P5.12 BRACHIAL-TO-RADIAL SYSTOLIC BLOOD PRESSURE AMPLIFICATION IS SIGNIFICANTLY BLUNTED IN PATIENTS WITH TYPE 2 DIABETES; UPPER LIMB HAEMODYNAMIC’S HAVE AN INFLUENTIAL ROLE

Abstract

Objectives: We recently found significant age-related increases in brachial-to-radial systolic blood pressure amplification (Bra-Rad-SBPAmp), and this has implications for correct central SBP estimation. Patients with type 2 diabetes mellitus (T2DM) have vascular irregularities that may alter Bra-Rad-SBPAmp and this study sought to determine the magnitude and mechanisms of Bra-Rad-SBPAmp in these patients. Methods: Twenty T2DM (64±8 years; 50% male) and 20 controls (60±8 years; 50% male) underwent simultaneous cuff auscultation and two-dimensional ultrasound imaging of the brachial and radial arteries. The 1st Korotkoff sound (denoting SBP) at each arterial site was identified from the first inflection point of Doppler flow during BP cuff deflation. Bra-Rad-SBPAmp was calculated by radial minus brachial SBP. Local and systemic haemodynamics were recorded by tonometry and ultrasound. Results: Radial SBP was higher than brachial SBP for both T2DM (136±16vs127±17; p<0.001) and controls (135±12vs121±11; p<0.001), and Bra-Rad-SBPAmp was significantly lower in T2DM (9±8mmHgvs14±7mmHg, p=0.042). Central SBP was significantly higher in both controls and T2DM when radial pressure waveforms were calibrated using radial, compared with brachial SBP (p<0.001 both). The product of brachial artery flow velocity and diameter was significantly increased in T2DM (213±108 versus 315±144cm/s/mm, p=0.023), and this was inversely correlated with Bra-Rad-SBPAmp (r=−643, p=0.003) even after adjustment for age and sex (β=−0.031, adjusted R2=0.366, p=0.002). Conclusions: Patients with T2DM have higher radial SBP than brachial SBP, but compared with controls, overall Bra-Rad-SBPAmp is significantly blunted. Local haemodynamics influence the magnitude of Bra-Rad-SBPAmp and overall these findings have implications regarding correct estimation of central BP.