Abstract

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.

© 2014 Optical Society of America

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2013 (1)

A. A. Kamshilin, V. Teplov, E. Nippolainen, S. Miridonov, and R. Giniatullin, “Variability of microcirculation detected by blood pulsation imaging,” PLoS ONE8(2), e57117 (2013).
[CrossRef] [PubMed]

2012 (2)

R. Sahni, “Noninvasive monitoring by photoplethysmography,” Clin. Perinatol.39(3), 573–583 (2012).
[CrossRef] [PubMed]

T. J. Akl, T. J. King, R. Long, M. J. McShane, M. Nance Ericson, M. A. Wilson, and G. L. Coté, “Performance assessment of an opto-fluidic phantom mimicking porcine liver parenchyma,” J. Biomed. Opt.17(7), 077008 (2012).
[CrossRef] [PubMed]

2011 (3)

2010 (2)

H. C. Hong, C. M. Chen, Y. C. Chou, and C. H. Lin, “Study of novel electrical routing and integrated packaging on bio-compatible flexible substrates,” Microsyst. Technol.16(3), 423–430 (2010).
[CrossRef]

G. Cennini, J. Arguel, K. Akşit, and A. van Leest, “Heart rate monitoring via remote photoplethysmography with motion artifacts reduction,” Opt. Express18(5), 4867–4875 (2010).
[CrossRef] [PubMed]

2009 (5)

B. Hinz, “Tissue stiffness, latent TGF-beta1 activation, and mechanical signal transduction: implications for the pathogenesis and treatment of fibrosis,” Curr. Rheumatol. Rep.11(2), 120–126 (2009).
[CrossRef] [PubMed]

P. Zakharov, M. S. Talary, and A. Caduff, “A wearable diffuse reflectance sensor for continuous monitoring of cutaneous blood content,” Phys. Med. Biol.54(17), 5301–5320 (2009).
[CrossRef] [PubMed]

P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

P. J. Wang, F. He, D. H. Liao, J. Zhang, W. C. Li, Y. F. Zhang, T. Z. Huang, X. Y. Li, and Y. J. Zeng, “The impact of age on incremental elastic modulus and incremental compliance of pig hepatic portal vein for liver xenotransplantation,” Xenotransplantation16(1), 5–10 (2009).
[CrossRef] [PubMed]

N. Westerhof, J. W. Lankhaar, and B. E. Westerhof, “The arterial Windkessel,” Med. Biol. Eng. Comput.47(2), 131–141 (2009).
[CrossRef] [PubMed]

2008 (2)

E. L. Carstensen, K. J. Parker, and R. M. Lerner, “Elastography in the management of liver disease,” Ultrasound Med. Biol.34(10), 1535–1546 (2008).
[CrossRef] [PubMed]

W. Verkruysse, L. O. Svaasand, and J. S. Nelson, “Remote plethysmographic imaging using ambient light,” Opt. Express16(26), 21434–21445 (2008).
[CrossRef] [PubMed]

2007 (2)

J. Allen, “Photoplethysmography and its application in clinical physiological measurement,” Physiol. Meas.28(3), R1–R39 (2007).
[CrossRef] [PubMed]

E. Zahedi, K. Chellappan, M. A. Ali, and H. Singh, “Analysis of the effect of ageing on rising edge characteristics of the photoplethysmogram using a modified Windkessel model,” Cardiovasc. Eng.7(4), 172–181 (2007).
[CrossRef] [PubMed]

2006 (1)

S. C. Millasseau, J. M. Ritter, K. Takazawa, and P. J. Chowienczyk, “Contour analysis of the photoplethysmographic pulse measured at the finger,” J. Hypertens.24(8), 1449–1456 (2006).
[CrossRef] [PubMed]

2005 (5)

M. Sandberg, Q. Zhang, J. Styf, B. Gerdle, and L. G. Lindberg, “Non-invasive monitoring of muscle blood perfusion by photoplethysmography: evaluation of a new application,” Acta Physiol. Scand.183(4), 335–343 (2005).
[CrossRef] [PubMed]

