P5.10 MAJOR BRACHIAL-TO-RADIAL-SYSTOLIC-BLOOD-PRESSURE-AMPLIFICATION OCCURS IN HEALTHY PEOPLE AND IS SIGNIFICANTLY INCREASED WITH AGE

Abstract

Objectives: The reference standard for non-invasive central blood pressure (BP) measurement is radial tonometry calibrated using brachial BP. Brachial-to-radial-systolic-BP-amplification (Bra-Rad-SBPAmp) may introduce error into central BP measurement but the magnitude of Bra-Rad-SBPAmp in healthy people is uncertain. This study aimed to determine the magnitude of Bra-Rad-SBPAmp as well as effects of ageing. Methods: Forty healthy younger (28±5 years; 50% male) and 20 older (60±8 years; 50% male) participants underwent brachial and radial artery ultrasound measurement to identify SBP (1st Korotkoff sound) from the 1st Doppler flow inflection point during BP cuff deflation. Regional and local haemodynamics were recorded by ultrasound and tonometry. Bra-Rad-SBPAmp was calculated by radial minus brachial SBP. Results: Radial SBP was significantly higher than brachial SBP in both younger (118±12mmHg versus 110±10mmHg; p<0.001) and older (135±12mmHg versus 121±11mmHg; p<0.001) participants. However, the magnitude of Bra-Rad-SBPAmp was higher in older age (14±7mmHg versus 8±7mmHg; p=0.004), and this was independent of heart rate, mean arterial pressure and sex. A higher proportion of older participants had major (>15mmHg) Bra-Rad-SBPAmp (45% versus 12.5%; p=0.028). Recalibration of radial waveforms using radial versus brachial SBP resulted in higher central SBP in both younger (p<0.001) and older (p<0.001) age groups (p<0.001 between groups). Brachial artery stiffness was related to Bra-Rad-SBPAmp in females only. Conclusions: Major Bra-Rad-SBPAmp occurs in healthy people and is significantly increased with age. These findings have implications for correct central BP estimation using radial tonometry and brachial BP calibration, whereby greater underestimation of central SBP is likely with advancing age.