Effects of body positions on arterial stiffness as assessed by pulse wave velocity.

ABSTRACT

BACKGROUND: Assessing arterial stiffness through pulse wave velocity (PWV) usually requires participants to be in a supine position. If this position is not feasible, adjustments such as tilting the bed or bending the knees may be made. The Vicorder device also recommends tilting the upper body to prevent jugular vein interference in the recorded carotid pulse. OBJECTIVE: To examine the impact of varying body positions on PWV. METHODS: Seventy adults were studied in the fully supine (0°) to 40° upper body tilted-up positions with and without knee bend. Carotid-femoral PWV (cfPWV) was measured using two different testing devices (Omron VP-1000plus and Vicorder) and brachial-ankle PWV (baPWV) was measured using Omron. RESULTS: cfPWV measured at 10° tilt-up was not different from 0° position while baPWV increased significantly from 10°. Elevations in cfPWV were 7% at 20° and 15% at 40° compared with 0° position. Knee bend did not affect cfPWV but decreased baPWV at each angle ( P  < 0.05). Jugular vein interference on the Vicorder was observed in 78% of participants in supine position, decreasing as body angle increased (7% at 30°). However, cfPWV values measured by Vicorder were consistent with those obtained by Omron even with jugular vein interference. CONCLUSION: Arterial stiffness assessed by PWV increased gradually and significantly in semi-Fowler's position ≥20°. Knee bend decreased baPWV but did not seem to affect cfPWV. PWV should be measured in supine position if possible. If the supine posture is not tolerated, knee bend followed by a slight incline position may be recommended.