3rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and Sciences (EEECOS)-2016
Simulation of lung representing the diseases –
Bronchial Emphysema and COPD using NI-Multisim and
LabVIEW
Madhan Djearadjane [1], Soundarya Rangarajan [2], Aditya L. Kashyap [3], Manoj Kiran [4],
T Jayanthi [5]
[1] [2] [3] [4] [5]Department
of Bio-Medical Engineering, SRM University,Kattankulathur, Chennai, India
madhand8@gmail.com, jamunasow@gmail.com, adiketchup@gmail.com, jayanthi.t@ktr.srmuniv.ac.in
Keywords: Medical simulation, Bronchial Emphysema,
COPD, Multisim, LabVIEW.
Abstract
The purpose of our work is to develop a medical simulation
system by an unconventional approach, to reduce the
likelihood of a patient succumbing to a Ventilator Induced
Lung Injury (VILI) or Ventilator Associated Lung Injury
(VALI). Ventilator despite being a saviour for patients whose
respiratory systems are compromised is also capable of
aggravating the pre-existing anomaly if not used properly. In
our work, we have used analogies to remodel and represent
the respective first approximation electrical circuit equivalent
of the pathological lung, which mimic the pathophysiology of
Bronchial Emphysema and Chronic Obstructive Pulmonary
Disease (COPD). The idea is to simulate the virtual lung
using real time ventilator-parameters and check the responses
of the lung, to arrive at model based inferences and
extrapolate the physiological lung's conditions to the current
ventilator patterns so as to reduce the likelihood of ventilator
related hazards. We observed typical waveforms of the
compliance of the lung which by our analogy depicts the
functionality of the pathophysiological lung. Through real
time simulation and circuit response analysis, the ventilator
parameters can be adjusted to suit the needs of the patient
thereby reducing any unintended damage to the lung.
1 Introduction
Respiration as we know is the movement of air from outside
the body to the cells inside tissue resulting in the
simultaneous expulsion of carbon dioxide and any anomaly
that prevents this exchange from happening is called a
pathology.
Lung diseases are basically of two types: Obstructive and
Restrictive [1]. The primary symptoms of obstructive and
restrictive lung diseases are similar except the fact that the
diseases involving obstruction cause narrowing of the airway
causing an abnormally high volume of air to linger in the
lungs even after forceful exhalation. The diseases we have
considered for our work are of the former type.
Chronic Obstructive Pulmonary Disease (COPD) is a long
term lung disease presenting with a cluster of conditions,
referred to by different names based on the severity and the
parts of the lung affected [2]. The typical clinical symptoms
of COPD are: shortness of breath, tightness in chest,
accumulation of mucus and coughing up of mucus.
Bronchial Emphysema is not a severe condition by itself but
is a hyponym of the condition COPD. Chronic bronchitis as
the name suggests, is an inflammation of the bronchus and
accumulation of mucus in the airways.
At the tissue level, Bronchial Emphysema affects the deeper
bronchioles and the alveoli and COPD affects the left and the
right bronchus, bronchioles and the alveoli.
Lungs are spongy tissues that help in respiration. When the
lungs lose their ability to perform their destined function with
spontaneity, the patient finds it difficult to breathe. When
such a situation arises, there is a need for an external support.
Mechanical ventilation is a method of artificially providing
oxygen to an incompetent respiratory system either because
of an ailment or a trauma [3, 4].
The problem gets complicated when the mechanical device
intended to provide respiratory assistance, causes unintended
harm to the patient.
According to the National Trauma Institute, 40-50% of the
cases admitted in the ICU succumb to VALI [5].
In India, the possibility of a patient succumbing to some form
of ventilator related injury is far more likely and has been
found to vary between 50 and 60 percent [6, 7].
We have used this superficial knowledge of lung physiology
and existing clinical problems to come up with a ventilation
assessment unit that virtually analyses the ventilation
parameters by checking the response of an electrical
analogous lung and provide insight as to how the parameters
can be changed to effectively ventilate a lung and reduce the
negative effects caused therein.
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3rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and Sciences (EEECOS)-2016
2 Previous Work
The need to come up with a safe ventilation strategy has been
considered carefully and solutions have been provided from a
clinical point of view. All the work to reduce the negative
effects of ventilation has been through the careful monitoring
and manipulation of tidal volume (Tv) and PEEP components
of ventilation [8].
