# Chemistry And Physics Of Anesthesiology Quiz! Trivia

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Chemistry and physics of anesthesiology quiz trivia. An anesthetist deals with different liquid and gasses under pressure at varying temperature and volume. It is therefore important to understand the changes that each of them go through and what to term as odd. In this quiz, you will get to test out how much you know about these drugs, their effects, uses as well as quantities to use. Do give it a try and see how informed you are.

• 1.

### The expression that for a fixed mass of gas at constant temperature, the product of pressure and volume is constant is known as:

• A.

Graham's law

• B.

Bernoulli's law

• C.

Boyle's law

• D.

Dalton's law

• E.

Charles' law

C. Boyle's law
Explanation
Boyle's law states that for a fixed mass of gas at constant temperature, the product of pressure and volume is constant. This concept can be applied to estimate the volume of gas remaining in compressed-gas cylinder by measuring the pressure within the cylinder

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• 2.

### The pressure gauge on size "E" compressed-gas cylinder containing O2 reads 1,600 pounds per square inch absolute temperature (psia). How long could O2 be delivered from this cylinder at a rate of 2 L/min

• A.

90 min

• B.

140 min

• C.

245 min

• D.

320 min

• E.

Cannot be calculated

C. 245 min
Explanation
E-size O2 cylinder filled with pressure 2,200 psia contains approximately 625 L of gas. According to Boyle's law the volume of gas can be estimated by measuring the pressure within the container. Therefore, when pressure gauge on cylinder shows 1,600 psia, it contains approximately 490 L of O2. At gas flow of 2L/min it will be delivered for 245 min.

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• 3.

### An otherwise healthy 25-year-old patient is udergoing a femoral hernia repair. General anesthesia is induced with thiopental, 3,5 mg/kg, and after administration of succinylcholine, 1,5 mg/kg, tracheal intubation is performed under direct laryngoscopy without difficulty. Bilateral breath sounds are auscultated and end-expired CO2 is noted on mass spectrometer. Anesthesia is maintaned with isoflurane and N2O, 50% in O2, and the patient's lungs are mechanically vemtilated. Suddenly, the "low-arterial-saturation" warning signal on pulse oximeter alarms. After being disconnected from the anesthesia machine, the patient is ventilated with AMBU bag with 100% O2 without difficulty and arterial saturation quickly improves. During inspection of your anesthesia equipment, you notice that bobbin in O2 rotameter is not rotating. This most likely indicates:

• A.

The flow of N2O through the O2 rotameter

• B.

No flow of O2 through the O2 rotameter

• C.

A flow of O2 through the O2 rotameter that is markedly lower than indicated

• D.

A leak in the O2 rotameter above the bobbin

• E.

A leak in the O2 rotameter below the bobbin

B. No flow of O2 through the O2 rotameter
Explanation
All of the choices listed in this question can potentially result in inadequate flow of O2 to the patient; however, given the description of the problem, no flow of O2 through the O2 rotameter is the correct choice. In a normal functioning rotameter, gas flows between the rim of the wall of the Thorpe tube, causing the bobbin to rotate. If the bobbin is rotating you can be certain that gas is flowing through the rotameter and that the bobbin is not stuck.

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• 4.

### The O2 pressure-sensor-shutoff valve requires what O2 pressure to remain open and allow N2O flow into the N2O rotameter?

• A.

10 psia

• B.

25 psia

• C.

50 psia

• D.

100 psia

• E.

600 psia

B. 25 psia
Explanation
Fail-safe valve is a synonym for pressure-sensor shutoff valve. The purpose of the fail-safe valve is to prevent delivery of hypoxic gas mixtures from the anesthesia machine to the patient in case of failure of the O2 supply. When the O2 pressure within the anesthesia machine decreases below 25 psia, this valve discontinues the flow of N2O or proportionally decreases the flow of all gases. It is important to realize that this valve will not prevent delivery of hypoxic gas mixtures or pure N2O when the O2 rotameter is off but the O2 pressure within the circuits of the anesthesia machine is maintained by an open O2 compressed-gas cylinder or central supply source. Under these circumstances, an O2 analyser would be needed to detect delivery of a hypoxic gas mixture.

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• 5.

### A copper kettle vaporizer is filled with a volitile anesthetic that is a saturated vapor pressure of 304 mm Hg at 20ºC. The carrier-gas flow through the vaporizing chamber is 90 ml/min. What diluent fresh-gas flow is required to deliver from the vaporizer a final concentration of the anesthetic of 1,5%?

• A.

1,000 ml/min

• B.

2,000 ml/min

• C.

3,000 ml/min

• D.

4,000 ml/min

• E.

