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An equivalent astable multivibrator model to assess flow instability and dysfunction risk in in-vitro stenotic arteriovenous grafts.

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Title: An equivalent astable multivibrator model to assess flow instability and dysfunction risk in in-vitro stenotic arteriovenous grafts.
Authors: Chia-Hung Lin1 eechl53@gmail.com, Chung-Dann Kan2 kcd56@mail.ncku.edu.tw, Wei-Ling Chen3, Ming-Jui Wu4, Fan-Ming Yu5, Lin, Chia-Hung1 (AUTHOR), Kan, Chung-Dann2 (AUTHOR), Chen, Wei-Ling3 (AUTHOR), Wu, Ming-Jui4 (AUTHOR), Yu, Fan-Ming5 (AUTHOR)
Source: Technology & Health Care. 2016, Vol. 24 Issue 3, p295-308. 14p.
Subjects: Multivibrators, Relaxation oscillators, Flow instability, Fluid flow, Richtmyer-Meshkov instability, Mathematical models, Surgical arteriovenous shunts, Blood flow measurement, Blood pressure, Hemodialysis, Hemodynamics, Vibration (Mechanics), Stenosis
Abstract: Narrowed vessel accesses produce blood flow changes, and induce flow instability and vessel wall vibration, resulting in blood pressure, flow velocity, and flow resistance increases. The vessel wall vibrates and propagates the low axial blood flow, as representing the resistance (R) to blood flow. The compliance is a blood pressure-blood volume relation, representing the systole and diastole capacity of the blood vessel. These dynamic behaviors increase blood flow resistances and reduce blood vessel compliances. Vibration phenomena result on the elastic vessel walls and induce simple harmonic motion due to transverse vibration pressure (TVP). The rise time, amplitude, and pulse duration of transverse waves are determined by the flow resistances (R) and vessel compliances (C). Thus, a stenotic arteriovenous access has high resistance and low compliance, which can be expressed an astable multivibrator as an equivalent model consisting of a lumped resistor (R) and a lumped capacitor (C). TVP's oscillation frequency, rise time, and amplitude are determined by the flow resistances and vessel compliances. Hence, an astable multivibrator is used to model TVP parameters to estimate negative time constants, τ=(R× C), which are used to evaluate the flow instability and the dysfunction risk in in-vitro arteriovenous grafts (AVGs). Experimental results show the average negative time constants have the positive correlation as the degree of stenosis (DOS) increases (R2 = 0.8944), and their variations with the flow resistance and vessel compliance are also validated. Positive pole values, s=(-1/τ), are used to show that the force responses of the vessel walls grow in a finite time, 0.5415 ± 7.60 × 10-3 sec, and the equivalent model would be also unstable as DOS increases (R2 = 0.8802). By comparison with hemodynamic analysis, the finding of proposed model can be further carried out for screening AVG dysfunction risk during hemodialysis treatment. [ABSTRACT FROM AUTHOR]
Copyright of Technology & Health Care is the property of Sage Publications Inc. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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  Data: An equivalent astable multivibrator model to assess flow instability and dysfunction risk in in-vitro stenotic arteriovenous grafts.
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  Data: <searchLink fieldCode="AR" term="%22Chia-Hung+Lin%22">Chia-Hung Lin</searchLink><relatesTo>1</relatesTo><i> eechl53@gmail.com</i><br /><searchLink fieldCode="AR" term="%22Chung-Dann+Kan%22">Chung-Dann Kan</searchLink><relatesTo>2</relatesTo><i> kcd56@mail.ncku.edu.tw</i><br /><searchLink fieldCode="AR" term="%22Wei-Ling+Chen%22">Wei-Ling Chen</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Ming-Jui+Wu%22">Ming-Jui Wu</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Fan-Ming+Yu%22">Fan-Ming Yu</searchLink><relatesTo>5</relatesTo><br /><searchLink fieldCode="AR" term="%22Lin%2C+Chia-Hung%22">Lin, Chia-Hung</searchLink><relatesTo>1</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Kan%2C+Chung-Dann%22">Kan, Chung-Dann</searchLink><relatesTo>2</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Chen%2C+Wei-Ling%22">Chen, Wei-Ling</searchLink><relatesTo>3</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Wu%2C+Ming-Jui%22">Wu, Ming-Jui</searchLink><relatesTo>4</relatesTo> (AUTHOR)<br /><searchLink fieldCode="AR" term="%22Yu%2C+Fan-Ming%22">Yu, Fan-Ming</searchLink><relatesTo>5</relatesTo> (AUTHOR)
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  Data: <searchLink fieldCode="JN" term="%22Technology+%26+Health+Care%22">Technology & Health Care</searchLink>. 2016, Vol. 24 Issue 3, p295-308. 14p.
