1. Project Report on
Simple Lung Equivalent
(Project Related Team Work – WS 2014)
Masters in Biomedical Engineering Sciences
Winter Semester 2014
By: Sandeep Ambardekar
Rohit Hadia
Narasimharaju Gottumukkala (G N Raju)
Raju Koorakula (K Raju)
Supervisor : Dip-Ing (FH) Michael Windisch
Vienna , January 31, 2015

2. Table of Contents
1 Introduction ............................................................................................................1
2 Funtioning and Structure of a Lung.........................................................................2
3 Concept Developement..........................................................................................4
3.1 Initial Concept Development.............................................................................4
3.2 Block Diagram of a System ..............................................................................5
3.3 Final Concept Development ............................................................................ 6
4 Pressure Measurement ..........................................................................................9
4.1 Electronic Circuit Design for Pressure Measurement........................................9
4.2 Observation Table (Pressure Readings)......................................................... 10
5 Usability Aspects and Integration.......................................................................... 11
6 Project Plan and Time Log Sheet ......................................................................... 12
7 Conclusion ........................................................................................................... 14
8 References........................................................................................................... 15
9 Tables and Figures .............................................................................................. 16

3. 1
1 Introduction
Simple Lung Equivalent is a mechanical-hydraulic circuit that replicates the blood circulation
similar to that of blood circulation of an actual human lung. This circuit has the input blood
flow pressure same as that incase of a human lung. And the out flow blood pressure is same
as that of a out flow pressure in human lung. The purpose of this Simple Lung Equivalent is
to replace an Animal Lung which is being used for early stage testing in an AlveoPic project.
An AlveoPic is the system designed to store a human lung before transplantation. By using
this system, the shelf life of a lung can be increased so that surgeons will have enough time
for surgery. With the increased shelf life of a lung, it will be also possible to transport a lung
to another facility in case situation arises.
It is obvious that this artifial simple lung model is not an alternative to an animal lung for
testing of an AlveoPic system. However, this artificial lung model is very useful during early
stage initial testing of an AlveoPic system due to its handling easiness, infinte shelf life. And
the most important feature is predictable behavior. It means an artifial lung model will always
work at parameters those are set for. In case of an animal lung, it is possibility that test
results would be affected if the second lung is different in nature than the previous one. Due
to the limited shelf life of an animal lung, it is not possible to carry out tests using only one
animal lung. So use of an artifical lung model has the best advantage of having reliability and
repeatabilty in testing.
The simple lung equivalent is the first step to model an artifial lung. It is named as a Simple
as this lung modelas it is designed by taking considerations of only In-flow Pressure of blood
and Out-flow Pressure of blood. This simple model does not take consideration of oxygen
perfusion, temperatures and blood contents. This model is demonstrated with noraml or
distilled water. After successful design an working of a simple lung equivalent, a mor
complex model can be built.
In order to design a simple lung equivalent, we did literature search on functioning and
working of a lung. We studied the structure of an actual human lung and try to design an
artifial model as close as possible. The major specifications we received are about In-flow
Pressure and Out-flow Pressure. The range of In-flow pressure is between 10mm of Hg to
25 mm of Hg and Out-flow Pressure is between 2 mm of Hg to 5 mm of Hg. In extened
research we found that average In-flow Pressure is considered as 14mm of Hg. Based on
this literature study, we design a simple lung circuit that can generate the resistance on
blood flow to reduce the pressure by around 10 mm of Hg. The report further describes the
design and development process of a Simple Lung Equivalent.[1][2]

4. 2
2 Functioning and Structure of a Lung
Lung is roughly divided into number of zones. Each zone has a different behaviour with
respect to blood flow. These four zones are, 1. Collapse 2. Waterfall, 3. Distention, 4.
Interstitial Pressure.
PA: Pulmonary Arterial Pressure
Pv: Pulmonary Venous Pressure
Pa: Alvolar Pressure (Resistance)
Fig.1 Zonal blood distribution in lungs [4]
Zone 1 – Collapse
Pulmonary artery pressure basically negligible Because alveolar pressure exceeds
pulmonary artery pressure, the distensible capillaries in the alveolar wall are
collapsed. PA>Pa>Pv There is NO blood flow in zone 1
In this zone, the veins are of collapsible nature. Pa > Ppa > Ppv
Zone 2 – Waterfall
Pulmonary artery pressure exceeds alveolar pressure. Has blood flow Pa>PA>Pv
The pulmonary artery pressure minus alveolar pressure (Pa-PA) gradient.
It falls into the pulmonary venous system (like a waterfall) Zone 2 is the waterfall zone

