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Serious Fluid Accumulation in the Brain and Lungs of Marathon Runners
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What is the problem and what is known about it so far?
Medical complications can occur in people who run long distances. One such complication is an abnormally low blood level of sodium, a salt that is present in body fluids. Low sodium levels can lead to accumulation of water in the brain (cerebral edema) and lungs (pulmonary edema). Both conditions are potentially deadly, yet little is known about these complications in runners.
Why did the researchers do this particular study?
Since little is known about this complication, the researchers wanted to describe what they had observed in long-distance runners who accumulated water in their brains and lungs.
Who was studied?
Seven runners, cared for by the authors, who developed medical complications during marathon races between 1993 and 1999.
How was the study done?
While the authors were caring for the patients who became ill while running, they studied the patients' medical histories, physical examinations, chest x-rays, and tests for blood sodium and blood oxygen. They also evaluated the patients' hearts using electrocardiograms (recordings of the electrical activity of the heart) and echocardiograms (ultrasound pictures of the heart). For 5 of the 7 patients, the doctors also inserted a pressure-measuring device directly into the circulation. Six of the 7 patients had special x-ray pictures of their brains.
What did the researchers find?
All of the patients developed nausea, vomiting, and confusion while running in a marathon. All had used nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, before the race. (NSAIDs can affect the way the body handles salt and water.) On arrival at the emergency room, all patients had so much fluid in their lungs (pulmonary edema) that they required machines called ventilators to help them breathe. They also had low blood levels of sodium and oxygen. Tests of heart function were all normal, indicating that heart abnormality was not responsible for the illness. X-ray pictures in the 6 patients who had them showed swelling of the brain. These 6 patients received treatment with intravenous fluids that contained sodium (hypertonic saline); all recovered completely. The seventh patient died suddenly in the emergency room when his heart stopped working, but the autopsy showed that this patient also had the same problems as the other patients.
What were the limitations of the study?
While this report demonstrates that this condition can occur in marathon runners, it does not tell us how often it happens or how it might be prevented. It also does not say whether certain types of runners (such as those who use NSAIDs) are at particular risk for developing this complication.
What are the implications of the study?
Healthy marathon runners can develop low blood sodium levels and accumulate water in their brains and lungs. The condition may be fatal but can be treated with intravenous sodium-containing fluids and breathing machines. The relationship of NSAIDs to this complication is unknown.
Article and Author Information
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The summary below is from the full report titled “Hyponatremia, Cerebral Edema, and Noncardiogenic Pulmonary Edema in Marathon Runners.” It is in the 2 May 2000 issue of Annals of Internal Medicine (volume 132, pages 711-714). The authors are J.C. Ayus, J. Varon, and A.I. Arieff.
- Copyright ©2004 by the American College of Physicians
