Distensibility of digital blood vessels in cold environment

¹ Departments of Physiology and Medicine, University of Southern California School of Medicine, Los Angeles, California

To determine finger-tip vascular distensibility when all of the vessels are subjected to a uniform pressure, an appropriate plethysmograph is used to follow the increase after local venous occlusion. When the finger shows no further systematic increase in volume (volume B), an arterial occlusion is applied to the upper part of the arm. Blood will then flow from the high pressure parts of the vascular bed of the finger tip until the pressure level is related to the venous occlusion cuff pressure to give a new volume (C). Release of the venous occlusion cuff permits all of the blood vessels in the finger tip to come into equilibrium with the pressures in the vessels of the arm to give a measure of the volume (D) contained at the low pressure. The difference between volumes C and D represents the distention of the entire vascular bed of the finger tip for the pressure difference between the occlusion and the final static pressure level. When subjects are exposed to a cold environment, distensibility of the finger-tip vessels decreases, with evidence for involvement of both high- and low-pressure vessels.

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