Design of an Implantable Peritoneovenous Shunt for Patients Affected by Refractory
Ascites in End-Stage Liver Disease
1. Drain ascitic fluid from peritoneum
into femoral vein (on order of
L/week or 30-40 mL/min)
2. Prevent backflow from the femoral
vein into the peritoneum (>5% of
fluid flows back into peritoneum)
3. Prevent occlusion for at least 2
years after implantation
PROBLEM
Refractory ascites is a condition that
affects >100,000 patients/year with
end-stage liver disease (ESLD).
Figure 1: On the left is a typical belly from a patient affected by refractory ascites. On the right is an example
peritoneovenous (PV) shunt to drain this fluid from the peritoneum into the subclavian vein.
Fluid builds up in the abdominal cavity
called the peritoneum, and , if left
untreated, can lead to respiratory
failure, hypertension, and death.
The most common procedure
(paracentesis) is invasive, requiring a
needle inserted into a patients to drain
this fluid every 2 weeks.
1
Vasquez ,
Alexandra
José
Kate
2
2
Dr. James Monaco , Dr. Mike Kassin
NAME: The Clavus ® Shunt System
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Figure 2: On the left is the assembly of the final device design in SolidWorks. Note that there would be a catheter inserted into
the holes on the bottom part of the housing. To the right are orthographic drawings for this assembly produced in SolidWorks.
0
DEVICE SPECIFICATIONS:
•Catheter’s total length is roughly the
distance from the peritoneum to femoral
vein (< 1.5 ft)
•Catheter’s radius is between 0.5-1.0 mm
•Flow rate into femoral vein 5-15 mm Hg
•Sterile, single-use device made from
biocompatible materials
•Uses at least four pistons and a grooved
screw to pump fluid (limits occlusion)
•Check valve to prevent backflow of
ascetic fluid back into the peritoneum
0.5 mm
1 mm
1.5 mm
2 mm
4 mm
0
20
30
40
50
60
Cycles Rate (cycles/min)
80
90
30 mL/min flow rate is reached
with a screw rotation frequency
6.21 cycles/min.
Assuming 3 pushes/cycle, the
patient will have to push the
device 18 times in one minute,
or one time every 3 seconds to
achieve optimal fluid flow.
License to Industry
• License device to a larger
company in biomedical industry
MODELING
COLLABORATIONS
Bernoulli Equation with
Friction and Pump Work
Prototype
Flow Rate vs Pressure
Flow Rate vs Reynolds
200
2200
0.5 mm
1 mm
1.5 mm
2 mm
4 mm
2000
1800
Figure 3: Figure showing the mock-up of the device.
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Patent and Trademark
Applications
• Provisional patent already filed
(advised by Kilpatrick Townsend)
• Submit an application to trademark
the Clavus ® shunt system
• Submit full patent application at
United States Patent and
Trademark Office (USPTO)
Figure 5: Flow rate as a function of the cycles rate at different pump chamber radius.
DEVICE IDEATIONS,
MOCKUP, PROTOTYPE
Mock-up
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Figure 4: Figure showing the first prototype of the device.
1600
160
140
1400
Alternative shunt approaches can
greatly enhance the quality of life for
patients affected with this condition,
with a potential market size of >$350
million/year.
1200
1000
Table 1: A morphological chart showing various design ideations contemplated for the mock-up and prototype.
120
100
80
Special Thanks to all the collaborators
that made this project a reality!
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400
40
200
20
0
0.5 mm
1 mm
1.5 mm
2 mm
4 mm
180
600
www.PosterPresentations.com
Standardized Testing
• Burst Strength Testing (ISO 7198:
1998)
• Shunt leak rate (ISO 10555-1)
• Tensile strength (ISO 527-1)
• Fluid Entry Pressure (ISO
7198:1998)
150
100
Timothy
1
Ibru ,
NEXT STEPS
Flow Rate vs Cycles Rate
800
TEMPLATE DESIGN © 2008
1
Raskauskas ,
PERFORMANCE
TESTING
DESIGN SOLUTION
Flow Rate (mL/min)
To build a peritoneovenous (PV)
shunt that can:
1
Low ,
Flow Rate (mL/min)
OUR MISSION
Graham
1
McAdory ,
Reynolds
Jim
1
Schwoebel ,
0
20
40
60
80
100
120
Flow Rate (mL/min)
140
160
180
200
Figure 6: This figure plots flow rate as a function of
Reynold’s Number for various catheter radii. Under the
design parameters for the final design, turbulence is unlikely
to develop because the lowest sized radius (0.5 mm, blue
curve) does not reach turbulence until flow rates go above 50
mL/min and the second lowest sized radius (1.0 mm, red
curve) does not reach turbulence until 180 mL/min. The
current device will use a radius above 0.5 mm and below 1
mm, so a laminar flow assumption is valid.
0
0
5
10
15
Pressure (mmHg)
20
25
30
Figure 7: The figure plots flow rate as a function of
pressure at various radii for the catheter. Note that this
is important in selecting the vein to drain the PV shunt
into. For the purposes of this project, since the flow rate
will need to be roughly 30 mL/minute with a pressure
of 15 mmHg (in femoral vein) the radius of the catheter
needs to be above 0.5 mm and below 1 mm.
WEBSITE/REFERENCES
http://shunt.gtmdea.org