Faster procedure for deriving regional blood flow by the noninvasive transient thermal clearance method.

The noninvasive transient clearance method provides absolute quantitative measurement of skin blood flow. It is based on thermally insulating the skin under investigation and measuring the time constant of the resultant exponential skin temperature increase. Conventional assessment of the time constant, by measuring the temperature increase until final equilibrium skin temperature is achieved, has the disadvantage of long time of measurement. A procedure shortening the measurement time is presented. The time constant of the exponential temperature increase is calculated without obtaining the final equilibrium temperature. The method can be used for calculating the time constant of an exponential change of any variable, even though the asymptotic value of that variable is not known.