Swimming-induced pulmonary edema

Swimming induced pulmonary edema (SIPE), also known as immersion pulmonary edema, is a life threatening condition that occurs when fluids from the blood leak abnormally from the small vessels of the lung (pulmonary capillaries) into the airspaces (alveoli).

SIPE usually occurs during exertion in conditions of water immersion, such as swimming and diving. With the recent surge in popularity of triathlons and swimming in open water events there has been an increasing incidence of SIPE. It has been reported in scuba divers, apnea (breath hold) free-diving competitors, combat swimmers, and triathletes. The causes are incompletely understood as of 2010. Some authors believe that SIPE may be the leading cause of death among recreational scuba divers, but there is insufficient evidence at present.