5,000 ml/min

D. 4,000 ml/min
Explanation
The amount of volatile anesthetic vapor leaving the vaporizing chamber will constitute a fractional volume of the total gas leaving the chamber which is proportional to the ratio of the saturated vapor pressure of the volatile anesthetic and atmospheric pressure. In this quiestion, 40% of the total gas flow leaving the vaporizing chamber will be anesthetic vapor. Since the carrier gas flow is 90 ml/min, 60 ml of anesthetic vapor plus 90 ml of carrier gas will exit the vaporizing chamber (i.e., 150 of 40% anesthetic). A diluent fresh gas flow of approximately 4,000 ml/min wil be required to mix with the 150 ml of 40% anesthetic emerging from the vaporizing chamber to produce a delivered concentration of 1,5%.

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• 6.

### The second-stage O2 pressure regulator delivers a constant O2 pressure to the rotameters of:

• A.

4 psia

• B.

8 psia

• C.

16 psia

• D.

32 psia

• E.

64 psia

C. 16 psia
Explanation
O2 and N2O enter the anesthesia machine from a central supply source or compressed-gas cylinders at pressures greater than 2,000 psia. First-stage pressure regulators reduce this pressure to approximately 50 psia. Prior to entering the rotameters , second-stage O2 pressure regulators further reduce the pressure to approximately 16 psia.

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• 7.

### The highest trace concentration of N2O allowed in the operating room atmosphere by the National Institute for Occupational Safety and Health (NIOSH) is:

• A.

1 ppm

• B.

5 ppm

• C.

25 ppm

• D.

50 ppm

• E.

100 ppm

C. 25 ppm
Explanation
The correct answer is 25 ppm. The National Institute for Occupational Safety and Health (NIOSH) has set the highest trace concentration of N2O allowed in the operating room atmosphere at 25 ppm. This limit is in place to ensure the safety and well-being of healthcare workers who may be exposed to N2O during procedures. Higher concentrations of N2O can have adverse health effects, including dizziness, nausea, and even long-term neurological damage. Therefore, it is crucial to adhere to this limit to maintain a safe working environment.

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• 8.

### Halothane vaporizer will deliver an accurate concentration of an unknown volatile anesthetic if the latter shares which property with halothane?

• A.

Molecular weight

• B.

Viscosity

• C.

Vapor pressure

• D.

Blood/Gas partition coefficient

• E.

Oil/Gas partition coefficient

C. Vapor pressure
Explanation
Agent-specific vaporizers are designed for each volatile anesthetic. However, volatile anesthetics with identical saturated vapor pressures could be used interchangeably with accurate delivery of volatile anesthetic.

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• 9.

### After entering the anesthesia machine at 45 to 55 psia (from a compressed-gas cylinder), O2 is directed to provide for which of the following functions of the anesthesia machine?

• A.

A pneumatic source for the gas-driven anesthesia ventilator

• B.

The O2 supply fail-safe system

• C.

To open the pressure-sensor shutoff valve

• D.

O2 to the O2 rotameters

• E.

All of above

E. All of above
Explanation
After O2 enters the anesthesia machine from a compressed-gas cylinder or from a central supply line, the pressure within the tubing reduced to 45 to 55 psia by the first-stage pressure regulators. This pressure provides for several functions of the anesthesia machine. In addition to the choices in this question, the O2 is also diverted to vaporizing chambers to provide a reliable means to deliver selected concentrations of volatile anesthetic to the patient.

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• 10.

### Which of the following rotameter flow indicators is read in the middle of the dial?

• A.

Bobbin

• B.

"H" float

• C.

Ball float

• D.

Skirted float

• E.

Nonrotating float

C. Ball float
Explanation
Five types of rotameter indicators are commonly used to indicate the flow of gases delivered from the anesthesia machine. As with all anesthesia equipment, proper understanding of their function is necessary for safe and proper use. All rotameters should be read at the upper rim exept ball floats, which should be read in the middle.

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• 11.

### When the pressure gauge on size "E" compressed-gas cylinder, containing N2O begins to fall from its previous constant pressure of 750 psia, how many liters of gas remain in cylinder?

• A.

200

• B.

400

• C.

600

• D.

800

• E.

Cannot be calculated

B. 400
Explanation
The pressure gauge on size "E" compressed-gas cylinder containing N2O shows 750 psia when it is full and will continue to register 750 psia until approximately three quarters of the gas has left the cylinder. A full cylinder of N2O contains 1,600 L. Therefore, when 400 L of gas remain in the cylinder, the pressure within the cylinder will begin to fall.

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• 12.

### The maximum volume of CO2 that can be absorbed by 100 g of absorbent granules is:

• A.

5 L

• B.

10 L

• C.

15 L

• D.

20 L

• E.

25 L

E. 25 L
Explanation
In semiclosed anesthetic-breathing circuits, CO2 is eliminated from the circuit by chemical neutralization. This process is achieved by directing exhaled gases through a container with CO2-absorbent granules, such as soda lime o baralyme. Their efficiency influenced by many factors. Maximum volume of CO2 that can be absorbed by 100 g of granules is 25 L.

