Breathing Difficulty While Diving

By Fred Bove, M.D., Ph.D.

Breathing Difficulty While Diving

“…I went down to the bottom, knelt in the sand and remained still so as not to disturb the fish. I was in about 25 to 30 feet of water for about 10 minutes or so when I started coughing into my regulator. I noticed my breathing was a little fast for someone who was inactive. Over the next five minutes or so, my coughing became more and more frequent. I started to become a little concerned and signaled to my buddy that I was going up. By the time I surfaced I was very short of breath. I swam to the stern of the boat and just hung on to the ladder. I kept coughing and coughing and coughing. …I kept coughing up a lot of secretions. I was having coughing fits. By the time we got back to the dock, my coughing slowed up. The shortness of breath cleared up after I was inactive and sitting for a few minutes. It was about five or six hours before I felt totally normal. If I had to put a label on what I was experiencing, it would be that of pulmonary edema. This episode was the third and worst yet…”For the past 10 years or so we have been aware of an interesting and worrisome problem that occurs in some divers while they are underwater. The problem is the rapid development of severe shortness of breath caused by fluid leaking from the bloodstream into the air spaces in the lungs, and impairing the flow of oxygen into the blood. In medicine we call this pulmonary edema. It is somewhat akin to drowning, but the fluid comes from the body and not from the outside environment. A letter from a diver describes the sensation:

This problem was described in 1990 at a scientific meeting of diving medical physicians. The syndrome occurred in divers who were wearing wetsuits in cold water. In the first report they were all over 50 years old, and it was thought that these individuals had heart problems that occurred for the first time while diving. However, subsequent reports were published that included younger divers in warm water with no medical history of any serious disease. Some of these individuals were taken to hospitals and were found to have fluid scattered throughout the air spaces of the lungs and inadequate oxygen in the blood.

This problem, called pulmonary edema, usually occurs because the heart is injured or damaged, or because a process has occurred in the lung to allow fluid to leak from the bloodstream and fill the air spaces with plasma. The most serious and discomforting symptom is the rapid onset of severe shortness of breath and coughing while diving. The diver describes this well in the letter, which is a typical description.

Although immersion pulmonary edema is rare, it is certainly not trivial and can cause significant problems with divers. The mechanism for it is not well-understood, but some precautions are worth stating:

    • Be sure your regulator is breathing normally. If there is resistance to inspiration, have the regulator checked and adjusted. A malfunctioning regulator that does not supply adequate air will cause negative pressure breathing and may induce pulmonary edema.
    • Don’t dive if you have high blood pressure. Be sure your blood pressure is treated and normal before diving.
    • Be careful with excess fluid intake. There have been a few documented instances when divers were given large amounts of fluid just prior to diving and developed immersion pulmonary edema.
    • If you have a heart problem, be sure you discuss diving with your physician and avoid diving unless your heart problem is stable and well controlled with medication. Most divers who experience immersion pulmonary edema are found to have normal hearts.

Although the cause for immersion pulmonary edema is unknown, these precautions can provide some protection. If you develop severe shortness of breath underwater, ascend at a normal rate to avoid lung overpressure. If your symptoms persist on the surface, breathe 100 percent oxygen if it is available. Consult your physician to be certain that your health is normal before returning to diving.

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