MV-TRAINER USER MANUAL
Computational Tool for Modeling and Simulation of Mechanically Ventilated
Patients
Version 0.2 – January 2014
Leidy Yanet Serna
Mauricio Hernández
Miguel Ángel Mañanas
MV-TRAINER User Manual
Content
1.
About MV-Trainer ....................................................................................................................1
1.1.
Respiratory System Model................................................................................................1
1.2.
Ventilatory Modes .............................................................................................................2
1.3.
Patient–Ventilator Interaction .........................................................................................3
2.
Running MV-Trainer.................................................................................................................3
3.
Interactive Panel ........................................................................................................................6
4.
Signal Monitor ............................................................................................................................8
5.
Saving Simulation Data .............................................................................................................9
6.
Contact and Support .............................................................................................................. 10
7.
References................................................................................................................................ 11
MV-TRAINER User Manual
MV-Trainer User Manual
1
1. About MV-Trainer
MV-Trainer is a tool based in mathematical models, developed to make easier the study
of the interaction between a mechanical ventilator and a patient. It describes all stages of
system development, including simulated ventilatory modes, the pathologies of interest and
interaction between the user and the system through a graphical interface implemented using
Simulink and Matlab version R2012b or R2013b (© The Mathworks Inc., Natick, MA),
which provides a graphical programming environment that promotes modularization of the
overall model into hierarchically smaller subsystems.
The developed computational tool allows the study of most widely used ventilatory
modes and its advantages in the treatment of different kind of patients. The graphical
interface displays all variables and parameters in the common way of last generation
mechanical ventilators do and it is totally interactive, making possible its use by clinical
personal, hiding the complexity of implemented mathematical models to the user. The
evaluation in different clinical simulated scenes adjusts properly with recent findings in
mechanical ventilation scientific literature.
1.1. Respiratory System Model
The model used in this work for the spontaneous respiratory simulation was proposed
by (Poon et al. 1992) with the order of describing the stable state respiratory response before
stimuli of hypercapnia and exercise. This model has an optimal controller that fits the
ventilation in order to minimize the respiratory work and it includes dynamic elements that
relate neural activity with mechanical ventilatory characteristics (Younes et al. 1981).
Additionally the model distinguishes between the mechanical work of the breathing during
inspiration and expiration. Therefore the model not only fits the ventilation, but also the
assembly of variables associated with the ventilatory pattern based on the minimum respiratory
work (see Figure 1).
Logarithmic
Coupler
Optimal
Controller
Quadratic
Coupler
Work Rate
Index
Neuro-mechanical
Efector
Gas
Exchanger
Chemorreceptors
Figure 1. Model of the respiratory control system proposed by (Poon et al. 1992)
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1.2. Ventilatory Modes
The modes ventilator implemented in MV-Trainer are available in the major modern
mechanical ventilators. These are based in three main modes described in Table I:
mandatory-synchronized, spontaneous and intermittent-synchronized. The operation of
these ventilatory modes and related parameters has been widely described in literature (Tobin
1994, A. Perel et al. 1992, Tobin et al. 1986).
The P-CMV and (S) CMV are known as mandatory modes controlled by pressure and
volume respectively. These modes allow the synchronization of the patient's inspiratory
efforts with the breaths generated by the ventilator. The P-SIMV and (S) SIMV are modes
that combine intermittent mandatory breaths controlled by pressure or volume respectively,
with spontaneous breaths. In all cases, the synchronization can be adjusted by volume or
pressure. In spontaneously (SPONT) all breaths are controlled by the patient.
Each ventilatory mode has a set of parameters to be adjusted by physicians depending on
the patient condition. MV-Trainer includes all parameters related with each mode, some of
them are described in Table I.
TABLE I. VENTILATORY MODES
MandatorySynchronized
PEEP/C
PAP
I:E
Flow
Wavefor
m
Rate
ETS
Plateau
VT
Pramp
Psupport
VENTILATORY MODE
Pcontrol
CONTROL PARAMETERS
Pressure
Control
x
x
x
x
x
P-CMV
Volume
Control
x
x
x
x
x
x
(S)CMV
Spontaneous
Pressure
Support
x
x
x
x
SPONT
IntermittentPressure
Synchronized
Control
x
x
x
x
x
x
x
x
P-SIMV
Volume
Control
x
x
x
x
x
x
x
x
x
(S)SIMV
Pcontrol, pressure above PEEP/CPAP to be applied during inspiration. Psupport, pressure above
PEEP/CPAP triggered by the patient. Pramp, time required for inspiratory pressure to reach the set
pressure. VT, delivered tidal volume. Plateau, pressure after the delivery of the tidal volume but before the
patient is allowed to exhale. ETS, expiratory trigger sensitivity. Rate, respiratory frequency. I:E,
inspiratory/expiratory ratio. Flow Waveform, defines the waveform supplied by the gas flow
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1.3. Patient–Ventilator Interaction
The interaction between the patient and the ventilator involves various subsystems (see
Figure 2); ventilatory modes described above and the parameters associated with the
ventilator configuration (block 2, Figure 2), respiratory patients with different levels and kind
of disease (block 1, Figure 2), and the patient-ventilator interaction (Block 3, Figure 2).
