Noninvasive determination of small vessel distensibility in man

The present study describes and illustrates a noninvasive method for computing extensibility of the 'resistance vessels', from an experimentally obtained resistance vs transmural pressure plot, in a maximally dilated vascular bed of man. Limb blood flow was measured plethysmographically following 10 min of arterial occlusion, and blood pressure was measured by the arm cuff method. A ratio of two resistance values taken 30 mm Hg apart was used to compute percent change in radius and the extensibility, E. The computed values of E were 0.71 mm Hg-1 for normal hand and 0.13, 0.22 and 0.69 for the hypertensive forearm, hand and finger respectively. These results indicate that the method may prove useful in the understanding and management of diseases such as hypertension or other small vessel diseases.