ERGONOMIC ULTRASOUND DEVICE May 5 2004 BME301 Department of Biomedical Engineering University of Wisconsin Madison Team Members Yao Lu Meghan Olson Emily Putzer Heather Waldeck Client Mark Kliewer M D Department of Radiology UW Hospital Advisor Professor Naomi Chesler Department of Biomedical Engineering Abstract Eighty percent of sonographers suffer from musculoskeletal disorders These occurrences are attributed to the combination of sustained pinching and pushing needed during some ultrasound procedures as well as applying a force while the arm is in an unnatural position In order to alleviate the need for the sonographer to apply a sustained force we developed a design that can maintain a force for the duration of the procedure The design consists of an arc attached over the echocardiogram bed connected to a transducer by an arm Movement is possible via a slider over the arc a ball and socket joint a hinge joint and a joint where the transducer is attached 0 which allows slight rotation The sonographer is able to lock the arm in place to sustain a force and performs the detailed movements necessary 1 Problem Statement During echocardiogram and biopsy procedures sonographers must apply high levels of pushing force with an unnatural arm position while performing detailed movements The combination of these factors increases the number of work related injuries and many times prevents the sonographer from performing their jobs Our goal is to develop an ergonomic design which will minimize the forces applied and thereby reduce injuries to sonographers Background Information Ultrasound is a widely used technique for imaging the inner organs of the body using sound waves An ultrasound transducer Figure 1 is used by a specialized technician called a sonographer to probe the outer surface of a patient s body and produce a relevant image of the inner organs The tip of the transducer made with a piezoelectric material and is used to sense sound waves given off from the body structures and convert them to electric signals so they can be made into an image A gel must be used on the surface of the skin in order to propagate the sound waves which do not travel through air In addition to the transducer a large console made up of a keyboard and viewing screen is used in an ultrasound reading to compile and display the image make various adjustments and change settings 2 Figure 1 An ultrasonic transducer Murphey There are many types of procedures performed by sonographers using ultrasound Two of the most time consuming and fatiguing procedures are biopsies and echocardiograms Kliewer A biopsy is performed by a doctor who inserts a needle in a patient s body aiming to take a sample of a tumor The doctor guides the needle using the image created by the sonographer which must be very exact to include the small dimensions of the needle and to accommodate for the precise nature of the procedure Similar to a biopsy an echocardiogram has duration of approximately 45 minutes and can be made difficult in large patients who have excess skin and tissue surrounding the heart The procedure images the heart of a patient to identify problems in heart valves or the function of the heart muscles The sonographer must apply a large amount of force to the transducer in order to penetrate the tissue and circumvent the ribs to create a good image The patient lies on his her side Figure 2 while the sonographer first applies pressure on a certain position on the patient s 3 chest and then on a position on the patient s side in an upward direction through a hole in the bed The latter position is to take advantage of the fact that due to gravity the patient s heart will be more superficial and easier to image Kliewer Figure 2 An echocardiogram The Franklin Institute These types of procedures especially the echocardiogram require the sonographer to apply large amounts of force for long periods of time while still needing to make detailed movements These factors lead to a high incidence of musculoskeletal injuries In fact 80 of sonographers suffer from an injury such as this most commonly in the neck shoulder and or wrist Murphy Studies show that these disorders arise primarily because of the force needed in certain procedures See Figure 3 It can also be noted that the pinching motion needed in conjunction with the force may 4 cause problems as well by having the stretched tendons rub across the carpal bones thus causing swelling of the tendons Figure 3 Survey of sonographers Tasks that aggravate musculoskeletal symptoms Mean scores on a 5 point scale Murphy Some of the main musculoskeletal injuries affecting sonographers are carpal tunnel syndrome tendonitis and shoulder bursitis Chattanooga Website The former occurs in a region of the wrist that forms a tunnel of ligaments and tendons When these structures become overused as can happen with the repetitive movements made by a sonographer they become inflamed and cut off the nerve that runs from the arm to the hand through the carpal tunnel Tendonitis develops when the tendons in the wrist or elbow connecting muscle to bone become inflamed Bursitis arise when the bursa fluid filled sacs located at the joints is inflamed putting pressure on the joints and causing discomfort The symptoms of all three musculoskeletal disorders mentioned can include pain numbness swelling 5 or weakness Chattanooga Website A visual description of carpal tunnel syndrome tendonitis and bursitis is shown in Figure 4 a b Figure 4 a Carpal Tunnel Syndrome Everybody Health b Shoulder Bursitis and Tendonitis Orthopaedics Northeast Due to the prevalence of the aforementioned injuries many companies and research groups have tried to improve the current design and ultrasound procedure all with little improvement Companies have designed more ergonomic transducers with grooves or varied shapes that accommodate a palmer grip Chattanooga Website Also groups have urged sonographers to use proper posture and to stretch occasionally However these improvements have not lowered the incidence of injury because they do not eliminate the most important contributing factor force applied for an extended period of time with an unnaturally positioned arm Currently research groups are working on more handle re designs in the hopes of alleviating sonographer injuries 6 Client Requirements The client specified several requirements for the new transducer design First the design should not interfere in any way with the
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