title: Heat-washout: a new method for measuring cutaneous blood flow rate in areas with and without arteriovenous anastomoses.
abstract: A new method, the heat-washout method, for measuring total cutaneous blood flow rate is introduced. The measurements were performed with a transcutaneous (tc) PO2-electrode that is capable of heating and measuring local temperature, and it is constructed with a thermostatically controlled cap. The probe was heated electrically to a selected temperature 2-10 degrees above normal skin temperature. When the temperature was stable, the heating element was turned off, and the temperature was registered every 10 s until a stable baseline temperature, Tb, was obtained. Tb was subtracted from the registered temperatures giving deltaTs that were plotted in a semilogarithmic diagram. The heat-washout was monoexponential, and the slope was used for calculating blood flow rate in accordance with the principle of Kety, using a known partition coefficient. The method was applied to the forearm in two subjects, and the results were compared to blood flow rates obtained simultaneously by the 133Xe-washout method in the same area. The equation of the regression line was y = 2.5 + 0 x 968X and the correlation coefficient was 0 x 986 at temperature levels of 37-45 degrees C. In the pulp of the thumb, blood flow rates, in arteriovenous anastomoses, were estimated in two subjects by subtracting the capillary blood flow rate, measured by 133Xe-washout, from the total cutaneous blood flow rate, measured by heat-washout. Due to a relatively low diffusions coefficient for 133Xe compared to heat, 133Xe cannot be used for measurement of blood flow rate in arteriovenous anastomoses.
authors: Department of Medical Physiology, The Panum Institute, University of Copenhagen, Denmark.
authors: M
authors: M
authors: Midttun
authors: P
authors: P
authors: Sejrsen
authors: M
authors: M
authors: Colding-Jorgensen
mesh_terms: D000328:Adult; D001163:Arteriovenous Anastomosis / Q000502:physiology*; D001785:Blood Gas Monitoring, Transcutaneous; D004566:Electrodes; D005260:Female; D005385:Fingers / Q000098:blood supply; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D010992:Plethysmography, Impedance; D012039:Regional Blood Flow / Q000502:physiology; D012867:Skin / Q000098:blood supply*; D013696:Temperature; D014980:Xenon Radioisotopes
chemical_list: D014980:Xenon Radioisotopes