Effect of supine versus sitting position on noninvasive assessment of aortic pressure waveform: a randomized cross-over study

Abstract

Biomarkers derived noninvasively from the aortic blood pressure (BP) waveform provide information regarding cardiovascular (CV) risk independently of brachial BP (bBP). Although body position has significant impact on the assessment of bBP, its effect on aortic hemodynamics remains unknown. This study investigated the changes in both brachial and aortic hemodynamics, between the supine and sitting position. In this randomized cross-over study, the bBP and the aortic pressure waveform were assessed after a 5 min rest (sitting and supine in randomized order); aortic BP, pulse pressure (PP) amplification, augmentation index (AIx) and subendocardial viability index (SEVR) were assessed. Sixty-one subjects were examined (36 males, mean age 50±12 years). Mean BP did not differ between the sitting and supine position (110.8±13.7 vs 110.9±14.9, respectively, P=0.945). However, significant difference between the sitting and supine position in brachial PP (45.9±16.0 vs 52.6±15.6, respectively, P<0.001), aortic PP (36.7±15.2 vs 43.1±13.9, P<0.001), PP amplification (1.28±0.1 vs 1.23±0.1, P<0.001), AIx (26.9±11.9 vs 31.1±10.2, P<0.001) and SEVR (179.6±25.7 vs 161.2±25.8, P<0.001) were found. Review of the literature identified underestimation of the role of body position on aortic hemodynamics. In conclusion, increased PP in both the aorta and brachial artery were found in the supine compared to the sitting position. Reduced PP amplification and SEVR were further observed in the supine position, due to increased pressure wave reflections (AIx).

Effects of gravity-induced upper-limb blood pressure changes on wave transmission and arterial radial waveform

“…Currently, both seated (with the wrist often below the heart level) and supine postures are accepted for radial waveform assessment, often providing different results [22,23], and especially when associated systemic hemodynamic changes are detected [24,25]. Our data are in keeping with the findings by Vrachatis et al [26], who reported that changes in distending pressure were responsible for the differences in HR-adjusted AIx and PP amplification between the seated and the supine position. This issue is of particular relevance in light of the recent commercial availability of devices enabling 24-h noninvasive central BP assessment, based on brachial or radial sensors for waveform assessment [27].…”

Assessing cerebrovascular autoregulation from critical closing pressure and resistance area product during upright posture in aging and hypertension

“…Unlike the systolic peak of the arterial pulse, mean and diastolic pressures are relatively stable between the aorta and resistance arterioles (31). In addition, the use of peripheral PP to reflect changes in cerebral PP is supported by the observation of a strong correlation between posture-related changes in peripheral and central PP (50).…”

“…Several observations point to a need to examine within-beat pulsatile characteristics. Importantly, posture-related shifts in pulse pressure (PP) have been shown to be a function of changes in systolic and diastolic pressures, independent of mean pressure (50). Despite similar posture-induced changes in mean pressure, PP is reduced in young adults and maintained in older adults during standing (29).…”

Optimization of Simple Sphygmomanometric Blood Pressure Measurement in Routine Prenatal Care

“…Applied on our study, based on AUC's, we noticed a slightly better predictive outcome with standing blood pressures instead of supine blood pressures. There is however some inconsistency concerning the influence of position on the blood pressure: lower supine blood pressures are reported as compared to sitting [1,28,29], but also higher values have been observed [30] as well as no differences at all [31,32]. These conflicting results may relate to different populations or other methods of measurement.…”