F. P. Wieringa, F. Mastik, and A. F. van der Steen, “Contactless multiple wavelength photoplethysmographic imaging: a first step toward “SpO2 camera” technology,” Ann. Biomed. Eng.33(8), 1034–1041 (2005).
[CrossRef] [PubMed]

M. Ziol, A. Handra-Luca, A. Kettaneh, C. Christidis, F. Mal, F. Kazemi, V. de Lédinghen, P. Marcellin, D. Dhumeaux, J.-C. Trinchet, and M. Beaugrand, “Noninvasive assessment of liver fibrosis by measurement of stiffness in patients with chronic hepatitis C,” Hepatology41(1), 48–54 (2005).
[CrossRef] [PubMed]

R. Bataller and D. A. Brenner, “Liver fibrosis,” J. Clin. Invest.115(2), 209–218 (2005).
[CrossRef] [PubMed]

G. Varotti, G. L. Grazi, G. Vetrone, G. Ercolani, M. Cescon, M. Del Gaudio, M. Ravaioli, A. Cavallari, and A. Pinna, “Causes of early acute graft failure after liver transplantation: analysis of a 17-year single-centre experience,” Clin. Transplant.19(4), 492–500 (2005).
[CrossRef] [PubMed]

2004 (2)

M. N. Ericson, M. Wilson, G. Cote, C. L. Britton, W. Xu, J. Baba, M. Bobrek, M. Hileman, M. Moore, and S. Frank, “Development of an implantable oximetry-based organ perfusion sensor,” Conf. Proc. IEEE Eng. Med. Biol. Soc.3, 2235–2238 (2004).
[PubMed]

M. N. Ericson, M. A. Wilson, G. L. Coté, J. S. Baba, W. Xu, M. Bobrek, C. L. Britton, M. S. Hileman, M. R. Moore, M. S. Emery, and R. Lenarduzzi, “Implantable sensor for blood flow monitoring after transplant surgery,” Minim. Invasive Ther. Allied Technol.13(2), 87–94 (2004).
[CrossRef] [PubMed]

2003 (3)

B. Terjung, I. Lemnitzer, F. L. Dumoulin, W. Effenberger, H. H. Brackmann, T. Sauerbruch, and U. Spengler, “Bleeding complications after percutaneous liver biopsy. An analysis of risk factors,” Digestion67(3), 138–145 (2003).
[CrossRef] [PubMed]

R. G. Gosling and M. M. Budge, “Terminology for describing the elastic behavior of arteries,” Hypertension41(6), 1180–1182 (2003).
[CrossRef] [PubMed]

T. Aoyagi, “Pulse oximetry: its invention, theory, and future,” J. Anesth.17(4), 259–266 (2003).
[CrossRef] [PubMed]

2002 (2)

V. Kamat, “Pulse oximetry,” Indian J. Anaesth46, 261–268 (2002).

S. C. Millasseau, R. P. Kelly, J. M. Ritter, and P. J. Chowienczyk, “Determination of age-related increases in large artery stiffness by digital pulse contour analysis,” Clin. Sci.103(4), 371–377 (2002).
[PubMed]

2001 (2)

A. Manduca, T. E. Oliphant, M. A. Dresner, J. L. Mahowald, S. A. Kruse, E. Amromin, J. P. Felmlee, J. F. Greenleaf, and R. L. Ehman, “Magnetic resonance elastography: non-invasive mapping of tissue elasticity,” Med. Image Anal.5(4), 237–254 (2001).
[CrossRef] [PubMed]

M. Hirata, S. M. F. Akbar, N. Horiike, and M. Onji, “Noninvasive diagnosis of the degree of hepatic fibrosis using ultrasonography in patients with chronic liver disease due to hepatitis C virus,” Eur. J. Clin. Invest.31(6), 528–535 (2001).
[CrossRef] [PubMed]

2000 (2)

