1. A dye-dilution method has been developed for the determination of leg blood flow in man. The method is based on the infusion of indicator into the distal part of the femoral vein with blood sampling from the same vein at the level of the inguinal ligament. Catheterization of the femoral artery is not required. Evidence of adequate mixing of dye and blood is presented, based on the finding of the same dye concentration in samples from two different levels in the femoral vein.
2. Leg blood flow measured by this technique at rest and during exercise in six healthy subjects was found to agree closely with simultaneous determinations with an intra-arterial indicator-dilution technique. The reproducibility of the blood-flow measurements, expressed as the coefficient of variation for a single determination, was 9·8%.
3. A routine procedure is suggested for leg blood-flow determination based on femoral venous dye infusion. Using this procedure, leg blood flow was measured in twelve healthy subjects at rest and during exercise at work loads of 100, 200, 400 and 600 kpm/min. A linear relationship was found between leg blood flow and pulmonary oxygen uptake.
4. The applicability of this method to the study of patients with occlusive arterial disease of the leg is illustrated by findings in two patients before and after vascular reconstruction.