A RESPIRATION INTEGRATOR

An electronic circuit, constructed from commercially available modular units is described, which integrates the voltage from a micromanometer, to give the volume of gas flowing through the detector. Drift is minimized by starting each volume from a fixed baseline on the record. Interpretation of the results is simplified as inspired and expired volumes lie on opposite sides of the baseline. The circuit is such that, at normal settings, the output is linear from 200 ml to several litres, to within 5 per cent for rates above 10/min; although the linearity can be improved by restricting the range of rates. The circuit can be adjusted for different volume ranges.