Risk for open air swimmers from little known condition

how Wild Swimming in cold water could risk fluid in the lung, even in young healthy people and what doctors and healthcare staff should look out for

New research warns that open air swimmers could risk fluid in their lungs. How Wild Swimming in cold water could risk fluid in the lung, even in young healthy people and what doctors and healthcare staff should look out for.

According to Hippocrates, cold water therapy relieved fatigue. In 1810, Lord Byron sparked the modern fashion for outdoor swimming when he swam several miles across the Dardanelles (Hellespont) from Europe to Asia.

Open air swimming has hugely increased in popularity, with more than three million people presently enjoying the activity in the UK, but researchers have found that it can trigger a potentially fatal condition of fluid on the lungs, particularly in those with high blood pressure and heart disease.

A team of researchers from the Royal United Hospitals, Bath NHS Foundation have for the first time observed how changes in different parts of the brain interact with each other after a person’s body is immersed in cold water. This helps to explain why people often feel more positive, lively and more energetic after swimming outside, or taking cold showers.

The Bath medics found that a fit woman, in her 50s, who is a keen competitive long distance swimmer and triathlete, with no adverse medical conditions, began having difficulties breathing and to cough up blood after participating in an open water swimming event at night.

She was wearing a wetsuit. The water had been 17C which is relatively warm for the English sea, even the during summer months. The swimmer reported that she had begun experiencing breathing difficulties after swimming around 300 metres and had noticed an unpleasant metallic taste in her mouth. It seemed that she had suffered a fluid accumulation in her lung resulting in swimming-induced pulmonary oedema (SIPE) which can lead to low levels of oxygen in the body. This woman had experienced a milder event with similar breathing difficulties during a swimming competition a couple of weeks earlier, which compelled her to drop out and it affected her breathing for a few days afterwards.

A chest x-ray in hospital showed the woman had pulmonary oedema, although she had no structural heart disease, wrote the Bath medics, in the journal BMJ Case Report. Further imaging revealed fluid had penetrated her heart muscle, causing myocardial oedema and she was monitored overnight in hospital, before being discharged after her symptoms had settled the following morning.

The researchers are not sure exactly what caused the woman’s SIPE, but there is likely to be a connection to how the blood responds to swimming in cold water, together with a magnified constriction of blood vessels reacting to cold and expanding blood flow during physical effort. Her problems started after swimming just 300 metres and she was otherwise fit and well. This condition has also been seen in scuba divers.

If you want to improve your alertness and energy levels by cold water swimming, make sure you are not alone and consider currents, tides, jellyfish, pollution levels and waves. Remember that your muscles don’t function as well when you are cold and your hands and feet may go numb. Take a hot drink in a thermos flask and warm, preferably waterproof clothing in case it rains. If you feel any pain, or begin to shiver leave the water straight away.

For those experiencing symptoms for the first time, the researchers recommend stopping swimming and getting out of the water right away if you begin to feel breathless or your hands or feet begin to go numb. When you are on dry land sit upright, warm up with a hot drink and warm clothes and call for medical help if needed.

When you are planning your autumnal outdoor swim, make sure you pack towels, warm clothes and a hot drink. Don’t swim for long periods of time in cold water and plan how you are going to get out of the water safely. Think about wearing a wetsuit.

Factors that increase the risks of getting into trouble swimming in open water include being older, female or having heart disease – but the authors of the report stress that it also often happens to the young, athletic and healthy. This risk is greater when swimmers swim long distances.

The authors of the research are keen to raise awareness amongst medical staff and swimmers of the relatively little known condition.



Rebecca Wallersteiner: Rebecca Wallersteiner is a health and arts journalist, who writes for The Daily Mail, Mail on Sunday, NetDoctor, Telegraph, The Times, Traveller and The Oldie magazines. She also works for the NHS and is the Hippocratic Post's roving reporter.

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