||Diver's Lung Function: Influence of Smoking
Habit: Shinya Suzuki. Japan Maritime Self-Defense Force Undersea
Medical Center-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 (V75) 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 (V25) 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 V75 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 V25 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.