Self-Adjusting Gastric Banding System Erin Crosby Andrew Dickerman Josh Mabasa Brian Reis

Overview of Gastric Banding Minimally invasive bariatric weight loss procedure Involves inflatable gastric band around upper part of stomach Saline solution used to inflate band to decrease appetite

Lap Band Functionality Band reduces stomach size Induces an early feeling of satiety Feel full quickly after eating small amount Fullness lasts for several hours

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

Problem Statement Currently band loses effectiveness between injections Invasive for the patient Currently 7-14% of soft tissue infection, port leakage and tube cracks

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

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

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

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

Possible Causes for Pressure Loss Loss of Volume across the semi-permeable silicone membrane that cannot currently be detected Change in elastic properties of silicone diaphragm Evacuation of trapped air across membrane Reduction of post operative swelling

Solution Mechanically-constricting, self-adjusting band Will resolve problems associated with fluid- filled system Frequent self-adjustments will remove the need for regular post-op corrections

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

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, port leakage and tube cracks

Factors Biocompatible materials Fabrication Power Limitations – daily/weekly adjustments Cost effectiveness relative to current procedure Less cost involved in device maintenance Failsafe mechanism to avoid severe physical damage

System Operation Measure force exerted on band Loosen Tighten Do nothing Greater than Target Equal Less than Target

Short-term Goals Meet with company Sign legal documents Secure funding Research and design Mechanical design Feedback system (electrical design) Begin CAD design