Unexpected cyanosis in a haemodialysis patient—did someone add hydrogen peroxide to the dialysis water?

Haemodialysis patients are at risk of poisoning by contaminants in dialysis fluid [1]; they are exposed to large volumes of water every time they dialyse, dialysis membranes offer a less effective barrier than the gastrointestinal tract and their renal failure renders them less able to eliminate toxins. Aluminium remains the classic example of such toxicity. Renal patients are also at risk of exposure to chemicals used to disinfect their dialysis water [2]. We wish to report the cases of four patients who became unwell during dialysis and were found to have methaemoglobinaemia following inadvertent exposure to hydrogen peroxide that had been used to decontaminate the hospital’s main water tank. We believe that this is only the second such report of its kind and that patients dialyzing in renal units that still rely on mains water for dialysis remain at risk.