Computer-Generated Graphic Displays for Pulmonary Function Tests

Abstract

The purpose of this project was to develop off-line "classical" representations of various pulmonary function tests. By using expanded BASIC on a Tektronix 4051 computer with 32K bytes of memory, we produced graphic representations of several measurements. Histograms illustrated actual and predicted lung subdivisions, closing volume or closing capacity, and arterial and alveolar respiratory gases, and we graphed, on X-Y coordinates, airway conductance versus lung volume, ventilatory responses to hyperoxic hypercarbia and isocapnic hypoxia, and hydrogen ion concentration (pH) versus Paco2 with bicarbonate isopleths. When available, 95 per cent confidence limits were included on the graphs. The graphs add visual assessment of performance related to predicted values, and help to explain either a physiologic principle or the test itself, making the graphs useful for the understanding and teaching of pulmonary function tests. The programming can be done on various computers, using existing laboratory equipment and methods.