The measurement of nonelastic work of breathing using a commercially available respiratory integrator

The authors compared real-time, breath-by-breath work of breathing (WOB) measurements made with a Hewlett-Packard 8815A respiratory integrator with nonelastic WOB values obtained by planimetry of pressure-volume tracings. They measured WOB while normal subjects breathed through a low-resistane mouthpiece. The integrator-derived values for WOB correlated well with planimeter-derived values (r = 0.97). Valid measurements of nonelastic WOB can be made at the bedside in realtime using the Hewlett-Packard 8815A without the addition of custom-built circuitry or hardware.