Assessment of regional blood flow and specific microvascular resistance in the foot by means of the transient thermal clearance method.

Measurements of skin blood flow have been made in a group of 34 patients presenting with symptoms of peripheral vascular disease. Of the patients, 18 were non-diabetic and the remainder diabetic. Measurements of blood flow were made using the transient thermal clearance method, and of systolic blood pressure in the dorsalis pedis artery using a CW ultrasonic Doppler blood velocimeter and an occluding cuff. There was no difference in pressure index between the two groups. Neither a linear pressure/flow relationship nor the presence of autoregulation was demonstrated. The derivation of specific vascular resistance (SVR) for the two groups shows that in the diabetic it was 7.07 +/- 2.2, while in the non-diabetic it was 11.12 +/- 3.9. The difference is significant (P less than 0.005) and suggests that measurement of SVR may be useful in the differential diagnosis of vascular disease.