P6.8 COMPARISON OF CENTRAL BLOOD PRESSURE ESTIMATED BY UPPER-ARM CUFF-BASED DEVICE WITH RADIAL TONOMETRY

Abstract

Background: New techniques that measure central blood pressure (BP) using an upper arm cuff-based approach require assessment for performance. The aim of this study was to compare a cuff-based device (CuffCBP) to estimate central BP indices [systolic BP, diastolic BP, pulse pressure (PP), augmentation pressure (AP), augmentation index (AIx)] with the non-invasive reference standard of radial tonometry (TonCBP). Methods: Consecutive CuffCBP (SphygmoCor XCEL) and TonCBP (SphygmoCor 8.1) duplicate recordings were measured at seated rest in 182 people with treated hypertension (aged 61±7 years, 48% male). Agreement of estimated central BP indices between methods was assessed using standard calibration of brachial (CuffCBP) and radial (TonCBP) waveforms with brachial systolic BP and diastolic BP (measured with the XCEL device), as well as by re-calibration with brachial mean arterial pressure (MAP) and diastolic BP. Results: The mean difference±SD for systolic BP, diastolic BP, and PP between CuffCBP and those derived from TonCBP were −0.89±3.48 mmHg (intra-class correlation [ICC]=0.98, p<0.001), −0.50±1.54 mmHg (ICC=0.99, p<0.001), and −0.42±3.57 mmHg (ICC=0.97, p<0.001), indicating good agreement. Wider limits of agreement were observed for AP and AIx (0.91±5.31 mmHg, ICC=0.75, p<0.001; −0.99±10.91%, ICC=0.75, p<0.001). Re-calibration with MAP and diastolic BP resulted in an overestimation of systolic BP with CuffCBP compared with TonCBP (8.58±19.06 mmHg, ICC= 0.14, p=0.045). Conclusion: Central systolic BP, diastolic BP and PP derived from CuffCBP are substantially equivalent to TonCBP, although the level of agreement is dependent on calibration method. Further validity testing of CuffCBP by comparison with invasive central BP will be required.