5. 3
In this zone, the veins are stiffer and are not collapsible like in zone 1.
Ppa > Pa > Ppv
Zone 3 – Distention
Blood flow is proportional to the pulmonary artery pressure minus pulmonary vein pressure
(Pa - Pv) gradient Pa>Pv>PA
In this zone, the veins are not collapsible but these are elastic and expands due to the blood
flow. Due to the elastic nature, it creates compliance within the system.
Ppa > Ppv > Pa
Zone 4 – Interstitial
Blood flow is proportional to the pulmonary artery pressure minus pulmonary interstitial fluid
(ISF) pressure gradient (Pa – PISF)
In this zone, there is a negative pressure. This is due to the fluid surrounding the veins which
exerts pressure on the veins and so expressed in negative.
Ppa>Pisf>Ppv>Pa

6. 4
3 Concept Developement
From the literature search about the functioning of lung, we understands the
blood pressure at inlet of pulmonary artery which is In-flow pressure (10-25 mm
of Hg) and at outlet of pulmonary vein which is Out-flow pressure (2-5mm of
Hg). Hence, we understand that we have to create a resistance that ensures the
pressure drop of about 10-12 mm of Hg between inlet and outlet of the Simple
Lung Equivalent model. This is considering an average blood In-flow of 14mm of
Hg that is derived from the In-flow range of 10-25mm of Hg.
3.1 Initial Concepts
From the above initial data, we did brainstorming sessions with all team
members. The following initial concepts were generated:
Fig.2 Different Flow Resistance concepts designed and discussed
A. A simple flow resistance using semi permeable membrane
B. Pressure regulation by compression mechanism of the Tubes
C. Flow Resistance variation using Poiseuille's law choosing different
arrangement of tubes with different cross-section diameters

7. 5
From the extensive literature research on structure and blood flow of a lung, we
carefully divided lung into separate modules. We created each module that
resembles the actual lung and tested for its functioning. We came with following
refined design that will mimic the blood circulation same as it happened in the
actual lung.
3.2 Block Diagram of a System
Block Diagram in Fig.8 shows the working flow of Simple Lung Equivalent Circuit consisting
of various blocks as mentioned in figure to measure the pressure parameters
Fig.3 Block Diagram of simple Lung Equivalent Circuit

8. 6
3.3 Block Diagram and Final Concepts of a Lung Model
With reference to the literature search, we designed a circuit that has 4 different
zones. Each zone is designed with respect to the nature of veins in that
particular zone in a lung where variation of inlet and outlet pressures varies
based on varying resistance due to parellel connections of the tubes as well as
gravity . [3][4]
Fig 4a. Finalised Concept for Simple Lung Equivalent Circuit
Fig 4b. Block Diagram for Simple Lung Equivalent Circuit
Design of Zone 1:
In this zone the alveolar pressure is higher than pulmanory pressure. So veins
remains collapse most of the time. And there is almost no blood flow in this
zone.So we used soft tubes in this zone. These soft tubes are then kept collpse
by using tie-wraps. So now, the veins in this zone remains collapse and no blood

