1. Self-Adjusting Gastric Banding System
Erin Crosby
Andrew Dickerman
Joshua Mabasa
Brian Reis

2. Overview of Gastric Banding
Minimally invasive bariatric weight loss procedure for adults with BMI > 35
Involves inflatable gastric band around upper part of stomach
Saline solution used to inflate band to decrease appetite

3. Current Lap Band

4. Lap Band Functionality
Band reduces stomach size
On average: From 1500 mL without band to 30 mL with band in place
Induces an early feeling of satiety
Feel full quickly after eating small amount
Fullness lasts for several hours

5. Adjustments with Current Band
First adjustment typically done 6 to 8 weeks after surgery
Total number of adjustments depends on individual’s weight-loss rate and results
Adjustments are simple office visits that only take 10 or 15 minutes

6. Obesity – Health Care Costs
**Expenditure in Billions of Dollars
Finkelstein, Fiebelkorn, and Wang, 2003
NHA = National Health Accounts
MEPS = Medical Expenditure Panel Survey
Based on obesity data from NHIS

7. Cost of Obesity versus the Current Procedure
ITEMS
Estimated Annual Costs
Mean medical/drug costs (BMI≥35)
$7,337
Out-of-pocket healthcare expenses
$2,684
Employment inactivity costs
$1,017
Commercial weight-loss program fees
$678
Prescription co-pays (5 meds at $10)
$738
Grocery and dining cost
$6,012
TOTAL
$18,466
Cost of current Lap-Band Procedure (facility, surgeon, and anesthesiologists) can run from $12,000 to $25,000

8. Success Rate of Current Procedure
Average loss of 50% of excess weight in 1-2 years
Mortality rate 0.1%
Re-operation rate of less than 5%
Weight Loss

9. Problem Statement Invasive for the patient
Currently 7-14% patients experience soft tissue infection, port leakage and tube cracks
Currently band loses effectiveness between injections
*add pressure graph in!!
* There is incremental pressure loss between band adjustments absent “measurable” loss in band volume

10. Possible Causes for Pressure Loss
Loss of Volume across the semi-permeable silicone membrane that cannot currently be detected
Evacuation of trapped air across membrane
Reduction of post-operative stomach tissue swelling

11. Intra-Band Volume is Constant Between Adjustments In-Vivo Band
Fill # * +
Paired T-test: # p = 0.08 , * p = 0.09, + p = 0.83
From “Pressure Directed Lap-Band Adjustment – Is There a Role?” by Thomas P. Rauth, M.D., Michael D. Holzman, M.D., MPH

12. Intra-Band Volume is Constant Between Adjustments Ex-Vivo Band
From “Pressure Directed Lap-Band Adjustment – Is There a Role?” by Thomas P. Rauth, M.D., Michael D. Holzman, M.D., MPH

13. Intra-Band Pressure Degrades between Adjustments In-Vivo Band
Fill # * +
Paired T-test: # p < , * p < , + p <
From “Pressure Directed Lap-Band Adjustment – Is There a Role?” by Thomas P. Rauth, M.D., Michael D. Holzman, M.D., MPH

14. Intra-Band Pressure Degrades between Adjustments Ex-Vivo Band
From “Pressure Directed Lap-Band Adjustment – Is There a Role?” by Thomas P. Rauth, M.D., Michael D. Holzman, M.D., MPH

15. Solution Mechanically-constricting, self-adjusting band
Will resolve problems associated with fluid-filled system
Soft tissue infection around port
Port leakage
Tube cracks
Frequent self-adjustments will reduce number of regular post-op corrections

16. Primary Objectives
Eliminate the need for saline injections and reservoirs used in current systems
Automatically maintain a constant applied force in between checkups

17. Goals
Band needs to uniformly constrict stomach through electro-mechanical means
Band, motor, pressure sensor, and electronic components all confined to one unit
Decrease internal space needed for device
Eliminate soft tissue infection around port, port leakage and tube cracks

18. Design Considerations
Fabrication feasibility
Battery power limitations – daily/weekly adjustments
Cost effectiveness relative to current procedure
Less cost involved in device maintenance
Factors parameters varied to yield benefit what affects cost, quality, benefits, etc  List them.

19. Pro/Engineer Model

20. Pro/Engineer Model

21. Pro/Engineer Model

22. Pro/Engineer Model

23. Pro/Engineer Model
~2 cm

24. Gearing/Torque Equations
Energy Balance
Fl => Δr
P increases
Fl = Prw
Force required to maintain constant radius (r)
V = Volume c = Circumference w = Width P Δr Fl

25. Gearing/Torque Equations
Fl = Prw
Force required to maintain constant radius
τr = Torque from motor

26. FlexiForce Force Sensors
Variable resistor
Resistance inversely proportional to applied force
Versatile, durable piezoresistive force sensor
Customizable
Senses contact force
Force vs. Resistance and Force vs. Conductance (1/R)

27. Short-term Goals Fabricate prototype Order parts Circuit Design
Force sensors
Motor
Gearhead
Circuit Design
Testing