Cigarette smoke; its effect on pulmonary function measurements.

Inhaling cigarette smoke with each breath, with the subject at rest, by use of a smoking device that brought more smoke into the lungs than would be the case in ordinary smoking, produced consistent significant decreases in arterial blood oxygen saturation and in arterial pO(2) in most subjects who had severe or very severe pulmonary emphysema. In normal subjects and in those with a moderate degree of emphysema no significant changes in blood gas exchange resulted. No consistent significant changes in blood gas exchange were noted after the smoking of two cigarettes, either with the subject at rest or after a one-minute step-up exercise.A decrease in oxygen uptake occurred when treadmill exercise was done after smoking two cigarettes, and the ventilation volume was also decreased, probably accounting for part of the oxygen decrease. Pulmonary compliance measurements after smoking one cigarette were consistently and significantly decreased in most subjects-normal as well as those with pulmonary emphysema. The elastic work of breathing was increased in the majority of cases. In two cases in which studies were done after the subjects stopped smoking, one for three months and one for two years, significant reductions in residual air were noted. The results indicated that persons with severe or very severe emphysema would be better off to stop smoking.