Diver's lung function: Influence of smoking habit

Abstract

To assess the influence of smoking habit on divers' lung function, we measured static lung volumes, dynamic lung volumes and flows and diffusing capacity for carbon monoxide (DLco) on 71 healthy, male, JMSDF active-duty uniformed divers (46 smokers and 25 nonsmokers). All measurements were conducted with an automated system (CHESTAC-25V model; Chest Ltd., Tokyo, Japan). Comparison of lung functions between smokers and nonsmokers was assessed using a Mann-Whitney rank-sum test. Vital capacity in smokers was 120.4 ± 11.3 (mean ± SD)% of the predicted value for age and height, and in nonsmokers was 119.9 ± 15.1%. In the static lung volumes there were no differences between smokers and nonsmokers. Although the forced vital capacity (FVC), the forced expired volume in the 1st second (FEV1.0), and the forced expiratory flow rate at 75% of FVC expired (V̇75) showed no difference between two groups, the peak expiratory flow rate (PEFR) in smokers was lower than that in nonsmokers (p<0.005). The forced expiratory flow rate at 25% of FVC expired (V̇25) showed no difference, while the DLco in smokers was worse than in nonsmokers (p<0.01). Lung Volumes of the divers in JMSDF were larger than predicted values in the general population. Judging from the ratio of the residual volume to total lung capacity, emphysematous change with aging was negative. PEFR, FEV1.0 and V̇75 depend on the ventilatory muscle strength and diameter of the large respiratory tract. To investigate the reason why only PEFR was lower in smokers than nonsmokers in this population, more data should be collected. The finding of no difference in V̇25 between the two groups could not indicate that smokers had emphysematous change compared to nonsmokers. The decrease in DLco with age in smokers compared to nonsmokers, however, suggested the possibility of emphysema. Considering that emphysema is a contraindication for diving, a diver should not smoke.