Increasing numbers of people are braving the cold and opting to dip ourselves in open water across the UK, with more than three million ‘wild swimming’ enthusiasts in England in 2021 alone.
However, doctors have issued a serious warning about a relatively unknown condition linked to the hobby, after treating a woman with a fluid on the lungs.
Doctors in the journal BMJ Case Reports warn that fluid on the lungs, or pulmonary oedema as it’s formally known, can occur in those who are fit and healthy.
Despite this, older age, swimming long distances, exposure to cold water and your sex – it’s more common among women – are among the risk factors, as are high blood pressure and pre-existing heart disease.
According to the medical professionals, there is mounting evidence that points to a link between wild swimming and a condition called swimming-induced pulmonary oedema, or SIPE for short.
First reported in 1989, SIPE leaves swimmers struggling to draw breath and depletes their blood of vital oxygen.
It affects an estimated 1-2% of open water swimmers, but cases are likely to be underreported, warn doctors in the journal.
The woman that was treated with the condition was in her fifties and a keen competitive long distance swimmer and triathlete.
Despite being incredibly fit and healthy, she was struggling to breathe and coughing up blood after taking part in an open water swimming event at night in water temperatures of around 17°C while wearing a wetsuit.
According to the report, her symptoms started after she swam 300m.
Although she had no notable medical history, she had experienced breathing difficulties during an open water swim a fortnight earlier which had forced her to abandon the event and left her feeling breathless for some days afterwards.
On arrival at hospital, her heartbeat was rapid and a chest x-ray revealed that there was water on her lungs.
Further scans revealed that fluid had infiltrated the heart muscle, a sign of strain known as myocardial oedema, even though she had zero signs of heart disease.
Fortunately, her symptoms settled within two hours of arrival at hospital and after careful monitoring, she was discharged the following morning.
According to the doctors, it’s not clear exactly what causes SIPE, but it likely involves “increases in arterial pressure in the lungs secondary to centralisation of blood volume in a cold environment, combined with an exaggerated constriction of these blood vessels in response to the cold and increased blood flow during physical exertion.”
To reduce someone’s chances of developing the condition, the experts advise swimming at a slower pace, accompanied, in warmer water, without a tight-fitting wetsuit, and avoidance of non-steroidal anti-inflammatories, such as ibuprofen, to minimise the risk.
For those experiencing symptoms for the first time, the authors recommend stopping swimming and getting out of the water straight away, then sitting upright, and calling for medical assistance if required.
This is just one case, stressed the authors, whose aim in reporting it is to raise awareness among doctors and swimmers of a relatively little known condition.
“The UK Diving Medical Committee has published guidance for divers. However, at present, there are no formal national medical guidelines concerning the recognition and management of this complex condition,” they added.