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• 13.

### If the diameter of any intravenous catheter is doubled, flow through the catheter will

• A.

Decrease by factor of 2

• B.

Decrease by factor of 4

• C.

Increase by factor of 8

• D.

Increase by factor of 16

• E.

Increase by factor of 32

D. Increase by factor of 16
Explanation
Factors that influence the rate of flow of a substance through a tube are described by Hagen-Poiseuille law of friction. If diameter of catheter is doubled, flow will increase by a factor 2 raised by the fourth power.

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• 14.

### Of the following statements concerning the safe storage of compressed-gas cylinders, choose the one that is false.

• A.

Should not be handled with oily hands

• B.

Should not be stored near flammable material

• C.

Should not be stored in extreme heat or cold

• D.

Paper or plastic covers should not be removed from the cylinders before storage

• E.

All of the above statements are true

D. Paper or plastic covers should not be removed from the cylinders before storage
Explanation
The safe storage and handling of compressed-gas cylinders is of vital importance. They should not be stored in extremes of heat or cold and should be unwrapped when stored or when in use. Flames should not be used to detect the presence of gas. Oily hands can lead to difficulty in handling of the cylinder, which can result in dropping the cylinder. This can cause damage or rupture of the cylinder, which can lead to an explosion.

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• 15.

### Compliance is defined as

• A.

A change in pressure per unit change in volume

• B.

A change in volume per unit change in pressure

• C.

A change in pressure per unit change in flow

• D.

A change in flow per unit change in pressure

• E.

A change in volume per unit change in flow

B. A change in volume per unit change in pressure
Explanation
Compliance is a measure of how easily a substance or system can change its volume in response to a change in pressure. It is defined as the change in volume per unit change in pressure. This means that compliance quantifies the relationship between the change in volume and the change in pressure, indicating how much the volume of a substance or system will change for a given change in pressure.

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• 16.

### A mechanical ventilator is set to deliver a Vt of 500 ml at a rate of 10 breaths/min and an inspiratory-to-expiratory (I:E) ratio of 1:2. The fresh-gas flow into the breathing circuit is 6 L/min. In a patient with normal total pulmonary compliance, the actual Vt delivered to the patient be

• A.

400 ml

• B.

500 ml

• C.

600 ml

• D.

700 ml

• E.

800 ml

D. 700 ml
Explanation
The contribution of the fresh-gas flow from the anesthesia machine to the patient's Vt should be considered when setting the Vt of a mechanical ventilator. Because of the ventilator pressure-relief valve is closed during inspiration, both the gas from the ventilator bellows and the fresh gas flow will be delivered to the patient breathing circuit. In this question 2 L/min, a 1/3 of fresh gas is in inspiration phase. Every breath (10 bpm) is 200 ml will be augmented to Vt.

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• 17.

### A mechanical ventilator is set to deliver a Vt of 500 ml at a rate of 6 breaths/min and an inspiratory-to-expiratory (I:E) ratio of 1:2. The fresh-gas flow into the breathing circuit is 6 L/min. In a patient with normal total pulmonary compliance, the actual Vt delivered to the patient be

• A.

600 ml

• B.

700 ml

• C.

800 ml

• D.

900 ml

• E.

1000 ml

C. 800 ml
Explanation
The contribution of the fresh-gas flow from the anesthesia machine to the patient's Vt should be considered when setting the Vt of a mechanical ventilator. Because of the ventilator pressure-relief valve is closed during inspiration, both the gas from the ventilator bellows and the fresh gas flow will be delivered to the patient breathing circuit. In this question 2 L/min, a 1/3 of fresh gas is in inspiration phase. Every breath (6 bpm) â‰ˆ330 ml will be augmented to Vt.

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• 18.

### Vaporizers for which of the following volatile anesthetics could be used interchangeably with accurate delivery o the concentration of anesthetic set on the vaporizer dial?

• A.

Halothane, enflurane, and isoflurane

• B.

Enflurane, isoflurane

• C.

Halothane, enflurane

• D.

Halothane, isoflurane

• E.

None of above

D. Halothane, isoflurane
Explanation
The saturated vapor pressures of halothane and isoflurane are very similar (â‰ˆ240 mm Hg at room temperature), so they could be used interchangeably in agent-specific vaporizers.

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• 19.

### According to National Institute for Occupational Safety and Health (NIOSH) regulations, the highest concentration of volatile anesthetic contamination allowed in the operating room atmosphere when administred in conjunction with N2O is

• A.

0,5 ppm

• B.

2 ppm

• C.

5 ppm

• D.

25 ppm

• E.

