[Contamination of an oxygen delivery circuit by compressed air]

Routine checking of the FIO2 of a mixture delivered by a ventilator revealed large discrepancies between the FIO2 assigned and that effectively delivered, the latter being low. Measurements of FIO2 at the wall outlets showed the O2 delivery pipeline to be contaminated by compressed air. By disconnecting all the ventilators supplied by this pipeline one after the other, one ventilator, or rather its blender, was found responsible.