Measurement of blood flow in minute volumes of specific tissues in man

¹ Department of Medicine, The Ohio State University, Columbus, Ohio

The theory, instrumentation and technique of a thermal method for measuring the blood flow in a small volume of tissue is described. With present instrumentation the volume sampled is about 4 or 5 mm³. The technique has been applied to the relation between tissue temperature and skin blood flow in the calf of the leg. In 25 observations on 3 subjects, values ranging from 1.3 to 82 x 10^–4 gm of blood per gm of tissue per second have been obtained. An extension of the technique has led to the measurement of the temperature coefficient of flow, (1/F)(F/T), when flow is influenced by very local temperature changes. A mean value of +39%/°C with a range of –57% to +81%/°C was found. Periodic fluctuations in tissue temperatures of the frequencies of the heart beat and respiration are described.