50 ppm

A. 0,5 ppm
Explanation
According to National Institute for Occupational Safety and Health (NIOSH) regulations, the highest concentration of volatile anesthetic contamination allowed in the operating room atmosphere when administered in conjunction with N2O is 0.5 ppm. This means that the maximum allowable concentration of volatile anesthetic in the operating room atmosphere, when N2O is being used, is 0.5 parts per million. This regulation is in place to ensure the safety of healthcare workers and prevent excessive exposure to volatile anesthetics, which can have harmful effects on health.

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• 20.

### The device on anesthesia machines that most reliably detects delivery of hypoxic gas mixtures is the

• A.

Fail-safe valve

• B.

O2 analyser

• C.

Second-stage O2 pressure regulator

• D.

Promotion-limiting control system

• E.

Diameter index safety system

B. O2 analyser
Explanation
The O2 analyzer is the last line of defense against inadvertent delivery of hypoxic gas mixtures. It should be located in the inspiratory limb of the patient breathing circuit to provide maximum safety. Since the O2 concentration in the fresh-gas supply line may be different from that in the patient breathing circuit, the O2 analyzer should not be located in fresh-gas supply line.

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• 21.

### A ventilator pressure-relief valve stuck in the closed position can result in

• A.

Barotrauma

• B.

Hypoventilation

• C.

Hypoxia

• D.

Hyperventilation

• E.

A low breathing-circuit pressure

A. Barotrauma
Explanation
The ventilator pressure-relief valve is pressure-controlled via pilot tubing that communicates with the ventilator bellows chamber. As the pressure within the bellows chamber increases during the inspiratory phase of the ventilator cycle, the pressure is transmitted via the pilot tubing to close the pressure-relief valve, thus making the patient breathing circuit "gas-tight." This valve should open during the expiratory phase of the ventilator cycle to allow the release of excess gas from the patient breathing circuit into the waste-gas-scavenging circuit after the bellows has fully expanded. If the ventilator pressure-relief valve were stuck in the closed position, there would be a rapid buildup of pressure within the circle system which would be readily transmitted to the patient. Barotrauma to the patient's lungs would result if this situation were to continue unrecognized.

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• 22.

### The agency responsible for manufacturing and testing compressed gases is the

• A.

Compressed Gas Association

• B.

Department of Transportation

• C.

• D.

National Fire Protection Association

• E.

Joint Commission on Accreditation of Healthcare Organizations

B. Department of Transportation
Explanation
Department of Transportation regulates the manufacturing and testing of compressed-gas cylinders. National Fire Protection Association and the Compressed Gas Association publish materials outlining standards for safe use and storage of compressed-gas cylinders.

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• 23.

### The ratio of the density of a solution to the density of cerebrospinal fluid (CSF) is called

• A.

Specific gravity

• B.

Mass

• C.

Baricity

• D.

Absolute density

• E.

None of above

C. Baricity
Explanation
Density is the weight in grams of 1 ml of a solution at specific temperature. The ratio of the density of a solution at a specific temperature to the density of cerebrospinal fluid at the same temperature is called baricity. Local anesthetic used for spinal anesthesia can be defined as hypobaric, isobaric, or hyperbaric. Hypobaric local anesthetic solutions are less dense than cerebrospinal fluid, isobaric local anesthetic solutions are equally dense as cerebrospinal fluid, and hyperbaric solutions are more dense than cerebrospinal fluid. The density of normal human cerbrospinal fluid at 37ÂºC is 1.0001 to 1.0005 (95% confidence limits). Local anesthetic solutions can be made hyperbaric by adding glucose in sufficient quantities to increase the baricity > 1.0008

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• 24.

### Select the false statement.

• A.

If a Magill forceps is used for nasotracheal intubation, the right nares is preferable of the nasotracheal tube.

• B.

Extension of the neck can convert an endotracheal intubation to an endobronchial intubation.

• C.

Bucking signifies the return of coughing reflex.

• D.

Postintubation pharyngitis is more likely to occur in females.

• E.

Stenosis becomes symptomatic when the adult tracheal lumen is reduced to less than 5 mm.

B. Extension of the neck can convert an endotracheal intubation to an endobronchial intubation.
Explanation
The statement "Extension of the neck can convert an endotracheal intubation to an endobronchial intubation" is false. Extension of the neck does not convert an endotracheal intubation to an endobronchial intubation. Endobronchial intubation occurs when the endotracheal tube is inadvertently inserted into one of the mainstem bronchi instead of the trachea. This can happen due to factors such as improper positioning or incorrect placement of the tube. Extension of the neck does not play a role in this process.

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• 25.

### Gas from an N2O compressed-gas cylinder enters the anesthesia machine through a pressure regulator that reduces the pressure to

• A.

60 psia

• B.

45 psia

• C.

30 psia

• D.

15 psia

• E.

