Invasive validation of a novel brachial cuff-based oscillometric device (SphygmoCor XCEL) for measuring central blood pressure.

BACKGROUND: Studies have established the prognostic value of central SBP and pulse pressure (PP). The SphygmoCor XCEL (AtCor Medical, Sydney, Australia) device provides practical central blood pressure (BP) measurement for daily clinical use with its easy-to-use, operator-independent procedure. However, this device has not been validated against invasive measurement.
METHOD: Simultaneous oscillometric and high-fidelity invasive measurements of central SBP and PP were compared for 36 patients who underwent coronary arteriography. Invasive measurement of brachial BP was also performed. Oscillometrically measured brachial SBP and DBP were used for calibration.
RESULTS: The differences between the invasive and the oscillometric measurements were -4.6 ± 9.9 mmHg for central SBP and -18.5 ± 10.6 mmHg for central PP (mean ± SD). We found strong correlation between the invasive and oscillometric measurements (central SBP and central PP, respectively: r = 0.91 and 0.89; slope, 1.28 and 1.38; both P < 0.001). Although the large slopes of the regression lines indicated a systemic bias toward lower values when measuring in high pressure ranges, the bias was mainly due to calibration error rather than device-specific error because errors of the central measurements correlated well with those of brachial measurements (SBP and PP, respectively: r = 0.80 and 0.77; both P < 0.001).
CONCLUSION: The impaired accuracy of central BP measurement was mainly due to calibration-derived, but not device-dependent, bias. Strong correlation between oscillometric and invasive measurements indicates that SphygmoCor XCEL warrants future investigations to determine the clinical validity of this device.