Device Specifications Sleep Disordered Breathing Combined Thermistor, Pressure, and ETCO2 Device for Use in a Sleep Laboratory Lindsey Carlson, Nicole Daehn, Jack Page, Robyn Hrobsky Client: Dr. Christopher Green, Department of Pediatrics, University of Wisconsin Hospital Advisor: Professor Willis Tompkins, Department of Biomedical Engineering, University of Wisconsin Abstract Device Specifications Testing and Results • Measure air flow, pressure, and ETCO2 from both nostrils and mouth • Disposable • Device should fit pediatric patients • Should stay on patient throughout the duration of a sleep study (~8 hours) • Comfortable, durable, and limit sleep disruption • Be compatible with existing equipment Current methods of polysomnography can lead to inaccurate measurements, discomfort, and sleep disruption. The goal of this project is to design and develop a prototype that combines breath, pressure, and ETCO2 measurements into one device, sampling from both nostrils and the mouth, and attaching in both a durable and comfortable fashion. Amplified voltage across thermistors during normal breathing Tested with surface mount and wire lead thermistors Used LabView to obtain real-time voltage vs. time data Qualitatively analyzed for breath detection Additional testing on thermistors within normal breathing temperature range Sleep Disordered Breathing Final Design Affects 18 million Americans 10 million of which remain undiagnosed [1] Disrupts sleep hundreds of times each night Can lead to: Behavior, emotional, social problems Delayed mental/physical growth Design selected based on disposability, accuracy, and cost Uses Salter Lab 5055 oral/nasal cannula Measures ETCO2, nasal pressure, and temperature change via thermistors Three 10 kΩ surface mount thermistors mounted to each nasal/oral extension 2” x 0.6” silicone attachment pieces on either side of cannula prongs Thermistor wires fixed to cannula tubing Low cost ensures disposability Polysomnography Figure 5. Voltage vs. Time of wire lead thermistor (left) and surface mount thermistor (right) Future Work Sleep Study Brain Activity Muscle movements Respiratory effort O2 Saturation Order GrassLead Safety Connectors for thermistors Test the prototype in the Sleep Lab Work with manufacturer to produce device commercially Figure 1. Pediatric Sleep Study[2] References Three measurements from each breath Airway Pressure End Tidal CO2 Flow [1] Dallas Center for Sleep Disorders. Pediatric Sleep Apnea. Retrieved from http://www.dallas-sleep.com/pediatric-sleep-apnea.php [2] Davey, Margot. The Royal Children’s Hospital of Melbourne.  Sleep Studies. Retrieved from http://www.rch.org.au/sleep/studies.cfm?doc_id=5040 [3] Rochester Sleep. Ultra Flow Respiration Monitors. Retrieved from http://www.rochestersleep.com/Respiration.htm [4] Salter Labs. Growing Steadily on a Quality Foundation. Retrieved from http://www.salterlabs.com/ Figure 2. Thermistors measuring flow [3] Figure 3. Cannula for Pressure & ETCO2 [4] Acknowledgements Figure 4. Final design. Dr. Christopher Green, Professor Willis Tompkins, Professor Steve Weber, Sleep Lab staff, Amit Nimunkar, University of Wisconsin Hospital, University of Wisconsin-Department of Biomedical Engineering