10 psia

B. 45 psia
Explanation
The correct answer is 45 psia because the pressure regulator in the anesthesia machine is designed to reduce the pressure of the gas from the N2O compressed-gas cylinder. The pressure is reduced to 45 psia to ensure that the gas is delivered at a safe and controlled pressure to the patient during anesthesia administration.

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• 26.

### Which of the following factors is least responsible for killing bacteria in anesthesia mechines?

• A.

Metallic ions

• B.

High O2 concentration

• C.

Anesthetic gases (a clinical concentrations)

• D.

Shifts in humidity

• E.

Shifts in temperature

C. Anesthetic gases (a clinical concentrations)
Explanation
Anesthetic gases at clinical concentrations are least responsible for killing bacteria in anesthesia machines. While high O2 concentration, metallic ions, shifts in humidity, and shifts in temperature can all contribute to the death of bacteria, anesthetic gases at clinical concentrations do not possess strong bactericidal properties. They primarily function to induce anesthesia and maintain the desired level of sedation in patients.

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• 27.

### Which of the following systems prevents attachment of gas-amdinistering equipment to the wrong type of gas line?

• A.

Pin-index safety system

• B.

Diameter index safety system

• C.

Fail-safe system

• D.

Proportion-limiting control system

• E.

None of above

A. Pin-index safety system
Explanation
The pin-index safety system is designed to prevent the attachment of gas-administering equipment to the wrong type of gas line. This system uses a specific arrangement of pins and corresponding holes on both the gas cylinder and the equipment to ensure that they can only be connected in the correct configuration. This helps to avoid dangerous situations where incompatible gases are used, reducing the risk of accidents or damage to the equipment.

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• 28.

### A volatile anesthetic has a satureted vapor pressure of 360 mm Hg at room temperature. At what flow would this agent be delivered from a bubble-through vaporizer if the carrier-gas flow through vaporizing chamber is 100 ml/min?

• A.

30 ml/min

• B.

60 ml/min

• C.

90 ml/min

• D.

120 ml/min

• E.

150 ml/min

C. 90 ml/min
Explanation
The saturated vapor pressure of a volatile anesthetic at room temperature indicates the maximum pressure at which the anesthetic can exist as a vapor. The carrier-gas flow through the vaporizing chamber determines the rate at which the anesthetic is delivered. To ensure that the anesthetic is delivered effectively, the flow rate of the carrier gas should be high enough to maintain the vapor pressure of the anesthetic. In this case, a flow rate of 90 ml/min would be sufficient to deliver the anesthetic effectively from the bubble-through vaporizer.

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• 29.

### The total saturated vapor pressure in half-full size "E" compressed-gas cylinder containing 50% O2 and 50% N2O by volume (Entonox) is 1,100 psia. The partial saturated vapor pressure of N2O within this cylinder is

• A.

375 psia

• B.

450 psia

• C.

500 psia

• D.

550 psia

• E.

Cannot be calculated

D. 550 psia
Explanation
Entonox is a commercially available single-cylinder gas mixture of O2 and N2O (1:1 by volume). Bacause the attractive forces between N2O molecules are not as strong when mixed with O2, condensation of N2O does not occur when the ambient temperature is greter than -5,5ÂºC. Therefore, this gas mixture obeys the principles of Dalton's law, which states that the total pressure exerted by constituents of the gas mixture. The pressure within a size "E" cylinder filled with Entonox is 2,200 psia (partial pressure of N2O 1,100 psia). Thus, partial pressure exerted by N2O in half-full cylinder is 550 psia.

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• 30.

### High-pressure endotracheal tube cuffs must be inflated to what pressure to produce an adequate seal between the cuff and the wall of the trachea?

• A.

30-50 mm Hg

• B.

75-125 mm Hg

• C.

130-175 mm Hg

• D.

180-250 mm Hg

• E.

300-500 mm Hg

D. 180-250 mm Hg
Explanation
High-pressure endotracheal tube cuffs must be inflated to a pressure of 180-250 mm Hg to produce an adequate seal between the cuff and the wall of the trachea. This range of pressure ensures that the cuff effectively seals the airway, preventing leakage and minimizing the risk of aspiration or airway complications. Inflating the cuff to a lower pressure may result in inadequate sealing, while inflating it to a higher pressure may cause damage to the tracheal wall. Therefore, maintaining the cuff pressure within the range of 180-250 mm Hg is crucial for proper airway management.

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• 31.

### Body plethysmography can be used to measure lung volumes by application of

• A.

Boyle's law

• B.

Dalton's law

• C.

Newton's law

• D.

Laplace's law

• E.

Bernoulli's law

A. Boyle's law
Explanation
Boyle's law states that at a constant temperature, the product of pressure and volume is constant. Thia principle can be applied to the measurement of lung volumes; a change in plethysmograqph pressure will reflect a change in the lung volume. This technique is most frequently used to measure the functional residual capacity.

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• 32.