The base reference for our work is Tinku Biswas et al’s [9]
concept that represents the physiological lung in its electrical
equivalent to study the step and ramp responses of the lung
and compare the decay time for the respective transfer
function. The conclusion was that, the alveolar compliance is
directly proportional to the stability of the lung.
Figure 2: Remodelled electrical analogue of COPD
Zhongai He et al’s [10] technique to recreate the clinical
conditions of a patient-ventilator using LabVIEW and
Simulink, used a muscle driven pressure system virtually to
study the response of the respiratory system during manual
control of ventilator output, was also considered to model our
system.
Much of the existing work concentrates on building virtual
patient-ventilator systems and very less work exists on
assessing a ventilation system prior to its prescription to a
patient.
3 Project Overview
Figure 3: Transient analysis output for the remodelled circuit
We have used three familiar software to devise the model and
experiment with. The software is enlisted below:
• NI-Multisim
• MathWorks MATLAB
• NI-LabVIEW
3.1.2 MathWorks MATLAB
3.1.1 NI-Multisim
Mutisim is a powerful electronic schematic capture and
simulation program that we used to construct and remodel our
virtual lung model in [11]. The remodelled circuit of
‘Bronchial emphysema’ and ‘COPD’ are shown in figure 1
and figure 2. The software was also used to perform transient
analysis of the modelled circuit to arrive at inference of
dynamic stability of system. Figure 3, shows the transient
analysis for different values of R, L, C is shown in the
following
figure.
MathWorks MATLAB was used as a coding platform to
simulate step and ramp responses to arrive at an interpretation
of decay times of the circuit [12]. We exploited the concept
that, the airway resistance and compliance of the alveoli of
the physiological lung are analogous with electrical
component properties of resistance and capacitance
respectively. The proof of concept has been provided by step
& ramp response simulation in MATLAB.
Figure 4: Step response for a set of values of R, L, C
Figure 1: Remodelled electrical analogue of
Bronchial Emphysema
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4 Results
Table 1 shows the step and ramp response simulations for the
circuits remodelled which is a proof of concept that the
analogy actually exists. The decay time of the step and ramp
responses is almost the same which indicates the stability and
response of systems for different inputs.
Figure 5: Ramp response for the same set of
values as in figure 4
R
L
C
0.001
Step
Response
Decay
Time(s)
0.25
Ramp
Response
Decay
Time(s)
0.3
1
0.17
10
0.17
0.0001
0.50
0.50
50
17
0.0001
60
65
3.1.3 LabVIEW
LabVIEW is a user controllable interface that was used in
our work to simulate the modelled circuit in real time. The
circuit constructed in Multisim was imported into LabVIEW
and the “control and simulation module” was used to simulate
the circuit.
Table 1: Step & Ramp response decay times for different
values of R, L, and C
Figure 6: Front panel of LabVIEW simulation
Figure 7: Block Diagram of LabVIEW simulation
Figure 8: Step Reponse for case 2
Figure 6, 7 represent the LabVIEW based user controllable
screen. The Front panel is an operational unit for the user to
control and simulate the medical condition.
Since the ultimate aim is to develop a virtual ventilation
assessment system, we went on to import the remodelled
circuit into LabVIEW and control the analogous circuit from
LabVIEW’s front panel.
Figure 9: Ramp response for case 2
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3rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and Sciences (EEECOS)-2016
Figure 13: Block diagram for pressure cycle loop
Figure 10: Step response for case 3
Figure 14: Block diagram for volume cycled loop
Figures 13, 14 represent the corresponding block diagram of
figure 12.
Conclusion & Future Work
Figure 11: Ramp response for case 3
Figures 9, 10, 11 represent the step and ramp response curves
for different stages of severity of the diseases considered.
Figure 12: Front panel of the intended simulation screen
Figure 12 represents the user controllable screen of our
intended model. The user can select the disease he wants to
simulate, can select the mode of ventilation for respiratory
support and control the tidal volume (T v) / pressure of air
delivered to the patient by controlling the analogous voltage
input to the circuit.
