Which device on an anesthesia machine most reliably detects delivery of hypoxic gas mixtures?

Which device on an anesthesia machine most reliably detects delivery of hypoxic gas mixtures?

• A. Fail-safe valve
• B. O2 analyzer
• C. Second-stage O2 pressure regulator
• D. Proportion-limiting control system

Answer: (B)

The key idea is that patient safety hinges on knowing the actual oxygen concentration the patient is receiving. An O2 analyzer provides a direct, continuous measurement of the fraction of inspired oxygen in the gas mixture delivered to the breathing circuit. By sampling the gas just before it reaches the patient, it confirms the FiO2 and triggers alarms if the level falls too low, making it the most reliable detector of a hypoxic gas delivery. Other components play protective roles but do not measure delivered oxygen content. A fail-safe valve responds to low O2 pressure by limiting nonoxygen gases, but it doesn’t quantify FiO2 and can’t detect the exact oxygen concentration reaching the lungs. A second-stage O2 pressure regulator simply reduces pipeline pressure, not the actual gas composition. A proportion-limiting control system prevents the delivery of deficient oxygen concentrations by constraining other gases, but again it’s not a direct readout of the FiO2.

The key idea is that patient safety hinges on knowing the actual oxygen concentration the patient is receiving. An O2 analyzer provides a direct, continuous measurement of the fraction of inspired oxygen in the gas mixture delivered to the breathing circuit. By sampling the gas just before it reaches the patient, it confirms the FiO2 and triggers alarms if the level falls too low, making it the most reliable detector of a hypoxic gas delivery.

Other components play protective roles but do not measure delivered oxygen content. A fail-safe valve responds to low O2 pressure by limiting nonoxygen gases, but it doesn’t quantify FiO2 and can’t detect the exact oxygen concentration reaching the lungs. A second-stage O2 pressure regulator simply reduces pipeline pressure, not the actual gas composition. A proportion-limiting control system prevents the delivery of deficient oxygen concentrations by constraining other gases, but again it’s not a direct readout of the FiO2.