M. Stevanov, J. Baruthio, and B. Eclancher, “Fabrication of elastomer arterial models with specified compliance,” J. Appl. Physiol.88(4), 1291–1294 (2000).
[PubMed]

U. Settmacher, B. Stange, R. Haase, M. Heise, T. Steinmüller, W. O. Bechstein, and P. Neuhaus, “Arterial complications after liver transplantation,” Transpl. Int.13(5), 372–378 (2000).
[CrossRef] [PubMed]

1999 (1)

P. Thampanitchawong and T. Piratvisuth, “Liver biopsy:complications and risk factors,” World J. Gastroenterol.5(4), 301–304 (1999).
[PubMed]

1998 (1)

C. J. Bruns, D. Neuhof, H. Erasmi, and T. Schmitz-Rixen, “In vivo biomechanical properties of three different graft materials in peripheral vascular surgery,” Int. J. Angiol.7(1), 52–56 (1998).
[CrossRef]

1997 (2)

P. E. Hickman, J. M. Potter, and A. J. Pesce, “Clinical chemistry and post-liver-transplant monitoring,” Clin. Chem.43(8 Pt 2), 1546–1554 (1997).
[PubMed]

S. P. Glasser, D. K. Arnett, G. E. McVeigh, S. M. Finkelstein, A. J. Bank, D. J. Morgan, and J. N. Cohn, “Vascular compliance and cardiovascular disease: a risk factor or a marker?” Am. J. Hypertens.10(10), 1175–1189 (1997).
[CrossRef] [PubMed]

1996 (1)

J. A. Clark, J. C. Cheng, and K. S. Leung, “Mechanical properties of normal skin and hypertrophic scars,” Burns22(6), 443–446 (1996).
[CrossRef] [PubMed]

1991 (1)

J. Quiroga, I. Colina, A. J. Demetris, T. E. Starzl, and D. H. Van Thiel, “Cause and timing of first allograft failure in orthotopic liver transplantation: a study of 177 consecutive patients,” Hepatology14(6), 1054–1062 (1991).
[CrossRef] [PubMed]

1973 (1)

T. R. Dawber, H. E. Thomas, and P. M. McNamara, “Characteristics of the dicrotic notch of the arterial pulse wave in coronary heart disease,” Angiology24(4), 244–255 (1973).
[CrossRef] [PubMed]

Akbar, S. M. F.

M. Hirata, S. M. F. Akbar, N. Horiike, and M. Onji, “Noninvasive diagnosis of the degree of hepatic fibrosis using ultrasonography in patients with chronic liver disease due to hepatitis C virus,” Eur. J. Clin. Invest.31(6), 528–535 (2001).
[CrossRef] [PubMed]

Akl, T.

Akl, T. J.

T. J. Akl, T. J. King, R. Long, M. J. McShane, M. Nance Ericson, M. A. Wilson, and G. L. Coté, “Performance assessment of an opto-fluidic phantom mimicking porcine liver parenchyma,” J. Biomed. Opt.17(7), 077008 (2012).
[CrossRef] [PubMed]

T. J. Akl, R. Long, M. J. McShane, M. N. Ericson, M. A. Wilson, and G. L. Coté, “Optimizing probe design for an implantable perfusion and oxygenation sensor,” Biomed. Opt. Express2(8), 2096–2109 (2011).
[CrossRef] [PubMed]

Aksit, K.

Ali, M. A.

E. Zahedi, K. Chellappan, M. A. Ali, and H. Singh, “Analysis of the effect of ageing on rising edge characteristics of the photoplethysmogram using a modified Windkessel model,” Cardiovasc. Eng.7(4), 172–181 (2007).
[CrossRef] [PubMed]

Allen, J.

J. Allen, “Photoplethysmography and its application in clinical physiological measurement,” Physiol. Meas.28(3), R1–R39 (2007).
[CrossRef] [PubMed]

Amromin, E.

