Open AccessQuantifying tissue mechanical properties using photoplethysmography
Author(s) -
Tony J. Akl,
Mark A. Wilson,
M.N. Ericson,
Gerard L. Coté
Publication year - 2014
Publication title -
biomedical optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.362
H-Index - 86
ISSN - 2156-7085
DOI - 10.1364/boe.5.002362
Subject(s) - photoplethysmogram , pulsatile flow , biomedical engineering , heartbeat , pulse (music) , waveform , blood volume , signal (programming language) , materials science , compliance (psychology) , medicine , cardiology , computer science , optics , physics , computer vision , filter (signal processing) , psychology , telecommunications , social psychology , radar , computer security , detector , programming language
Photoplethysmography (PPG) is a non-invasive optical method that can be used to detect blood volume changes in the microvascular bed of tissue. The PPG signal comprises two components; a pulsatile waveform (AC) attributed to changes in the interrogated blood volume with each heartbeat, and a slowly varying baseline (DC) combining low frequency fluctuations mainly due to respiration and sympathetic nervous system activity. In this report, we investigate the AC pulsatile waveform of the PPG pulse for ultimate use in extracting information regarding the biomechanical properties of tissue and vasculature. By analyzing the rise time of the pulse in the diastole period, we show that PPG is capable of measuring changes in the Young's Modulus of tissue mimicking phantoms with a resolution of 4 KPa in the range of 12 to 61 KPa. In addition, the shape of the pulse can potentially be used to diagnose vascular complications by differentiating upstream from downstream complications. A Windkessel model was used to model changes in the biomechanical properties of the circulation and to test the proposed concept. The modeling data confirmed the response seen in vitro and showed the same trends in the PPG rise and fall times with changes in compliance and vascular resistance.