Prognosis in chronic obstructive pulmonary disease.

The results of pulmonary function tests in 663 patients and pulmonary vascular resistance in 136 patients were evaluated in relation to prognosis. The studies included spirogram, lung volumes, arterial blood gases, nitrogen washout, lung recoil at total lung capacity, airway resistance, diffusing capacity, and pulmonary vascular resistance. Forced expired volume in 1 second contributed significantly to predicting survival. Other tests probably contributed to predicting survival independent of 1-second forced expiratory volume. These tests were diffusing capacity for carbon monoxide, recoil pressure at total lung capacity, radiographic emphysema, arterial carbon dioxide tension, and single breath nitrogen washout. Decrease in 1-second forced expiratory volume averaged 52 ml per year. Changes from one follow-up period to another in any 1 patient showed considerable variability.