The inventive flexible structure has at least two heat transfer portions. One of heat transfer portions is positioned in contact with the body of the patient. The structure is hermetically sealed and a fluidized medium responsive to temperature change is provided in the structure between the heat transfer portions. The fluid is changeable between a liquid state and a gaseous state, when it is exposed to heat and cold. The heat absorbed by the heat transfer portion in contact with the patient is carried by the fluidized medium, as latent heat in the gas that results when the liquid is vaporized to its gaseous state, to the heat transfer portion layer not in contact with the patient, so that the latent heat in the gaseous vapor is dissipated. Upon dissipation, the gaseous vapor is condensed and the fluidized medium returns to its liquid state.
