in the CO2

-

absorbent canister, which can increase carboxyhemoglobin blood concentration.

Production of carbon monoxide is increased by using low fresh gas flow rates, high

concentrations of volatile agent, and a dry absorbent.

Patient Monitoring

Darren Hyatt, Ala Nozari, and Edward Bittner

1. To help encourage universal quality and safety practices, the ASA has adopted and

mandates the use of all the following monitors during general anesthesia, except

A. An oxygen analyzer

B. Capnography

C. Continuous visual display of an ECG

D. A peripheral nerve stimulator

2. Current ASA standards require that during anesthesia, systemic blood pressure and

heart rate be evaluated at least every

A. 3 minutes

B. 5 minutes

C. 7 minutes

D. 10 minutes

3. Lead II of an ECG is represented by placing the

A. Positive electrode on the right arm and the negative electrode on the left leg

B. Negative electrode on the right arm and the positive electrode on the left leg

C. Positive electrode on the right arm and the negative electrode on the left arm

D. Negative electrode on the right arm and the positive electrode on the left arm

4. During the course of a complicated cardiac case, the surgeon informs you that he is

worried about damage to the right coronary artery in a patient with a right-dominant

coronary system. During reperfusion, you are looking for signs of ischemia, and are

most interested in leads

A. V1–V3

B. V4–V6

C. II, III, and AvF

D. I and AvL

5. Use of lead V5 alone on ECG results in the detection of _____ (%) of ischemic

episodes:

A. 35

B. 55

C. 75

D. 95

6. You are taking over a case from another anesthesia provider with a patient in the

beach chair position and a history of moderate carotid artery disease. You are told

during pass-off that the patient’s blood pressures have consistently been 90/50 mm

Hg. You notice the blood pressure cuff on the left arm is one or two sizes small and

barely stays on the patient. A blood pressure cuff that is too small will

A. Incorrectly underestimate the true blood pressure

B. Incorrectly overestimate the true blood pressure

C. Randomly both over- and underestimate the true blood pressure

D. Not give an incorrect blood pressure, but will be uncomfortable in an awake

patient

7. When performing the oscillometric method to measure blood pressure, for example,

when you do not have a stethoscope or automated blood pressure cuff, it is important

to remember that you will not be able to measure the

A. Systolic blood pressure

B. Diastolic blood pressure

C. Mean arterial pressure

D. Diastolic or mean arterial blood pressure

8. The diastolic blood pressure recorded with an automated blood pressure cuff using

the oscillometric method will be

A. Approximately 10 mm Hg higher when compared to direct arterial measurement

B. Approximately 10 mm Hg lower when compared to direct arterial measurement

C. Equal to direct arterial measurement

D. Random and unreliable

9. When measuring blood pressure manually and listening for Korotkoff sounds, the

diastolic blood pressure is measured at the onset of

A. Phase 1

B. Phase 2

C. Phase 3

D. Phase 5

10. You are preparing for an emergent mitral valve repair that will need to be done on

cardiopulmonary bypass (CPB). While on CPB

A. A pulse oximeter can be used to monitor oxygen saturation

B. A noninvasive blood pressure cuff can be used to monitor perfusion pressures

C. An arterial line can be used to measure perfusion pressures

D. None of the above

11. The incidence of distal ischemia resulting from arterial cannulation is less than

A. 10%

B. 1%

C. 0.1%

D. 0.01%

12. When considering the advantages and disadvantages of different sites for arterial

cannulation such as radial, ulnar, femoral, brachial, and dorsalis pedis, the

A. Radial artery provides the principal source of blood to the hand

B. Cannulation of ulnar artery is commonly associated with damage to the median

nerve

C. Dorsalis pedis artery is commonly used during emergencies and low-flow states

D. Cannulation of the femoral artery risks local and retroperitoneal hematoma

13. Systolic blood pressures are generally higher and diastolic blood pressures are

generally lower in which of the following conditions?

