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Hand‐Wrist Vascular Compliance as Assessed by Volume Changes with Gravity

Vascular compliance is a measure of an elastic deformation and is measured by altered volume and pressure. Our goal was to provide a simple method to examine age and gender effects on vascular compliance. Hand‐wrist volume was measured with 3% alcohol in distilled water (more accurate due to the decrease in surface tension) during two randomized conditions: 1) arm lowered for 5 min to allow for normal local pressure and volume, and 2) arm raised for 5 min to reduce local pressure and to induce a blood volume shift out of the elevated limb. Blood flow was occluded by an arm cuff to prevent arterial and venous flow. Percent differences in volume between the two experimental conditions were compared and significance was set at p<0.05. All subjects showed higher volume of displaced blood in the arm‐lowered position (463.34±13.60 ml) than that in the arm‐raised position (447.74±13.48 ml) (p<0.001). Percent difference in hand‐wrist volume in the young group (8 males and 8 females) was significantly greater (4.11±0.61%) than in the old group (2.85±0.61%) (9 males and 10 females) (p=0.017), but no statistically significant difference was found in gender comparison (p=0.062). Thus, hand volumetry is a quick, simple and potentially‐valuable method to measure blood volume shifts in the hand and wrist with gravity, and it can provide clinical information about cardiovascular risk in aged populations. Supported by NASA grant NNJ04HF71G.