Evaluation of a Novel Brachial Cuff-Based Oscillometric Method for Estimating Central Systolic Pressure in Hemodialysis Patients

Abstract

Background/Aims: Elevated wave reflections and arterial stiffness, as well as ambulatory blood pressure (BP) are independent predictors of cardiovascular risk in end-stage-renal-disease. This study is the first to evaluate in hemodialysis patients the validity of a new ambulatory oscillometric device (Mobil-O-Graph, IEM, Germany), which estimates aortic BP, augmentation index (AIx) and pulse wave velocity (PWV). Methods: Aortic SBP (aSBP), heart rate-adjusted AIx (AIx(75)) and PWV measured with Mobil-O-Graph were compared with the values from the most widely used tonometric device (Sphygmocor, ArtCor, Australia) in 73 hemodialysispatients. Measurements were made in a randomized order after 10 min of rest in the supine position at least 30 min before a dialysis session. Brachial BP (mercury sphygmomanometer) was used for the calibration of Sphygmocor's waveform. Results: Sphygmocor-derivedaSBP and AIx(75) did not differ from the relevant Mobil-O-Graph measurements (aSBP: 136.3 ± 19.6 vs. 133.5 ± 19.3 mm Hg, p = 0.068; AIx(75): 28.4 ± 9.3 vs. 30.0 ± 11.8%, p = 0.229). The small difference in aSBP is perhaps explained by a relevant difference in brachial SBP used for calibration (146.9 ± 20.4 vs. 145.2 ± 19.9 mm Hg, p = 0.341). Sphygmocor PWV was higher than Mobil-O-Graph PWV (10.3 ± 3.4 vs. 9.5 ± 2.1 m/s, p < 0.01). All 3 parameters estimated by Mobil-O-Graph showed highly significant (p < 0.001) correlations with the relevant measurements of Sphygmocor (aSBP, r = 0.770; AIx(75), r = 0.400; PWV, r = 0.739). The Bland-Altman Plots for aSBP and AIx(75) showed acceptable agreement between the two devices and no evidence of systemic bias for PWV. Conclusion: As in other populations, acceptable agreement between Mobil-O-Graph and Sphygmocor was evident for aSBP and AIx(75) in hemodialysis patients; PWV was slightly underestimated by Mobil-O-Graph.

Ambulatory Recording of Wave Reflections and Arterial Stiffness during Intra- and Interdialytic Periods in Patients Treated with Dialysis

“…First, Mobil-O-Graph records brachial BP and pulse waves using the oscillometric method; although this differs from the most widely applied technique of applanation tonometry (23), previous validation studies in different populations (including patients with ESRD) showed acceptable agreement between Mobil-O-Graph-derived variables and invasive and noninvasive measurements (23,24,28,30,31). Second, because this was a pilot study, no power estimation was performed before its initiation; we believe, however, that the number of participants, together with the high number of readings (.120) during the 48-hour recordings, provided adequate power.…”

Comparison of 24-hour and Office Pulse Wave Velocity for Prediction of Mortality in Hemodialysis Patients

“…The device uses the integrated ARCSolver algorithms (Austrian Institute of Technology, Vienna, Austria) to derive aortic stiffness surrogates based on brachial BP readings by a generalized transfer function [31,32]. Previous studies have proven the validity of the Mobil-O-Graph for BP monitoring and pulse wave analysis against established invasive and noninvasive techniques in various populations, including hemodialysis patients [23,[32][33][34][35]. The measurements were taken of the non-fistula arm with circumference-adapted arm cuffs and started before the midweek dialysis session independent of the dialysis shift.…”

Ambulatory Pulse Wave Velocity Is a Stronger Predictor of Cardiovascular Events and All-Cause Mortality Than Office and Ambulatory Blood Pressure in Hemodialysis Patients

“…20,[22][23][24] In hemodialysis patients, Mobil-O-Graph provided comparable estimates of office aortic SBP, AIx, and PWV with that obtained by Sphygmocor (ArtCor, Sydney, Australia), which is the most widely applied method for noninvasive assessment of these parameters. 14 …”

“…13 However, PWV displayed only a minimal increase over time that reached again statistical significance at the end of the 3-day interval. 13 All devices measuring arterial stiffness and central BP indexes use brachial BP for calibration of the aortic waveforms 14 ; such measurements are subject to errors inserted by predialysis or postdialysis office BP readings, which are known to be highly inaccurate and poorly reflect the true BP load due to numerous factors, such as the white-coat effect, patient frustration to start dialysis and leave the unit quickly, anxiety for correct arteriovenous fistula needling, and truly high BP variability during the intra-and interdialytic periods. 11 We have, therefore hypothesized that ambulatory estimates of arterial stiffness and central BP parameters may have stronger associations with cardiovascular events and mortality in this population.…”