Viagra relieves pulmonary edema in divers

Sildenafil, best known as Viagra, can help reduce life-threatening swimming-induced pulmonary edema (SIPE), according to a study by researchers at the Duke Center for Hyperbaric Medicine and Environmental Physiology

Viagra is normally used for treatment of male impotence but also for pulmonary arterial hypertension.

The researchers found that Sildenafil dilated blood vessels, giving it the potential to ease an abrupt cold water-induced constriction of blood vessels in the arms and legs that can lead to SIPE symptoms; blood pooling in the heart and lungs.

Richard Moon, medical director of the Duke Center for Hyperbaric Medicine and Environmental Physiology in Durham, NC led the team of researchers.

Moon said: “During immersion in water, particularly cold water, susceptible people have an exaggerated degree of the normal redistribution of blood from the extremities to the chest area, causing increased pressure in the blood vessels of the lungs and leakage of fluid into the lungs.”

The study looked at ten athletes that had previously experienced SIPE and 20 who had not. The researchers had the participants exercise under water in a dive pool that recreated the conditions of a swim that could trigger the SIPE response.

None of the participants in either group had heart abnormalities, but the SIPE-susceptible athletes had higher pulmonary arterial pressure and pulmonary artery wedge pressure during the underwater exercise, according to Duke’s Sarah Avery.

When the SIPE participants were given sildenafil and then performed the same underwater exercise, the pressures were no longer as elevated.

Moon said larger studies are needed to replicate the results and learn more about possible adverse side effects of the drug. He also said research is ongoing to further illuminate the causes of SIPE and potential ways of diagnosing it early.