[Prospective lung function determination using an electronic miniature spirometer for detection of acute obstructive respiratory changes in diving students during occupational diving training].

BACKGROUND

Changes in lung function have been shown in experienced divers. The purpose of this study was to measure the pulmonary function of diving trainees who were not exposed to a hyperbaric environment before.

METHODS

We measured the lung function in a sample of fifteen randomized selected young healthy non-smoking diving trainees parallel to fourteen open water dives. Five subjects used common compressed air diving apparatuses (breathing gas: 21% O2/78% N2) and ten subjects used closed circuit diving apparatuses (breathing gas compositions depended to the diving depths; 24 m: 60% O2/40% N2, 42 m: 40% O2/60% N2, 54 m: 32.5% O2/67.5% N2). The values (FVC, FEV1, PEF, MEF 25, MEF 50, MEF 75) were obtained by an electronic miniature-spirometer directly before descent, upon surfacing, and after one hour and four hours.

RESULTS

The lung function values of the subjects who used compressed air showed no relevant impairment of lung function after the diving exposures. Significant (p < 0.05) post dive lung function reductions (FVC, FEV1, PEF, MEF 25, MEF 50, MEF 75), were evident in subjects using closed circuit diving apparatuses, after deep dives and shallow water dives.

CONCLUSIONS

The decreased lung function of the used diving apparatuses. The impaired lung functions in subjects using closed circuit diving apparatuses may be induced by a subclinical lung edema generated by pressure differences between breathing gas and thorax tissues as well as the influences of soda-lime dust. Compared to compressed air diving the significantly increased oxygen partial pressures (p < 0.001) in closed circuit diving apparatuses may be an additional reason for the reversible airway obstructions.