Method and system for control of a patient's body temperature by way of a transluminally insertable heat exchange catheter
View Patent ↗Methods and apparatuses for temperature modification of a patient, or selected regions thereof, including an induced state of hypothermia. The temperature modification is accomplished using an in-dwelling heat exchange catheter within which a fluid heat exchange medium circulates. A heat exchange cassette of any one of several disclosed variations is attached to the circulatory flow lines of the catheter, the heat exchange cassette being sized to engage a cavity within one of various described re-usable control units. The control units include a heater/cooler device, a user input device, and a processor connected to receive input from various sensors around the body and the system. The heater/cooler device may be thermoelectric to enable both heating and cooling based on polarity. A temperature control scheme for ramping the body temperature up or down without overshoot is provided. The disposable heat exchange cassettes may include an integral pump head that engages with a pump drive mechanism within the re-usable control unit. More than one control unit may be provided to receive the same heat exchange cassette so that a large capacity control unit can be used initially, and a smaller, battery-powered unit can be substituted once the patient reaches the desired target temperature.
1. A method of controlling the rate of change of a patient's body temperature using a heat transfer catheter and associated controller, comprising:
providing a heat transfer catheter for insertion into a body cavity, the heat transfer catheter having a heat transfer region thereon;
sensing the patient's body temperature in the body cavity or in another location;
determining the temperature of the catheter heat transfer region;
providing a controller in communication with the heat transfer catheter via conduits through which circulates a heat exchange fluid, the controller being adapted to elevate or depress the temperature of the catheter heat transfer region relative to the body temperature by adding or removing heat from the heat exchange fluid;
selecting a target temperature different than the body temperature;
monitoring the temperature differential between the target temperature and the body temperature; and
actuating the controller to increase or decrease a rate of heat addition or removal from the heat exchange fluid as a function of the temperature differential between the target temperature and the body temperature; and
wherein the steps of sensing, determining and monitoring are accomplished at rates of multiple times a second.
2. The method of claim 1 , wherein the step of setting the temperature of the catheter heat transfer region comprises setting the temperature of the circulating heat exchange fluid.
3. The method of claim 2 , wherein the step of determining the temperature of the catheter heat transfer region comprises sensing the temperature of the circulating heat exchange fluid.
4. The method of claim 3 , further including comparing the target temperature and the temperature of the circulating fluid and using the comparison to adjust the temperature of the circulating fluid.
5. The method of claim 1 , wherein the controller includes a microprocessor, and wherein the steps of monitoring and reducing are accomplished automatically by the microprocessor.
6. The method of claim 1 , further including:
providing operator inputs for the controller to enable manual adjustment of the target temperature and the selected rate of heat addition or removal.
7. The method of claim 1 , further including:
selecting a ramp rate equal to a desired time rate of change of temperature from the body temperature to the target temperature;
setting the initial temperature of the catheter heat transfer region based on the selected ramp rate; and
wherein the step of actuating the controller includes actuating the controller to increase or decrease the rate of heat addition or removal from the heat exchange fluid to obtain the selected ramp rate.