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Open Access Research article

Validity, intra- and inter-observer reliability of automated devices for the assessment of ankle brachial index using photo-plethysmography

Andrej Teren12, Frank Beutner12, Kerstin Wirkner1, Markus Loeffler13 and Markus Scholz13*

Author Affiliations

1 LIFE- Leipzig Research Center for Civilization Diseases, University of Leipzig, Leipzig, Germany

2 Department of Internal Medicine/Cardiology, Heart Center of the University Leipzig, Leipzig, Germany

3 Institute of Medical Informatics, Statistics and Epidemiology, LIFE, University of Leipzig, Haertelstrasse 16-18, 04107 Leipzig, Germany

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BMC Cardiovascular Disorders 2013, 13:81  doi:10.1186/1471-2261-13-81

Published: 8 October 2013

Abstract

Background

Ankle-brachial-Index (ABI) measured by manual Dopplersonography is an easily assessable marker of global cardiovascular risk. The aim of this study was to establish novel photo-plethysmography (PPG)-based ABI assessments in an epidemiologic context and to compare its results with those of Doppler.

Methods

Two devices for PPG-based ABI assessments (Vicorder, Vascular Explorer) were tested and compared against Doppler in 56 putatively healthy subjects. We determined acceptance, time requirements, agreement of repeat measurements, agreement with Doppler and intra- and inter-observer concordances for both devices and compared the results. Differences between cuff inflation- and deflation-based methods were also studied for Vascular Explorer.

Results

Acceptance was similar for both devices but Vascular Explorer was more time consuming. Agreement of multiple measurements was moderate for both methods highlighting the importance of measurement replicates. Both automated devices showed significantly higher ABI compared to Doppler which can be traced back to higher brachial pressures (Vicorder) or higher ankle pressures (Vascular Explorer). This effect is more pronounced for Vascular Explorer but can be ameliorated using the deflation method of measurement. Intra-observer concordances were similar. Inter-observer concordance was non-significantly better for Vicorder.

Conclusions

Both devices proved to be feasible in epidemiologic studies, but compared to Doppler, do not constitute an advantage regarding time requirement and accuracy of ABI assessment. Since PPG-based ABI values are inflated compared to Doppler, it will be necessary to adjust Doppler-based cut-offs for risk stratification.

Keywords:
Ankle-brachial index; Feasibility; Vascular explorer; Vicorder