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System and method for controlling the temperature of a catheter-mounted heater

  • US 5,553,622 A
  • Filed: 11/04/1994
  • Issued: 09/10/1996
  • Est. Priority Date: 01/29/1991
  • Status: Expired due to Term
First Claim
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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:

  • 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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