9. 7
flows through this zone.The another great idea would be, do not create this zone
at all. As there is no blood flow withing this zone, there is no need to create this
zone. However, we created this zone so as to understand the complete sturcutre
of a lung circuit. Elimination of this zone from the system would have no effect
on the ciruit performance but may lead to little confusion about the missing
zone. Hence, we decided to mentioned the zone 1 and also created an actual
circuit for this zone to avoid any confusion.
Fig 5. Simple Lung Equivalent Zone 1
(No blood flow in zone 1)
Design of Zone 2:
This zone is consist of veins that are not collapsible and elastic. The blood flows
as it fills the vein. It is usually called as waterfall zone. So we built this zone with
tubes which are non-collapsible and non-elastic.
Design of Zone 3:
In this zone, the veins have elasticity. Due to this, first - the blood gets filled in
these veins. Then, the veins expands to accommodate more blood and
compliance get created. Then, blood flows due to compliance. This is usually
known as distention.So we built this zone using tubes which can expand to
create compliance.
Fig 6. Simple Lung Equivalent Zone 2(Ppa>Pa>Ppv) and Zone 3 (Ppa>Ppv>Pa)

10. 8
Design of Zone 4:
In the zone 4, the veins are surrounded by interstitial fluid that created pressure
on the veins. It means there is negative pressure exists in the zone 4.
So in out model, we created this negative pressure by applying mechanical force
on the tubes in this zone. The tubes are pressed from out side to create negative
pressure inside the tubes.
Fig.7 Alternative Design for Zone 4 (Ppa>Pisf>Ppv>Pa)
Alternate option to create negative pressure in the zone 4:
We also thought another design that creates negative pressure in this zone. In
this we proposed to create a small reservior around the tubes. This small
reservoir can be a leak proof pouch or similar structure filled with fluid. This fluid
can be a type of gel or thick liquid or plasmic substances to act like interstitial
fluid of body.
Fig.8 Alternative Design for Zone 4 to create –ve pressure
However, we opted for our first concept i.e. Applying mechanical force on the
tubes to create negative pressure. This was quiet obvious choice as it is easy to
built and convenient to handle over any kind of a gel or liquid or fluid to create
negative pressure.

11. 9
4 Pressure Measurement
4.1 Electronic Circuit Design for Pressure Measurements
As Required pressure difference between inlet and outlet of blood vessel is very
low in range of 0-15 mmHg a pressure transducer with very high sensitivity
5µv/v/mmHg is used which are also used to measure the invasive blood
pressure and are also suggested by AAMI(Association for the Advancement of
Medical Instrumentation) ,which was excited using a 5V supply making its
sensitivity of 25µv/mmHg and the output from transducer is amplified using INA
122 a non-inverting instrumentation amplifier whose output can be directly read
on Digital multimeter or can be feeded to microprocessor .
PT :Pressure Transducer
Fig.9 Pressure Measurement Circuit Diagram
Pressure measurement was done using practical method of gravitational hydrolic
pressure using specific gravity of water as water was the fluid used throughout
as the liquid which has to be flowed through Simple Lung Equivalent circuit and
also cross reference using electronic calculation using the gain and output
voltage of INA 122.Gain Resistance (Rg) as shown in Fig.9 was choosen of 40.1
Ohms giving gain of 5000 for INA 122 from datasheet of INA 122 as well as
formula for gain calculation. Following are the pressure difference values
between inlet and outlet of the Simple lung Equivalent circuit measured on using
gravitational flow of water through circuit

12. 10
4.2 Observation Table
Table.1 : Pressure Measurement Table for simple Lung Equivalent Circuit
As Per Table.1 we got pressure difference of approximately in range of 10-
15mmHg for various inlet Pressure , which shows that Our simple Lung
Equivalent Circuit is able to reduce the outlet pressure by almost 10-15mmHg in
comparision to inlet which is also required as per all the researched literature
about the Pressure drop in blood flow between pulmonary artery and plumonary
vein in Human lungs.

