Method and system for control of a patient's body temperature by way of a transluminally insertable heat exchange catheter
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 conduits 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 15″ 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, for example, 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 system for controlling the rate of change of a patient's body temperature using a heat transfer catheter and associated controller, comprising:
a heat transfer catheter for insertion into a body cavity, the heat transfer catheter having a heat transfer region disposed thereon and in fluid communication with a heat exchange unit having a pump head having a toothed head gear;
a sensor for sensing the patient's body temperature, the sensor providing a signal representative of the patient's body temperature;
a housing configured to removably receive the heat exchange unit, the housing including a pump motor and a toothed drive gear actuated by the pump motor, the teeth of the drive gear being engaged with the teeth of the head gear of the heat exchange unit only when the heat exchange unit is received by the housing;
an input for selecting a target temperature of the patient;
a controller in communication with the input to receive the inputted target temperature, and also in communication with the sensor to receive the signal representative of the patient's body temperature, the controller also in communication with the heat transfer catheter via fluid conduits, the controller being adapted to increase or decrease the amount of heat being added to or removed from the body cavity by the heat transfer catheter in response to the signal received from the sensor, the controller configured to select a ramp rate equal to a selected time rate of change of temperature from the sensed patient's body temperature to the target temperature, to monitor the temperature differential between the target temperature and the body temperature, to sample the sensor signal and monitor the temperature differential at a rate of multiple times per minute, and to control the ramp rate by adjusting the speed of a fluid circulating through the heat transfer catheter by adjusting the speed of the motor in accordance with the monitored temperature differential as the patient's body temperature approaches the target temperature.
2. The system of claim 1 , wherein the heat transfer catheter and conduits define a fluid circulation path therethrough.
3. The system of claim 1 , further comprising a sensor for directly or indirectly sensing the temperature of the circulating fluid.
4. The system of claim 3 , wherein the controller is further configured to compare the target temperature and the temperature of the circulating fluid and to use the comparison to adjust the temperature of the circulating fluid.
5. The system of claim 1 , wherein the controller includes a microprocessor.
6. The system of claim 1 , further comprising an input for inputting a selected ramp rate.
7. The system of claim 1 , wherein the heat exchange unit is a cassette.