A cassette for use in a system for adjusting the temperature of a patient. The cassette comprises a heat exchanger, the heat exchanger having a primary fluid circuit side and a secondary fluid circuit side. The primary fluid circuit side includes releasable couplers for releasably coupling to a primary fluid circuit. The secondary fluid circuit side is in fluid communication with a heat exchange catheter (263) insertable within a patient, a secondary fluid circuit (255), and a secondary fluid circuit pump (261) for flowing a heat exchange fluid through the secondary fluid circuit to the heat exchange catheter (263) and back through the secondary fluid circuit to the secondary fluid circuit pump (261). The releasable couplers (231,233) have check valves disposed therein to fluidly seal the primary fluid circuit side when the primary fluid circuit side is not connected to the primary fluid circuit to minimize primary fluid loss from the primary fluid circuit side of the heat exchanger
