Expiratory flow limitation in compressed air divers and oxygen divers

Abstract

Divers are exposed to dense gases under hyperbaric and hyperoxic conditions and, therefore, may be at risk of developing respiratory disease. Long-term effects on respiratory function have been found in commercial divers who perform deep dives. This study was conducted to detect possible lung function changes in scuba divers who dive in shallow water using compressed air or oxygen as a breathing gas. A cross-sectional sample of 180 healthy male divers (152 air divers and 28 oxygen divers) and 34 healthy male controls underwent a diving medical examination including body plethysmography, diffusion capacity measurement and a cold-air isocapnic hyperventilation test (CAIH). Air divers and oxygen divers had a lower mid-expiratory flow at 25% of vital capacity (MEF25) than controls (p<0.01 and p<0.05, respectively). Oxygen divers also had a decreased mid-expiratory flow at 50% of vital capacity (MEF50) (p<0.05). Divers' groups and controls did not differ with respect to age, smoking or medical history. The prevalence of airway hyperresponsiveness to CAIH was 1.4% (n=3 divers). MEF25 and MEF50 were inversely related to years of diving (p<0.01 and p<0.001, respectively). The pattern of lung function changes obtained in scuba divers is consistent with small airways dysfunction and the association between diving exposure and lung function changes may indicate long-term effects on respiratory function.

Short- and long-term effects of diving on pulmonary function

“…These findings were taken as evidence to suggest development of small airways disease in divers. Subsequent cross-sectional studies in German Navy scuba divers [42] confirmed a pattern of reduced expiratory flow rates at low lung volumes when compared to non-diving controls, and mid-expiratory flows at 25% and 50% of vital capacity were inversely related to years of diving. However, different group characteristics and selection effects may have confounded the results [43].…”

Effects of ambient cold and depth on lung function in humans after a single scuba dive

“…The question whether a single scuba-dive elicits adverse eects on pulmonary function is of concern, since there is consensus that compressed-air diving is associated with long-term respiratory changes. A respiratory pattern indicating dysfunction of the small airways has been the unanimous ®nding of cross-sectional studies in compressed-air divers (Bermon et al 1994;Tetzla et al 1998). In longitudinal surveys a pronounced decrease in the reduction in small airways¯ows and a decrease in gas transfer function have been reported as well (Bermon et al 1994(Bermon et al , 1997.…”

“…Thus, hyperoxia and venous gas microembolism may be less important in contributing to eects of compressed-air dives on the lungs of healthy subjects, when these dives are made within the recommended guidelines. Ambient cold may be an important factor since the adverse long-term eects have been reported only in divers who dive predominantly in cold waters (Bermon et al 1994;Tetzla et al 1998).…”

A pilot study on the impact of recreational diving on the airway patency depending on a diver’s age

“…This improvement in older participants with a greater amount of diving experience can be primarily connected with the work of the sympathetic nervous system causing the enlargement of the airways lumen, or blocking the action of the parasympathetic system [9,10]. The authors anathematised a possible greater "tolerance" of the trachea and larger bronchi walls to elevate oxygen partial pressures in longer dives because, when assuming the reaction of the bronchial walls to hyperbaric oxygen in the shape of the mucous membrane oedema and the contraction [9,14] after diving, we would not observe the improvement of the parameters researched by means of PEV but their deterioration.…”