Pressure-sensitive ventilator disconnection alarms may fail to functio
n correctly when used with discharging compliance ventilators such as
the Manley Blease. The increase in gas flow on disconnection generates
raised pressure owing to the resistance provided by components of the
breathing system. Thirty-four anaesthetists, who were unaware of the
nature of the survey, were observed to see if previous recommendations
for the correct adjustment of the ventilator alarm were being followe
d. It was found that 77% of alarms were incorrectly adjusted and would
not have alarmed in the event of a true disconnection occurring.