A thermal control unit for controlling the temperature of a patient includes a fluid circulation channel with an inlet and outlet, a first heat exchanger, a controller, and a cartridge receptacle. The controller controls the first heat exchanger to adjust the temperature of the circulating fluid toward a desired temperature. The cartridge receptacle is adapted to receive a cartridge having a second heat exchanger and to allow fluid to flow from the cartridge into the fluid circulation channel of the thermal control unit. The cartridge may include a vacuum chamber and a coolant whereby the expansion of the coolant into the vacuum chamber cools the fluid in the cartridge. Flow of the coolant in the vacuum chamber may be automatically initiated upon insertion of the cartridge into the cartridge receptacle, or by other means.