A. The further you are from the heart when using a direct arterial measurement

B. The closer you are to the heart when using a direct arterial measurement

C. When using an automated noninvasive blood pressure cuff compared to a direct

arterial measurement

D. When recording from an over dampened arterial tracing

14. While taking care of a patient, you notice that the arterial monitor transducer has

slipped off its stand and is hanging approximately 30 cm lower than where it was

originally leveled. This would correspond to a blood pressure reading that is

A. 30 mm Hg lower than the actual pressure

B. 30 mm Hg higher than the actual pressure

C. 22 mm Hg lower than the actual pressure

D. 22 mm Hg higher than the actual pressure

15. An important consideration in using the subclavian approach for central venous

access includes the

A. Ease of compressibility if a hematoma or laceration develops

B. Lower risk of pneumothorax when compared to internal jugular approach

C. Ability of the vessel to remain patent in the setting of hypovolemia

D. Increased risk of damaging the brachial plexus when compared to internal

jugular approach

16. When interpreting a CVP waveform, the end of systole best coincides with the

A. A wave

B. C wave

C. V wave

D. X decent

17. When interpreting a CVP waveform, the beginning of systole is best represented by

the

A. A wave

B. C wave

C. V wave

D. X decent

18. After placing a central line in an unstable patient in the ICU, you notice the initial

CVP tracing shows very prominent C–V waves. If an echocardiogram was then

obtained, you might expect to find

A. Cardiac tamponade

B. Significant tricuspid regurgitation

C. Atrial fibrillation

D. AV dissociation

19. You receive a patient from the emergency department with multiple stab wounds to

the upper abdomen. The patient is unstable, and needs to emergently come to the

operating room with minimal to no time for fluid resuscitation. After placing a central

line, you notice loss of the Y descent on the CVP tracing, as well as universally

elevated filling pressures. If you were to then do an echocardiogram, you might

expect to find which of the following?

A. Cardiac tamponade

B. Significant tricuspid regurgitation

C. Descending thoracic aortic dissection

D. AV dissociation

20. The risk of complication from pulmonary artery catheter placement is less than

A. 0.05%

B. 0.5%

C. 5%

D. 15%

21. Insertion of a pulmonary artery catheter can be beneficial in the management of all of

the following cases, except

A. Helping to determine cardiogenic versus noncardiogenic pulmonary edema

B. Following cardiac output in an unstable patient with acute-onset tricuspid

regurgitation

C. Following the response to therapy in a patient with severe pulmonary

hypertension

D. Following response to therapy in an unstable septic patient using mixed venous

oxygen tension

22. During placement of a pulmonary artery catheter, you are watching the pressure

tracing, as shown. At the point indicated by the arrow, the catheter tip is located in

the

Figure 4-1.

A. Right atrium

B. Right ventricle

C. Pulmonary artery

D. Wedge position

23. The tip of a pulmonary artery catheter typically enters the pulmonary artery at

approximately

A. 15 to 25 cm

B. 25 to 35 cm

C. 35 to 45 cm

D. 45 to 55 cm

24. Typical mixed venous oxygen tension in a healthy adult is

A. 25 mm Hg

B. 40 mm Hg

C. 55 mm Hg

D. 75 mm Hg

25. A pulmonary artery catheter is placed to help guide management of hypotension.

Cardiac output is found to be markedly decreased with low central venous,

pulmonary artery, and pulmonary artery occlusion pressures. Systemic vascular

resistance is moderately elevated. Of the options listed below, the most beneficial

intervention at this time would be to

A. Administer volume

B. Begin diuresis

C. Start an infusion of milrinone

D. Start an infusion of epinephrine

26. A pulmonary artery catheter is placed to help guide management of an obese patient

with a known history of poorly controlled obstructive sleep apnea who is admitted

with refractory hypotension. Cardiac output and pulmonary artery occlusion

pressures are markedly decreased, while central venous and pulmonary artery

pressures are markedly increased. Of the options listed below, the most beneficial

intervention at this time would be to

A. Administer volume

B. Begin diuresis

C. Start an infusion of milrinone

D. Start an infusion of epinephrine

27. Normal systemic vascular resistance ranges between ______ (dynes)(s)/cm5

:

