Estimation of pulse transit time as a function of blood pressure using a nonlinear arterial tube-load model

Mingwu Gao, Hao Min Cheng, Shih Hsien Sung, Chen Huan Chen, Nicholas Bari Olivier, Ramakrishna Mukkamala*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


Objective: pulse transit time (PTT) varies with blood pressure (BP) throughout the cardiac cycle, yet, because of wave reflection, only one PTT value at the diastolic BP level is conventionally estimated from proximal and distal BP waveforms. The objective was to establish a technique to estimate multiple PTT values at different BP levels in the cardiac cycle. Methods: a technique was developed for estimating PTT as a function of BP (to indicate the PTT value for every BP level) from proximal and distal BP waveforms. First, a mathematical transformation from one waveform to the other is defined in terms of the parameters of a nonlinear arterial tube-load model accounting for BP-dependent arterial compliance and wave reflection. Then, the parameters are estimated by optimally fitting the waveforms to each other via the model-based transformation. Finally, PTT as a function of BP is specified by the parameters. The technique was assessed in animals and patients in several ways including the ability of its estimated PTT-BP function to serve as a subject-specific curve for calibrating PTT to BP. Results: the calibration curve derived by the technique during a baseline period yielded bias and precision errors in mean BP of 5.1 ± 0.9 and 6.6 ± 1.0 mmHg, respectively, during hemodynamic interventions that varied mean BP widely. Conclusion: the new technique may permit, for the first time, estimation of PTT values throughout the cardiac cycle from proximal and distal waveforms. Significance: the technique could potentially be applied to improve arterial stiffness monitoring and help realize cuff-less BP monitoring.

Original languageEnglish
Article number7574337
Pages (from-to)1524-1534
Number of pages11
JournalIEEE Transactions on Biomedical Engineering
Issue number7
StatePublished - Jul 2017


  • Arterial stiffness
  • Blood pressure (BP)-dependent arterial compliance
  • Cuff-less BP
  • Nonlinear model
  • Pulse transit time (PTT)
  • Pulse wave velocity
  • Wave reflection


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