DAANCE Anesthesia Equipment and Delivery 2 — Questions and Answers
Question 1: Which component of an anesthesia machine reduces high-pressure oxygen from the cylinder to a safe working pressure?
- Flowmeter
- Pressure regulator (yoke block) (Correct answer)
- Vaporizer
- Scavenging system
Correct answer: Pressure regulator (yoke block)
The pressure regulator reduces cylinder pressure to approximately 50 psi before gas enters the flowmeters.
Oxygen and nitrous oxide cylinders store gas at very high pressures. The pressure regulator steps pressure down to approximately 50 psi. Without this reduction, the flowmeters and circuit would be damaged.
Question 2: A demand-valve oxygen delivery system provides oxygen only when the patient:
- Exhales forcefully
- Initiates an inspiratory effort (Correct answer)
- Is placed in Trendelenburg position
- Has a pulse oximetry reading below 95%
Correct answer: Initiates an inspiratory effort
A demand valve senses the patient inspiratory effort and opens to deliver oxygen on demand.
Demand-valve systems use a pressure-sensing mechanism that detects the slight negative pressure created when the patient inhales. This triggers oxygen flow, making delivery responsive to patient breathing effort and reducing waste.
Question 3: The function of a reservoir bag in an anesthesia breathing circuit is to:
- Filter exhaled carbon dioxide
- Serve as a visual indicator of breathing and allow manual ventilation (Correct answer)
- Deliver nitrous oxide to the patient
- Monitor end-tidal CO2 levels
Correct answer: Serve as a visual indicator of breathing and allow manual ventilation
The reservoir bag allows the assistant to visually monitor respiratory rate and tidal volume and can be squeezed to assist or control ventilation manually.
The reservoir bag accommodates tidal volume during exhalation and provides a gas reservoir for inhalation. Its movement is a real-time visual indicator of spontaneous breathing. During emergencies, it can be squeezed to deliver positive-pressure ventilation.
Question 4: Which mask size is generally appropriate for a preschool-aged child ages 3 to 5 during nitrous oxide sedation?
- Size 0 (neonatal)
- Size 1 (infant)
- Size 2 (pediatric small) (Correct answer)
- Size 5 (adult large)
Correct answer: Size 2 (pediatric small)
Size 2 pediatric masks fit most children aged 3 to 5, minimizing gas leakage and ensuring accurate delivery of the N2O/O2 mixture.
Nasal mask sizing is critical in pediatric patients. A mask that is too large causes gas to leak around the face. A mask that is too small may be uncomfortable and restrict airflow. Size 2 is the standard choice for small children.
Question 5: After each patient use, nitrous oxide nasal masks should be:
- Disposed of and replaced with new masks
- Sterilized in an autoclave or disinfected per manufacturer guidelines (Correct answer)
- Rinsed with water only
- Stored in an open container for the next patient
Correct answer: Sterilized in an autoclave or disinfected per manufacturer guidelines
Nitrous oxide nasal masks must be disinfected or sterilized according to manufacturer instructions between patients to prevent cross-contamination.
Reusable nasal masks are semi-critical items (contact with mucous membranes) and require at minimum high-level disinfection between uses. Many practices use disposable covers or fully sterilize reusable masks.
Question 6: When using a nonrebreather mask for supplemental oxygen, flow rates are typically set at:
- 1 to 2 L/min
- 4 to 6 L/min
- 10 to 15 L/min (Correct answer)
- 20 to 25 L/min
Correct answer: 10 to 15 L/min
Nonrebreather masks require 10 to 15 L/min to keep the reservoir bag inflated and deliver approximately 60 to 90 percent oxygen.
The reservoir bag on a nonrebreather mask must remain at least two-thirds full throughout the respiratory cycle. At 10 to 15 L/min the bag stays sufficiently inflated. Lower flows allow the bag to collapse and reduce FiO2.
DAANCE Anesthesia Equipment and Delivery 2
Which component of an anesthesia machine reduces high-pressure oxygen from the cylinder to a safe working pressure?