An Unusual Cause of Diver Deaths and What You Can Do To Prevent It

Last month in Undercurrent, Dan Clements wrote about the loss of older divers who went missing during separate dives in the Pacific Northwest. We also wrote about the repercussions of a diving fatality in Malta where the body was recovered and an autopsy revealed the fatality was the result of Immersion Pulmonary Edema (IPE) or Scuba Diver's Pulmonary Edema (SDPE).

This medical condition has caused a lot of discussion among diving doctors recently. Fluid leaks from the bloodstream into the lungs, where it accumulates in the air sacs and prevents oxygen from being absorbed, thereby making it difficult to breathe and possibly result in respiratory failure. It usually occurs early in a dive in temperate or cold water and while at depth. It appears to be more frequent among those who dive in colder water. However, the medical community doesn't fully understand the condition.

It was first noted in 1981 by cardiologist Peter Wilmshurst who attributed it mainly to the effects of the cold, inducing hypertensive pulmonary oedema." (http://archive.rubicon-foundation.org/xmlui/)

Carl Edmonds of the South Pacific Medical Society (SPUMS) published a paper in Diving and Hyperbaric Medicine (Dec. 2009) where he suggests,"The scuba divers affected are an older group and may have pre-existing or occult cardiovascular disease."

Several diving fatalities were ascribed to SDPE in 2014. Although it can affect both surface swimmers suffering extreme exertion and free divers who are generally young and fit, scuba diver's pulmonary edema (SDPE) is usually described as an uncommon disorder often occurring in apparently healthy individuals. Edmonds says that the actual incidence of SDPE is unknown, but it is probably under-diagnosed. It occurs more frequent in older divers and exertion may play a role.

Because it is difficult to diagnose before the event, we can only suggest that older divers have an annual medical examination and if they have heart or circulatory problems, they should avoid diving in cold water.

Dr. Fiona Sharp, a diving doctor based in Perth, Western Australia, says, "Initial symptoms include fast short respiration, shortness of breath, fatigue and a cough (sometimes producing blood). Often it is connected to divers with hypertension or ischemic heart disease or reduced respiratory function." She also comments, "There really aren't any good answers to the cause as yet, but this condition needs to be covered (by the diving press) as aging and frequent divers need to know of the warning signs and risks.

Dr. Patrick Farrell, a member of the UK Diving Medical Council and experienced with cold water diving advises, "There is no way a standard medical will pick up undiagnosed heart disease. The only way to do so is have an angiogram or stress perfusion scan performed. The National Institute of Health and Care Institute has discarded treadmill tests (Bruce protocol) as unreliable. The only thing worth doing is ensuring you don't have high blood pressure as this is associated with SDPE."

Dr. Petar J. Denoble of DAN adds, "DAN learns every year about a few fatalities and a couple dozen survivors of IPE. We agree that IPE is under-diagnosed: Mild cases resolve spontaneously without being reported and diagnosed while severe cases result in drowning. IPE occurs in both young and older divers, divers with known risk factors and divers without previously known or retrospectively identifiable risk factors. Divers who experience an episode of difficulty breathing at depth, should abort the dive, surface, exit the water and ask for help. If they have also rattling or gurgling in their chest, they should suspect IPE and seek emergency evaluation. Even if their symptoms resolve spontaneously, they should seek a thorough medical evaluation before returning to diving."

(DAN's Annual Diving Report may be downloaded here: (www.ncbi.nlm.nih.gov/books/NBK344435/)