Background: Central BP is an independent predictor of mortality. Current methods for non-invasively estimating central BP are operator-dependent and require skill to obtain quality recordings. The aims of this study were firstly, to determine the validity of an automatic, upper arm oscillometric cuff method for estimating central BP (O_CBP) by comparison with the non-invasive reference standard of radial tonometry (T_CBP). Secondly, we sought to determine the intra-test and inter-test reproducibility of O_CBP.

Methods: To assess validity, central BP was estimated by O_CBP (R6.5B Vascular Monitor) and compared with T_CBP (SphygmoCor) in 47 participants aged 57±9 years in supine, seated and standing postures. Brachial mean arterial pressure and diastolic BP from the O_CBP device was used to calibrate both devices. Duplicate measures were recorded in each posture on the same day to assess intra-test reliability and participants returned within 10±7 days for repeat measurements to assess inter-test reliability.

Results: There was a strong correlation (ICC=0.987, p<0.001) and small mean difference (1.2±2.2 mmHg) for central systolic BP determined by O_CBP compared with T_CBP. Ninety-six percent of all comparisons (n=495 acceptable recordings) were within 5 mmHg. With respect to reproducibility, there were strong correlations but higher limits of agreement for the intra-test (ICC=0.975, p<0.001, mean difference 0.6±4.5mmHg) and inter-test (ICC=0.895, p<0.001, mean difference 4.3±8.0 mmHg) comparisons.

Conclusions: Estimation of central systolic BP using cuff oscillometry is substantially equivalent to radial tonometry and has good reproducibility. As a non-invasive, relatively operator-independent method, O_CBP may be useful for estimating central BP in clinical practice.