EFFECT OF CIGARETTE SMOKING ON FORCED EXPIRATORY FLOW RATE

Abstract

Sixteen normal persons and 16 subjects with pulmonary disease were studied spiro-metrically before, immediately after, and 45 to 60 minutes after inhaling the smoke from one to two cigarettes. The volume exhaled in the first second of a forced expiration (FEV1.0) and the forced vital capacity (FVC) were measured. In both the normal subjects and those with bronchitis and/or chronic obstructive pulmonary disease there was in most cases (28 of 32 subjects) a decrease in the FEVl.0 immediately after smoking. After one hour, most subjects (23 of 32) had higher values than immediately after smoking, and some had volumes even greater than the basal values (12 of 32 subjects). The FVC values were not as consistent. Thus, smoking decreased the expiratory flow rate, probably because of increased airway resistance. The study indicates than even small changes in airway resistance can be detected with measurements of the first-second forced expiratory volume, whereas determinations of the forced vital capacity and the FEVl.0 in per cent of the actual FVC are less valuable in this respect.