Estimation of central aortic blood pressure: a systematic meta-analysis of available techniques

Central aortic blood pressure (cBP) is often promoted to be a superior predictor of cardiovascular risk compared to brachial blood pressure, and brachial-central pulse pressure amplification is also suggested as prognostic. Several devices and techniques, each purporting to estimate cBP, have entered commercial use. The interchangeability of cBP measurements between devices and the influence of disease states on central to brachial pulse pressure amplification remain unclear. The useful measurement of cBP in clinical trials is dependent on clarification of these issues.

We performed a systematic meta-analysis of studies reporting cBP between 2000 and 2012. Studies were included if both central and brachial SBPs (cSBP and bSBP) were reported. Studies were categorized by technique and according to the prevalent disease state with the bSBP - cSBP difference calculated. Random-effects modeling (inverse variance weighted approach) was used to estimate the pooled mean difference associated with each technique.

Of the 164 eligible studies, the SphygmoCor device was most commonly reported (110 studies), with direct carotid applanation second-most utilized (31 studies). In 30 included invasive cohorts, the measured cSBP did not differ significantly from the oscillometric bSBP recorded [mean difference 4.19  mmHg, 95% confidence interval (CI) -4.13 to 12.51], whereas mean differences of 12.77  mmHg (95% CI 11.93, 13.60) and 8.83  mmHg (95% CI 7.86, 9.79) were obtained with the SphygmoCor and carotid applanation estimates of cSBP, respectively (both P < 0.05). Conversely, the reported mean cSBP-to-bSBP differences measured across various disease states with SphygmoCor did not differ significantly.

This meta-analysis suggests that noninvasive cBP estimation is device/technique-dependent. Consequently, caution is advisable in applying these devices and techniques across clinical studies.