Abstract
Pulse transit time (PTT) is defined as the time it takes the blood pressure (BP) wave to propagate from the heart to a specified point on the body. After an initial BP measurement, PTT can track BP over short periods of time. This paper evaluates two PTT algorithms: Chen’s and Poon’s algorithm; two of the most cited works in the area. The criteria for evaluating them were: which was capable of best tracking changes in BP and which provided the longest time between subsequent BP measurements. These establish the suitability of the PTT method for practical applications, which has not been examined previously. Accuracy was evaluated using the Association of Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society’s (BHS) standards. Results show that Chen’s algorithm is dependent on its lookup table at short intervals but remains accurate using a 6-min calibration interval, with r=0.96 and r2=0.98. Poon’s algorithm fails when using a 2-min calibration interval, but is more capable of reflecting changes in BP. The short calibration interval and accuracy limit the usefulness of calculating BP using PTT. Therefore, neither of the algorithms can be recommended because of their shortcomings when estimating BP.
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Acknowledgements
We thank Intel and the IRCSET Embark Initiative for funding this project, National Access Program for funding research for hardware development, John O’Donoghue in the Computer Science Department in UCC and Tyndall National Institute for providing the facilities and equipment used in this project. Tyndall is part of the SFI funded CSET, CLARITY centre for sensor web technologies.
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McCarthy, B., Vaughan, C., O'Flynn, B. et al. An examination of calibration intervals required for accurately tracking blood pressure using pulse transit time algorithms. J Hum Hypertens 27, 744–750 (2013). https://doi.org/10.1038/jhh.2013.41
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DOI: https://doi.org/10.1038/jhh.2013.41
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