Studies of human peripheral blood flow: the effect of injection volume on the intramuscular radiosodium clearance rate. Circulation. 8

The effects of changes in injection volume on the intramuscular ra(liosodiumii clearance rate was investigated in six normal young men. The clearance rate was found to be quite sensitive to the volume of solution injected, and an increase in the rate of clearance corresponding to a dlecrease in volume was uniformly noted. Rigid control of the injection volume is necessary Allen this method is used for regional blood flow measurements. T HE development of practical methods of measuring regional blood flow has been the aim of a number of investi-gators, particularly since the use of isotopic tracer technics has become more widespread. The work in this field has been ably reviewed by Wright ' and by M~cGirr.2 In1 general, the approaches to a study of peripheral and/or regional blood flow have taken two principal pathways. The first general method consists of the measurement of the build-up of activity at a given site following the intravenous injection of a radio-isotope. Smith and Quimby3 have pioneered this method, employing sodium24 as the isotope, and have used it extensively in the study of peripheral vascular disorders. Others,4 5 however, have questioned the sensi-tivity of the method. From our ownII observa-tions, this lack of sensitivity may be due in part to the complications caused by the distributive events occurring elsewhere in the body after intravenous injection of radio-sodium.24 The second principal method of approach in the study of regional blood flow consists of the measurement of the rate of disappearance of a radioisotope following its local injection, as From the Ilepartment of Physiology and th