Cigarette smoking and pulmonary diffusing capacity. (Transfer factor).

Cigarette smoking caused a reduction in the diffusing capacity of the lungs for carbon monoxide and a reduction in coefficient of diffusion of carbon monoxide. This implies that cigarette smoking should be considered in prediction equations. The reduction in the diffusing capacity appeared to be due to a change in the volume of blood in the capillaries. This could account for some of the reversible changes observed in ex-cigarette smokers. The membrane component changed more with age. Prediction formulas were developed for diffusing capacity for the ratio, diffusing capacity/alveolar volume, based on age, height, and life-time packs smoked.