Swimming-induced pulmonary edema in triathletes

BackgroundPulmonary edema related to water immersion has been reported in military trainees and scuba and breath-hold divers, but rarely in the community. To date, no risk factors for this phenomenon have been identified by epidemiological methods. Recently, sporadic reports of swimming-induced pulmonary edema (SIPE) have emerged in the triathlon community. We surveyed the population of a national North American triathlon organization (USA Triathlon) to determine prevalence of and risk factors for symptoms compatible with SIPE.MethodsWe surveyed the population of USA Triathlon through the organization's monthly newsletter distribution channel. We evaluated prevalence of symptoms compatible with pulmonary edema, and then followed up with a case-control study that included additional cases we had identified previously, to identify risk factors for this condition among triathletes.ResultsSymptom history compatible with SIPE was identified in 1.4% of the population. Associated factors identified in multivariable analysis included history of hypertension, course length of half-Ironman distance or greater, female gender and use of fish oil supplements. Of the 31 cases reported, only 4 occurred in the absence of any associated factors.ConclusionsThe identification of hypertension and fish oil in particular as risk factors raise questions about the role of cardiac diastolic function in the setting of water-immersion cardiac preload, as well as the hematologic effects of fish oil. Mechanistic studies of these risk factors in a directly observed prospective cohort are indicated.