Common Circulatory Measurements in Smokers and Nonsmokers

Pulse rates and blood pressure, and circulatory responses to pressor stimuli were compared in habitual smokers and nonsmokers in an attempt to ascertain possible "chronic effects" of tobacco smoking on the circulation. Several common cardiovascular measurements were made in 4 groups, a total of 1,093 men, ages 17 to 67, and comparisons made with reference to the cigarette smoking habit. Acute effects of smoking were eliminated and, when possible, effects of age and weight were eliminated statistically. Relative body weight is consistently lower in the "heavy" cigarette smokers compared to those who "never" smoked. Basal oxygen consumption is slightly higher in smokers than in nonsmokers. Pulse rate during work and recovery is significantly higher in one group of middle-aged men if pathologic cases in the group are considered. In "normal" populations, somewhat preselected for absence of hypertension, no differences in resting blood pressures are found between smokers and nonsmokers. In the broader studies, involving samples of the working population, smoking is associated with lower systolic and diastolic pressures. Circulatory responses to stimuli of the cold pressor test and carbon dioxide inhalation reveal a small but significant diminished diastolic pressure response to cold and possibly a greater systolic response to carbon dioxide in smokers. Young student groups, with short duration of smoking habit, show no significant differences between smokers and nonsmokers for these circulatory parameters. The associations found do not provide evidence for large or important differences in circulatory reactivity between groups of habitual smokers and nonsmokers. There is little evidence for deterioration of cardiovascular "fitness" in smokers performing work tests. The small magnitude of the differences found in circulatory measurements, plus certain sources of bias which are discussed, preclude serious consideration at present of these factors as underlying causes of the increased mortality rate among smokers. Other questions unanswered concern the importance of individual circulatory responses, individual hypersensitivity to smoking, and the significance of acute pressor and other effects of smoking on persons with cardiovascular disease, latent or manifest.