A. 50 and 150

B. 300 and 600

C. 900 and 1500

D. 1800 and 2100

28. Normal pulmonary vascular resistance ranges between ______ (dynes)(s)/cm5

:

A. 50 and 150

B. 300 and 600

C. 900 and 1500

D. 1800 and 2100

29. The cardiac index in a healthy adult ranges between ______ L/min/m2

:

A. 0.8 and 1.2

B. 1.4 and 2.0

C. 2.2 and 4.2

D. 4.4 and 6.0

30. Serious complications with transesophageal echocardiography (TEE), such as oral or

pharyngeal injury or esophageal rupture, have an incidence as high as

A. 0.01%

B. 0.1%

C. 1%

D. 10%

31. When evaluating regurgitant lesions with transesophageal echocardiography, the

Nyquist limit should be set between ______ cm/s:

A. 30 and 40

B. 40 and 50

C. 50 and 60

D. 60 and 70

32. When evaluating flow at a specific point during echocardiography, you would use

A. Continuous-wave Doppler

B. Pulse-wave Doppler

C. Color Doppler

D. Pulse-wave or continuous-wave Doppler

33. Pulse oximetry illuminates tissue samples with two wavelengths of light in order to

calculate oxygen saturation. These wavelengths are ______ nm:

A. 540 and 780

B. 660 and 940

C. 720 and 960

D. 480 and 720

34. The accuracy of pulse oximetry can be significantly reduced by all of the following,

except

A. Intravenous bolus of methylene blue

B. Intravenous bolus of heparin

C. Severe acidosis

D. Low blood flow

35. A patient with carboxyhemoglobin will have a pulse oximetry reading that

A. Converges around a saturation of 85%

B. Converges around a saturation of 65%

C. Converges around a saturation of 45%

D. Varies widely

36. A patient with methemoglobinemia will have a pulse oximetry reading that

A. Converges around a saturation of 85%

B. Converges around a saturation of 65%

C. Converges around a saturation of 45%

D. Varies widely

37. For the removal of a complex spinal cord tumor, the surgeon expresses concern of

damage to the anterior spinal artery. The monitoring that would be helpful to

determine viability of the anterior spinal cord intraoperatively would include

A. Electroencephalography

B. Motor-evoked potentials

C. Somatosensory-evoked potentials

D. Bispectral index or Sedline monitoring

38. A sudden drop in somatosensory-evoked potentials (SSEPs) would cause you to be

worried about

A. Damage to the anterior spinal artery

B. Damage to the posterior spinal arteries

C. An insufficient depth of anesthesia

D. The inadvertent administration of a neuromuscular blocking agent

39. During cervical spine surgery for the resection of an intradural mass, the patient

begins to cough. The concentration of isoflurane is subsequently increased. With

respect to somatosensory-evoked potential (SSEP) monitoring, you would expect

A. Amplitude and latency to decrease

B. Amplitude and latency to increase

C. Amplitude to decrease and latency to increase

D. Amplitude to increase and latency to decrease

40. While monitoring somatosensory-evoked potentials, an increase in amplitude is

noted. Of the options listed below, the most likely medication to have caused this

increase in amplitude would be

A. Etomidate

B. Propofol

C. Midazolam

D. Sevoflurane

41. If somatosensory-evoked potentials change significantly, the anesthesia provider

should consider

A. Increasing blood pressure

B. Hyperventilating the patient

C. Cooling the patient

D. Hemodilution

42. In the capnogram below, the segment that correlates with the exhalation of anatomic

dead space is represented by points

Figure 4-2.

