A heater-cooler apparatus 1 for a perfusion system heat exchanger 26 comprises an intermediate heat exchanger 40 between a heater-cooler device 10 and an intermediate passage 30. The heater-cooler device 10 supplies heater-cooler fluid 11 to the intermediate heat exchanger 40. The intermediate passage 30 supplies an intermediate fluid 31 to the perfusion system heat exchanger 26. The intermediate heat exchanger 40 permits heat exchange between the heater-cooler fluid 11 and the intermediate fluid 31. Thereby, the heater-cooler fluid 11 is fluidically isolated from the perfusion system heat exchanger 26. This arrangement allows an antiseptic fluid to be used in the heater-cooler device 10, which in turn reduces the risk of cross-contamination originating from the heater-cooler device 10.
