venturi mask

 

a) Schematic diagram of the venturi mask used in the breathing system. A: Loose plastic venturi mask B: Venturi entrainment device (1:1). b) A section of a respiratory trace from one subject demonstrating the tidal CO2 trace (top) and the tidal volume trace from the bellows (bottom). The end-tidal CO2 (PETCO2) trace was formed by interpolating between the end expiration peaks (dotted line, top trace). The breath hold duration was calculated from the time between the end of expiration CO2 trace and the beginning of the subsequent expiration trace, to minimise inclusion of head movement. The vocalisation duration was calculated from the duration between the beginning and end of a vocalisation expiration trace.