The Draeger anaesthetic machine has a poorly understood issue with its APL valve. When lifted it is actually open – even though it appears closed – creating an inability to pressurise the breathing circuit.
It can be jammed open (see valve on right above) particularly when the gas sample line becomes trapped underneath. In turn patients can’t be ventilated – anaesthetists are often unable to diagnose the cause placing patients at unnecessary risk.
Draeger know about this problem and have introduced a bevelled APL valve on newer anaesthetic machines (see valve on right below):
There are numerous anaesthetic machines being used with the old hazardous APL valve. The new beveled APL valve can be retro-fixed onto older machines – we should ensure this is done.
In all of these cases the reporting anaesthetist is caught unaware – this is despite alerts (see below) demonstrating the inefficiency of alerts on their own as a safety solution. Still many anaesthetists are unaware of this problem.
The function of the APL valve being open when elevated is unique to Draeger machines. It is not a function intuitive to the majority of anaesthetists.
The case reports above represent only a fraction of the actual events. The author is aware of numerous other cases not reported here.
Several similar events have been reported to the FDA. We’re suspicious they may be due to APL trapping – there’s an inability to pressurise the circuit with manual ventilation mode on induction, in some instances being able to with mechanical modes which bypass the APL valve.