APL Valve Open Spontaneous — FRCA Primary MCQ

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EasyPhysics & Clinical MeasurementAPL Valve Open SpontaneousFRCA Primary

The adjustable pressure-limiting (APL) valve on a breathing circuit:

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Correct answer: E — Should be fully open during spontaneous ventilation to prevent barotrauma

The APL valve should be fully open during spontaneous ventilation to allow exhaled gas to escape to the scavenging system with minimal resistance. During manual ventilation it is partially closed to generate positive pressure for bag ventilation. It is spring-loaded and adjustable from 0-70 cmH2O. It must be present in all adjustable breathing circuits.

Reference: Al-Shaikh Stacey 2019 Essentials of Anaesthetic Equipment