BACKGROUND:To investigate the accuracy of the SphygmoCor and Omron HEM9000-AI devices in the estimation of central blood pressure (BP) in comparison with the simultaneous invasive catheter measurement. METHODS:The radial arterial pulse was sequentially recorded by the use of the Omron and SphygmoCor devices in 33 patients, with the calibration of the brachial oscillometric BP, to derive central BPs, which were also measured simultaneously with a catheter-based fluid-filled manometer system. The procedure was repeated three times to obtain 99 pairs of noninvasive and invasive measurements. RESULTS:The noninvasive central systolic BP estimations were significantly (P < 0.001) associated with the invasive measurement at the ascending aorta, with a correlation coefficient of 0.91 and 0.90 for the SphygmoCor and Omron devices, respectively. However, both devices underestimated central systolic BP with a difference of -15 mm Hg (95% confidence interval (CI), -17 to -13 mm Hg, P < 0.001) for SphygmoCor and -2 mm Hg (95% CI, -4 to 0 mm Hg, P < 0.05) for Omron. In comparison with the invasive catheter measurement at the brachial artery, the oscillometric Omron device underestimated brachial systolic BP by -19 mm Hg (95% CI, -23 to -15 mm Hg, P < 0.001). CONCLUSIONS:Both devices underestimated central systolic BP, with a larger deviation by SphygmoCor. Nonetheless, these noninvasive estimations of central BP closely correlate with the invasive measurements, and can still be properly used, on the condition that device specific diagnostic thresholds become available.