System and method for controlling the temperature of a catheter-mounted heater
First Claim
1. A system for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising:
- a core temperature monitor for monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of the thermodilution catheter;
a power source for supplying electric power to said thermodilution heater element;
a power monitor for monitoring an amount of the electric power that is supplied to said thermodilution heater element;
surface temperature calculating means, in communication with said core temperature monitor and said power monitor, for calculating the surface temperature;
condition determining means, in communication with said surface temperature calculating means, for determining when a potentially physiologically harmful temperature condition exists; and
control means, in communication with said core temperature monitor, said power monitor, said power source, and said condition determining means, for controlling the amount of the electric power that is supplied to said thermodilution heater element by said power source, to keep the surface temperature within safe physiological limits;
wherein said condition determining means comprises(i) means for detecting when the surface temperature exceeds a predetermined physiologically safe temperature limit, and(ii) time-temperature product determining means, for determining a time-temperature product of (1) time during which the surface temperature is above the predetermined physiologically safe temperature limit and (2) extent to which the surface temperature exceeds the predetermined physiologically safe temperature limit,(iii) a time based integrator for collecting and storing the time-temperature product; and
(iv) means, in communication with said time based integrator, for comparing the time-temperature product to a predetermined maximum time-temperature value; and
the system further comprising condition indicating means, in communication with said condition determining means, for indicating when the time-temperature product exceeds the predetermined maximum time-temperature value.
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Accused Products
Abstract
A system for keeping the surface temperature of an electric resistance-type heater element in a thermodilution catheter within safe physiological limits includes, in the preferred embodiment, a heater element core temperature monitor, a monitor for monitoring the power that is supplied to the heater element, and a surface temperature calculator for calculating the surface temperature of the heater element based on the core temperature, supplied power, and information representing the characteristics of the particular catheter under anticipated clinical conditions. A second aspect of the invention involves a system for determining the supply of power to the heater element based on the core temperature of the heater element. A third aspect of the invention involves is a system readiness test for determining, in vivo, that the thermodilution catheter system is properly calibrated before the system is operational. Methods of operation for each of the above-referenced aspects of the invention are also disclosed.
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Citations
23 Claims
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1. A system for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising:
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a core temperature monitor for monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of the thermodilution catheter; a power source for supplying electric power to said thermodilution heater element; a power monitor for monitoring an amount of the electric power that is supplied to said thermodilution heater element; surface temperature calculating means, in communication with said core temperature monitor and said power monitor, for calculating the surface temperature; condition determining means, in communication with said surface temperature calculating means, for determining when a potentially physiologically harmful temperature condition exists; and control means, in communication with said core temperature monitor, said power monitor, said power source, and said condition determining means, for controlling the amount of the electric power that is supplied to said thermodilution heater element by said power source, to keep the surface temperature within safe physiological limits; wherein said condition determining means comprises (i) means for detecting when the surface temperature exceeds a predetermined physiologically safe temperature limit, and (ii) time-temperature product determining means, for determining a time-temperature product of (1) time during which the surface temperature is above the predetermined physiologically safe temperature limit and (2) extent to which the surface temperature exceeds the predetermined physiologically safe temperature limit, (iii) a time based integrator for collecting and storing the time-temperature product; and (iv) means, in communication with said time based integrator, for comparing the time-temperature product to a predetermined maximum time-temperature value; and the system further comprising condition indicating means, in communication with said condition determining means, for indicating when the time-temperature product exceeds the predetermined maximum time-temperature value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A system for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising:
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a core temperature monitor for monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of said thermodilution catheter; a power source for supplying electric power to said thermodilution heater element; a power monitor for monitoring the amount of electric power that is supplied to said thermodilution heater element; and control means, in communication with said core temperature monitor and with said power monitor, for controlling the amount of the electric power that is supplied to said thermodilution heater element by said power source to maintain the surface temperature within safe physiological limits; wherein said power source comprises means for supplying power at, electively, either a first fixed power level or a second fixed power level which is greater than the first fixed power level; and said control means controls whether said power source supplies power at the first fixed power level or the second fixed power level. - View Dependent Claims (15, 16)
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17. A method for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising the steps of:
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(a) monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of said thermodilution catheter; (b) supplying electric power to said thermodilution heater element; (c) monitoring the amount of electric power that is supplied to said thermodilution heater element; (d) calculating the surface temperature, based at least in part on the core temperature and the amount of the electric power that is supplied to the thermodilution heater element; (e) determining, based at least in part on the surface temperature, whether a potentially physiologically harmful temperature condition exists; and (f) controlling the amount of the electric power that is supplied to said thermodilution heater element to keep the surface temperature within safe physiological limits; wherein step (e) comprises the steps of; (i) collecting and storing a time-temperature integration product based on the extent to which surface temperature exceeds a predetermined safe temperature limit; and (ii) comparing the time-temperature product to a predetermined maximum time-temperature value. - View Dependent Claims (18, 19, 20)
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21. A method for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising:
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(a) monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of said thermodilution catheter; (b) supplying electric power to said thermodilution heater element; (c) monitoring an amount of the electric power that is supplied to said thermodilution heater element by said power source, (d) controlling the amount of the electric power that is supplied to said thermodilution heater element based on the core temperature so that the surface temperature is kept within safe physiological limits; wherein step (d) is performed by alternating the amount of the electrical power that is supplied to said thermodilution heater element between a first fixed power level and a second fixed power level which is greater than the first fixed power level.
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22. A method for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising:
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(a) monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of said thermodilution catheter; (b) supplying electric power to said thermodilution heater element; (c) monitoring an amount of the electric power that is supplied to said thermodilution heater element; (d) controlling the amount of the electric power that is supplied to said thermodilution heater element based on the core temperature so that the surface temperature is kept within safe physiological limits; wherein step (d) is further performed by; (i) when the electric power is being supplied at a first power level, increasing the electric power to second power level when the core temperature is equal to or less than a first predetermined temperature value; and (ii) when the electric power is being supplied at the second power level, decreasing the electric power to the first power level when the core temperature is equal to or greater than a second predetermined temperature value; and (iii) wherein the first predetermined temperature value is less than the second predetermined temperature value.
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23. A system for keeping a surface temperature of a blood contacting surface of a thermodilution catheter within safe physiological limits, comprising:
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a core temperature monitor for monitoring a core temperature of a core of an electric resistance-type thermodilution heater element of the thermodilution catheter; a power source for supplying electric power to said thermodilution heater element; a power monitor for monitoring an amount of the electric power that is supplied to said thermodilution heater element; surface temperature calculating means, in communication with said core temperature monitor and said power monitor, for calculating the surface temperature; condition determining means, in communication with said surface temperature calculating means, for determining when a potentially physiologically harmful temperature condition exists; control means, in communication with said core temperature monitors, said power monitor, said power source, and said condition determining means, for controlling the amount of the electric power that is supplied to said thermodilution heater element by said power source, to keep the surface temperature within safe physiological limits;
wherein said condition determining means comprises means for determining when the surface temperature exceeds a predetermined physiologically safe temperature limit; andfurther comprising means, in communication with said determining means, for warning an operator to check the position of said thermodilution catheter when the surface temperature exceeds the predetermined safe physiological temperature limit.
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Specification