Office of Naval Research 2014
Immersion pulmonary edema (IPE) or swimming-induced pulmonary edema (SIPE) manifests with coughing, blood in sputum, difficulty breathing and a drop in the oxygen content of arterial blood. It may occur during surface swimming or diving, and can affect subjects of all ages and levels of health. Risk factors include exaggerated vasoconstriction in cold water, strenuous exercise, negative static lung load caused by immersion, fluid overload and low vital capacity.
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.
Diving with asthma is still a bit of a controversial issue due to insufficient research of how divers with asthma respond to dive conditions and lack of data on their dive safety. A recent study conducted by a group of researchers associated with DAN Europe contributes to current knowledge how diving may affect small airways function in divers with asthma. They conducted pulmonary function tests in 22 divers with asthma and 15 healthy control divers, before and after a single pool dive to 15 feet (5 meters). A single pool scuba dive to a depth of 15 feet may impair small airways function in divers with asthma. Among the subjects, no one experienced any symptoms, but the effect on small airways varied significantly among divers with asthma. Most showed a minimal reduction of function (3 – 10%) not seen in healthy divers, while one diver exhibited a reduction of 22-26% in FVC, FEV1 and PEF of the predive values. The latter change was significant enough to advise the diver against further diving.
It is important to notice that all divers with asthma participating in this study were previously cleared for diving and have been diving for an average of four years. They did not report any incident of asthma attack or difficulty breathing while diving although they recorded between 10 and 220 dives in the past.
Asthma manifests in various forms; provocative factors, frequency and severity of symptoms and fitness to dive should be evaluated on an individual basis. Obviously, not all people with asthma would qualify for diving. The individuals included in this study are those that passed medical evaluation. It appears that they and their physicians made a reasonable decision. The only diver who had significant changes in small airway functions somehow bypassed physical evaluation by a physician prior to diving and made his choice without a physician’s opinion.
The article is a good read for any diver or would-be diver with asthma as well as for diving physicians. It gives an overview of available literature on the topic and provides extensive discussion of factors that should be considered in the fitness evaluation process.
Post written by: Petar Denoble, MD, D.Sc.
SIPE, which is also known as Immersion Pulmonary Edema, has been occasionally reported during the last two decades. It may affect scuba divers, breath-hold divers and swimmers. The incidence of SIPE is probably underestimated, because mild cases may resolve on their own and the most severe cases may be mistaken for drowning or cardiac-related death. Two recent papers present three documented and unusual cases of SIPE.
Case 1
A 33-year-old healthy military diver was immersed for 10 minutes in 50 F (10 C) while wearing a 5 mm neoprene wetsuit. After two breath-hold dives to 18 ft (6 m) for 0.5-1 min duration with a surface interval of 1 min, he noted wheezing and coughed pink, frothy sputum. At admission to a hospital, he had already improved but imaging of his lungs showed obvious signs of SIPE. This was an unusually short exposure, shallow dive and quick onset of symptoms.1
Case 2
A 46-year-old man was spearfishing in 5 m of water in a 5 mm neoprene wetsuit. He did not report feeling cold, although the water was 57.2 F (14 C).While swimming back to shore against strong current for only two minutes, he suddenly felt such respiratory distress that he could not call for help or swim. His wife brought him back to shore; he was unconscious. He recovered in a few hours and was discharged from the hospital after three days.2
Case 3
A 48-year-old man was performing an 800-m swim test. The day before, during the same exercise he reported becoming severely breathless, but recovered within a short period of time. On his next attempt, he had to swim 500 m with a snorkel while wearing his complete scuba equipment. After 250 m his buddy discovered he was unconscious and sinking. An emergency medical team responded quickly and properly, but he was in a coma when admitted to a hospital where he was kept in artificially induced protective hypothermia (the initial diagnosis was cardio-circulatory arrest and drowning).2
In all three cases, the victims recover – some sooner, others later. Medical causes, except hypertension in the first case, could not be identified; all victims appeared to be in normal health, except for the findings of lung edema.
The lesson learned is that SIPE may occur suddenly and be very severe. It can be life threatening while in water and it may require intensive care to recover. The apparently low incidence of SIPE may be due to misidentification of some fatalities as a cardiac-related death instead of SIPE.
Authors suggest two major points to prevent SIPE and fatal outcome in case of it:
To learn more, read “Immersion Pulmonary Edema.”
Studies referenced in this post:
Post written by: Petar Denoble, MD, D.Sc.
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