A. A to B

B. A to C

C. C to D

D. D to E

43. In the capnogram (Fig. 4-2), the segment correlating with inspiration is represented

by points

A. A to B

B. A to C

C. C to D

D. D to E

44. Capnography can help detect all of the following, except

A. Endobronchial intubation

B. Esophageal intubation

C. Bronchospasm

D. Pulmonary embolism

45. The capnograph depicted in Figure 4-3 is most likely a result of

Figure 4-3.

A. Pulmonary embolism

B. Bronchospasm or airway obstruction

C. Esophageal intubation

D. Elimination of neuromuscular blockers

46. Approximately 30 minutes after the induction of general anesthesia in a healthy adult

patient, you notice that core body temperature has dropped by a full degree Celsius.

This is most likely due to

A. Conduction

B. Convection

C. Redistribution

D. Radiation

47. According to the American Society of Anesthesiologists, temperature monitoring is

A. Always required

B. Never required, but recommended

C. Required for all general anesthetics, however not required for sedation

D. Up to the discretion of the anesthesia provider

48. Detrimental effects of hypothermia include all of the following, except

A. Increasing cerebral oxygen consumption

B. Increasing surgical site infections

C. Impairment of platelet function

D. Increasing the duration of action of muscle relaxants

49. During a complex mitral valve replacement, it is determined that the patient will

benefit from brief protective hypothermia. Of the options listed below, core

temperature is best measured via the

A. Tympanic membrane

B. Bladder

C. Nasopharnyx

D. Rectum

50. While monitoring a patient for return of neuromuscular function after using

rocuronium, you notice the patient has regained four twitches using train of four

stimulations. With four twitches on train of four stimulations, the patient may still

have blockage of acetylcholine receptors of up to

A. 25%

B. 50%

C. 75%

D. 90%

CHAPTER 4 ANSWERS

1. D. ASA standards mandate the use of pulse oximetry, capnography, an oxygen

analyzer in the breathing system, disconnect alarms, a visual display of an ECG,

systemic blood pressure and heart rate monitoring, and temperature monitoring (when

clinically indicated) for all cases. The use of a peripheral nerve stimulator is not a

mandated monitor.

2. B. During the delivery of anesthesia, the current standard of care is to measure

systemic blood pressure and heart rate every 5 minutes at a minimum. The clinical

scenario and phase of the operation may mandate more frequent monitoring, which is

up to the judgment of the anesthesia provider.

3. B. Lead I correlates with the placement of the negative electrode on the right arm

and the positive electrode on the left arm. Lead II correlates with the placement of the

negative electrode on the right arm and the positive electrode on the left leg. Lead III

correlates with the placement of the negative electrode on the left arm and the

positive electrode on the left leg.

4. C. The understanding of coronary anatomy and regions of ischemia on an ECG is

fundamental. The right coronary artery provides perfusion to the inferior of the heart

in approximately 80% of patients who are considered to be right-dominant (the

posterior descending artery is supplied by the right coronary artery in a rightdominant system). This inferior distribution is represented by leads II, III, and AvF.

The anterior wall is supplied by the left anterior descending artery, and is represented

roughly by leads V1–V4. The lateral wall of the heart is supplied primarily by the

left circumflex artery, and is represented by I, AvL, V5, and V6.

5. C. The use of the V5 lead results in the detection of 75% of ischemic episodes.

This can be increased to 90% with the addition of the V4 lead, and up to 96% with

the addition of leads II and V4.

6. B. A properly-sized noninvasive blood pressure cuff should encompass 40% of the

circumference of the arm. A cuff that is too small will result in a reading that is

incorrectly high, whereas a cuff that is too large will result in a lower-than-accurate

pressure. This is particularly worrisome in this patient when considering her cerebral

perfusion pressure, since she already has a history of carotid artery disease and is in

the beach chair position.

