APL Valve Function and Safety in Anesthesia Machines

Pre-Use Checking and Function

The Association of Anaesthetists of Great Britain and Ireland recommends that the APL valve be checked before each case to ensure it can be fully opened and closed, and its function should be tested during the two-bag test by squeezing both bags to confirm proper pressure regulation during manual ventilation 1, 2, 3
Perform an occlusion test on the inner tube for Bain-type and circle co-axial systems to verify APL valve function 1, 2, 3
Verify the APL valve can be fully opened and closed during the pre-use check 1, 2, 3

Failure to close the APL valve during mechanical ventilation will result in inadequate tidal volumes and hypoventilation 1
The APL valve should be fully closed or the circuit switched to ventilator mode during mechanical ventilation 3
Have backup ventilation equipment immediately available in case of APL valve failure during induction of anesthesia 1

If inadequate manual ventilation occurs, verify APL valve position, check for circuit disconnections or leaks, inspect APL valve for visible damage, switch to backup ventilation method, and replace or repair the APL valve before continuing 1, 2, 3
Check that the APL valve is not fully open and inspect for visible cracks or damage to the valve housing if manual ventilation becomes ineffective 3

The APL valve exhaust must be connected to the scavenging system to prevent operating room pollution, and verify that scavenging tubing is attached to the appropriate exhaust port of the breathing system before use 1, 2, 3