A. Manduca, T. E. Oliphant, M. A. Dresner, J. L. Mahowald, S. A. Kruse, E. Amromin, J. P. Felmlee, J. F. Greenleaf, and R. L. Ehman, “Magnetic resonance elastography: non-invasive mapping of tissue elasticity,” Med. Image Anal.5(4), 237–254 (2001).
[CrossRef] [PubMed]

Aoyagi, T.

T. Aoyagi, “Pulse oximetry: its invention, theory, and future,” J. Anesth.17(4), 259–266 (2003).
[CrossRef] [PubMed]

Arguel, J.

Arnett, D. K.

S. P. Glasser, D. K. Arnett, G. E. McVeigh, S. M. Finkelstein, A. J. Bank, D. J. Morgan, and J. N. Cohn, “Vascular compliance and cardiovascular disease: a risk factor or a marker?” Am. J. Hypertens.10(10), 1175–1189 (1997).
[CrossRef] [PubMed]

Baba, J.

M. N. Ericson, M. Wilson, G. Cote, C. L. Britton, W. Xu, J. Baba, M. Bobrek, M. Hileman, M. Moore, and S. Frank, “Development of an implantable oximetry-based organ perfusion sensor,” Conf. Proc. IEEE Eng. Med. Biol. Soc.3, 2235–2238 (2004).
[PubMed]

Baba, J. S.

M. N. Ericson, M. A. Wilson, G. L. Coté, J. S. Baba, W. Xu, M. Bobrek, C. L. Britton, M. S. Hileman, M. R. Moore, M. S. Emery, and R. Lenarduzzi, “Implantable sensor for blood flow monitoring after transplant surgery,” Minim. Invasive Ther. Allied Technol.13(2), 87–94 (2004).
[CrossRef] [PubMed]

Bank, A. J.

S. P. Glasser, D. K. Arnett, G. E. McVeigh, S. M. Finkelstein, A. J. Bank, D. J. Morgan, and J. N. Cohn, “Vascular compliance and cardiovascular disease: a risk factor or a marker?” Am. J. Hypertens.10(10), 1175–1189 (1997).
[CrossRef] [PubMed]

Baruthio, J.

M. Stevanov, J. Baruthio, and B. Eclancher, “Fabrication of elastomer arterial models with specified compliance,” J. Appl. Physiol.88(4), 1291–1294 (2000).
[PubMed]

Basdogan, C.

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T. J. Akl, R. Long, M. J. McShane, M. N. Ericson, M. A. Wilson, and G. L. Coté, “Optimizing probe design for an implantable perfusion and oxygenation sensor,” Biomed. Opt. Express2(8), 2096–2109 (2011).
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M. N. Ericson, M. Wilson, G. Cote, C. L. Britton, W. Xu, J. Baba, M. Bobrek, M. Hileman, M. Moore, and S. Frank, “Development of an implantable oximetry-based organ perfusion sensor,” Conf. Proc. IEEE Eng. Med. Biol. Soc.3, 2235–2238 (2004).
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M. N. Ericson, M. A. Wilson, G. L. Coté, J. S. Baba, W. Xu, M. Bobrek, C. L. Britton, M. S. Hileman, M. R. Moore, M. S. Emery, and R. Lenarduzzi, “Implantable sensor for blood flow monitoring after transplant surgery,” Minim. Invasive Ther. Allied Technol.13(2), 87–94 (2004).
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S. C. Millasseau, R. P. Kelly, J. M. Ritter, and P. J. Chowienczyk, “Determination of age-related increases in large artery stiffness by digital pulse contour analysis,” Clin. Sci.103(4), 371–377 (2002).
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M. Ziol, A. Handra-Luca, A. Kettaneh, C. Christidis, F. Mal, F. Kazemi, V. de Lédinghen, P. Marcellin, D. Dhumeaux, J.-C. Trinchet, and M. Beaugrand, “Noninvasive assessment of liver fibrosis by measurement of stiffness in patients with chronic hepatitis C,” Hepatology41(1), 48–54 (2005).
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King, T. J.

