Sleep Lab Monitor Lindsey Carlson, Nicole Daehn, Robyn Hrobsky, Jason Tham BME 402 March 6, 2009

School of Medicine and Public Health Client: Christopher G. Green, MD Dept of Pediatrics School of Medicine and Public Health Advisor: Willis Tompkins Dept. of Biomedical Engineering University of Wisconsin - Madison

Overview Background Problem Statement Current Prototype Testing Future Work

Sleep Disordered Breathing Affects 18 million Americans 10 million of which remain undiagnosed Sleep disrupted 100s of times each night Behavioral, emotional, and social problems Irritability, agitation, fatigue Low alertness, attention deficit Other Health Problems Delayed mental and physical growth High blood pressure

Problems Air Flow Airway Pressure & ETCO2 Thermistors: Measure ΔT between inhaled and exhaled air Airway Pressure & ETCO2 One side of cannula to a pressure measuring device Other side to a Capnograph Problems Disrupting sleep, uncomfortable Obstructive, increases nasal resistance Both don’t measure nasally and orally Expensive

Problem Statement Combine ETCO2, pressure, & flow into one apparatus Samples from both nostrils and the mouth Attach in both a durable & comfortable fashion

Prototype Design 3 Thermistors attached to cannula body Wires are injected molded onto cannula body Wires allow flexibility of oral and nasal extensions Entire interface is disposable

Thermistor Comparison Test Purpose: Measure the difference between Pro-Tech Thermistor device and prototype on sleep lab’s system Reason for Test: Want prototype to function on standard system with similar performance to baseline Characterize prototype How test was performed: Simultaneous measurements of thermistors Thermistors compared in different breathing cycles

Breaths Detected (prototype) Breaths Detected (Pro-tech thermistor) Thermistor Comparison Test Prototype Pro-tech Thermistor Type of Breathing Breaths Detected (prototype) Breaths Detected (Pro-tech thermistor) Normal 11 Shallow and fast 39 40 Deep and slow 8 Deep and fast Unable to determine 26

Thermistor Distance Test Purpose: Determine thermistor response from different distances from airways Reason for Test: Children pull on thermistor if uncomfortable Moves it out of direct airway How test was performed: Took normal breathing measurements at several distances from airway. Used prototype and currently used thermistor

Thermistor Distance Test Prototype Pro-tech Thermistor Distance (mm) Average Amplitude of Prototype (peak-to-peak) Average Amplitude of Pro-tech thermistor (peak-to-peak) 44 2000 3 36 800 7 14 350 10 11 90

Figure XX: Temperature Test Set-up Thermistor Temperature Test Purpose: To compare the thermistor calibration curves to measured temperature. Reason for Test: Need to know the change in resistance for each unit temperature change Make sure the thermistors operate correctly in specified temperature range How Test was Performed: Used a heated water bath and thermometer, while monitor resistance using LabVIEW Figure XX: Temperature Test Set-up

Thermistor Temperature Test Used a voltage divider with R2 as 30 kΩ and R1 as our thermistor device Calculated the Resistance across the thermistor using voltage of the known resistance Used calibration data from manufacture to calculate temperature

Thermistor Temperature Test Average change in resistance/degree temperature change = 0.8873 kΩ Calibration curve fits with theoretical temperature readings from thermometer (R=0.99751)

Future Work Indentify new thermistor Characterize new thermistor Assess demand for product

References Dallas Center for Sleep Disorders. Pediatric Sleep Apnea. Retrieved from http://www.dallas-sleep.com/pediatric-sleep-apnea.php Dept of Respiratory Care Eduation. KU Medical Center. Polysomnography. Retrieved from http://classes.kumc.edu/cahe/respcared/cybercas/sleepapnea/trenpol y.html Davey, Margot. The Royal Children’s Hospital of Melbourne. Sleep Studies. Retrieved from http://www.rch.org.au/sleep/studies.cfm?doc_id=5040 Viasys Healthcare. SleepScreen. Retrieved from http://www.jaeger- toennies.com/english/products/sleep- diagnostics/sleepscreening/sleepscreen/ Salter Labs. Growing Steadily on a Quality Foundation. Retrieved from http://www.salterlabs.com/ Rochester Sleep. Ultra Flow Respiration Monitors. Retrieved from http://www.rochestersleep.com/Respiration.htm

QUESTIONS???