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– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Narrowed vessel accesses produce blood flow changes, and induce flow instability and vessel wall vibration, resulting in blood pressure, flow velocity, and flow resistance increases. The vessel wall vibrates and propagates the low axial blood flow, as representing the resistance (R) to blood flow. The compliance is a blood pressure-blood volume relation, representing the systole and diastole capacity of the blood vessel. These dynamic behaviors increase blood flow resistances and reduce blood vessel compliances. Vibration phenomena result on the elastic vessel walls and induce simple harmonic motion due to transverse vibration pressure (TVP). The rise time, amplitude, and pulse duration of transverse waves are determined by the flow resistances (R) and vessel compliances (C). Thus, a stenotic arteriovenous access has high resistance and low compliance, which can be expressed an astable multivibrator as an equivalent model consisting of a lumped resistor (R) and a lumped capacitor (C). TVP's oscillation frequency, rise time, and amplitude are determined by the flow resistances and vessel compliances. Hence, an astable multivibrator is used to model TVP parameters to estimate negative time constants, τ=(R× C), which are used to evaluate the flow instability and the dysfunction risk in in-vitro arteriovenous grafts (AVGs). Experimental results show the average negative time constants have the positive correlation as the degree of stenosis (DOS) increases (R2 = 0.8944), and their variations with the flow resistance and vessel compliance are also validated. Positive pole values, s=(-1/τ), are used to show that the force responses of the vessel walls grow in a finite time, 0.5415 ± 7.60 × 10-3 sec, and the equivalent model would be also unstable as DOS increases (R2 = 0.8802). By comparison with hemodynamic analysis, the finding of proposed model can be further carried out for screening AVG dysfunction risk during hemodialysis treatment. [ABSTRACT FROM AUTHOR]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Technology & Health Care is the property of Sage Publications Inc. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.3233/THC-161130
    Languages:
      – Code: eng
        Text: English
    PhysicalDescription:
      Pagination:
        PageCount: 14
        StartPage: 295
    Subjects:
      – SubjectFull: Multivibrators
        Type: general
      – SubjectFull: Relaxation oscillators
        Type: general
      – SubjectFull: Flow instability
        Type: general
      – SubjectFull: Fluid flow
        Type: general
      – SubjectFull: Richtmyer-Meshkov instability
        Type: general
      – SubjectFull: Mathematical models
        Type: general
      – SubjectFull: Surgical arteriovenous shunts
        Type: general
      – SubjectFull: Blood flow measurement
        Type: general
      – SubjectFull: Blood pressure
        Type: general
      – SubjectFull: Hemodialysis
        Type: general
      – SubjectFull: Hemodynamics
        Type: general
      – SubjectFull: Vibration (Mechanics)
        Type: general
      – SubjectFull: Stenosis
        Type: general
    Titles:
      – TitleFull: An equivalent astable multivibrator model to assess flow instability and dysfunction risk in in-vitro stenotic arteriovenous grafts.
        Type: main
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            NameFull: Chia-Hung Lin
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            NameFull: Chung-Dann Kan
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            NameFull: Wei-Ling Chen
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            NameFull: Ming-Jui Wu
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            NameFull: Fan-Ming Yu
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            NameFull: Chen, Wei-Ling
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          Dates:
            – D: 01
              M: 05
              Text: 2016
              Type: published
              Y: 2016
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            – TitleFull: Technology & Health Care
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