Central Pressure Waveform-Derived Indexes Obtained From Carotid and Radial Tonometry and Brachial Oscillometry in Healthy Subjects (2-84 Y): Age-, Height-, and Sex-Related Profiles and Analysis of Indexes Agreement.

Yanina Zócalo,Daniel Bia

doi:10.3389/fphys.2021.774390

Abstract

Aortic blood pressure (aoBP) waveform-derived indexes could provide valuable (prognostic) information over and above cardiovascular risk factors (CRFs). To obtain aoBP waveform-characteristics, several (i) techniques, (ii) recording sites, (iii) pressure-only waveform analysis mathematical approaches [e.g., pulse wave analysis (PWA), wave separation analysis (WSA)], and (iv) indexes [augmentation pressure and index (AP and AIx), forward (Pf) and backward (Pb) components of aoBP, reflection magnitude (RM), and reflection index (Rix)], were proposed. An accurate clinical use of these indexes requires knowing their physiological age-related profiles and the expected values for a specific subject. There are no works that have characterized waveform-derived indexes profiles in large populations considering: (i) as a continuous, data from different age stages (childhood, adolescence, and adulthood), (ii) complementary indexes, (iii) data obtained from different techniques and approaches, and (iv) analyzing potential sex- and body height (BH)-related differences. In addition, (v) there is a lack of normative data (reference intervals, RIs) for waveform-derived indexes.Aims(1) to evaluate the association and agreement between PWA- and/or WSA-derived indexes obtained with different techniques and approaches; (2) to determine the need for sex-, BH-, and/or age-specific RIs; (3) to define RIs for PWA- and WSA-derived indexes in a large cohort of healthy children, adolescents, and adults.Methods3619 subjects (3–90 y) were included; 1688 healthy (2–84 y). AP, AIx, AIx@75, Pf, Pb, RM, and RIx were obtained (carotid and radial tonometry, brachial oscillometry/plethysmography). The association and agreement between indexes were analyzed (Concordance correlation coefficients, Bland–Altman analysis). Mean and SD equations and sex-specific BH- and age-related profiles were obtained (regression methods; fractional polynomials).ResultsWaveform-derived indexes were not equivalent; for a specific index, there were systematic and proportional differences associated with the recording site (e.g., carotid vs. radial) and technique (e.g., tonometry vs. oscillometry). The need for sex-, BH-, or age-specific RIs was dependent on the index and/or age considered. RIs were defined for each index considering differences between recording sites and techniques. Equations for waveform-derived indexes age-related profiles were included, enabling to determine for a specific subject, the expected values and potential data deviations.

Highlights

Central aortic blood pressure waveform contains valuable information beyond and in addition to the obtained from its corresponding systolic, diastolic, and pulse pressure levels (Mynard et al, 2020)
Despite we previously demonstrated that aortic blood pressure (aoBP) and some waveformderived indexes could vary depending on the calibration schema considered (Zinoveev et al, 2019), in this work, we opted for the schema most used in the literature
This study adds to the knowledge of the physiological variations in waveform-derived indexes and arterial pulse propagative properties that would be expected during growth and aging, analyzing at the same time the behavior of different indexes, obtained with three different approaches

Summary

Introduction

Central aortic blood pressure (aoBP) waveform contains valuable (e.g., prognostic) information beyond and in addition to the obtained from its corresponding systolic, diastolic, and pulse pressure levels (aoSBP, aoDBP, aoPP) (Mynard et al, 2020). AP represents the augmentation level (a positive AP indicates “additional” pressure arising from reflections) (Baksi et al, 2009; Sugawara et al, 2010). It is calculated from the inflection point in the pressure waveform (systolic phase) that “signalizes or identifies” the reflected component’s arrival to the aortic root (Kelly et al, 1989). AIx, calculated as AP/aoPP, is considered as a surrogate index of wave reflection ( it is known that it depends on factors like heart rate or ventricle function) (Hametner and Wassertheurer, 2017). It is to note that the Pf represents the integration of forward

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