Pulmonary function changes in Navy divers during their professional careers

In divers, conflicting results regarding the development of small airway disease and "large lungs" have been reported.

To analyze the changes in pulmonary function over time, the development of "large lungs" and to see whether the pulmonary function deviates from subjects with "non-large lungs."

It is a longitudinal cohort study from 1983 till 2013 in professional navy divers, in which lung functions tests were performed annually.

In 1,260 navy divers, 8,149 pulmonary function tests were analyzed. The forced expiratory volume (FEV1) did not change except initially in those with abnormally low lung function (baseline value ⟨lower-limit-of-normal for the general population (LLN). In that group, FEV1 increased by 35 (SE 7) ml/year. For the entire cohort, the inspiratory vital capacity (iVC) increased by 73 ml/year (SE 25). In the ⟨LLN cohort, it increased by an additional 40 ml/year (SE 18). For the entire cohort, the FEV1/iVC annual drop was 0.37% (SE 0.9), but in the ⟨LLN cohort it increased by 0.25%/year (SE 0.04). For the entire cohort, the forced expiratory flow at 75% of expiration (FEF75) annual drop was 23 ml/s/year (SE 7), in contrast in the ⟨LLN cohort it increased by an additional 45 ml/second/year (SE 7). Of the navy divers, 6.3% showed "large lungs," but changes over time were not different from above except for an additional 0.2% (SE 0.1%) decline in FEV1/iVC.

In professional navy divers, long-term pulmonary function changes (FEV1 and FEV1 /iVC and FEF75) are not different from those in the non-diving population. The iVC increases probably due to training effect.