During cardiopulmonary bypass (AVR) the perfusionist noticed blood in the water lines that connect the heater cooler unit to the oxygenator's (paragon) heat exchanger 37 minutes in to bypass. This suggests a leak in the heat exchanger and the patients' blood and water could be mixing.

The water lines were immediately switched off and disconnected, and the consultant surgeon informed. The patient remained on bypass while a new bypass circuit was prepared. Bypass was temporarily stopped and re-commenced with the new circuit using a new heater-cooler and the patient fully rewarmed. Bypass was discontinued and the patient was stable. It should be noted that a full heat exchanger leak test was performed before the bypass circuit was primed and no fault was detected (water circulated at 37oC for 5mins prior to adding prime solution, no pressure test). Blood and water samples were sent for testing. Antibiotics were given by the consultant anaesthetist.