Malfunction of the Expiratory Valve During Spontaneous Ventilation.

The integrity of inspiratory and expiratory unidirectional valves is very important in the normal functioning of an anesthetic circle breathing system. We describe our experience of an emergency manipulation of a ceramic valve disk of a circle breathing system (Dräger Fabius GS, Dräger Medical Inc) that altered its characteristics and led to rebreathing only during spontaneous ventilation.

An abrupt reduction in end-tidal carbon-dioxide during neurosurgery is not always due to venous air embolism: a capnograph artefact.

Venous air embolism (VAE) is a well recognized complication during neurosurgery. Pre-cordial doppler and trans-esophageal echocardiography are sensitive monitors for the detection of VAE. A sudden, abrupt reduction in the end-tidal carbondioxide (ETCO2) pressure with associated hypotension during neurosurgery might suggest VAE, when more sensitive monitors are not available.