Breast Implant Pump Fall 2003Breast Implant PumpUniversity of Wisconsin –MadisonCollege of Engineering-Biomedical EngineeringBME 200/300November 21, 2003Team Members: Joe Bothwell BWIG IT Ryan Fischer CommunicatorBrant Koschiek Team Leader Brian Schwartz BWIG David Ugai BSAC Dan Carlson BSAC Client:Venkat K. Rao, M.D., MBADivision of Plastic SurgeryUW Medical SchoolAdvisor:Naomi C. Chesler, Ph. DBiomedical EngineeringAbstractThe objective of the project is to design a device to fill silicone breast implant bags with saline to a specified volume, without exposing the saline to the atmosphere. The surgeon currently inserts the breast implant bag into the patient, and fills the bag withsaline solution using 60 mL syringes. Most bags need to be filled with saline volumes between 300 and 600 mL, so the filling of the bags requires the refilling of one 60 mL syringe up to ten times. This is a time consuming process. The use of a pump drawing saline from a 1,000 mL IV bag and dispensing the exact amount saline into the breast implant bag in less than five minutes would be the desired design. Some peristaltic pumps can pump up to 3,400 mL per minute, and that is the type of pump we adapted for use in our design. Also, a manual withdrawing syringe is adapted through a three-way luer connector to remove any air or excess saline in the implant bags. An automated peristaltic pump (Masterflex) is the chosen design, while a manually controlled peristalticpump (Klein), which the hospital already owns, is the current incorporation due to financial constraints.2Background Breast implants are saline filled sacs inserted into a woman’s breast to enhance the size or shape of her breast. When a woman receives an implant, there are four typicalpositions where an incision can be made. They are as follows: transaxillary (under the armpit), areola (under the nipple), inframammary fold (underneath the breast), or transumbilical (though the belly button). After the surgeon makes the initial incision he/she prepares a cavity within the breast for the implant to sit. This area can either be sub-mammorary or sub-muscularly. Sub-muscular placement results in the implant resting below the chest muscle, while sub-mammorary placement lets the implant rest within the breast tissue. As the surgeon is preparing the breast for the implant, the nurse must prepare the implants for placement. A saline filled implant is shipped full of air so the nurse removesit by squeezing as much out as possible, and then adds approximately 50 ml of solution tothe implant. The remaining air is withdrawn from the implant using the syringe until liquid flows through the tube. In many cases this is a tedious process and saline must be gently added and removed until the nurse is confident no air left in the implant. In practice it is nearly impossible to remove 100% of the air, but it is best to get as much outas possible. If air does remain inside the implant, it can result in “sloshing” of the saline, which is neither good for, nor desirable, by the patient.After the breast is ready for the implant a pre-filled sizing implant is inserted to give an estimate of how a particular size will look, or possible complications that may result from it. When the proper size has been determined the permanent implant is ready for placement. The surgeon places the implant in the correct orientation, and connects IVtype tubing to it. The connection of the tubing to the implant consists of a valve that can be closed when the operation is complete so the implant remains sealed. The current 3methods of filling an implant vary according to the surgeon’s preference, but all incorporate the use of a 60 ml syringe. Some surgeons will have the nurse fill the syringefrom a saline reservoir behind the operating table, and some prefer to keep the system closed by drawing the saline directly from the IV bag. In this situation, a 3-way pump is needed to ensure saline is only drawn from the IV bag when filling the syringe and only put into the implant when emptying the syringe. In both cases the nurse has to keep trackof how many times the syringe is filled and emptied, which is easy to lose track of since implants are commonly filled with more than 300 ml of saline.These methods of filling implants are common throughout the practice. Although they do work, surgeons are not completely satisfied, mostly due to the probability of human error, inaccuracy, possibility of contamination, and frustration from having to continuously refill the syringes while filling the implants. Problem StatementThe goal of this project was to develop a breast implant device for filling implantsbags with saline solution after the insertion of the silicone implant bag into the patient. This device should dispense saline accurately (+/- 3 mL) and quickly (less than five minutes).Literature SearchPossible methods for filling breast implant bags with saline were researched. No current techniques use an automated pumping system to fill the bags. Most of the surgeons utilize syringes, where they either draw saline directly from a 1,000 mL saline IV bag or the surgeon draws the saline from a bowl filled with saline. The process of drawing the saline directly from the IV bag keeps the saline unexposed to the atmosphere 4by the use of a three-way luer connector with a stopcock. The three-way luer connector allows for the saline to be draw into the syringe from the IV bag, and then the surgeon can change the stopcock to allow the distribution of the saline into the silicone implant bag already in the patient. The process of drawing the saline from the bowl of saline exposes the saline to the atmosphere, which could lead to contamination.The adapting of these current techniques to a new automated technique required the research of pumping systems currently on the market. The most practical pumps that were found are peristaltic pumps. These pumps are usually used to dispense small amounts of fluid (around 0.1 mL/min to 50 mL/min) and at low pressures (0.10 MPa). These dispensing systems are not fast enough or at high enough pressures for a breast implant pump. After much research, some larger peristaltic pumps were found that could dispense saline up to 3,400 mL/min at pressures up to 0.5 MPa. The dispensing rate and pressures were met for our design requirements. One of these pumps that
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