Clinical severity of immersion pulmonary edema: A 14-year cohort study

Immersion pulmonary edema (IPE) is an increasingly recognized cause of acute hypoxemic respiratory failure associated with aquatic activities. Although determinants of IPE occurrence have been described, factors associated with severe initial clinical presentation remain poorly understood.

What proportion of patients with IPE present with severe manifestations, and what clinical or exposure-related factors are associated with severity?

We conducted a retrospective cohort study of all consecutive IPE cases managed at a French national hyperbaric referral center between 2010 and 2023. Severe IPE was defined as the occurrence of acute respiratory distress requiring immediate advanced medical management, loss of consciousness, or cardiac arrest. Clinical characteristics, cardiovascular risk factors, and diving-related variables were analyzed using univariate and multivariable logistic regression models.

Among 288 patients with IPE, 90 (31.3%) presented with severe manifestations. Severe presentations included acute respiratory distress (63.4%), loss of consciousness (32.2%), and cardiac arrest (4.4%). Scuba diving accounted for 79.9% of cases, breath-hold diving for 11.8%, and surface swimming for 8.3%. In univariate analysis, active smoking was associated with severe IPE (P = 0.048). Among scuba divers, shorter dive duration (P = 0.001) and incomplete decompression (P < 0.001) were associated with severity. In multivariable analysis, active smoking showed a borderline association with severe presentation (adjusted OR 2.77; 95% CI 0.99-8.07; P = 0.053). No other evaluated variables independently predicted severity.

Nearly one-third of patients with IPE present with severe clinical manifestations, highlighting that this condition is frequently life-threatening. The absence of strong independent predictors of severity underscores the difficulty in anticipating severe presentations and supports a high index of suspicion and early recognition of IPE in all patients developing respiratory symptoms after aquatic exposure.