Patent ID: 7087026

Claim:
A method for determining cardiac output or discerning a substantial change in cardiac output in a mammalian patient, the method comprising the steps of: A) providing a heat exchange catheter that comprises an elongate catheter body having a heat exchanger positioned thereon; B) inserting the heat exchange catheter into the vasculature of the patient and positioning the heat exchanger within a blood vessel through which the blood flow rate is substantially the same as or bears a known relationship to cardiac output; C) causing heat to be exchanged between the heat exchanger and blood flowing past the heat exchanger; D) determining the amount of heat exchanged between the heat exchanger and the blood within a time period; E) determining the flow rate of blood past the heat exchanger based on the amount of heat exchanged in the time period, the flow rate of blood being determined by reference to a database which correlates flow rate values to corresponding amounts of heat exchange measured in Step D for blood in vessels having different luminal diameters; and F) computing at least an estimate of cardiac output or discerning a change in cardiac output, on the basis of the flow rate determined in Step E.