To rapidly induce hypothermia to a patient, in the event the patient has astroke, hyperthermia or some othertem-perature related heath problems which requires prompt action to regulatethe temperature of the patient, a flat flexible structureconformable to the body of the patient is placed into contact with the patientThe structure has at least two heat transfer portionsOne of heat transfer portions is positioned in contact with the body of thepatient The structure is hermetically sealed and aflu-idized medium responsive to temperature change is provided in thestructure between the heat transfer portions The fluid ischangeable between a liquid state and a gaseous state, when it is exposed toheat and cold
