Determination of lower leg blood flow in man by thermodilution

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Abstract
A thermodilution method for measuring distal femoral vein flow in man is presented. The catheter is introduced percutaneously in central direction into the popliteal vein. Tests for accuracy in vitro (r = 0.999, range of true flow 63–2600 ml/min) and in dog experiments (r = 0.994, range of electromagnetic flow measurements 110–780 ml/min) are presented and discussed in relation to the anatomical (dissections on corpses) and functional conditions in the popliteal/distal femoral vein of man. A group of normal persons [7] and of patients suffering from ischaemic lower limb disease [17] were studied at rest and during exercise on an ergometer in supine and sitting positions. In all but two, reliable measurements were obtained. In the normals, a mean resting flow of 114 ml/min (range 82–140 ml/min) was found. The individual coefficient of correlation between load and flow measurements in the normals varied from 0.80 to 0.94 during stepwise increasing load exercise. No serious complications occurred. The method causes little discomfort for the subjects. Venous samples from the working leg and recording of deep venous pressure can be obtained in connection with the flow measurements. Provided the superficial venous flow is halted (compression bandage around the knee), the distal femoral vein flow closely reflects the total arterial blood flow into the lower leg. The great number of rapidly successive determinations thus makes a nearly continuous recording of lower leg blood flow possible for long periods irrespective of leg position and working condition.