Abstract: A disposable, in-line heating cassette and apparatus for raising the temperature of fluids. The cassette comprises a spacer defining a sinuous or serpentine flow pathway interposed between flexible foils and mounted on a frame. The frame comprises inlet and outlet tubes and related input and output ports which communicate with the serpentine path. Juxtaposed heating plates in direct contact with the cassette substantially contact the entire heating surface of the foils, providing a highly efficient thermal path from the heating plate to the foil, and then to the fluid. The heating blocks have several electrically conductive strips thereon for generating a gradation of heat energy such that more heat energy is available for transfer at the inlet end than the outlet end of the serpentine flow path.

Abstract: An apparatus for heating parenteral fluids for intravenous delivery to a patient. The apparatus includes a disposable cassette which in one presently preferred embodiment is made up of a unitary member which is divided to form a serpentine flow path by a plurality of path separators. Thin, flexible metallic foil membranes are sealingly joined to the unitary member on the upper and bottom surfaces thereof to form an enclosed, fluid-tight serpentine flow path between the plurality of path separators. The entire periphery of the unitary member and the thin, flexible heat conductive foil membranes are sealingly held by a framework. The disposable cassette slides between first and second heating blocks which contact the thin, flexible heat conductive foil membranes so as to provide heat transfer to fluid flowing in the serpentine flow path.