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M. N. Ericson, M. A. Wilson, G. L. Coté, J. S. Baba, W. Xu, M. Bobrek, C. L. Britton, M. S. Hileman, M. R. Moore, M. S. Emery, and R. Lenarduzzi, “Implantable sensor for blood flow monitoring after transplant surgery,” Minim. Invasive Ther. Allied Technol.13(2), 87–94 (2004).
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E. L. Carstensen, K. J. Parker, and R. M. Lerner, “Elastography in the management of liver disease,” Ultrasound Med. Biol.34(10), 1535–1546 (2008).
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J. A. Clark, J. C. Cheng, and K. S. Leung, “Mechanical properties of normal skin and hypertrophic scars,” Burns22(6), 443–446 (1996).
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F. P. Wieringa, F. Mastik, and A. F. van der Steen, “Contactless multiple wavelength photoplethysmographic imaging: a first step toward “SpO2 camera” technology,” Ann. Biomed. Eng.33(8), 1034–1041 (2005).
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T. R. Dawber, H. E. Thomas, and P. M. McNamara, “Characteristics of the dicrotic notch of the arterial pulse wave in coronary heart disease,” Angiology24(4), 244–255 (1973).
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A. A. Kamshilin, V. Teplov, E. Nippolainen, S. Miridonov, and R. Giniatullin, “Variability of microcirculation detected by blood pulsation imaging,” PLoS ONE8(2), e57117 (2013).
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M. Umut Ozcan, S. Ocal, C. Basdogan, G. Dogusoy, and Y. Tokat, “Characterization of frequency-dependent material properties of human liver and its pathologies using an impact hammer,” Med. Image Anal.15(1), 45–52 (2011).
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A. Manduca, T. E. Oliphant, M. A. Dresner, J. L. Mahowald, S. A. Kruse, E. Amromin, J. P. Felmlee, J. F. Greenleaf, and R. L. Ehman, “Magnetic resonance elastography: non-invasive mapping of tissue elasticity,” Med. Image Anal.5(4), 237–254 (2001).
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G. Varotti, G. L. Grazi, G. Vetrone, G. Ercolani, M. Cescon, M. Del Gaudio, M. Ravaioli, A. Cavallari, and A. Pinna, “Causes of early acute graft failure after liver transplantation: analysis of a 17-year single-centre experience,” Clin. Transplant.19(4), 492–500 (2005).
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S. C. Millasseau, J. M. Ritter, K. Takazawa, and P. J. Chowienczyk, “Contour analysis of the photoplethysmographic pulse measured at the finger,” J. Hypertens.24(8), 1449–1456 (2006).
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C. J. Bruns, D. Neuhof, H. Erasmi, and T. Schmitz-Rixen, “In vivo biomechanical properties of three different graft materials in peripheral vascular surgery,” Int. J. Angiol.7(1), 52–56 (1998).
[CrossRef]

Settmacher, U.

U. Settmacher, B. Stange, R. Haase, M. Heise, T. Steinmüller, W. O. Bechstein, and P. Neuhaus, “Arterial complications after liver transplantation,” Transpl. Int.13(5), 372–378 (2000).
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E. Zahedi, K. Chellappan, M. A. Ali, and H. Singh, “Analysis of the effect of ageing on rising edge characteristics of the photoplethysmogram using a modified Windkessel model,” Cardiovasc. Eng.7(4), 172–181 (2007).
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B. Terjung, I. Lemnitzer, F. L. Dumoulin, W. Effenberger, H. H. Brackmann, T. Sauerbruch, and U. Spengler, “Bleeding complications after percutaneous liver biopsy. An analysis of risk factors,” Digestion67(3), 138–145 (2003).
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J. Quiroga, I. Colina, A. J. Demetris, T. E. Starzl, and D. H. Van Thiel, “Cause and timing of first allograft failure in orthotopic liver transplantation: a study of 177 consecutive patients,” Hepatology14(6), 1054–1062 (1991).
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U. Settmacher, B. Stange, R. Haase, M. Heise, T. Steinmüller, W. O. Bechstein, and P. Neuhaus, “Arterial complications after liver transplantation,” Transpl. Int.13(5), 372–378 (2000).
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[CrossRef] [PubMed]

Svaasand, L. O.

