Relationship between the radioisotope test using 131I-labelled serum albumin and plethysmographic blood flow measurements in the study of the circulation in the foot.

A radioisotope test using 131I-labelled serum albumin and venous occlusion plethysmography were performed simultaneously on the feet of normal individuals and patients with peripheral arterial disease during a period of reactive hyperemia. The radioisotope test includes a circulation time and a build-up curve reflecting a local clearance process which is characterized by the parameter M/2 -- delay. Between the parameter M/2 -- delay of the radioisotope test and the blood flow measured by the plethysmograph, the power relationship was found to be: M/2 -- delay = 74.01 F-0.74 with r = 0.69. The experimental data show that the plethysmographic blood flow measurement is an accurate method for the assessment of the peripheral circulation in normal individuals but is less suitable in patients with peripheral arterial disease. The radioisotope test appears to be more valuable than the plethysmographic blood flow measurement for the differentiation of normal individuals from patients with peripheral arterial disease and for the evaluation of the grade of ischemia.