Acute breathing difficulty during swimming or diving may be associated with Immersion Pulmonary Edema (IPE). At SPUMS 2014, Peter Wilmshurst presented a summary of his rich clinical experience. In his opinion, IPE is an underestimated cause of fatalities. Problem with diagnosis of IPE in scuba diving is its rapid evolution. Divers may be overwhelmed with an internal lung flood before they realize the nature of their breathing difficulty and can safely exit the water.
IPE occurs in subjects with cardiovascular diseases as well as in healthy and apparently healthy subjects. Overhydration may create conditions for IPE to occur, even in healthy subjects. Similarly, negative-pressure breathing, which can occur in closed-circuit diving or in open-circuit diving with a faulty regulator, can result with acute flash pulmonary edema. Hypertension, even mild if not properly regulated, may predispose for IPE. In several reported cases, narrowing of renal artery was associated with IPE. Women experiencing premenstrual fluid retention seem to also be at an increased risk. Extreme psychological stress causing strong sympathetic arousal and a rush of adrenaline may cause IPE.
Two characteristics of IPE must be kept in mind. First, the sudden evolution of difficulty breathing and coughing followed by a rapid lung flooding with fluid leaking from lung capillaries can quickly incapacitate diver. Diver must ascend to a surface, signal for help and be quickly retrieved from the water. Sometimes divers do not succeed to emerge and their death is later ascribed to drowning or other causes. Fortunately, in some divers IPE evolves slower and they survive. However, they do not necessarily recognize the nature of their symptoms until more severe episodes require them to go to the hospital. This constitutes the second major characteristic of IPE: It tends to happen again. Thus, a history of difficulty breathing while in water must be taken seriously. A diver experiencing such symptoms must be thoroughly evaluated for cardiovascular and pulmonary diseases. Regardless of the finding, return to diving is not advised in most cases. Some medications may help to reduce the risk of IPE, but this is considered only in those divers who must dive for a living.
David Smart presented two fatal IPE cases in scuba divers. The main finding at autopsy was a froth filling the airways and a large increase in size and weight of lungs. These findings are not specific enough to distinguish IPE from drowning. The most important help in diagnosis is a thorough dive (or snorkeling and swimming) history, which sometimes reveals past episodes of breathlessness.
Another case was presented by Sarah Lockley. Again, there was a history of breathlessness, coughing and cyanosis (bluish skin discoloration and the mucous membranes due to insufficient oxygen in the blood) while swimming that were disregarded until a tragic accident revealed the true nature of it.
Divers and other individuals engaged in sports involving immersion must not leave any episode of respiratory issues unexplained. Surviving IPE once is a blessing, not a trend.
Post written by: Petar Denoble, MD, D.Sc.