Maybe This Is the Reason Why His Wife Drowned

Guy Cooper, the writer of this first-person story about the snorkeling death of his wife, Nancy Peacock, cites the build-up of exhaled carbon dioxide in her full-face mask as the probable villain. However, some recent snorkeling deaths have involved conventional masks and snorkels, so, despite full-face masks now being banned from use in Hawaii, where Peacock died, could the blame be misplaced? Is there a different culprit?

In the "Why Divers Die" article in the February issue, we wrote about immersion pulmonary edema (IPE), now thought to be the cause of many mysterious drownings of scuba divers who still had plenty of air in their tanks. IPE can be caused by hyperhydration. It happens when fluid leaks from the bloodstream into air sacs in the lungs, possibly leading to heart failure or other cardiac problems. Doug Ebersole, a cardiologist in Lakeland, FL, and a technical dive instructor who consults for Divers Alert Network and the British Sub Aqua Club (BSAC), has now issued guidance to those groups' members on recognizing and reacting to the symptoms of IPE.

Peter Wilmshurst, a British cardiologist wellknown in dive medicine circles for his research in birth defects of the heart and their relation to decompression sickness, says that IPE is now thought to be probably the most common form of death during both scuba diving and triathlon swims. (The precise number is unknown because pathologists usually mistake IPE for drowning.)

IPE happens when immersed in water, and the effects are more severe nearer the surface, where a person can experience a shallow-water blackout. It's more prevalent in colder waters, which is why there have been so many cases in the United Kingdom. IPE causes some or all alveoli in the lungs to become filled with water, and that water from the lungs' capillaries diffuses through the blood just as carbondioxide normally does. The hydrostatic pressure of being immersed in water increases capillary pressure in your body.

Wilmshurst says there is no doubt that if you drink too much liquid before entering the water for a dive, you'll increase your risk of suffering an IPE. Exertion and stress also increase the risk, as does high blood pressure -- a minority of people who have suffered IPE have undiagnosed heart disease -- but it can also occur in normally healthy and superfit divers.

Margaret Baldwin, the snorkel instructor-trainer for BSAC, says, "It could be easy to dismiss IPE as something that is only relevant to scuba diving; however, as snorkelers, we are immersed in water, and it is not unknown for a snorkeler to suffer from IPE. Therefore, we should all be aware of the effects of IPE and encourage snorkelers to be aware of the condition and what to do if you recognize any of the indicators for it."

The extreme breathlessness caused by IPE is similar in many ways to that of carbon-dioxide poisoning -- and the post-mortem examination of a fatality caused by IPE often will reveal fluid in the lungs similar to that of drowning. Could it be that tourists visiting Hawaii, not used to the tropical climate, drink excessive amounts of liquid, thus overhydrating, before going snorkeling? It's worth considering.