Introduction: The aim of this study was to evaluate the effect of a single, shallow, swimming pool scuba dive on pulmonary function in divers with asthma as compared to controls. Opinions concerning the risks of diving with asthma are still contradictory and inconclusive in the diving community.
Methods: Baseline pulmonary function tests (PFTs) were performed on a group of 22 divers with asthma and on a control group of 15 healthy divers. The same PFTs were repeated within 10 minutes after a single pool dive, at 5 metres' depth for 10 minutes. PFTs were measured using a portable Jaeger SpiroPro™ device. Student's paired t-tests and linear mixed effects model comparisons and interactions within the groups were used in the data analysis.
Results: Divers with asthma initially presented significantly lower values of FEV1/FVC%* (P < 0.01), FEF25* (P < 0.01), FEF50* (P < 0.001), FEF75* (P < 0.01) and FEF25-75* (P < 0.001) compared to controls. There were significant reductions in FEV1 (P < 0.01), FEV1/FVC% (P < 0.05), FEF50* (P < 0.01), FEF75* (P < 0.05) and FEF25-75* (P < 0.001) in the asthma group after the dive as compared to the control group. PEF was initially lower, although not significantly, in the asthma group and did not change significantly after the dive in either group (P > 0.05).
Conclusions: A single, shallow, pool scuba dive to 5 metres' depth may impair function of small airways in asthmatic divers. More studies are necessary to estimate the risks when divers with asthma practise scuba diving. PFT results should be analysed after replicated dives in deeper pools and controlled open-water conditions.