Functional and high-resolution computed tomographic studies of divers' lungs

Objectives Several cross-sectional studies have described a decrease in the expiratory flow rates of divers. The objective of this study was to determ ine whether the combined application of high-resolution computed tomography (HRCT) and lung function testing supports the reported development of smal l airway obstruction in divers. Methods Thirty-two navy divers, 27 commercial divers, and 48 referents matc hed for age and smoking history underwent pulmonary function testing and HR CT of the lungs supplemented by a Limited number of expiratory scans. The c ommercial divers were older and dived longer than the navy divers. Multivar iate regression analysis was used to assess the relevant correlations of ag e, height, pack-years of cigarette smoking, and indices of diving exposure with lung function parameters. Results The inspiratory vital capacity and forced vital capacity (FVC) were greater, while the FEV% [(100 x FEV1.0)FVC] and maximum expiratory flow (M EF) at 25% (MEF25) of the FVC were lower for the navy divers than for the r eferents. The lung volumes and expiratory airflow pattern did not differ be tween the commercial divers and the corresponding referents. The forced exp iratory volume in 1 second (FEV1.0), FEV%, MEF75, and MEF25 correlated nega tively with the years of diving experience. This association was independen t of age, height, and pack-years of cigarette smoking. For the majority of the divers and referents the expiratory HRCT revealed minor lobular air tra pping without any difference between the groups. The HRCT did not show rele vant morphologic abnormalities of small or large airways. Conclusions The data confirm that diving may affect pulmonary function. How ever, there is no radiologic evidence for the development of small airway d isease in these 2 subgroups of divers.