Hyponatremia, cerebral edema, and noncardiogenic pulmonary edema in marathon runners.

BACKGROUND: Noncardiogenic pulmonary edema is often associated with increased intracranial pressure and can be the initial manifestation of hyponatremic encephalopathy. Marathon runners tend to develop conditions that lead to hyponatremia.
OBJECTIVE: To describe the development and treatment of noncardiogenic pulmonary edema in marathon runners that was associated with hyponatremic encephalopathy.
DESIGN: Case series.
SETTING: One university hospital and two community hospitals. PATIENTS: Seven healthy marathon runners who had a history of nonsteroidal anti-inflammatory drug use. The runners collapsed after competing in a marathon and were hospitalized with pulmonary edema. MEASUREMENTS: Plasma sodium levels, chest radiograph, electrocardiogram, cardiac enzyme levels, and magnetic resonance imaging or computed tomographic scans of the brain.
RESULTS: Patients had nausea, emesis, and obtundation. The mean (+/-SD) plasma sodium level was 121 +/- 3 mmol/L, and oxygen saturation was less than 70%. Electrocardiograms and echocardiograms were normal. Chest radiographs showed pulmonary edema with a normal heart. Creatine phosphokinase-MB bands, troponin levels, and pulmonary wedge pressure were not elevated. Scanning of the brain showed cerebral edema. All patients were intubated and mechanically ventilated. Treatment with intravenous NaCl, 514 mmol/L, increased plasma sodium levels by 10 mmol/L in 12 hours. Pulmonary and cerebral edema resolved as the sodium level increased. One patient had unsuspected hyponatremic encephalopathy and died of cardiopulmonary arrest caused by brainstem herniation. All six treated patients recovered and were well after 1 year of follow-up.
CONCLUSIONS: In healthy marathon runners, noncardiogenic pulmonary edema can be associated with hyponatremic encephalopathy. The condition may be fatal if undiagnosed and can be successfully treated with hypertonic NaCl.