13. 11
5 Usability Aspects and Integration
In Designig Simple Lung Equivalent Circuit usability aspect were taken into
consideration while designing as the basic purpose of this circuit is to be used as
replacement of the actual animal lung for research studies so basic class of users
will be reserachers or research related people , following are the main point
taken into cosideration as per usability aspect:
Fig.10 Usability Considerations
1.Variable Design As Per requirement :
The circuit is designed using simple tubes and connectors made up of silicon
rubber or plastic material which can be assembled and disassembled easily to
make any structural changes in the circuit as per the requirement of the studies
also inlet and outlet points can be varied zone wise so as to get varios pressure
results and effect of gravity as well structure on pressure variation and flow
variations etc.
2.Pressure Cross Referencing Table :
The Pole of the circuit is provided with the Centimeter scale so that cmH20
pressure value can also be measured parallel with the pressure measurement by

14. 12
the pressure transducer which adds to the precision of the pressure values
obtained at the pressure transducers.
3.Variable inlet pressure :
Inlet pressure in the Simple Lung Equivalent circuit can be varied simply by the
changing the height of the pole which adjust the water column level thus
resulting in the increase or decrease of the inlet pressure as per requirement
quite simply also a flow pump can be fixed at the inlet to create a constant
pressure or a variable pressure by changing the rotation of the pump.
6 Project Plan and Time Log Sheet
Figure 5. shows the project plan over entire summer semester 2014 in which our primary
goal is to achieve exact user requirements and do related research for technical as well as
usability aspect of the Device. Practical assembling and execution of the project is planned
in winter semester 2014 . Work is equally distributed among a four member team to do all
the related phases like research , implementation and execution .External support for user
needs is provided by Mr.Stephan Krauter who is a working member of Hospital named
Sanatorium Hera. Regular review , feedbacks and guidelines were provided by FH-Prof. DI
Dr.techn. Stefan Sauermann throughout semester.
Figure 11. Project plan for Winter Semester 2014

15. 13
Calendar
Week
Activities
Time Log (hrs)
Sandeep Rohit GN Raju K Raju
CW36
PRTW Kick-off
1. Info on various projects is presented to all students by staff and ex-students. 1 1 1 1
2. PRTW briefing by Mr Forjan 2 2 2 2
CW37
Project Planning & Project Initiation
1. Project plan is prepared indicating measure activities, review stages. 3 3 3 3
2. Work initiated with literature search and project briefing by alveopic team. 3 3 3 3
CW38
Literature study continued. 4 6 8 8
1. Meetings with other team for briefing on lung anatomy, working and blood circulation in the
lung. 1 4 4 4
CW39
Literature study continued. 2 2 6 6
1. Knowledge sharing session by members of other team about working of a lung. 2 2 2 2
CW40
Initial Concept Development
1. Based on literature study, constraints are identified. Brain storming sessions are conducted
to generate initial concepts. 8 6 6 6
CW41
1. Concepts developed by each members are presented within team. 2 2 2 2
2. More specific concepts are generated and feed back from first session were incorporated in
revised concepts. 8 4 4 4
3. Prepare system block diagram and Lung Block Diagram 4 0 0 0
CW42
Initiate braid-board modelling
1. Concept development continued with detailing. Components and part specifications identified
to check feasibility of concepts. 6 4 4 3
2. With available components, parts, braid-board modelling was done to check concepts 4 4 4 4
CW43
Concept Finalisation & Initiate Prototyping
1. Prepare draft Bill of Materials for finalised concept 4 3 3 2
2. Start search for vendor/ supplier for components 6 8 8 8
CW48
Develop electronics for the project
1. Identify components for electronics 2 6 2 2
2. Design electronic circuit for pressure transducer and signal amplifying circuit. 2 8 1 1
3. Usability Aspect Studied for the system 4 2 2 2
CW49
1. Usability Integration into the system 4 4 4 4
2. Conclusions from first prototypes, braid-board models. 6 4 4 4
3. Concept Refinement and finalization 4 4 2 2
CW50
1. Electronic sensor and amplifier studies and calibrations 8 10 6 4
2. Final Prototyping initiated. 2 2 2 2
3. Final electronic assembling and use 6 8 4 4
CW51 Final Concept Refinement 8 6 8 6
CW52 Final Testing 20 24 20 20
CW01 Complete set up and final readings and design variations 2 6 6 2
CW02
Final Presentation & Initiate Report Writing
1. All collected data during literature search, brainstorming sessions, testing, observations are
collated to generate final report. 6 2 2 3
2. A presentation is prepared and presentated to all students and supervisors 1 1 1 1
CW03 Final Testing & concluding the project. 3 3 2 2
CW04 Final Report Preparation. 6 2 2 2
Total Time for each team member 145 147 129 120
Table 2 : Time Log Sheet of Team Members

