EXPONENTIAL ANALYSIS OF THE LUNG PRESSURE-VOLUME CURVE AS A PREDICTOR OF PULMONARY-EMPHYSEMA

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Abstract
To compare the predictive value of different pulmonary function tests in the diagnosis of morphologic emphysema, measurements of subdivisions of lung volume, gas exchange, maximal expiratory flow rates and static deflation pressure-volume [PV] curves were performed on 55 [human] subjects [Ss] prior to surgery for removal of an isolated peripheral pulmonary lesion. Emphysema was graded on the resected lung specimen and the PV data were fitted to an exponential equation (V = A - Be-KP). By chi-square analysis, K was the best predictor of emphysema in individual Ss and it was the only test that distinguished Ss with moderate emphysema from Ss with mild or without emphysema, but K did not distinguish those with mild emphysema from those without emphysema. As a group those with mild emphysema were distinguishable from predicted normal with K and elastic recoil pressures at 90 and 60% of predicted total lung capacity. Minimal emphysema may be detected by exponential analysis of the lung PV curve.