Nontuberculous Mycobacterium (NTM) Infections
A common concern during cardiopulmonary bypass surgery is the possibility of NTM contamination of the water in the heater-cooler unit used to control the temperature of the patient and the blood going through the membrane oxygenator. As indicated in this FDA Safety Communication, Nontuberculous Mycobacterium (NTM) is widespread in nature, including tap water, and is not typically dangerous.
However, complications have been found when present in cardiac procedures with immunocompromised patients or seriously ill patients. This CDC Alert notes that specific heater-cooler devices have been associated with these infections.