Flashcards on Modern Anesthesia Machine Overview
Modern Anesthesia Machine Overview: Functions & Safety
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Anesthesia Systems
22 cards
Card 1
Question: What is a measured-flow vaporizer, and what common example is mentioned for anesthesia systems?
Answer: A measured-flow vaporizer has independent circuits for fresh gas and inhaled anesthetic that join after the vaporizer; the most common example is the
Card 2
Question: Why does desflurane require a heated vaporizer, and at what temperature is it maintained?
Answer: Because it has a low boiling point and high volatility; it is constantly heated to 39 °C.
Card 3
Question: How are the circuits arranged in a measured-flow vaporizer for desflurane?
Answer: There are two independent parallel circuits (fresh gas flow and inhaled anesthetic flow) that do not mix until just before the inspiratory limb.
Card 4
Question: What is the function of the Adjustable Pressure-Limiting (APL) valve in the anesthesia circuit?
Answer: It acts as a pressure relief valve between the expiratory unidirectional valve and the CO2 absorber to prevent excessive pressures in the circuit and
Card 5
Question: How is the APL valve adjusted during spontaneous ventilation and during positive pressure ventilation?
Answer: During spontaneous ventilation, it remains open to facilitate breathing; during positive pressure ventilation, it is partially closed (usually <20 cm
Card 6
Question: Where does the gas released by the APL valve go when it limits pressure, and why?
Answer: It goes to the scavenging system to minimize operating room air contamination.
Card 7
Question: What does the oxygen flush button do, and what flow rate/pressure does it deliver?
Answer: It opens a direct connection between the oxygen line and the regulator to deliver pure oxygen at 35–70 L/min at a pressure of 45–60 psi.
Card 8
Question: When is the oxygen flush commonly used, and what precautions should be taken when using it?
Answer: It is used during mask ventilation when there is no adequate seal; it is important to remember that it only administers oxygen (no anesthetic or N2O)
Card 9
Question: What is the function of the carbon dioxide absorber in the circle system?
Answer: To chemically remove CO2 from exhaled gases to prevent its re-entry into the inspiratory circuit and allow gas reuse (low-flow anesthesia).
Card 10
Question: What are CO2 absorbers typically composed of, and how do they indicate saturation?
Answer: They contain mixtures of hydroxides/hydrated lime such as calcium, sodium, potassium, and barium hydroxide; they usually have chemical indicators that