7. B. When using the oscillometric method to measure blood pressure, the cuff is

inflated until no oscillations on the sphygmomanometer are seen. The cuff is then

slowly deflated until oscillations are seen, which represents the systolic blood

pressure. As the cuff continues to be deflated, you note the point where maximal

oscillations occur. This point of maximal oscillation represents the mean arterial

pressure. It is not possible to measure a diastolic blood pressure with the

oscillometric method.

8. A. The DINAMAP (device for indirect noninvasive automatic mean arterial

pressure) method for measuring blood pressure uses an automated cuff that measures

oscillometric variations with reduction in cuff pressure to calculate systolic, mean,

and diastolic pressures. In general, diastolic measurements with DINAMAP are

about 10 mm Hg higher with automated as opposed to direct arterial measurement,

whereas systolic and mean pressures tend to correlate well.

9. D. Korotkoff sounds are used to interpret blood pressure when using a stethoscope

and a noninvasive blood pressure cuff, and is described in 5 phases of sound. Phase

1 heralds the onset of the first sound heard and correlates with the systolic blood

pressure. Phase 5 occurs at the cuff pressure at which the sound first disappears, and

is the phase recommended by the American Heart Association to correspond most

reliably with the diastolic heart sound. In cases where Phase 5 does not occur (the

sound never fully disappears), Phase 4 is then used to represent the diastolic blood

pressure, and is described as a thumping or muting of the sound just before diastole.

Phases 2 and 3 have no clinical significance.

10. C. Both pulse oximetry and noninvasive blood pressure cuffs require pulsatile

blood flow in order to obtain measurements. These monitors will not be effective

during CPB when blood flow is artificially sustained with a more continuous flow.

This can also be the case with some patients on left ventricular assist devices, and

venous to arterial extracorporeal membrane oxygenation devices, where pulsatile

flow is minimal.

11. C. Complications from arterial cannulation include distal ischemia (<0.1%),

infection, and hemorrhage. Common sites for cannulation include radial, brachial,

axillary, dorsalis pedis, and femoral arteries. Common indications for direct blood

pressure monitoring include cardiopulmonary bypass, when wide swings in BP are

expected, when rigorous control of BP is necessary, and when there is need for

multiple arterial blood gas measurements.

12. D. The ulnar artery is the principal source of blood flow to the hand. Hence radial

artery cannulation is much more commonly used for invasive blood pressure

monitoring. Cannulation of the brachial artery risks damage to the median nerve. The

femoral artery is often used in emergencies, since it is a large vessel and can still be

identified in low flow states. Cannulation of the femoral artery risks both local and

retroperitoneal hematoma. Dorsalis pedis artery cannulation, while not ideal since it

is far from the central circulation, can reliably measure mean arterial pressure.

13. A. Systolic blood pressures are generally higher and diastolic blood pressures are

generally lower the further you are from the heart when using direct invasive arterial

measurement. For example, when comparing a dorsalis pedis arterial measurement to

a femoral arterial measurement, the dorsalis pedis will record higher systolic and

lower diastolic pressures compared to the femoral line. However, the mean arterial

pressures will be approximately the same. A noninvasive automated blood pressure

cuff will tend to correlate with systolic arterial blood pressures, but the diastolic

pressure will be approximately 10 mm Hg lower when measured via the direct

invasive arterial monitor. An over dampened arterial line tracing will tend to reduce

systolic pressures and increase diastolic pressures.

14. D. For every 30 cm in height that a transducer is moved up and down, there is a

corresponding change of 22 mm Hg in the blood pressure reading (1 cm H2O = 0.74

mm Hg).

