TEMPLATE DESIGN © 2008

www.PosterPresentations.com

OUR MISSIONTo build a peritoneovenous (PV) shunt that can:

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

DESIGN SOLUTION

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

PERFORMANCE TESTING

COLLABORATIONS

NEXT STEPS

WEBSITE/REFERENCES

Refractory ascites is a condition that affects >100,000 patients/year with end-stage liver disease (ESLD).

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.

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. http://shunt.gtmdea.org

Design of an Implantable Peritoneovenous Shunt for Patients Affected by Refractory Ascites in End-Stage Liver Disease

Jim Schwoebel1, Graham McAdory1, Alexandra Low1, José Vasquez1, Kate Raskauskas1, Timothy Ibru1 ,Dr. James Monaco2, Dr. Mike Kassin2

NAME: The Clavus ® Shunt System 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)

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)

License to Industry • License device to a larger

company in biomedical industry

Bernoulli Equation with Friction and Pump Work

MODELINGDEVICE IDEATIONS,

MOCKUP, PROTOTYPEMock-up Prototype

0 10 20 30 40 50 60 70 80 900

50

100

150Flow Rate vs Cycles Rate

Cycles Rate (cycles/min)

Flo

w R

ate

(m

L/m

in)

0.5 mm

1 mm

1.5 mm2 mm

4 mm

Figure 5: Flow rate as a function of the cycles rate at different pump chamber radius.

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.

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.

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.

Figure 3: Figure showing the mock-up of the device. Figure 4: Figure showing the first prototype of the device.

Table 1: A morphological chart showing various design ideations contemplated for the mock-up and prototype.

0 20 40 60 80 100 120 140 160 180 2000

200

400

600

800

1000

1200

1400

1600

1800

2000

2200Flow Rate vs Reynolds

Rey

nold

s

Flow Rate (mL/min)

0.5 mm

1 mm

1.5 mm2 mm

4 mm

0 5 10 15 20 25 300

20

40

60

80

100

120

140

160

180

200Flow Rate vs Pressure

Flo

w R

ate

(mL/

min

)

Pressure (mmHg)

0.5 mm

1 mm

1.5 mm2 mm

4 mm

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.

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.

Special Thanks to all the collaborators that made this project a reality!