Engineering World Health: Aspirator Nick Harrison, Communications Jonathan Meyer, BWIG Lucas Vitzthum, Leader Fan Wu, BSAC BME 200/300 Department of Biomedical Engineering University of Wisconsin-Madison December 12, 2007 Advisor: John Webster, Ph.D, Professor Department of Biomedical Engineering Client: Bonnie Tompkins, M.D.2Abstract Medical aspirators are suction devices used to remove mucous and other bodily fluids from patients. Many developing world hospitals do not possess aspirators because they cannot afford or repair the current devices on the market. The goal of this project is to create an inexpensive, locally repairable, and electricity independent alternative to current medical aspirators. The design should provide the broadest range of possible uses for developing world hospitals. The end result of this work is to produce a detailed, easy to read set of instructions that includes how to build, test, and operate the device.3Table of Contents Page Abstract 2 Table of Contents 3 Problem Statement 4 Background Information 4-5 Current Devices 5-6 Design Constraints 6-7 Previous Design 7-11 Testing and Results 11-13 Three Major Improvements Needed 13-18 Final Design 19-21 Cost and Availability 21-23 Testing 23-24 Future Work 24-26 Conclusion 26-26 References 27 Appendix A: PDS 28-29 Appendix B 314Figure 1: Tip of surgical aspirator. Source: http://www.valleylabeducation.org/esself/Pages/esself23.html Problem Statement Engineering World Health (EWH), a nonprofit organization through Duke University, has asked for help in designing an inexpensive medical aspirator that can be built and repaired from locally available parts and expertise for developing world hospitals. The device must be able to function semi-autonomously off electricity since a constant electric power supply will not always be available. Developing hospitals will likely be able to afford only one aspirator, so the design must function under the broadest range of applications possible. Pressure and flow rate ranges should be comparable to current medical aspirators on the market. Ultimately, EWH requires a detailed set of instructions for the construction, testing and use of an aspirator that can be built completely from locally available resources that will meet all the relevant criteria for functioning in a developing world hospital. Background Information Aspirating equipment can be found in almost any hospital, ambulance, or dental clinic in the United States. A medical aspirator is simply a suction device used to remove mucous, blood, or other bodily fluids from a patient (Figure 1). The apparatus generally includes disposable suction tips and a removable collection receptacle. This device is a necessary tool in dental practice, liposuction and most surgical procedures. Depending on their exact function, aspirators are generally powered by 120V AC outlets, batteries, or a combination of both. The size and portability of the device are also determined5by its application. Sizes can range from 5.17 kg battery powered hand held devices to 31.75 kg stationary surgical units (Gomco Suction Equipment, 2006). Aspirators currently on the market are designed for use in modern, state of the art medical environments. Differences between modern and developing hospitals render these models impractical for use in third world countries. Third world hospital conditions are radically different from their modern American counterparts. Electricity is spotty at best for developing world hospitals and therefore equipment cannot depend on a constant supply of electricity. Trained medical professionals are in short supply, requiring devices to have the simplest user interface possible. Limited space is another concern, as most rooms are overcrowded with patients, staff, and equipment (Hill D 2005). Current Devices There are many medical aspirators on the market today with a wide variety of functions. In the $500-600 price range, Gomco® provides a line of portable aspirators (Models G180, 405 & 300) that use diaphragm compressors to create vacuum ranges from 0-600 mmHg and flow rates of 30 liters per minute (lpm). Dimensioned at 30.5x22.9x30.5 cm, these devices weigh around 6.58 kg. Specialized stationary aspirators are available for uterine, thoracic drainage, endocervical, and dental operations. Most are powered via 120V AC current and range in weight from 22.7-31.8 kg. Thoracic and thermotic drainage pumps operate under low pressure and low flow conditions (0-50 cm H20, 2.3 lpm) to regulate drainage levels in postoperative care. Endocervical6aspiration alternatively requires high pressure ranges (600 mmHg) and high flow rates (20-30 lpm) for brief intermittent use (Gomco Suction Equipment, 2006). All of these designs, however, are inaccessible to a developing world hospital for several reasons. The most obvious limitation of these devices is their price; even the cheapest models exceed EWH’s projected $100 budget. In addition, the specialization of current devices provides another budgeting concern. Most aspirators on the market are designed for a very specific function. A hospital that can only afford a single aspirator would need the broadest range of applications possible. Finally, these devices cannot be repaired with locally available parts and expertise. Advanced circuitry and specially manufactured parts render these devices irreparable in developing world hospitals. Design Constraints Engineering World Health provided only a couple of constraints to follow and left the rest of the design quite open-ended, creating the need to establish additional guidelines. The biggest focus of the aspirator design is that it needs to be constructed entirely from locally available materials in third world countries. These materials can include anything already on hand in the hospitals, as well as anything that can be obtained from the surrounding environment, such as car batteries, simple motors, and tubing. The design must include autoclavable suction tips for easy sterilization. The final goal of this semester is to produce a working prototype for less than $100 and a set of detailed instructions, as specified by EWH. Since the apparatus will be used in a hospital setting, the final product must be safe for sterile use in the operating room. The7final device should not rely solely on electric power, due to its
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