Medical experts in Okinawa have identified 161 cases [1] of swimming-induced pulmonary edema, a condition causing sudden cardiac arrest in divers.
This discovery clarifies why some divers die in the water despite showing no signs of drowning. The condition, known as SIPE, suggests that traditional rescue and autopsy protocols may overlook the physiological triggers of these deaths.
Umemura Takeshi, director of the Rescue and Emergency Center at University of the Ryukyu Hospital, said he noticed a pattern when treating patients who appeared to have drowned but had stopped breathing. He said he began to question if some of these patients had actually drowned.
According to reports, SIPE accounts for 30% [2] of water-related deaths in the region. The condition is triggered by a combination of vigorous underwater activity and the use of tight wetsuits.
Umemura said that wetsuits used in diving tighten the body significantly, which constricts blood vessels. He said that when blood flow is congested, water leaks from the pulmonary blood vessels into the lungs. This fluid buildup can lead to rapid respiratory failure and cardiac arrest, even if the diver's airway remains clear of external water.
The findings come as cases were identified leading up to the summer season of 2026 [1]. The research highlights the danger of restrictive gear when paired with high physical exertion in cold or deep water.
“SIPE accounts for 30% of water-related deaths in the region.”
The identification of SIPE in Okinawa shifts the understanding of diving fatalities from external accidents to internal physiological failures. By linking restrictive equipment like wetsuits to pulmonary leakage, medical professionals can better diagnose non-drowning deaths and potentially develop safety guidelines to reduce the incidence of cardiac arrest during dives.
