Measurement of Muscle Blood Flow in the Human Forearm with Radioactive Krypton and Xenon

Abstract

Blood flow to forearm muscle in man was estimated by external monitoring of the rate of disappearance of radio-activity from the injection site following intramuscular injection of aqueous solutions of Krypton-85 and Xenon-133. Kr-85 clearance was markedly diminished by arterial occlusion and venous occlusion, while reactive hyperemia transiently increased the rate of clearance. The technique was atraumatic to the patient and yielded flow data similar to those of the indicator dilution method without the necessity of intra-arterial injections and multiple blood sampling. When measured simultaneously, Kr-85 clearance was consistently slower than both Xe-133 and Na-24. An important difference between Na-24, Kr-85, and Xe-133 is their relative solubility in fat, the last being the most soluble. The differences between the clearance rates of Kr-85 and Xe-133 can be attributed to the greater solubility of Xe-133 in blood relative to skeletal muscle. Differences in clearance rates of both Kr-85 and Xe-133 result from the relative proportions of lipid and water in a given individual.