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

2. 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

3. Overview Background Problem Statement Current Prototype Testing
Future Work

4. 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

5. 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

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

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

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

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

16. References
Dallas Center for Sleep Disorders. Pediatric Sleep Apnea. Retrieved from
Dept of Respiratory Care Eduation. KU Medical Center. Polysomnography. Retrieved from y.html
Davey, Margot. The Royal Children’s Hospital of Melbourne. Sleep Studies. Retrieved from
Viasys Healthcare. SleepScreen. Retrieved from toennies.com/english/products/sleep- diagnostics/sleepscreening/sleepscreen/
Salter Labs. Growing Steadily on a Quality Foundation. Retrieved from
Rochester Sleep. Ultra Flow Respiration Monitors. Retrieved from

17. QUESTIONS???