Pulmonary function changes in Navy divers during their professional careers

Abstract

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

Purpose: 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."

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

Results: 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.

Conclusions: 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.

Keywords: Navy divers; large lungs; pulmonary function; small airway disease.