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Thermal method and apparatus for measuring organ blood perfusion

  • US 4,739,771 A
  • Filed: 02/20/1986
  • Issued: 04/26/1988
  • Est. Priority Date: 02/20/1986
  • Status: Expired due to Term
First Claim
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1. Apparatus for measuring the true value of local tissue blood flow at a first location in an organ tissue wherein the first location resides outside of the interior of any blood vessels and wherein the organ tissue surrounding and located in close proximity to the first location defines a region of adjacent organ tissue, said apparatus comprising:

  • a. heat transfer means positionable at the first location and including means for maintaining said heat transfer means fixed at the first location for converting a flow of electrical current into heat energy and for transferring the heat energy into the adjacent organ tissue;

    b. control means electrically coupled to said heat transfer means for operating said heat transfer means in a non-self-heating mode to measure the ambient temperature of the adjacent organ tissue and for operating said heat transfer means in a self-heating mode to establish a temperature gradient between said heat transfer means and the adjacent organ tissue to transfer heat energy into the adjacent organ tissue;

    c. means coupled to said control means for measuring the heat energy transferred from said heat transfer means into the adjacent organ tissue, for computing the total conductivity of the adjacent organ tissue, and for generating a total conductivity readout;

    d. means for periodically injecting a predetermined volume of a calibration fluid into a blood vessel in fluid communication with but spaced apart from the adjacent organ tissue;

    e. calibration means for converting the total conductivity readout into a true local tissue blood flow readout or displacing said heat transfer means from the first location, said calibration means includingi. recording means for recording the changes in the total conductivity readout caused by the passage of said calibration fluid by said heat transfer means;

    ii. means for plotting a conductivity washout curve based on the recorded changes in the total conductivity readout to derive a total conductivity to true local blood flow correction factor; and

    iii. means for receiving the total conductivity readout and the total conductivity to true local blood flow correction factor and for computing and displaying a true local tissue blood flow readout representative of the true value of the local tissue blood flow at the first location in the organ tissue;

    whereby the true local tissue blood flow readout may be displayed on a continuous basis to accurately quantify the local tissue blood flow at the first location on a real time basis.

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