Relatively little known hazard linked to open water swimming explored

Fluid on the lungs, or pulmonary oedema as it's formally known, is a relatively little known hazard associated with open water swimming, warn doctors in the journal BMJ Case Reports after treating a woman with the condition. Older age, swimming long distances, cold water, and female sex are among the risk factors, as are high blood pressure and pre-existing heart disease. But it frequently occurs in those who are otherwise fit and healthy, highlight the authors.

The woman in question was in her 50s and a keen competitive long distance swimmer and triathlete. Otherwise fit and well, 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. Her symptoms started after swimming 300 metres. On arrival at hospital, her heartbeat was rapid, and a chest x-ray revealed pulmonary oedema. Further scans revealed that fluid had infiltrated the heart muscle, a sign of strain known as myocardial oedema. But she had no structural heart disease.

It’s not clear exactly what causes swimming-induced pulmonary oedema or 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.

The authors 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.

Reference:

Myocardial oedema in the setting of immersion pulmonary oedema - Cause or effect? Doi 10.1136/bcr-2022-251274,Journal: BMJ Case Reports