Volume-displacement body plethysmograph using a large flowmeter without pressure compensation

Abstract

A modification of the conventional volume-displacement whole-body [human] plethysmograph was done using a low-resistance flow element and integrating the plethysmographic pressure signal. A flow element with a resistance of 0.036 cmH2O/(l/s), linear to 75 l/s was fitted to a 440 l plethysmograph, resulting in an instrument with a volume-amplitude-frequency response flat to 15 Hz and in phase with mouth flow and esophageal catheter-balloon to at least 15 Hz without pressure compensation.