Volume-guarantee ventilation: pressure may decrease during obstructed flow

Abstract

BACKGROUND: Two unexpected observations were made during ventilation with the Dräger Babylog 8000+ in volume-guarantee mode: (a) during complete obstruction to gas flow down the endotracheal tube (ETT), positive inspiratory pressure (PIP) was reduced to half way between the maximum inflating pressure and the positive end expiratory pressure (PEEP) even though the set expired tidal volume had not been achieved; (b) an external Dräger waveform monitor may stop displaying real-time waveforms when a tube-obstructed alarm is activated. OBJECTIVE: To investigate these phenomena using a test lung. METHOD: A 50 ml Dräger test lung was attached to the ventilation circuit of a Dräger Babylog 8000+. Pa..