System and method for patient temperature control employing temperature projection algorithm
View Patent ↗Embodiments of the invention provide a system for temperature control of the human body. The system includes an indwelling catheter with a tip-mounted heat transfer element. The catheter is fluidically coupled to a console that provides a heated or cooled heat transfer working fluid to exchange heat with the heat transfer element, thereby heating or cooling blood. The heated or cooled blood then heats or cools the patient's body or a selected portion thereof. In particular, methods and devices, including software, are provided for administering cooling or rewarming and controlling the same based on a projected control temperature measured by a temperature sensor within the catheter.
1. A method of controlling the administration of a thermal therapy, comprising acts of:
inserting a catheter having a heat transfer element positioned at a distal tip of the catheter into a blood vessel of a patient, the catheter having a supply lumen for supplying a working fluid to the heat transfer element and a return lumen for returning a working fluid from the heat transfer element;
circulating a working fluid through the catheter and the heat transfer element, the working fluid having a temperature different from the patient temperature;
inserting a temperature sensor into an area in one of the supply lumen or the return lumen;
causing the working fluid to stop circulating at a time determined by a predictive algorithm;
receiving a signal from the temperature sensor at a time determined by the predictive algorithm while the circulating of the working fluid is stopped and prior to complete equilibration between the working fluid temperature and the patient temperature;
determining a control temperature based on the signal;
using the control temperature to control the temperature of the working fluid,
wherein the temperature sensor is selected from the group consisting of thermistors, thermocouples, and combinations thereof, and
further wherein the temperature sensor is two thermistors,
receiving a safety monitor signal from one of the two thermistors; and
causing the working fluid to stop circulating if a value of control temperature measured by the safety monitor signal falls outside a predetermined range.
2. The method of claim 1 , wherein the predetermined range is 31° C. to 37° C.
3. The method of claim 1 , comprising an act of attaching the sensor to one of the catheter or a guidewire prior to the act of inserting the temperature sensor.
4. The method of claim 1 , comprising an act of producing an estimate of power delivered or consumed by the heat transfer element using the predictive algorithm.
5. A catheter system having a heat transfer element at a distal end thereof for insertion into the vascular system of a patient for controlling or managing the temperature of the patient, the system comprising:
a catheter, the catheter having a heat transfer element mounted to a distal end thereof, the catheter having a supply lumen for transferring a working fluid to the heat transfer element and a return lumen for transferring a working fluid from the heat transfer element;
a source of working fluid, the source of working fluid having an outlet fluidically coupled to the supply lumen and an inlet fluidically coupled to the return lumen;
a control circuit to control the temperature of the working fluid using a predictive algorithm;
a remote temperature sensor disposed on or within a catheter within the patient, the remote temperature sensor coupled to the control circuit to provide a signal thereto at a time determined by the predictive algorithm while the source of the working fluid is stopped and prior to complete equilibration between a working fluid temperature and the patient temperature.
6. The system of claim 5 , wherein the sensor is attached to one of the catheter or a guidewire.
7. The system of claim 5 , wherein predictive algorithm produces an estimate of power delivered or consumed by the heat transfer element.