Acute haemolysis due to concentrated dialysis fluid.

Fatal acute haemolysis occurred in a 65-year-old man undergoing regular home haemodialysis for terminal renal failure. Circumstantial evidence indicating that the haemolysis resulted from exposure to concentrated dialysis solution was supported by in-vitro studies. Frank haemolysis in blood samples occurred at a dilution of greater than or equal to 1/2 of dialysis fluid. Osmotic fragility tests of surviving red blood cells showed 47% haemolysis at a dilution of 1/2 and greater than 90% haemolysis at a dilution of 1/1. Urgent design modifications to the proportionating machine are being undertaken to prevent such an accident recurring.