Sleep Lab Monitor BME 400 University of Wisconsin - Madison December 12, 2008 Team: Jack Page, Team Leader Nicole Daehn, Communicator Lindsey Carlson, BSAC Robyn Hrobsky, BWIG Client: Christopher G. Green, MD Department of Pediatrics School of Medicine and Public Health Advisor: Willis Tompkins Department of Biomedical Engineering University of Wisconsin - Madison2 Table of Contents Abstract ......................................................................................................................................3 Background ................................................................................................................................3 Sleep Disordered Breathing.....................................................................................................3 Polysomnography ...................................................................................................................4 Problem Overview and Problem Statement .................................................................................7 Product Design Specifications Summary.....................................................................................8 Alternate Designs........................................................................................................................8 Cuff Design............................................................................................................................8 Clip Design...........................................................................................................................10 Final Design .............................................................................................................................11 Imbedded Wire Design..........................................................................................................11 Attachment Alternative Designs................................................................................................13 Attachment Design Matrix ....................................................................................................14 Attachment Final Design...........................................................................................................15 Testing......................................................................................................................................17 Future Work .............................................................................................................................21 APPENDICES..........................................................................................................................23 References ............................................................................................................................23 Project Design Specifications................................................................................................243 Abstract Sleep disordered breathing (SDB) is a very common disorder among all ages which can be detrimental to behavioral, emotional, social, and physical health. These disorders are diagnosed by polysomnography, or more simply, sleep studies. Most of the people who suffer from SDB are undiagnosed, and thus these sleep studies become very important for diagnosing these disorders. For pediatric patients, there are many weaknesses to the current method of studies. Currently, a unit containing thermistors and a cannula are stacked on top of each other under the patient’s nose. Because of the small size of a child’s nose, this method can obstruct the nostrils and make it difficult to breathe. Also, because of the small size of a pediatric patient’s head and face, the method used to secure the devices is not sufficient and the devices may not stay in place throughout the night. These problems can lead to inaccurate measurements, discomfort, and sleep disruption, especially in pediatric patients. To help solve these problems, many different design options were explored and evaluated. A prototype of the design that best solves the current issues has been built. The prototype combines temperature change during exhalation, pressure, and end tidal carbon dioxide (ETCO2) measurements into one device, samples from both nostrils and the mouth, and attaches to a pediatric patient in both a durable and comfortable fashion. Background Sleep Disordered Breathing Sleep disordered breathing (SDB) refers to a class of breathing disorders which occur when a person is sleeping. SDB includes sleep apnea, hypopnea, heavy snoring, or even increased airway resistance during sleep. Three types of sleep apnea are included in this group,4 which affect more than 18 million Americans [1]. These are obstructive, central, and mixed apnea. Obstructive apnea is characterized by a blocked airway, which ceases breathing. However, with obstructive apnea, the patient is still attempting to breathe [2]. Central apnea means that the patient is not breathing, but there is no effort to breathe [2]. Mixed apnea is a combination of obstructive and central. Hypopnea is different than apnea because there is actually airflow occurring. However, the patient is experiencing very shallow breaths or a very low respiration rate [3]. These disorders can be very detrimental to the health of the individual experiencing them. These individuals can wake up hundreds of times each night without even knowing it [1]. This can lead to behavioral, social, emotional, and physical problems. Behavioral problems include the inability to pay attention which can lead to misdiagnoses of Attention Deficit Hyperactivity Disorder (ADHD), poor academic performance, or poor on the job performance caused by fatigue and being tired throughout the day. Social and emotional problems include irritability, being easily agitated, and depression [1] [2]. More serious physical health problems include delayed mental and physical growth, memory problems, weight gain, and hypertension which can lead to a heart attack or stroke [3] [2]. Since these disorders occur at night, most of the people who suffer from them do not even know that there is a problem. For example, it is estimated that more than 50 percent of the people who suffer from sleep apnea are undiagnosed [1]. This is an immense problem which needs to be resolved. The diagnosing of SDB is very important. Polysomnography Polysomnography is the technical name for a sleep study.