1. Neonatal Rat Gastrostomy
GERHARD VAN BAALEN
KARIN RASMUSSEN
LAURA PLATNER
SCOTT SOKN
CLIENT: SHARON BLOHOWIAK
ADVISOR: PROF. PAUL THOMPSON

2. Outline Problem Statement Background Information Client Specifications
Tip Designs
Insertion Technique
Design Matrix
Future
Questions

3. Problem Statement Motivation Percutaneous Endoscopic Gastrostomy (PEG)
Test iron deficiency and physiological development
Percutaneous Endoscopic Gastrostomy (PEG)
Our goal for this semester is to design a mechanism and/or procedure to secure a feeding tube inserted through the abdominal wall.

4. Current Procedure Use polyethylene tubing (PE-20) Anesthetize rat
Make phalanges
Insert needle
Insert tubing via catheter
Secure with washer
Clamp in neck

5. Problems with Existing Procedure
Survival Rate
Less than 50% survival rate
Problems with Catheter:
Needle is bigger than tubing

6. Problems with Existing Procedure
Problems with Tubing/phalanges
Phalanges fail
Phalanges are difficult to make
Tension on stomach wall
Tension on the tubing caused by rat movement

7. Specifications Performance requirements: Accuracy and Reliability
8-10 days continuous use
Needs to be secured in stomach for entire time
20 minutes per hour milk is pumped to Rat
Accuracy and Reliability
Repeatable fabrication
Repeatable surgical procedure

8. Design Alternatives - Tips
Phalanges Tip
Made by cutting tube’s tip with small scissors
Phalanges fold out once in stomach
Proven to have poor and inconsistent results
Disc Tip
Made by melting tip and immediately flattened out
Disc folds out once inserted through catheter
Once tip is melted, very difficult to make disc flat and pliable enough to fit inside catheter

9. Design Alternatives - Tips
Curlicue Tip
Tube wrapped around tip of small surgical pliers
Molded by holding in hot water then cold water
Nothing to stop tube from slowly working its way out
Balloon Tip
Tube inserted with deflated balloon around tube
Balloon Filled with water once inside stomach
Takes up a lot of space

10. Design Alternatives – Insertion Method
Insertion through mouth
Gastrostomy tube inserted via esophagus and out through stomach
Creates smaller hole
Expandable materials
Expands due to liquid stomach or peritoneal cavity
e.g. Sponge, Nylon, Hydrophilic gel or plastic
Fills in hole size issues
Sharp wire
Wire with sharp tip inserted inside tube

11. Design Matrix - Tips Tip Designs Function (x2) Ease of fabrication
Consistency (x2)
Size in stomach
Size for insertion
Total
Disk 4 3 2 1 20
Curlicue 22
Phalanges 19
Balloon

12. Design Matrix - Insertion
Feasibility
Ease
Hole size
Consistency
Total
Expandable material 3 12
Inserting through mouth 1 4 11
Wire 2 10

13. Future work Most promising design: Curlicue with expandable material
Order components
Fabricate prototypes
Test prototypes
Rats arrive in mid November

14. Questions?