Abstract: A patient operating table includes a support mattress with a plurality of pads. The plurality of pads includes a central pad located to support a midsection of a patient's body. The central pad includes an outer shell with a seam that has a hermetic seal and defines a cell therein. A support frame is integrally connected to the central pad. A central pedestal is located under the central pad and carries the support mattress on a base frame. A heating element and a hygroscopic substance is located in the cell. A conduit extends from the heating element and through the outer shell at a sealing ring that is connected to the outer shell with a hermetic seal.