### Which of the following combinations would result in delivery of a higher-than-expected concentration of volatile anesthetic to the patient?

• A.

Halothane vaporizer filled with enflurane

• B.

Halothane vaporizer filled with isoflurane

• C.

Isoflurane vaporizer filled with halothane

• D.

Isoflurane vaporizer filled with enflurane

• E.

Enflurane vaporizer filled with halothane

E. Enflurane vaporizer filled with halothane
Explanation
Enflurane have lower than isoflurane and halothane saturated vapor pressure, so enflurane vaporizer filled with halothane or isoflurane will deliver higher-than-expexted concentration of volatile anesthetic.

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• 33.

### The principles that determine the net flow of fluid across capillary membranes are described in

• A.

Fick's law

• B.

Graham's law

• C.

Fick's principle

• D.

Starling's law

• E.

Henry's law

D. Starling's law
Explanation
Starling's law of fluid exchange across capillaries states that the net direction of fluid flow is determined by the forces tending to move fluid out of the capillaries relative to the forces tending to move fluid into the capillaries. The total outward force is the sum of the pressures generated by the capillary hydrostatic pressure, negative interstitial free-fluid pressure, and interstitial fluid colloid osmotic pressure. The total inward force is the sum of the pressures generated by the interstitial pressure and plasma colloid osmotic pressure.

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• 34.

### The most important determinant of resistance to laminar gas flow through a tube is the

• A.

Length of the tube

• B.

• C.

Viscosity of the gas

• D.

Density of the gas

• E.

Mass of the gas

Explanation
Laminar flow occurs when a substance flows down parallel-sided tube at a rate less than critical velocity. Resistance to laminar gas flow through a tube is directly proportional to the viscosity of the gas and the length of the tube, and inversely proportional to the forth power of the radius of the tube. This is knows as Hagan-Poiseuille law of friction.

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• 35.

### All of the following would result in less trace gas pollution of the operating room atmosphere EXCEPT

• A.

Using a high gas flow in circular system

• B.

• C.

Use of scavenger system

• D.

Periodic maintenance of the anesthesia machine

• E.

Allow patient to breathe 100% O2 as long as possible before extubation

A. Using a high gas flow in circular system
Explanation
Although controversial, chronic exposure to low concentrations of volatile anesthetics may constitute a health hazard to operating room personnel. Therefore, removal of trace concentrations of volatile anesthetic gases from the operating room atmosphere with scavenger system and steps to reduce and control gas leakage into the environment are required. High-pressure system leakage of volatile anesthetic gases into the operating room atmosphere occurs when gas escapes from compressed-gas cylinders attached to the anesthetic machine (e.g., faulty yokes) or from tubing delivering these gases to the anesthesia machine from a central supply source. The most common cause of ;ow-pressure leakage of anesthetic gases into the operating room atmosphere is the escape of gases from sites located between the flowmeters of the anesthesia machine and the patient, such as a poor mask seal. The use of high gas flows in a circle system will not reduce trace gas contamination of the operating room atmosphere. In fact, this could contribute to the contamination if there is a leak in the circle system.

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• 36.

### The greatest source for contamination of the operating room atmosphere is leakage of volatile anesthetics

• A.

• B.

At the vaporizer

• C.

At the rotameter

• D.

At the CO2 absorber

• E.

At the endotracheal tube

Explanation
Some epidemiology studies suggest that chronic exposure to trace concentrations of volatile anesthetic gases constitutes a health hazard to operating room personnel. For this reason, proper and routine use of scavenging systems is recommended in the operating room. It is extremely difficult to keep trace volatile anesthetic gas concentrations within safe limits when they are delivered using a face mask. Although all of the choices in this question can contribute as sources of contamination, leakage around the anesthesia face mask poses the greatest threat.

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• 37.

### Uptake of enflurane from the lungs during the first minute of general anesthesia is 200 ml. How much enflurane would be taken up from the lungs between the 16th and 36th minutes?

• A.

100 ml

• B.

200 ml

• C.

400 ml

• D.

700 ml

• E.

2000 ml

C. 400 ml
Explanation
The amount of volatile anesthetic taken up by patient in the first minute i equal to that amount taken up between the squares of any 2 consecutive minutes. Accordingly, 200 ml would be taken up between the 16th(4x4) and 25th(5x5) minute, and another 200 ml would be taken up between the 25th and 36th (6x6) minute.

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• 38.

### The predominant component of baralyme granules is

• A.

Water

• B.

Silica

• C.

Barium hydroxide

• D.

Calcium hydroxide

• E.

Potassium hydroxide

D. Calcium hydroxide
Explanation
Baralyme granules are composed primarily of barium hydroxide (20%) and calcium hydroxide (80%). Unlike soda lime, baralyme granules are inherently hard and thus the addition of silica to the granules is not necessary. Furthermore, baralyme granules contain water in form of barium hydroxide octahydrate salt, and therefore can be used more efficiently in dry climates.

