IPE and Why It’s Good to Feel the Need to Pee

There have been many mysterious diving deaths where the drowned victim still has a tank of air. Investigators usually dismiss these as heart attacks. But these days, immersion pulmonary edema (IPE) is under increased scrutiny as the cause. Dan Orr, a previous CEO of the Divers Alert Network (DAN), says, "It is a very important subject and largely can be misdiagnosed by medical examiners who, in many cases, work under the philosophy, 'if they are wet and dead, they must have drowned,' and look no further into the actual root cause."

For example, last September, there was a sad incident on the Thistlegorm in the Red Sea when an otherwise fit and healthy woman inexplicably drowned. It was ascribed to a heart attack. But maybe it was not.

In another case, Ian Gregory Wells, a few Zealand firefighter, had been a certified diver since 1991. The 54-year-old regularly attended cross-fit classes and cycled regularly. During a dive at Bauza Island in 2018, his buddy reported that Wells gestured across his throat with his hand, indicating he had no air, but when the purge button was pushed, his regulator gave air. Later forensic testing confirmed he did not run out of air, yet his friend thought he heard him shout, "I can't breathe."

In a postmortem report, probable sudden cardiac death was listed as the cause of death. Because his coronary arteries were relatively free of atherosclerosis, and there was no further evidence of cardiac disease, the coroner sought a second opinion from another pathologist, who could not determine the cause of death. Was it IPE?

DAN has written much on immersion pulmonary edema (IPE) in their annual diving report, and it's a regular topic in their physician courses. Dr. Peter Wilmshurst, the British cardiologist, Dr. Richard Moon of Duke University, and Dr. Petar Denoble at DAN are at the forefront of examining its relevance to diving fatalities. It is only recently becoming understood and not readily identified.

IPE has frequently been encountered among super-fit young people engaged in the cold-water swimming, especially in triathlons. Now, we realize it can happen to any person - including scuba divers - whether in cold or tropical water.

It appears that while under the hydrostatic pressure of the surrounding water, the victim's peripheries (arms and legs) eliminate water, which migrates to the lungs, not to the bladder, where it usually goes (which is why most feel the need to pee while underwater). This causes victims to have difficulty breathing, and they start to drown in their body fluids. A divers suffering from IPE often believe there is something wrong with the regulator rather than realizing what is truly happening. If they attempt to share air with another diver, the circumstances worsen, resulting in a tragedy, and later, a possible misdiagnosis of a heart attack.

The affected person needs to be removed from the water immediately. If rescue is timely, the fluid in the lungs will tend to return to its original and natural locations, and recovery can begin (which can confuse those who may have been involved in the rescue as to what really happened).

Only some people are susceptible. For example, John McIntyre, a professional underwater photographer, had to give up scuba diving after he nearly drowned. As a result, he was diagnosed as susceptible to immersion pulmonary edema. He is lucky.

Less lucky was Richard Sanders, an experienced British diver taking an advanced nitrox course at a flooded quarry. He thought he was out of gas because he could not inhale any, and signaled so to his instructor, Mark Culwick, who saw that his pressure gauge registered his tank was still half-full. A coroner's inquest in November 2021 heard how this misunderstanding resulted in Sanders eventually bolting to the surface, but he died before he got there. It was a classic case of IPE, and it was one of the first to be ascribed so by an investigating coroner.

The only solution for IPE is to remove the victim from the water, place them on 100 percent oxygen, and quickly get them to a medical facility. They may make a full recovery, though IPE could trigger further cardiac and pulmonary problems. After an IPE bout, that should be the end of diving.

Divers can help prevent problems. Some recommendations include regular diving physicals (especially if more than 45 years old), attention to cardiac conditions and risk factors, maintaining a high level of fitness, proper regulator maintenance, properly fitted wetsuits, avoiding overly strenuous dives, or cold water, and not over-hydrating.

John Bantin, with the assistance of by Dr. Jim Chimiak and Dr. Petar Denoble of DAN

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