The system is a ventilation assessment module which can be
used for real time simulation, for clinicians and professionals
to learn and visualize the behaviour of a physiological system
to a crude input before dealing with the reality, which we
believe would help them to take appropriate decisions not
only to support the life of the patient but also to minimize the
negative effects of the procedure itself and decrease the
postoperative care required and speed up recovery.
Currently, the project has covered only 2 diseases at a
superficial level. The physiology of the lung is to be studied
extensively to get a detailed approximation of each of the
components of the lung. Once the model is ready, the
electrical analogous concepts can be used to exploit the
physiological functioning of a lung, purely in electrical terms,
thereby creating a completely user definable virtual model of
a lung. The scope of the project can be extended to simulation
of other major diseases that require a ventilator support and
are susceptible to ventilator associated injuries. Trainees can
use the software to simulate and safely analyze a lungs
condition to ventilator settings. The software is user friendly,
user designable, user definable and user controllable. The
software could also be used by medical trainees for
simulation purposes for medical training. It could give us a
quick real time analysis before the patient is subjected to a
ventilator.
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3rd International Conference on Electrical, Electronics, Engineering Trends, Communication, Optimization and Sciences (EEECOS)-2016
References
[1] "Lung Diseases Overview", WebMD, 2016. [Online].
Available:
http://www.webmd.com/lung/lung-diseasesoverview.
[2] C. Disease and A. Medicine, "Chronic Bronchitis and
Chronic Obstructive Pulmonary Disease (ATS
Journals)", American Journal of Respiratory and Critical
Care Medicine, 2016.
Journal of Physiology-Lung Cellular and Molecular
Physiology 282.5 (2002): L892-L896.
[9] Biswas, Tinku, et al. “An Electrical Model for Bronchitis
and Emphysema of Human Respiratory System”, IJMER
Volume-2 Issue-5, Sep-Oct 2005.
[10] He, Zhonghai, and Yuqian Zhao. “Modeling in
[3] "Ventilator Management: Introduction to Ventilator
Respiratory Movement Using LabVIEW and Simulink.
Management, Modes of Mechanical Ventilation, Methods of
Modeling”. Software: 137-160.
Ventilatory Support", Emedicine.medscape.com, 2016.
[11] Borrello, Mike.” Biomedical systems: modeling and
[Online]. Available:
http://emedicine.medscape.com/article/810126-overview.
simulation of lung mechanics and ventilator controls design.
VisSim tutorial series”. Boston(1997).
[4] Ventilation Options for COPD-Topic Overview, WebMD,
[12] Mathworks - Makers Of MATLAB And Simulink.
2016. [Online].
In.mathworks.com. N.p.,2016. Web. 15 Apr. 2016.
[5] "National Trauma Institute", Nationaltraumainstitute.org,
[13] Downham, Mechanical Ventilation Series2016. [Online]. Available:
Pressure/Volume loop. - Critical Care Practitioner, Critical
http://www.nationaltraumainstitute.org/home/ventilatorinduced-lung-injury.html.
Care Practitioner, 2016.
http://www.jonathandownham.com/mechanical-ventilation-
[6] A. Vasudevan, R. Lodha and S. Kabra, "Acute lung injury
series-pressurevolume-loop/.
and acute respiratory distress syndrome",Indian J Pediatr,
vol. 71, no. 8, pp. 743-750, 2004.
[14] Hall, John E. Guyton and Hall textbook of medical
physiology. Elsevier Health Sciences, 2015.
[7] N. de Prost, J. Ricard, G. Saumon and D. Dreyfuss,
Ventilator-induced lung injury: historical perspectives and
clinical implications, Ann Intensive Care, vol. 1,no. 1, p. 28,
2011.
[8] Gahlot, Luxmi, Eric B. Milbrandt, and James Snyder.
Higher initial tidal volumes associated with the subsequent
development of acute lung injury in dose-response. American
[15] Ganong, William F., and Kim E. Barrett. Review of
medical physiology. Norwalk, CT: Appleton & Lange,
1995.
[16] Pilbeam, Susan P., and Jimmy M. Cairo. Mechanical
ventilation: physiological and clinical applications.
Mosby, 2006.
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[17] Tobin, Martin J. Principles and practice of mechanical
ventilation. (2006): 426.
506