Takazawa, K.

S. C. Millasseau, J. M. Ritter, K. Takazawa, and P. J. Chowienczyk, “Contour analysis of the photoplethysmographic pulse measured at the finger,” J. Hypertens.24(8), 1449–1456 (2006).
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P. Zakharov, M. S. Talary, and A. Caduff, “A wearable diffuse reflectance sensor for continuous monitoring of cutaneous blood content,” Phys. Med. Biol.54(17), 5301–5320 (2009).
[CrossRef] [PubMed]

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P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

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A. A. Kamshilin, V. Teplov, E. Nippolainen, S. Miridonov, and R. Giniatullin, “Variability of microcirculation detected by blood pulsation imaging,” PLoS ONE8(2), e57117 (2013).
[CrossRef] [PubMed]

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B. Terjung, I. Lemnitzer, F. L. Dumoulin, W. Effenberger, H. H. Brackmann, T. Sauerbruch, and U. Spengler, “Bleeding complications after percutaneous liver biopsy. An analysis of risk factors,” Digestion67(3), 138–145 (2003).
[CrossRef] [PubMed]

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P. Thampanitchawong and T. Piratvisuth, “Liver biopsy:complications and risk factors,” World J. Gastroenterol.5(4), 301–304 (1999).
[PubMed]

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T. R. Dawber, H. E. Thomas, and P. M. McNamara, “Characteristics of the dicrotic notch of the arterial pulse wave in coronary heart disease,” Angiology24(4), 244–255 (1973).
[CrossRef] [PubMed]

Tokat, Y.

M. Umut Ozcan, S. Ocal, C. Basdogan, G. Dogusoy, and Y. Tokat, “Characterization of frequency-dependent material properties of human liver and its pathologies using an impact hammer,” Med. Image Anal.15(1), 45–52 (2011).
[CrossRef] [PubMed]

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M. Ziol, A. Handra-Luca, A. Kettaneh, C. Christidis, F. Mal, F. Kazemi, V. de Lédinghen, P. Marcellin, D. Dhumeaux, J.-C. Trinchet, and M. Beaugrand, “Noninvasive assessment of liver fibrosis by measurement of stiffness in patients with chronic hepatitis C,” Hepatology41(1), 48–54 (2005).
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M. Umut Ozcan, S. Ocal, C. Basdogan, G. Dogusoy, and Y. Tokat, “Characterization of frequency-dependent material properties of human liver and its pathologies using an impact hammer,” Med. Image Anal.15(1), 45–52 (2011).
[CrossRef] [PubMed]

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F. P. Wieringa, F. Mastik, and A. F. van der Steen, “Contactless multiple wavelength photoplethysmographic imaging: a first step toward “SpO2 camera” technology,” Ann. Biomed. Eng.33(8), 1034–1041 (2005).
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van Leest, A.

Van Thiel, D. H.

J. Quiroga, I. Colina, A. J. Demetris, T. E. Starzl, and D. H. Van Thiel, “Cause and timing of first allograft failure in orthotopic liver transplantation: a study of 177 consecutive patients,” Hepatology14(6), 1054–1062 (1991).
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G. Varotti, G. L. Grazi, G. Vetrone, G. Ercolani, M. Cescon, M. Del Gaudio, M. Ravaioli, A. Cavallari, and A. Pinna, “Causes of early acute graft failure after liver transplantation: analysis of a 17-year single-centre experience,” Clin. Transplant.19(4), 492–500 (2005).
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Verkruysse, W.

Vetrone, G.

G. Varotti, G. L. Grazi, G. Vetrone, G. Ercolani, M. Cescon, M. Del Gaudio, M. Ravaioli, A. Cavallari, and A. Pinna, “Causes of early acute graft failure after liver transplantation: analysis of a 17-year single-centre experience,” Clin. Transplant.19(4), 492–500 (2005).
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P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
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Wang, P. J.

