Method for determining the effective thermal mass of a body or organ using a cooling catheter
First Claim
1. A method for determining an effective thermal mass of a patient, said method comprising the steps of:
- inducing hypothermia or hyperthermia in at least a selected portion of the patient with a device having a heat transfer surface, the surface being a metal or a balloon surface;
measuring power transferred between said device and the patient;
measuring a change in temperature over time which arises in the selected portion of the patient while performing the step of inducing hypothermia or hyperthermia; and
calculating an effective thermal mass based on the measured power and the measured temperature change over time.
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Abstract
A method and apparatus is provided for determining an effective thermal mass of a patient. The effective thermal mass is employed to determine a gain factor used in a feedback control system controlling patient temperature. The method begins by inducing hypothermia or hyperthermia in at least a selected portion of the patient with a device having a heat transfer surface. Next, power is transferred between the device and the patient. A change in temperature over time, which arises in the selected portion of the patient, is measured while performing the step of inducing hypothermia or hyperthermia. Finally, an effective thermal mass is calculated based on the measured power and the measured temperature change over time.
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Citations
22 Claims
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1. A method for determining an effective thermal mass of a patient, said method comprising the steps of:
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inducing hypothermia or hyperthermia in at least a selected portion of the patient with a device having a heat transfer surface, the surface being a metal or a balloon surface;
measuring power transferred between said device and the patient;
measuring a change in temperature over time which arises in the selected portion of the patient while performing the step of inducing hypothermia or hyperthermia; and
calculating an effective thermal mass based on the measured power and the measured temperature change over time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for controlling the temperature of at least a selected portion of a patient, said method comprising the steps of:
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introducing a metal or balloon catheter into a blood vessel supplying blood to the selected portion of the patient;
heating or cooling the catheter to introduce or remove heat from the selected portion of the patient, said heating or cooling being performed at a rate determined by a feedback control algorithm that employs a feedback control gain factor; and
wherein the step of heating or cooling includes the step of calculating an effective thermal mass for determining the feedback control gain factor, said calculating step including the steps of;
measuring power transferred between the catheter and the patient;
measuring a change in temperature over time which arises in the selected portion of the patient while heating or cooling the catheter; and
calculating the effective thermal mass based on the measured power and the measured temperature change over time. - View Dependent Claims (14, 15, 16, 17, 18, 20, 21, 22)
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19. The method of step 14 wherein the selected portion of the patient is the brain and the catheter is introduced into the carotid artery.
Specification