Measurement of regional lung function in the early detection of chronic obstructive pulmonary disease.

Radioisotopic regional lung function measurements using both 99mTc-labeled albumin microspheres and inhaled 133Xe were compared to measurements of total lung function in a population of 30 participants in an epidemiological study of the causative factors of obstructive pulmonary disease. Five of the 8 asymptomatic subjects who had no evidence of obstruction by the tests of total function had abnormal regional lung function measurements. The closing volume was abnormal in three of these five, suggesting the presence of small airways disease. Regional lung function was abnormal in all subjects who were symptomatic, who had a FEV1/FVC less than 75%, or who had an elevated closing volume or residual volume. The data indicate that the measurement of regional lung function may be a highly sensitive test for the early diagnosis of chronic obstructive pulmonary disease.