15. C. Risks and benefits of different central cannulation sites are important for an

anesthesia provider to understand. The internal jugular approach has good landmarks,

predictable anatomy, and the convenience of being easily accessible at the head of

the bed. Disadvantages include risk of carotid artery puncture, trauma to the brachial

plexus, and risk of pneumothorax with lower placements. The left internal jugular

vein carries the added risk of damage to the thoracic duct, and can be more difficult

to pass a pulmonary artery catheter when needed. The external jugular vein can also

be cannulated, and its superficial location makes it an easy target, but it can be more

difficult to thread a catheter centrally. The subclavian approach has the benefit of

also having good landmarks, as well as remaining relatively patent in a hypovolemic

patient. The subclavian however does carry the highest risk of pneumothorax, and

can be difficult to compress if a hematoma or laceration occurs.

16. C. In the CVP waveform depicted below, the A wave represents atrial contraction,

the C wave represents bulging of the tricuspid valve into the atrium during the

beginning of systole, the X decent occurs during systole and corresponds to atrial

relaxation, the V wave represents filling of the atrium while the tricuspid valve is

closed, and the Y descent occurs when the tricuspid valve opens and the atrium starts

to empty.

Figure 4-4.

17. B. In the CVP waveform depicted in Figure 4-4, the A wave represents atrial

contraction, the C wave represents bulging of the tricuspid valve into the atrium

during the beginning of systole, the X decent occurs during systole and corresponds

to atrial relaxation, the V wave represents filling of the atrium while the tricuspid

valve is closed, and the Y descent occurs when the tricuspid valve opens and the

atrium starts to empty.

18. B. During systole in a patient with tricuspid regurgitation, part of the ejected

volume flows backward into the atrium. Instead of seeing a small C wave that

normally represents the bulging of the tricuspid valve, a much larger C wave would

be seen as blood flows retrograde into the right atrium and toward the transducer.

This retrograde blood flow would continue throughout the systole, and would,

therefore, also increase the V wave size, since this is a systolic component of the

CVP trace. During cardiac tamponade, there will be elevated pressures throughout

the entire waveform, as well as loss of the Y descent. In patients with atrial

fibrillation, there will be a loss of the A wave, since there is no longer a uniform

atrial contraction, and an overall increase in the C wave size, since filling pressures

elevate to compensate and improve ventricular filling. With AV dissociation, there

are large and exaggerated A waves (often called “cannon” A waves), which represent

atrial contraction against a closed tricuspid valve.

19. A. See the answer explanation of Question 18. It would be highly unlikely to have

elevated filling pressures in a bleeding trauma patient who has not yet been

resuscitated. Aortic dissections can cause cardiac tamponade, but only if they

involve the aortic root and then extend into the pericardium.

20. B. While the incidence of complications is infrequent, some of the complications

can carry severe morbidity and mortality risks. In addition to universal complications

associated with central line placement, some additional pulmonary artery catheter

complications include dysrhythmias (most common), catheter knotting, cardiac valve

injury, pulmonary artery rupture, development of complete heart block in a patient

with preexisting left bundle branch block, pulmonary thromboembolism or air

embolism, bacteremia, endocarditis, and sepsis.

21. B. As well as knowing some valuable indications, it is important to know some of

the limitations of a pulmonary artery catheter before subjecting a patient to risks. For

example, the measurement of cardiac output in patients with tricuspid regurgitation or

ventricular septal defects is inaccurate due to dilution of the injectate. Pulmonary

artery occlusion pressure can also inaccurately represent left ventricular end

diastolic pressure in patients with mitral stenosis, left atrial myxomas, pulmonary

venous obstruction, elevated alveolar pressures, and decreased left ventricular

compliance. Other common errors in measurement that are not patient dependent can

include an inaccurate volume or temperature of the injectate solution.

22. B. A pulmonary artery catheter is placed while monitoring the pressure changes

measured at the tip of the catheter. The first section shows a traditional CVP

waveform measured in the right atrium. As the catheter is advanced, a systolic stepup is seen when entering the right ventricle, a diastolic step-up when entering the

pulmonary artery, and a return to a traditional CVP waveform when entering the

wedge position.

Figure 4-5.

 


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

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