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• 39.

### Select the FALSE statement regarding iatrogenic bacterial infections from anesthetic equipment

• A.

Even low concentrations of O2 are lethal to airborne bacteria

• B.

Bacteria that are released from the airway during violent exhalation originate almost exclusively from anterior oropharynx

• C.

Of all the bacteria forms, acid-fast bacteria the most resistant to destruction

• D.

Shifts in temperature and humidity are probably the most important factors responsible for bacterial killing

• E.

Bacterial filters in the anesthesia-breathing system lower the incidence of postoperative pulmonary infections

E. Bacterial filters in the anesthesia-breathing system lower the incidence of postoperative pulmonary infections
Explanation
There is no evidence that the incidence of postoperative pulmonary infection is altered by use of sterile disposable anesthesia breathing systems (compared with use of reusable systems that are cleaned with basic hygienic techniques) or by the inclusion of a bacterial filter in the anesthesia-breathing system.

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• 40.

### Frost develops on the outside of an N2O compressed-gas cylinder during general anesthesia. This phenomenon indicates that

• A.

The saturated vapor pressure of N2O within the cylinder is rapidly increasing

• B.

The cylinder is almost empty

• C.

There is a rapid transfer of heat to the cylinder

• D.

The flow of N2O from the cylinder into the anesthesia machine is rapd

• E.

None of above

D. The flow of N2O from the cylinder into the anesthesia machine is rapd
Explanation
Vaporization of liquid requires the transfer of heat from the objects on contact with the liquid (e.g., metal cylinder and surrounding atmosphere). For this reason, at high flows atmospheric water will condensate as frost on the outside of compressed-gas cylinders.

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• 41.

### The least reliable site for central temperature monitoring is the

• A.

Rectum

• B.

• C.

Distal third of esophagus

• D.

Nasopharynx

• E.

Tympanic membrane

Explanation
Rectal, esophageal, axillary, nasopharingeal, and tympanic membrane temperature measurements correlate with central temperature in patients undergoing noncardiac surgery. Skin temperature does not reflect central temperature and does not warn adequately of malignant hyperthermia or excessive hypothermia.

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• 42.

### A balanced anesthetic is administered to an otherwise healthy 38-year-old patient undergoing repair of a right inguinal hernia. During mechanical ventilation, the anesthesiologist notices that the scavenging-reservoir bag is distented during inspiration. The most likely cause of this is

• A.

An incompetent pressure-relief valve in the mechanical ventilator

• B.

An incompetent pressure-relief valve in the patient breathing circuit

• C.

An incompetent inspiratory unidirectional valve in the patient breathing circuit

• D.

An incompetent expiratory unidirectional valve in patient breathing circuit

• E.

None of above; the scavenging-reservoir bag is supposed to distend during inspiration

A. An incompetent pressure-relief valve in the mechanical ventilator
Explanation
In a closed scavenging system interface, the reservoir bag should distend during expiration and deflate during inspiration. During the inspiratory phase of mechanical ventilation, the ventilator pressure-relief valve closes, thereby directing the gas inside the ventilator bellows into the patient breathing circuit. If the ventilator pressure-relief valve is incompetent, there will be a direct communication between the patient breathing circuit and scavenging circuit. This would result in delivery of part of the mechanical ventilator Vt directly to the scavenging circuit, causing the reservoir bag to inflate during the inspiratory phase of the ventilator cycle.

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• 43.

### The reason a 40:60 mixture of helium:O2 is more desirable than a 40:60 mixture of nitrogen:O2 for a spontaneously breathing patient with tracheal stenosis is

• A.

Helium has lower density than nitrogen

• B.

Helium is smaller molecule than O2

• C.

Absorption atelectasis decreases

• D.

Helium has a lower critical velocity for turbulent flow than does O2

• E.

Helium is toxic to most microorganisms

A. Helium has lower density than nitrogen
Explanation
The critical velocity for helium is greater than that for nitrogen. For this reason, there is less work of breathing when helium is substituted for nitrogen.

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• 44.

### The maximum FiO2 that can be delivered by a nasal cannula is

• A.

0.25

• B.

0.30

• C.

0.35

• D.

0.40

• E.

0.45

E. 0.45
Explanation
The FiO2 delivered to patients from low-flow systems (e.g., nasal cannula) is determined by the size of the O2 reservoir, the O2 flow, and the patient's breathing pattern. As a rule of thumb, assuming a normal breathing pattern, the FiO2 delivered by nasal prongs increases by approximately 0.04 for each L/min increase in O2 flow up to maximum FiO2 of approximately 0.45 (at an O2 flow of 6 L/min). In general, the larger the patient's Vt or faster the inspiratory rate, the lower FiO2 for given O2 flow.

