Risk factors for immersion pulmonary edema in recreational scuba divers: a case-control study.

Background: Immersion can cause immersion pulmonary edema (IPE) in previously healthy subjects. We performed a case-control study to better identify IPE risk factors.

Methods: We prospectively included recreational scuba divers who had presented signs of IPE and control divers who were randomly chosen among diving members of the French Underwater Federation. We sent an anonymous questionnaire to each diver, with questions on individual characteristics, as well as the conditions of the most recent dive (controls) or the dive during which IPE occurred. Univariate logistic regressions were performed for each relevant factor. Then, multivariate logistic regression was performed.

Results: Of the 882 questionnaires sent, 480 (54%) were returned from 88 cases (90%) and 392 control divers (50%). Multivariate analysis identified the following independent risk factors associated with IPE: being aged over 50 years ((OR) 3.30, (95%CI) 1.76-6.19); female sex (OR 2.20, 95%CI 1.19-4.08); non-steroidal anti-inflammatory drug (NSAID) intake before diving (OR 24.32, 95%CI 2.86-206.91); depth of dive over 20 m (OR 2.00, 95%CI 1.07-3.74); physical exertion prior to or during the dive (OR 5.51, 95%CI 2.69-11.28); training dive type (OR 5.34, 95%CI 2.62-10.86); and daily medication intake (OR 2.79, 95%CI 1.50-5.21); this latter factor appeared to be associated with hypertension in the univariate analysis.

Conclusion: To reduce the risk of experiencing IPE, divers over 50 years of age or with hypertension, especially women, should avoid extensive physical effort, psychological stress, deep dives and NSAID intake before diving.