Methemoglobinemia Caused by Portable Dialysis in the Critically Ill.

OBJECTIVE: To evaluate the root cause of a series of methemoglobinemia cases in a medical ICU.

RESULTS: We report a sentinel case of methemoglobinemia that was associated with dialysis sessions using a portable dialysis unit in our hospital. This led to the identification of four additional patients who developed methemoglobinemia while undergoing portable dialysis. We determined that these episodes were caused by inadequate clearance of chloramine from the tap water used for portable dialysis. Introduction of larger capacity carbon filters into the portable dialysis systems resulted in no further cases of methemoglobinemia at our institution.

CONCLUSIONS: Clinicians should be aware of municipal tap water as a potential cause of methemoglobinemia and monitor for excessive levels of oxidants in dialysis water sources. The capacity of the hemodialysis equipment to clear chloramine can vary as a function of external factors. Using a reliable test method to identify chloramines in the water prior to entering the hemodialysis equipment is essential.