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Optimising the Windkessel Model for Cardiac Output Monitoring During Changes in Vascular Tone

Research output: Chapter in Book/Report/Conference proceedingConference paperpeer-review

Peter Charlton, John Smith, Luigi Camporota, Richard Beale, Jordi Alastruey

Original languageEnglish
Title of host publicationEngineering in Medicine and Biology Society (EMBC)
Subtitle of host publication2014 36th Annual International Conference of the IEEE
Number of pages4
PublishedAug 2014


  • Poster Presentation

    Opt_Wk_mod_CO_vasc_tone_3.pdf, 844 KB, application/pdf

    Uploaded date:03 Sep 2014

King's Authors


Algorithms for estimating cardiac output (CO) from the arterial blood pressure wave have been observed to be inaccurate during changes in vascular tone. Many such algorithms are based on the Windkessel model of the circulation. We investigated the optimal analytical approaches and assumptions that make up each algorithm during changes in vascular tone. Several analytical approaches and assumptions were evaluated on data from 15 critically ill patients by comparison with thermodilution measurements. We found that the most accurate algorithms assumed a constant compliance for the duration of the beat. They produced a percentage error of ±31% by maintaining the compliance and outflow terms in the Windkessel model. For any algorithm, the following assumptions gave highest accuracy: (i) outflow pressure into the microcirculation is zero; (ii) end of systole is identified using the second derivative of pressure. None of the tested algorithms reached the clinically acceptable accuracy of ±30%.

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