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• 45.

### All of the following statements concerning rotameters are true EXCEPT which one?

• A.

Rotation of the bobbin within the Thorpe tube is important for accurate function

• B.

The Thorpe tube increases in diameter from bottom to top

• C.

Its accuracy is affected by changes in temperature and atmospheric pressure

• D.

The rotameter for N2O and CO2 are interchangeable

• E.

The rotameter for O2 should be the last in the series

D. The rotameter for N2O and CO2 are interchangeable
Explanation
Rotameters consist of a vertically positioned tapered tube, which is smallest in diameter at the bottom (Thorpe tube). Gas enters at the bottom of the Thorpe tube elevating a bobbin or float, which comes to rest when gravity on the float is balanced by the fall in pressure across the float. The rate of gas flow through the tube depends on the pressure drop along the length of the tube, the resistance to gas flow through the tube, and the physical properties (density and viscosity) of the gas. Because few gases have the same density and viscosity, rotameters cannot be used interchangeably.

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• 46.

### Which color of nail polish would have the greatest effect on the accuracy of dual-wavelength pulse oxymeters?

• A.

Red

• B.

Yellow

• C.

Blue

• D.

Green

• E.

White

C. Blue
Explanation
The accurate function of dual-wavelength pulse oxymeters is altered by nail polish. Because blue nail polish has a peak absorbance similar to that of adult deoxygenated hemoglobin (near 660 nm), blue nail polish has the greatest effect on the SaO2 reading. Nail polish causes an artifactual and fixed decrease in SaO2 reading by these devices.

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• 47.

### The minimum macroshock current required to elicit ventricular fibrillation is

• A.

1 mAmp

• B.

10 mAmp

• C.

100 mAmp

• D.

500 mAmp

• E.

5,000 mAmp

C. 100 mAmp
Explanation
The minimum macroshock current required to elicit ventricular fibrillation is 100 mAmp. Ventricular fibrillation is a life-threatening condition where the heart's electrical signals become chaotic, causing the heart to quiver instead of pumping blood effectively. A macroshock refers to an electrical shock that occurs when current passes through the body externally. A current of 100 mAmp is sufficient to disrupt the heart's normal electrical activity and trigger ventricular fibrillation.

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• 48.

### The line isolation monitor

• A.

Prevents microshock

• B.

Prevents macroshock

• C.

Provides electrical isolation in the operating room

• D.

Sounds an alarm when grounding occurs in the operating room

• E.

Provides a safe electrical ground

D. Sounds an alarm when grounding occurs in the operating room
Explanation
The isolation monitor alarms when grounding occurs in the OR or when the maximum current that a short circuit could cause exceeds 2 mamp. Therefore, the line isolation monitor will not prevent microshock or macroshock.

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• 49.

### Kinking of the transfer tubing from the patient breathing circuit to the closed scavenging-system interface can result in

• A.

Barotrauma

• B.

Hypoventilation

• C.

Hypoxia

• D.

Hyperventilation

• E.

None of above

A. Barotrauma
Explanation
A scavenging system with closed interface is one in which there is communication with the atmosphere through positive and negative pressure-relief valves. The positive pressure-relief valve will prevent transmission of excessive pressure buildup to the patient breathing circuit, even if there is an obstruction distal to the interface or if the system is not connected to wall suction. However, obstruction of the transfer tubing from the patient breathing circuit to the scavenging circuit is proximal to the interface. This will isolate the patient breathing circuit from the positive pressure-relief valve of the scavenging system interface. Should this occur, barotrauma to the patient's lung can occur.

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• 50.

### At what concentration should the isoflurane vaporizer dial be set to deliver 1 minimal alveolar concentration (MAC) of isoflurane in Denver, Colorado (assume Pb is 630 mm Hg)

• A.

0.75%

• B.

0.9%

• C.

1.15%

• D.

1.4%

• E.

1.6%

C. 1.15%
Explanation
Agent-scecific vaporizers (in contrast to measured-flow vaporizers such as the copper kettle vaporizer) will deliver the same partial pressure of volatile anesthetic regardless to atmospheric pressure. Since the partial pressure of the volatile anesthetic in the brain, not the absolute concentration delivered to the patient. is the most important factor i achieving depth of anesthesia, the clinical effect of a give setting on the vaporizer dial will be affected by atmospheric pressure. In contrast, the concentration of volatile anesthetic (measures as volume percent) delivered from the vaporizer is influenced by atmospheric pressure. This effect may be calculated using following equation:
Cx = C*P/Px
where Cx is the output concentration in volume percent at atmospheric pressure x, C is the dial setting of the vaporizer in volume percent, P is the atmospheric pressure for which the vaporizer is calibrated, and Px is the atmospheric pressure for which Cx is being established.

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• Mar 21, 2023
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• Nov 29, 2011
Quiz Created by
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