Association of anaesthetist's checklist for anaesthetic machines. Problem with detection of significant leaks

Eight experienced anaesthetists performed a 'cockpit drill', following instructions in the Association of Anaesthetist's checklist, on an anaesthetic machine that had a significant leak (3 l.min-1 at a pressure of 16 kPa). Only one anaesthetist detected the leak and this was by audible means rather than by any of the protocol's set manoeuvres. We demonstrated that a leak of 3 l.min-1 from the flowmeter block resulted in an inspired oxygen concentration of 6% when the anaesthetic machine was used with a minute volume divider ventilator.