Hemodynamic responses to recumbent positions in healthy adults (1073.1)

Abstract

The effect of lateral decubitus positions on the autonomic nervous system and circulatory regulation has not been well clarified in normal healthy adults. Our aim was to evaluate whether the left and right lateral decubitus positions affect heart rate variability (HRV), including hemodynamics, compared to the supine position. We non‐invasively measured blood pressure (BP), heart rate (HR), stroke index (SI), cardiac index (CI) and total peripheral resistance index (TPRI) in each posture in 10 nonsmoking healthy volunteers. After lying in the supine position, the subjects maintained each lateral decubitus position in random order for 10 min at an angle of about 45 degrees. The postural change was performed manually by two trained researchers. No significant differences were observed in mean BP, low frequency HRV, high frequency HRV, and their ratio. However, in the left lateral decubitus position, HR was significantly lower than in the supine position. In both lateral decubitus positions, SI and CI tended to decrease compared to the supine position, and an upward trend was noted for TPRI. The HRV results suggest that the both recumbent positions have no influence on the autonomic nervous system. The reduction in HR and SI in the left recumbent position may not be related to autonomic nervous activity.