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.
Snorkeling-related, swimming-related or coincidental deaths?
In “Snorkelling-related deaths in Australia, 1994–2006” John M. Lippmann, et al. presented an analysis of 140 snorkeling-related deaths that occurred in Australia during the period of 1994-2006. The majority of the cases occurred due to cardiac-related causes (60) or drowning while at the surface (33). Only 19 deaths occurred after prolonged breath-hold diving and 10 were caused by trauma.
Cardiac cause was established based on medical examiners’ findings.
- In 34 cases there was a history of cardiac disease.
- In 19 cases cardiac pathology was established for the first time at autopsy.
- The remaining five there was neither a history nor conclusive autopsy finding. Medical experts believed these five occurred as a result of cardiac arrhythmias.
- Most deaths due to cardiac causes occurred in male snorkelers of a median age of 65, who were found silently floating in the water. Authors propose the term “fatal silent snorkeling syndrome” for these cases.
Overall, the incidence rate of snorkeling deaths is very small; with an average 10 cases per year and about 2 million snorkelers annually, it is approximately five deaths per 1 million snorkelers. In cases of cardiac death, there are about 2 deaths per 1 million snorkelers. While this small overall risk does not require any particular intervention, there are some people that may be at much higher risk. This includes individuals with a family history of sudden cardiac death and people with known heart disease. Among other causes of snorkeling death, there were four cases of epileptic seizures while snorkeling which may be either unrelated or provoked by water immersion (so called “water immersion epilepsy”).
There were only 19 breath-hold diving deaths including prolonged or deep diving in apnea; however, the number of people practicing breath-hold diving was not known and the relative risk could not be established. One may reasonably assume that true breath-hold diving involves greater risk than surface snorkeling (when controlled for age).
Snorkeling is widespread among recreational swimmers and does not necessarily involve submersion. Hazards for snorkelers are same as for swimmers, but statistics for drowning deaths were not compared here. According to this paper, in 2006 in Australia, out of 16 dive-related deaths, 10 were snorkeling related. Another source reports that diving-related deaths make up approximately 7% of drowning in open waters. Incidence rate for snorkeling deaths due to cardiac causes may not be different than incidence rate of drowning due to cardiac causes. The point is that “snorkeling deaths” and “swimming deaths,” with exclusion of true breath-hold diving deaths, may be the result of the same causes. While specific provocative factors may be present in immersion, beyond channelopathies and “immersion epilepsy,” they may not amount to a greater risk than the risk people are exposed to in their daily lives.
The paper brings out many other interesting details and is worth a read.
Post written by: Petar Denoble, MD, D.Sc.
Swimming induced pulmonary edema (SIPE)
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.
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
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
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:
- Do not struggle against a strong current; maintaining a good respiration is better than increasing the swimming effort.
- Always have diving or swimming buddy.
To learn more, read “Immersion Pulmonary Edema.”
Studies referenced in this post:
- Gempp E. et al. Pulmonary oedema in breath-hold diving: an unusual presentation and computed tomography findings. Diving Hyperb Med 2013; 43:162-163.
- Cochard G. et al. Swimming-induced immersion pulmonary edema while snorkeling can be rapidly life-threatening: Case reports. UHM 2013; 40(5): 411-415
Post written by: Petar Denoble, MD, D.Sc.