P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

P. J. Wang, F. He, D. H. Liao, J. Zhang, W. C. Li, Y. F. Zhang, T. Z. Huang, X. Y. Li, and Y. J. Zeng, “The impact of age on incremental elastic modulus and incremental compliance of pig hepatic portal vein for liver xenotransplantation,” Xenotransplantation16(1), 5–10 (2009).
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F. P. Wieringa, F. Mastik, and A. F. van der Steen, “Contactless multiple wavelength photoplethysmographic imaging: a first step toward “SpO2 camera” technology,” Ann. Biomed. Eng.33(8), 1034–1041 (2005).
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R. Long, T. King, T. Akl, M. N. Ericson, M. Wilson, G. L. Coté, and M. J. McShane, “Optofluidic phantom mimicking optical properties of porcine livers,” Biomed. Opt. Express2(7), 1877–1892 (2011).
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M. N. Ericson, M. Wilson, G. Cote, C. L. Britton, W. Xu, J. Baba, M. Bobrek, M. Hileman, M. Moore, and S. Frank, “Development of an implantable oximetry-based organ perfusion sensor,” Conf. Proc. IEEE Eng. Med. Biol. Soc.3, 2235–2238 (2004).
[PubMed]

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T. J. Akl, T. J. King, R. Long, M. J. McShane, M. Nance Ericson, M. A. Wilson, and G. L. Coté, “Performance assessment of an opto-fluidic phantom mimicking porcine liver parenchyma,” J. Biomed. Opt.17(7), 077008 (2012).
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T. J. Akl, R. Long, M. J. McShane, M. N. Ericson, M. A. Wilson, and G. L. Coté, “Optimizing probe design for an implantable perfusion and oxygenation sensor,” Biomed. Opt. Express2(8), 2096–2109 (2011).
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P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

Xu, W.

M. N. Ericson, M. A. Wilson, G. L. Coté, J. S. Baba, W. Xu, M. Bobrek, C. L. Britton, M. S. Hileman, M. R. Moore, M. S. Emery, and R. Lenarduzzi, “Implantable sensor for blood flow monitoring after transplant surgery,” Minim. Invasive Ther. Allied Technol.13(2), 87–94 (2004).
[CrossRef] [PubMed]

M. N. Ericson, M. Wilson, G. Cote, C. L. Britton, W. Xu, J. Baba, M. Bobrek, M. Hileman, M. Moore, and S. Frank, “Development of an implantable oximetry-based organ perfusion sensor,” Conf. Proc. IEEE Eng. Med. Biol. Soc.3, 2235–2238 (2004).
[PubMed]

Yao, B. C.

P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

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E. Zahedi, K. Chellappan, M. A. Ali, and H. Singh, “Analysis of the effect of ageing on rising edge characteristics of the photoplethysmogram using a modified Windkessel model,” Cardiovasc. Eng.7(4), 172–181 (2007).
[CrossRef] [PubMed]

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P. Zakharov, M. S. Talary, and A. Caduff, “A wearable diffuse reflectance sensor for continuous monitoring of cutaneous blood content,” Phys. Med. Biol.54(17), 5301–5320 (2009).
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P. J. Wang, F. He, D. H. Liao, J. Zhang, W. C. Li, Y. F. Zhang, T. Z. Huang, X. Y. Li, and Y. J. Zeng, “The impact of age on incremental elastic modulus and incremental compliance of pig hepatic portal vein for liver xenotransplantation,” Xenotransplantation16(1), 5–10 (2009).
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Zhang, J.

P. J. Wang, F. He, D. H. Liao, J. Zhang, W. C. Li, Y. F. Zhang, T. Z. Huang, X. Y. Li, and Y. J. Zeng, “The impact of age on incremental elastic modulus and incremental compliance of pig hepatic portal vein for liver xenotransplantation,” Xenotransplantation16(1), 5–10 (2009).
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Zhang, Q.

