Pulmonary oedema and hyponatraemia after an ironman triathlon

A 36-year-old man presented with symptoms of acute pulmonary oedema at the conclusion of the Australian ironman triathlon. He was alert, orientated, with an oxygen saturation of 75% on room air. Chest examination revealed bilateral basal crepitations. Serum sodium was 120 mmol/L and chest x ray revealed bilateral basal opacities. He was treated for acute pulmonary oedema with prompt improvement and given 200 ml of intravenous hypertonic saline followed by normal saline. Serum sodium decreased to 117 mmol/L and 30 hours after presentation he had a seizure. He fully recovered and was discharged 5 days after admission. This case highlights that exercise-associated hyponatraemia and pulmonary oedema are still not widely understood and there is still a reluctance to treat hyponatraemia aggressively with ongoing hypertonic saline.