Cuffless Estimation of Blood Pressure: Importance of Variability in Blood Pressure Dependence of Arterial Stiffness Across Individuals and Measurement Sites

Mark Butlin*, Fatemeh Shirbani, Edward Barin, Isabella Tan, Bart Spronck, Alberto P Avolio

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


OBJECTIVE: Measuring arterial pulse transit time (PTT) to estimate blood pressure (BP) without conventional brachial cuff-based measurement is not new, but is a focus of current wearable technologies research. Much research pertains to efficient, accurate sensing of artery-related waveforms, yet the relationship between PTT and BP receives less attention despite being key for accurate BP estimation. This study investigated BP/PTT calibration by quantifying anatomical site variability (n = 10, 3 female, age 30 9 years) and individual variability ( n = 103, 50 female, age 53 22 years).

METHODS: BP and pulse wave velocity (PWV) were measured in both seated and supine. Carotid-femoral PWV (cfPWV), carotid-radial PWV (crPWV), and carotid-finger-volume PWV (cvPWV) were measured with the wrist and hand positioned at the level of the upper thigh to achieve the same hydrostatic pressure effect across all measurements.

RESULTS: The postural change invoked a small (4 7 mmHg) change in brachial diastolic BP with an additional 27 2 mmHg change in hydrostatic pressure. cfPWV decreased in the supine position (1.75 0.17 m s-1, p < 0.001), but crPWV and cvPWV were more variable. The calibration term (BP/PWV) across the sample population varied from 6.6 to 98.3 mmHg sm-1 (mean 22 14 mmHg sm-1) and was correlated with age, heart rate, diastolic and pulse pressure, and weight. These variables did not explain the majority of the variability (R2 = 0.248).

CONCLUSION: There is anatomical site and between-individual variability in the calibration term for BP estimation from PTT.

SIGNIFICANCE: Using and accurately calculating hydrostatic changes in BP within the individual may be one method to increase the accuracy of this calibration term.

Original languageEnglish
Pages (from-to)2377-2383
Number of pages7
JournalIeee Transactions on Biomedical Engineering
Issue number11
Publication statusPublished - Nov 2018
Externally publishedYes


  • Adult
  • Aged
  • Aged, 80 and over
  • Blood Pressure/physiology
  • Blood Pressure Determination/methods
  • Calibration
  • Carotid Arteries/physiology
  • Female
  • Femoral Artery/physiology
  • Humans
  • Male
  • Middle Aged
  • Pulse Wave Analysis/methods
  • Signal Processing, Computer-Assisted
  • Vascular Stiffness/physiology
  • Young Adult

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