Characterizing Immersion Pulmonary Edema (IPE): A Comparative Study of Military and Recreational Divers

BackgroundImmersion Pulmonary Edema (IPE) is a common and potentially serious diving accident that can have significant respiratory and cardiac consequences and, in some cases, be fatal. Our objective was to characterize cases of IPE among military trainees and recreational divers and to associate their occurrence with exposure and individual background factors such as age and comorbidity. We conducted a retrospective analysis on the medical records and diving parameters of all patients who were treated for IPE at the Hyperbaric Medicine Department of Sainte-Anne Military Hospital in Toulon, France, between January 2017 and August 2019. In total, 57 subjects were included in this study, with ages ranging from 20 to 62 years. These subjects were divided into two distinct groups based on exposure categories: (1) underwater/surface military training and (2) recreational scuba diving. The first group consisted of 14 individuals (25%) with a mean age of 26.5 +/- 2.6 years; while, the second group comprised 43 individuals (75%) with a mean age of 51.2 +/- 7.5 years. All divers under the age of 40 were military divers.ResultsIn 40% of cases, IPE occurred following intense physical exercise. However, this association was observed in only 26% of recreational divers, compared to 86% of military divers. Among civilian recreational divers, no cases of IPE were observed in subjects under the age of 40. The intensity of symptoms was similar between the two groups, but the duration of hospitalization was significantly longer for the recreational subjects.ConclusionIt seems that the occurrence of IPE in young and healthy individuals requires their engagement in vigorous physical activity. Additionally, exposure to significant ventilatory constraints is a contributing factor, with the intensity of these conditions seemingly exclusive to military diving environments. In contrast, among civilian recreational divers, IPE tends to occur in subjects with an average age twice that of military divers. Moreover, these individuals exhibit more prominent comorbidity factors, and the average level of environmental stressors is comparatively lower. In the case of young, well-trained military divers without cardiovascular pathology, we have observed that the occurrence of IPE requires the simultaneous presence of intense finning exercise and/or a high negative Static Lung Load (SSL) during immersion. However, among civilian recreational divers, no instances of IPE were observed in individuals under the age of 40. In civilian divers, IPE appears to be more common among those who are older than their military counterparts (Average age/medians: 51.2 +/- 7.5 years) and may possess cardiovascular risk factors. Even milder environmental constraints (associated with a low negative SLL) seem sufficient to induce IPE in this particular group of divers.