Three kinds of patients can be simulated: Chronic Obstructive Pulmonary Disease
(COPD), Restrictive Pulmonary Disease (RPD) and arbitrary patients where Ers, Rrs and
patient effort are configured by the user. Once ventilatory mode and patient pathology are
selected, their interaction can be simulated. Variables such as respiratory frequency, fR and
lung volume, Vl, are included in the feedback and they allow the computation of respiratory
elastance and resistance continuously during the simulation. That means that the mechanics
ventilatory depends of the effect that the ventilator configuration produces.
Despite that in this version of MV-Trainer the patient's inspiratory efforts are assisted by
the mechanical ventilator, the real interaction between them has not yet been performance
because such efforts do not account for work done by machine. The implementation of this
interaction is not trivial due to the complexity of the respiratory system.
Setting patient
activity during
Mechanical
Ventilation
Pathology
Respiratory
Selection
Ventilaroty
Mode
Selection
2
1
3
Level of
EPOC or
EPR
Respiratory
compliance and
resistance
calculation
Ers , Rrs
Simulation of
ventilatory
mode selected
Setting control
parameters
Ers , Rrs
f R ,Vl
Pvent
+
Simulation of
Patient - Ventilator
Interaction
Recording
parameters and
ventilatory
variables
Pvent , Plung ,VT , Faw , Ers , Rrs , f R ,...
Figure 2. Block diagram of the patient-ventilator interaction
2. Running MV-Trainer
To begin using MV-Trainer, unzip the “MV_Trainer.rar” file and check that you have all
the necessary files. The list of files in “MV_Trainer.rar” file is:
MV-Trainer User Manual
Files: Sim_Modes.m, Sim_Modes.fig
Folders: Functions, Images, ModelsR2012b, ModelsR2013b, work
Files in Folder MV_Trainer\Functions\...
VentParameters.m
VentWaveForms.m
--Sub folder ...\GUIDE:
MechanicalParameters.m
PatternCurve.m
Relation.m
ModeSelection.m
SimulationSetup.m
StartSetupMode.m
StartSetupPatient.m
--Sub folder ...\PoonModel:
SfuncPoon.m
initopt.m
mainpoon.m
--Sub folder ...\PoonModel\funcs:
PWE.m
PWI1.m
PWI2.m
VExpidot.m
chem_plant.m
constrfun.m
fitfun.m
fitfunDATA.m
mech_plant.m
simulate.m
stimvect.m
Files in Folder \MV_Trainer \Images\...
CNS3.png
GIBIC.jpg
HG5.jpg
Lungs.jpg
Pulmon.bmp
muscles.jpg
patient.jpg
udea.png
4
MV-Trainer User Manual
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Files in Folder MV_Trainer \ModelsR2012b\...
MECHPLANT.slxp
MONITOR.slxp
MVTRAINER.mdl
VENTILATOR.slxp
Files in Folder MV_Trainer \ModelsR2013b\...
MECHPLANT.slxp
MONITOR.slxp
MVTRAINER.mdl
VENTILATOR.slxp
After you have unzipped the file, you are ready to run the program in the MATLAB
environment, make sure that you are in the Matlab directory where the unzipped files are
located. To Open MV- Trainer, in the Matlab command prompt, type (Figure 3):
“Sim_Modes.m”
Figure 3. Picture that exemplifies how to run MV-Trainer
The Control Panel graphic interface and a Simulink model will appear, as shown below.
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Figure 4. Initial GUI (Graphic Interface)
Figure 5. MV-Trainer (Simulink Model)
3. Interactive Panel
The graphic interface has two main panels: the left one for the configuration of parameters
related to the patient and the right one for the mechanical ventilator configuration and
visualization of variables (Figure 6).
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0.5
0
15
0.8
0.9
0.1
0.2
10
0.3
0.4
0.5
0.5
0.6
0.6
0.7
0.8
0.9
0.7 MODES
0.8
0.9
SIMULATION
0.8
0
2
4
0
0.1
0.2
0.3
Rate: 10
6 rpm
Tinsp:
8 1.67 s
PEEP:
10 5 cmH2O
12 ETS: 25%
I:E: 2:5
Texp: 4.33 s
Plateau: 10%
0.4
0.5
0.6
0.7
0.8
0 VT: 600ml 0.5
0.6
Pramp: 125ms
0.9
1
P
1
[cmH O]
aw20 cmH2O
2
Psupport:
0.4
Loop P/V
-50
0
500
0
15
VT [ml]
0
0.4
1
5
50
0
50
1
0.6
1
CONTROLS
0.2
2
4
6
8
10
12
0
400
0.2
Vaw[l/s]
5
1
Backup: CMV
15
0
0.7
0.5
0
0.1
0.2 SETTING
0.3
0.4
VENTILATOR
0
0.6
VT [ml]
Vaw [l/s]
0.4
0.8
MONITORING:
0
0.5
Paw [cmH2O]
V [l/s]
Effort Inspiratory
Magnitude:
1.5 cmH2O
0.3
VT [ml]
0
10
Respiratory Activity:
0.2
2
2
4
4
6
8
6
8
10 10
1212
8
10
12
VT [ml]
[ml]
Volume
■1 2 3 4
Vaw [l/s]
Disease Level:
0.1
10
300
0
0
0.5
200
1
Paw [cmH2O]
100
5
0
-50
2
4
6
4
6
t [s]
2
4
6
8
10
12
Vaw[l/s]
V [ml]
0
500
400
8
10
12
PPressure
[cmH2O]
aw
[cmH2O]
Ppeak_aw: 12.03 cmH2O
0
0
2
4
6
8
10
12
300
Pprom_aw: 8.52 cmH2O
Pmin_aw: 5 cmH2O
200
Pmin_Lung: 7.63 cmH2O
VPlung
T [ml]
[cmH2O]
15
VT [ml]
EPR
1
0
0
[ml]
VTPaw
[cmH2O]
Respiratory Pathology:
1
0.5
1
■EPOC
0
VT [ml]
PATIENT SETTING
1
Paw [cmH2O]
MV-TRAINER
Paw[cmH2O]
Paw[cmH2O]
1
0.5
PEEP: 5 cmH2O
10
100
R: 6.42 cmH2O/l/s
5
0
2
4
6
8
10
8.4 s
APNEA
SIMV
12
4 l/cmH2O
6
8
C: 0.07
RC: 0.48 s
Time
(s)
t [s]
SIMULATE
STOP
10
12
Paw [cmH2O]
CANCEL
EXIT
Figure 6. Graphical interface of MV-Trainer. Left panel, for patient selection and
right panel, for mode selection and parameters of ventilation setup.
The right panel has tree tabs: the first one, Modes, allows the ventilatory mode selection
among the modes presented in Table I, the Controls tab allows setting the mechanical
ventilator parameters associated with the ventilatory mode selected; and the third tab,
Simulation, shows all resulting variables in graphical and tabular ways for their monitoring:
airway and lung pressures, volume, flow and XYcurve of Volume vs. Pressure (Figure 6).
Figure 7 shows the parameters control for SIMV mode. The user can select the inspiratory
flow pattern through the selection box “FlowPattern” and adjust the value of the parameters
either by using the slider bar or by typing directly into the box. Both the “min” and the “max”
values are shown for each slider bar and represent the range of values that the user can
configure. The values that fall within the default spans indicated are recommended, since
these are consistent with physiologically feasible ranges.
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Figure 7. Parameters control for SIMV mode, intermittent mandatory controlled by
volume mode
The virtual tool allows the change of patient and ventilator configuration in an interactive
way, i.e. the user can change values during the simulation.
4. Signal Monitor
The tab “Simulation” shows all resulting variables in graphical and tabular ways for their
monitoring, these are (see Figure 8):





