NBCRNA Anesthesia Equipment and Technology 1 — Questions and Answers
Question 1: On the anesthesia machine, the fail-safe valve is designed to prevent the delivery of hypoxic gas mixtures by doing what?
- Proportionally reducing nitrous oxide flow when oxygen pressure drops (Correct answer)
- Alarming when FiO2 falls below 21%
- Shutting off the vaporizer when N2O is on
- Increasing oxygen flow automatically
Correct answer: Proportionally reducing nitrous oxide flow when oxygen pressure drops
The fail-safe (oxygen failure protection device) shuts off or proportionally reduces the flow of N2O and other gases when the oxygen supply pressure falls below a threshold.
Question 2: The circle breathing system uses soda lime to do what?
- Absorb carbon dioxide from exhaled gases (Correct answer)
- Generate fresh oxygen for rebreathing
- Remove volatile anesthetic vapors
- Filter bacterial contamination
Correct answer: Absorb carbon dioxide from exhaled gases
Soda lime (primarily calcium hydroxide with sodium and potassium hydroxide) absorbs exhaled CO2 through a chemical reaction, allowing low-flow rebreathing circuits.
Question 3: A capnograph waveform showing an elevated baseline (above zero) throughout the respiratory cycle suggests what problem?
- CO2 rebreathing due to exhausted absorbent (Correct answer)
- Esophageal intubation
- Bronchospasm
- Venous air embolism
Correct answer: CO2 rebreathing due to exhausted absorbent
An elevated baseline on capnography indicates that exhaled CO2 is being rebreathed, most commonly due to exhausted CO2 absorbent or an incompetent expiratory valve.
Question 4: During a pre-use anesthesia machine check, which test verifies that the low-pressure circuit is leak-free?
- Negative pressure (suction bulb) leak test (Correct answer)
- Oxygen flush valve test
- Vaporizer interlock test
- Flowmeter calibration check
Correct answer: Negative pressure (suction bulb) leak test
The negative pressure leak test uses a suction bulb to apply negative pressure to the low-pressure circuit; failure to re-expand indicates an intact, leak-free system.
Question 5: What does a sustained upslope (shark fin appearance) in the capnography waveform indicate?
- Obstructive airway disease or bronchospasm (Correct answer)
- Esophageal intubation
- Hyperventilation
- Pulmonary embolism
Correct answer: Obstructive airway disease or bronchospasm
A prolonged, slanted upslope on capnography (shark fin) reflects uneven CO2 elimination from lung units with different time constants, characteristic of obstructive disease.
Question 6: The purpose of a pressure-limiting (pop-off) valve in the anesthesia breathing circuit is to do what?
- Release excess gas pressure to scavenge system (Correct answer)
- Prevent negative pressure in the circuit
- Regulate fresh gas flow rate
- Monitor peak inspiratory pressure
Correct answer: Release excess gas pressure to scavenge system
The adjustable pressure-limiting (APL) valve vents excess gas from the breathing circuit to the scavenging system, preventing barotrauma during manual ventilation.
NBCRNA Anesthesia Equipment and Technology 1
On the anesthesia machine, the fail-safe valve is designed to prevent the delivery of hypoxic gas mixtures by doing what?