Patent ID: 8454525

Claim:
Apparatus for determining the perfusion of blood in living tissue comprising: means in thermal contact with tissue in a capillary bed for sensing the reference temperature of the capillary bed when the capillary bed is unheated; means in thermal contact with the capillary bed for heating the capillary bed; means for applying power to said heating means sufficiently rapidly to raise the temperature of said heating means to a temperature above said reference temperature so that the power necessary to maintain said heating means temperature varies as a function of time; means for determining the temperature difference between said heating means temperature and said reference temperature, means for determining the resistance of said heating means at said heating means temperature and means for determining the time varying relationship between the power required to maintain said heating means at said heating means temperature after said temperature has been reached and the time during which said power is being applied thereto; a data processor responsive to said temperature difference, said heating means resistance and said time varying power and time relationship for determining a perfusion related value; and means for evaluating conditions that affect the reference temperature of the capillary bed and recognizing conditions under which the reference temperature is no longer valid; and means for providing an output in response to said evaluating and recognizing means.