7D.09

Abstract

Objective: Estimation of central aortic pressure requires reliable acquisition of a peripheral pulse waveform either using radial tonometry or volumetric displacement within a brachial cuff. This study tests whether the radial and brachial waveforms are influenced by changes in properties of the peripheral vasculature of the hand, such an influence potentially compromising central aortic pressure estimation. Design and method: In 15 subjects (37 ± 15 years, 7 female), brachial waveform acquired by volumetric displacement (cuff-based) and radial waveform acquired by tonometry were simultaneously measured whilst a cuff around the hand on the same arm was inflated to pressures of 30, 15, 0, −15, −30, −60 mmHg with respect to mean arterial pressure to alter peripheral resistance and compliance. Aortic parameters were compared to measurements at baseline (no hand cuff pressure) using repeated measures ANOVA with post-hoc, Bonferroni-corrected, paired t-tests. Results: Altering peripheral resistance and compliance significantly changed computed mean arterial pressure (MAP), aortic systolic pressure (aSP), pulse pressure (aPP), augmentation pressure (aAP), augmentation index (aAIx) and pulse pressure amplification (PPA) relative to baseline conditions when using tonometric radial waveforms (Table, describing maximum change). Parameters derived from the cuff-based waveform assessment did not change with alterations in the peripheral vasculature. There was no significant change in brachial systolic and diastolic values throughout the experiment.Conclusions: Localised changes in peripheral resistance and compliance affect the radial waveform (tonometer-based acquisition) but not the brachial pressure waveform (cuff-based acquisition) as judged by significant effects on the computed central aortic parameters from radial but not brachial waveforms, the largest discrepancies occurring in aAIx and in PPA. This suggests that estimation of central aortic pressure from brachial cuff waveforms is less sensitive to disturbances in the peripheral vasculature of the upper limb that alter the peripheral arterial pulse morphology