M. Sandberg, Q. Zhang, J. Styf, B. Gerdle, and L. G. Lindberg, “Non-invasive monitoring of muscle blood perfusion by photoplethysmography: evaluation of a new application,” Acta Physiol. Scand.183(4), 335–343 (2005).
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Zhang, X. H.

P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

Zhang, Y. F.

P. J. Wang, F. He, D. H. Liao, J. Zhang, W. C. Li, Y. F. Zhang, T. Z. Huang, X. Y. Li, and Y. J. Zeng, “The impact of age on incremental elastic modulus and incremental compliance of pig hepatic portal vein for liver xenotransplantation,” Xenotransplantation16(1), 5–10 (2009).
[CrossRef] [PubMed]

Zhang, Z. H.

P. J. Wang, W. C. Li, G. M. Xi, H. Q. Wang, Z. H. Zhang, B. C. Yao, W. Tang, Z. H. Deng, and X. H. Zhang, “Biomechanical study of hepatic portal vein in humans and pigs and its value in liver transplantation,” Transplant. Proc.41(5), 1906–1910 (2009).
[CrossRef] [PubMed]

Ziol, M.

M. Ziol, A. Handra-Luca, A. Kettaneh, C. Christidis, F. Mal, F. Kazemi, V. de Lédinghen, P. Marcellin, D. Dhumeaux, J.-C. Trinchet, and M. Beaugrand, “Noninvasive assessment of liver fibrosis by measurement of stiffness in patients with chronic hepatitis C,” Hepatology41(1), 48–54 (2005).
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Acta Physiol. Scand. (1)

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Figures (13)

Fig. 1
Fig. 1

Schematic of the PPG signal showing the AC and DC signals.

Fig. 2
Fig. 2

A PPG waveform obtained by a Windkessel model showing the detected peaks (red circles) and valleys (red x) using custom automated software developed in MATLAB. The green symbols show the data points used in calculating the rise time.

Fig. 3
Fig. 3

Stress-strain curves for the three PDMS phantoms.

Fig. 4
Fig. 4

Schematic of the in vitro setup showing the PPG benchtop system, the peristaltic pump, and the flow circuit used to mimic the portal vein. The insets on the bottom left and bottom right show PPG waveforms collected during an upstream and a downstream occlusion respectively.

Fig. 5
Fig. 5

Schematic of the four-element Windkessel model used to simulate the arterial pulse.

Fig. 6
Fig. 6

(a) Modeled blood flow. (b) Three pressure waveforms with different mechanical properties showing the changes in the pulse shape.

Fig. 7
Fig. 7

Pulse measured from a soft (11.7 KPa) and a stiff (61 KPa) phantom (left and right respectively)

Fig. 8
Fig. 8

Changes in the pulse rise time with compliance.

Fig. 9
Fig. 9

Pulse rise time measured from three different PDMS phantoms with YM of 11.7, 15.1, and 61 KPa.

Fig. 10
Fig. 10

Example of a downstream (left column) and an upstream occlusion (right column). In both cases, the amplitude of the pulse (top line) decreases indicating a drop in flow level. The rise time (bottom line) increased only in the case of downstream occlusions.

Fig. 11
Fig. 11

Bar plot of the rise time during upstream (USO) and downstream (DSO) occlusions for the 11.7 and 61 KPa phantoms. The error bars correspond to +/− one standard deviation.

Fig. 12
Fig. 12

Changes in the rise time and fall time of the PPG pulse for different simulated compliance values using the Windkessel model. The green region indicates the range for normal tissue while the red correspond to fibrotic tissue at different stages. The right panel shows the data after conversion of the compliance values to YM.

Fig. 13
Fig. 13

Changes in the pulse rise and fall time for different levels of vascular resistance. The green region indicates the normal range while the red corresponds to increased vascular resistance that can be caused by downstream vascular complications.

Equations (2)

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i(t)={ I 0 .sin( π.mod(t,60/HR ). HR 60. t s , mod(t,60/HR) HR 60. t s 0 , otherwise
I P max P

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