Digital Blood Flow and Distensibility During Immersion in Cold Water. ∗

Abstract

The decreased distensibility of fingers immersed in ice water has been ascribed to increased venomotor tone(l). However, Edwards and Burton(2) found that there is an increase in volume of fingers immersed in ice water and have suggested that reduction in distensibility may be due to increased venous filling. In an attempt to determine the interrelationships between finger volume, digital distensibility, blood flow and venous pressure, studies have been made at different local and environmental temperatures.

Methods. The experiments were performed on 2 subjects with bath temperatures (T_w) at 5, 9.5, 20 and 38.5†C and room temperature (T_r) of 12, 20 and 28†C. The subjects lay on a cot with the right hand placed in a 27 1 water tank. The tank was raised so that when the hand was in position the tips of the fingers were about 15 cm above heart level.

Changes in finger volume were determined by a mercury-in-rubber strain gauge (3,4) compensated for temperature changes (5). The strain gauge was applied to the tip of the middle finger and changes in circumference recorded on a Sanborn polygraph. A cuff wrapped around the root of the finger was intermittently inflated and the final increase in volume at each of 7 cuff pressures observed. Regression equations of change in volume on cuff pressures between 20-50 mm Hg were calculated by the method of least squares. The slopes of the regression lines were taken as indices of distensibility and the calculated cuff pressures at which no changes in finger volume would take place were taken as venous pressure. Blood flow was estimated by observing the rate of change in finger volume immediately after inflation of the cuff to 70 mm Hg.

Results. Distensibility was positively related to both T_w and T_r.