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US 6,805,672 B2Granted
Blood flow monitor for shock and resuscitation
AssigneeThermal Technologies, Inc.
InventorsGregory T. Martin, Harry Frederick Bowman
Life of this patent
Estimating the term…
Abstract
A shock monitor comprising one or more probes, for measuring physiological conditions indicative of shock, and a controller for calculating blood flow values, as an indicator of the state-of-shock, is disclosed. The probe is used to introduce an input signal and produces an output signal, which represents the state-of-shock of the tissue in communication with the probe. The output signal is used to calculate a blood flow value.
Claims20
A system for monitoring shock comprising:
- means for supplying heat to tissue in which blood flow typically decreases during shock;
- means for cyclically energizing and deenergizing said heat supplying means;
- means for sensing in the tissue a thermal response functionally related to the perfusion of blood in the tissue during said energizing and deenergizing cycles;
- and
- means for calculating a value indicative of shock as a function of thermal responses sensed over more than one energizing and deenergizing cycle.
2 more elements
A shock monitor comprising:
- a thermistor for thermal contact with tissue at a site where blood flow typically decreases during shock;
- means for electrically energizing and deenergizing said thermistor to cyclically elevate the temperature of said thermistor above the baseline temperature of tissue at said site;
- means for producing over several temperature cycles an electrical signal the value of which is functionally related to the electrical energy supplied to said thermistor and the rate at which heat from said thermistor is transferred in said tissue;
- and
- means for producing a signal indicative of shock as a function of said electrical signal.
2 more elements
A shock monitor comprising:
- thermistor means for thermally contacting living tissue at a site on the inner wall of the rectum;
- means for electrically energizing and deenergizing said thermistor means cyclically to cause the temperature of said tissue to rise and fall cyclically;
- means for producing a signal functionally related to the power used to energize said thermistor during each energizing and deenergizing cycle;
- means responsive to the temperature change in said tissue and the power related signal from said producing means for producing a signal during each energizing and deenergizing cycle as a function of perfusion in said tissue;
- and
- means for computing a value for blood flow in said tissue indicative of shock during each energizing and deenergizing cycle as a function of the perfusion related signal.
3 more elements
A system for producing a signal indicative of shock comprising:
- a thermistor for contacting the inner wall of the rectum to establish thermal contact with tissue at a site in the inner wall of the rectum;
- control means for electrically energizing and deenergizing said thermistor cyclically to cause the temperature of said thermistor to cyclically rise and fall, the rate of temperature rise in an initial time period within each energizing and deenergizing cycle being substantially a function of the intrinsic thermal conductivity of tissue in thermal contact with said thermistor;
- means for producing a signal functionally related to the power used to energize said thermistor during each energizing and deenergizing cycle;
- and
- iterative calculating means for:
- calculating intrinsic thermal conductivity in the initial time interval during each energizing and deenergizing cycle as a function of the temperature rise in the initial time interval and the power related signal produced by said producing means;
- calculating perfusion in a subsequent time interval during each energizing and deenergizing cycle as a function of the calculated value of intrinsic thermal conductivity;
- recalculating intrinsic thermal conductivity in the first time interval using the calculated value of perfusion;
- recalculating perfusion in the subsequent time interval using the recalculated value of intrinsic thermal conductivity;
- and
- recalculating values for intrinsic thermal conductivity and perfusion, in alternating fashion, until the recalculated values of perfusion converge to a substantially unchanging value, using in each recalculation of perfusion the previously recalculated value of intrinsic thermal conductivity and in each recalculation of intrinsic thermal conductivity the previously recalculated value of perfusion.
8 more elements
A method of monitoring shock in a living subject comprising the steps of:
- supplying heat to tissue in the inner wall of the rectum so as to cause the temperature of the tissue to cyclically rise and fall;
- sensing in the tissue a thermal response functionally related to the perfusion of blood in the tissue over several temperature cycles;
- and
- calculating a blood flow value indicative of shock as a function said thermal response over more than one temperature cycle.
1 more element
A method of monitoring shock comprising the steps of:
- contacting tissue in which blood flow typically decreaces during shock with electrically energizable thermistor means to establish a heat transfer path between said thermistor means and said tissue;
- energizing and deenergizing said thermistor means to cyclically elevate the temperature of said thermistor means above the baseline temperature of said tissue;
- sensing the thermal response in said tissue to the application of heat from said thermistor means over several temperature cycles;
- and
- calculating a blood flow value indicative of shock as a function of the thermal response in said tissue sensed in said sensing step over more than one temperature cycle.
2 more elements
A method of monitoring shock comprising the steps of:
- contacting the inner wall of the rectum with electrically energizable thermistor means to establish a heat transfer path between said thermistor means and tissue at a site along the inner wall of the rectum;
- energizing said thermistor means to elevate the temperature of said thermistor means above the baseline temperature of said tissue;
- sensing the thermal response in said tissue to the application of heat from said thermistor means;
- calculating intrinsic thermal conductivity in a first time interval during said energizing step;
- calculating perfusion in a subsequent time interval during said energizing step using the calculated value of intrinsic thermal conductivity;
- recalculating values for intrinsic thermal conductivity and perfusion in alternating fashion, until the recalculated values of perfusion converge to a substantially unchanging value, using in each recalculation of perfusion the previously calculated value of intrinsic thermal conductivity and in each recalculation of intrinsic thermal conductivity the previously calculated value of perfusion;
- and
- calculating a blood flow value indicative of shock as a function of the converged value of perfusion.
5 more elements
A method of monitoring shock comprising the steps of:
- contacting the inner wall of the rectum with a thermistor to establish a thermal transfer path with tissue at a site in the inner wall of the rectum;
- electrically energizing and deenergizing said thermistor cyclically to cause the temperature of tissue in thermal contact with said thermistor to cyclically rise and fall, the rate of temperature rise in an initial time period within each energizing and deenergizing cycle being substantially a function of the intrinsic thermal conductivity of tissue in thermal contact with said thermistor;
- producing a signal functionally related to the power used to energize said thermistor during each energizing and deenergizing cycle;
- calculating intrinsic thermal conductivity of tissue at said site in an initial time interval during each energizing and deenergizing cycle as a function of the temperature rise and said power related signal in the energizing and deenergizing cycle;
- calculating perfusion in a subsequent time interval during each energizing and deenergizing cycle as a function of the calculated value of intrinsic thermal conductivity;
- recalculating intrinsic thermal conductivity in said first time interval using the calculated value of perfusion;
- recalculating perfusion in said subsequent time interval using the recalculated value of intrinsic thermal conductivity;
- recalculating values for intrinsic thermal conductivity and perfusion, in alternating fashion, until the recalculated values of perfusion converge to a substantially unchanging value, using in each recalculation of perfusion the previously recalculated value of intrinsic thermal conductivity and in each recalculation of intrinsic thermal conductivity the previously recalculated value of perfusion;
- and
- processing said substantially unchanging perfusion value during each energizing and deenergizing cycle to provide a blood flow signal indicative of shock.
7 more elements
A system for producing a signal indicative of shock comprising:
- thermistor means for thermally contacting living tissue at a site on the inner wall of the rectum;
- means for electrically energizing and deenergizing said thermistor means cyclically to cause the temperature of said tissue to rise and fall cyclically;
- means for producing a signal functionally related to the power used to energize said thermistor during each energizing and deenergizing cycle;
- and
- means responsive to the power related signal from said producing means for producing a signal, functionally related to blood flow and indicative of shock, during each energizing and deenergizing cycle as a function of perfusion in said tissue.
2 more elements
Dependencies are inferred from the claim text.