Computer-controlled large-animal pulmonary function system

Breath by breath determination of lung volume and specific lung conductance is challenging, yet desirable particularly when rapid changes in lung function accompany abrupt changes in lung volume. We have developed a large-animal pulmonary function data acquisition system using two personal computers with custom-made software which continuously tracks breath by breath changes in pulmonary function and lung volume. Accurate measurement of respiratory flow signals is accomplished by collecting separate pneumotachometer-derived expiratory and inspiratory flow signals, correcting them to standard temperature pressure dry (STPD) and summing them into a single flow data array. Calibration of inspiratory and expiratory flow is software corrected by comparison of the integrated flow signals with a sinusoidal pump system. Data are collected continuously for up to 120 min at 100 Hz/channel. Subroutines which configure the system to perform functional residual capacity, dosimetry and partial expiratory flow-volume maneuvers are user selected at any time during data collection.