A life-threatening condition that can affect fit and healthy open-water swimmers, causing them to “drown from the inside out,” may involve fluid buildup in the heart muscle, the researchers suggested.
Swimming-induced pulmonary edema – SIPE – is a form of immersion pulmonary edema and involves the accumulation of fluid in the lungs of swimmers without it having been inhaled. The condition is believed to be the result of increased pressure on the body’s blood vessels as a result of exertion, immersion and cold.
The disease can lead to difficulty breathing, low blood oxygen levels, coughing, frothy or blood-stained sputum, and in some cases, death.
“I suspect that the majority of people who die in the water [having entered voluntarily] – i.e. swimmers or divers – die of immersion pulmonary oedema, not drowning,” said Dr Peter Wilmshurst, consultant cardiologist at Royal Stoke University Hospital and member of the UK Diving Medical Committee , who first described EPI in the 1980s.
Wilmshurst added that the condition is far from uncommon: around 1 in 200 people who compete in Sweden’s annual race, the Vansbro Swim, get SIPE, while 1 in 20 young men have been reported to have the condition during selection for the US Navy Seals. .
Although cases occur frequently in fit and healthy people, there are a number of known risk factors, including age, high blood pressure, being female, and swimming in cold water. .
Figures from Sport England suggest around 2.7 million people took part in open water swimming in England between November 2020 and November 2021.
Now a medical team in the UK who diagnosed EPI in a fit, healthy woman in her 50s who had swum in open water at 17C say they found fluid buildup in her heart muscle .
“Although it is conceivable that this represents a pre-existing inflammatory process such as myocarditis, which contributed to the EPI, it is also potentially a consequence of the acute episode,” the team wrote in the reports of case from the BMJ, noting that it is not the first report of heart muscle dysfunction in the context of EPI.
The woman described how she had struggled while participating in a night swim at a quarry. “When I came out, I undid my suit and immediately felt the sensation of my lungs filling with fluid,” she said, noting that she had developed a cough and frothy pink sputum. “I was very lucky to be surrounded by a great career team who all knew I had SIPE.”
The woman’s symptoms subsided within two hours of her arrival at the emergency department and she was discharged from hospital the following day.
The authors say that although the woman had received a Covid booster shot a few hours before swimming, it is unlikely to be linked to the PEI. Indeed, the woman noted that she had experienced a milder form of shortness of breath after swimming in the sea two weeks prior, and during other exercises. “I was just assuming I was a little uncomfortable,” she said in the report.
Wilmshurt, who was not involved in writing the report, also said it was unlikely the vaccination caused the fluid in the heart muscle, given the short time between the shot and the onset of the symptoms. While it’s not possible to say whether it was caused by EPI or if it was a pre-existing condition, he said, he suspected the former.
Dr Doug Watts, medical director of DDRC Healthcare, which specializes in diving medicine, said people should be aware of EPI, get out of the water immediately and seek medical attention if they find themselves unusually short of breath in swimming. “If you have one episode, you’re likely to have another episode, and the next one could be fatal,” he said.
Wilmshurst said it’s important not to swim alone in open water and cited the need for medical attention in the case of EPI. “If you get it…it may be the first sign that you have an underlying heart condition or high blood pressure,” he said.