Limb Position Influences Peripheral Arterial Stiffness Reduction with Reactive Hyperemia

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Reactive hyperemia can acutely reduce peripheral arterial stiffness. The reduction in peripheral arterial stiffness with reactive hyperemia has been suggested to be flow dependent. However, no previous studies have manipulated the magnitude of hyperemia. We manipulated blood flow by altering limb position to test the hypothesis that a larger increase in blood flow would lead to a greater reduction in peripheral arterial stiffness. Fourteen healthy young adults (5 women; age: 25 ± 5 years; mean ± SD) were included in this study. Peripheral arterial stiffness assessed via brachial to radial pulse wave velocity (PWV) was measured by placing pulse tonometers simultaneously over the brachial and radial arteries. Doppler ultrasound was used to measure brachial arterial blood flow. Arterial blood pressure was continuously monitored via photoplethysmography on the middle finger of the contralateral hand. Reactive hyperemia was performed with the right arm positioned below (≍50°) and above (≍50°) heart level using a rapid-release cuff positioned on the upper arm, inflated to 220 mmHg, sustained for 5 min, then released. Measurements were recorded before cuff inflation and at 5, 15, and 30 min after cuff release. Repeated measures ANOVA revealed a significant condition effect (p<0.01) with peripheral PWV higher with the arm below the heart. There was a significant time x condition interaction (p<.05). At 5-min after reactive hyperemia, peripheral PWV was reduced more with the arm below the heart (9.58 ±1.65 to 7.26 ± 1.51 m/sec) than above the heart (7.08 ± 1.79 to 5.88 ± 1.43 m/sec). Mean arterial pressure did not change across time points (p>0.05). Peak brachial artery blood flow was greater with the arm below the heart (477.37 ± 145 vs 368.64 ± 137 ml/min; p<.001). The results show that reactive hyperemia produces an acute reduction in brachial to radial PWV. The reduction in peripheral arterial stiffness was greater when the arm was below the heart. The mechanism for position-related differences in the reduction in peripheral arterial stiffness with reactive hyperemia may be associated with the magnitude of increase in blood flow. REJ was supported by National Heart, Lung, and Blood Institute (5T32HL134634-04). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

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