Beat-to-Beat Blood Pressure Variations While Standing are Associated with Postural Changes in Blood Pressure

Abstract

While blood pressure variability (BPV) and orthostatic hypotension (OH) are independently related to an increase in prevalence of cardiovascular disease, the relationship between BPV and OH remains poorly understood. We evaluated the association between postural changes in blood pressure with beat-to-beat BPV during supine rest and standing. Continuous beat-to-beat blood pressure recordings were obtained from 832 individuals, aged 55 years and above, during ten minutes’ supine rest and three minutes’ standing. The maximal drop in systolic blood pressure (?SBP) and diastolic blood pressure (?DBP) with standing from the supine position, BPV in the supine and standing positions and standing to lying BPV ratio were computed. Standing systolic BPV and SLR for systolic BPV were correlated significantly with ?SBP (r=0.497, p=<0.001; r=0.476, p=<0.001). Standing diastolic BPV and SLR of diastolic BPV showed a moderate correlation ?DBP (r=0.397, p=<0.001; r=0.432, p=<0.001). Standing BPV and SLR for BPV were significantly higher for subjects with documented OH. Standing systolic BPV, height, weight and age were accounted 27% of the variability in ?SBP while the SLR of diastolic BPV accounted for 19% of the variability in ?DBP. The SLR for diastolic BPV, body weight, and cerebrovascular disease were independent predictors for OH (R²=0.157). The significance of beat-to-beat BPV remains unclear. Our study suggests that supine and erect BPV are influenced by different mechanisms. The impaired compensatory mechanism leading to OH, which are sympathetic hyporesponsiveness, are also associated with increased BPV while standing.