Method and system for control of a patient's body temperature by way of a trasluminally insertable heat exchange catheter

Abstract

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 . (canceled) 
     
     
         2 . A system for controlling the rate of change of a patient's body temperature, 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;   a pump configured to pump a heat transfer fluid through a fluid circuit defined by the heat transfer catheter and the heat exchange unit;   a pump motor configured to engage the pump;   a sensor for sensing a pressure of the heat exchange fluid in the fluid circuit, the sensor also configured to provide a signal representative of the sensed pressure;   a controller in communication with the-sensor to receive the signal representative of the sensed pressure in the fluid circuit, and configured to control a speed of the pump motor in accordance with the sensed pressure so as to maintain the pressure of the fluid circuit at a selected pressure.   
     
     
         3 . The system of  claim 2 , wherein the heat exchanger transfer catheter and the heat exchange unit are connected with fluid conduits and define a fluid circulation path. 
     
     
         4 . The system of  claim 2 , further comprising a sensor for directly or indirectly sensing a temperature of the circulating fluid. 
     
     
         5 . The system of  claim 4 , wherein the controller is further configured to compare a target temperature and the temperature of the circulating fluid and to use the comparison to adjust the temperature of the circulating fluid. 
     
     
         6 . The system of  claim 2 , wherein the controller includes a microprocessor. 
     
     
         7 . The system of  claim 2 , further comprising an input for inputting a selected ramp rate. 
     
     
         8 . The system of  claim 2 , wherein the heat exchange unit is a cassette. 
     
     
         9 . The system of  claim 2 , wherein the heat exchange unit includes the pump; and
 further comprising a housing configured to removably receive the heat exchange unit, the housing including the pump motor, the pump motor and pump configured to engage when the heat exchange unit is received by the housing.   
     
     
         10 . The system of  claim 2 , wherein the pressure being sensed in the fluid circuit is a back pressure. 
     
     
         11 . 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;   a pump configured to pump a heat transfer fluid through a fluid circuit defined by the heat transfer catheter and the heat exchange unit;   a sensor for sensing an amount of electric current being supplied to a pump motor when the pump motor is driving the pump to circulate heat exchange fluid through the fluid circuit, the sensor also configured to provide a signal representative of the sensed current; and   a controller in communication with the sensor and the pump motor, and configured to receive the signal representative of the current being supplied to the pump motor, and configured to control the speed of the pump motor to provide a desired torque value.   
     
     
         12 . The system of  claim 12 , wherein the torque value is proportional to the current supplied to the motor. 
     
     
         13 . The system of  claim 12 , wherein the controller is configured to control the speed of the pump motor to provide a desired torque value, wherein the torque value is proportional to a pressure in the fluid circuit. 
     
     
         14 . The system of  claim 13 , wherein the controller is configured to determine a pressure value from the sensed current and to compare the determined pressure value to a desired value, and alter the amount of electric current being supplied to the electric motor to increase or decrease the speed of the electric motor to increase or decrease the determined pressure of the heat transfer fluid in the fluid circuit. 
     
     
         15 . The system of  claim 11 , wherein the heat exchange unit includes the pump; and further comprising a housing configured to removably receive the heat exchange unit, the housing including the pump motor, the pump motor and pump configured to engage when the heat exchange unit is received by the housing.