Airway pressure
Lung Pressure
Volume
Flow
XY curve of Volume vs. Pressure
The resulting variables in tabular ways are:





Respiratory rate
Inspiratory time
Expiratory time
Tidal Volume
Peaks pressure
MV-Trainer User Manual





9
Mean pressure
AutoPEEP
Respiratory Resistance (Rrs)
Respiratory Compliance (Crs)
Time Constant (RC)…
Figure 8. Panel “Simulation” that shows all resulting variables in graphical and
tabular ways for their monitoring
5. Saving Simulation Data
The data resulting of the simulation can be saved through of the Matlab commands. In
the workspace are shows all resulting variables of the simulation. These can be saving by
writing in the command window (see Figure 9):
“save variable_name file_name.mat”
Where variable_name is the variable name that wish saved and file_name is the file name
whose extension is .mat.
The main variables of the simulation model are:
MV-Trainer User Manual






10
Paw: Airway pressure.
VT: Tidal volume.
Flow: Airway flow.
PLung: Lung pressure.
Rrs: Resistance of respiratory system.
Ers: Elastance of respiratory system.
Figure 9. Saving data with Matlab® commands.
6. Contact and Support
For questions and suggestions about MV-Trainer can send your valuable comments and
feedbacks to mail [email protected] or [email protected]. Once we have the
solution, then we will post it so that other users can benefit from it.
MV-Trainer User Manual
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7. References

A. Perel and Ch. Stock., 1992. Handbook of Mechanical Ventilatory Support. W.a.W.
BALTIMORE ed., ISBN 0-683-06856-3.

POON, C.S., LIN, S.L. and KNUDSON, O.B., 1992. Optimization Character of
Inspiratory Neural Drive. J Appl Physiol, 05/01, vol. 72, no. 5, pp. 2005-2017.

TOBIN, M.J., 1994. Principles and Practice of Mechanical Ventilation. McGraw-Hill ISBN
007064943X.

TOBIN, M.J., et al, 1986. The Pattern of Breathing during Successful and Unsuccessful
Trials of Weaning from Mechanical Ventilation. The American Review of Respiratory Disease,
12, vol. 134, no. 6, pp. 1111-1118.

YOUNES, M. and RIDDLE, W., 1981. A Model for the Relation between Respiratory
Neural and Mechanical Outputs. I. Theory. J Appl Physiol, 10/01, vol. 51, no. 4, pp. 963978.