16. 14
7 Conclusion
A simple lung equivalent model is created in order to carry out various testings of AlveoPic
system. This simple lung model can be adjusted to obtained in-flow pressure between 10mm
of Hg to 25 mm of Hg into the lung. The corresponding out-flow pressure will be between 2
mm of Hg to 5 mm of Hg. Further, this model can be adjusted to increase or decrease
pressure drop in order to facilitate more combination for experiementing. With this current
design of a simple lung model, the pressure is obtained by using gravity. And due to its
design, it is practically possible to adjust the inflow pressure at infinte steps by positioning
the reservoir at required height. The pressures of this model are calculated from the voltage
received by pressure transducer and using non-inverting op-amp circuit.
In the more advance version, this voltage can be further process through micro-controller
and direct display of pressure can be obtained on the LCD. It may be also possible to use
micro pressure gauges which can directly display the pressures on the gauge itself.
However, availability and cost for these sensors is require to be considered. Also, in the
more advancement of this simple lung model, the temperature sensors can be included to
study effect on circulation at different temperature conditions. In order to get more close to
the actual lung, air perfusion can be used to replicate oxygen perfusion as in case of the real
lung. Thus, step-by-step, this simple lung equivalent model can be improved so that it will
replicate the functioning very close to the actual human lung.

17. 15
8 References
[1] Ex vivo lung evaluation and reconditioning, The Journal of Heart and Lung
Transplantation December 2008.
-FERNANDES1, Alessandro Wasum MARI
3,
Fernando do Valle UNTERPERTINGER3, Mauro CANZIAN4, Fabio Biscegli JATENE5
http://www.producao.usp.br/bitstream/handle/BDPI/8482/art_PEGO-
FERNANDES_Avaliacao_e_recondicionamento_pulmonar_ex_vivo_2010.p
df?sequence=1
[2] The Journal of Heart and Lung Transplantation December 2008
Organ Preservation: Technique for Prolonged Normothermic Ex Vivo Lung Perfusion
Marcelo Cypel, MD, Jonathan C. Yeung, MD, Shin Hirayama, MD, Matthew Rubacha, MD,
Stefan Fischer, MD, Masaki Anraku, MD, Masaaki Sato, MD, Stephen Harwood, MD,
Andrew Pierre, MD, Thomas K. Waddell, MD, Marc de Perrot, MD, Mingyao Liu, MD, and
Shaf Keshavjee, MD
Link:
http://www.perfusix.com/uploads/3/1/2/4/31243771/9_cypel-technique_for_prolonged_evlp.pdf
[3] The Four Zones of a Lung
Link: http://www.patient.co.uk/health/the-lungs-and-respiratory-tract
[4] Blood Circulation in an upright Lung
Link:
http://web.squ.edu.om/med-
Lib/MED_CD/E_CDs/anesthesia/site/content/v02/020514r00.HTM

18. 16
9 Tables and Figures
Table 1. Measurement Table for simple Lung Equivalent Circuit..........................................10
Table 2. Time Log Sheet of Team Member..........................................................................13
Figure 1. Zonal blood distribution in lung................................................................................2
Figure 2. Different Flow Resistance concepts designed and discussed .................................4
Figure 3. Block Diagram of simple Lung Equivalent Circuitce..............................................5
Figure 4. a. Finalised Concept for Simple Lung Equivalent Circuit .........................................6
Figure 4. b. Block Diagram for Simple Lung Equivalent Circuit...............................................6
Figure 5. Simple Lung Equivalent Zone 1...............................................................................7
Figure 6. Simple Lung Equivalent Zone 2 and Zone 3...........................................................7
Figure 7. Simple Lung Equivalent Zone 4...............................................................................8
Figure 8. Alternative Design for Zone 4 to create –ve pressure..............................................8
Figure 9. Pressure Measurement Circuit Diagram..................................................................9
Figure 10. Usability Considerations......................................................................................11
Figure 11. Project Plan.........................................................................................................12