Exhaled Breath Measured using Tunable Diode Laser Absorption
Exhaled Breath Measured using Tunable Diode Laser Absorption Spectroscopy (TDLAS) Patrick J. Mc. Cann, Ph. D. Ekips Technologies, Inc. Norman, OK School of Electrical and Computer Engineering University of Oklahoma Norman, OK ATS Workshop Toronto, Canada December 14, 2002 www. breathmeter. com
Tunable Diode Laser Absorption Spectroscopy (TDLAS) • Molecules absorb infrared light: 1 Laser Chip Detector 1 2 Laser Chip Detector 2 3 Laser Chip • Simultaneous NO and CO 2 detection: Detector 3 Spectral Signals NO H 2 O+CO 2 Vibrational Frequency ( ~ 5. 2 µm) • Self-calibrating sensor – Patient’s own CO 2 is the calibration gas
e. NO Measurements with TDLAS Breath Flow Laser Light Path ( ~ 5. 2 mm) Laser and Detector Assembly Exhaled Breath Flowing through Gas Cell Results displayed in real-time (video) Single Exhalation Against Resistance (10 -20 sec)
Asthmatic Examples Age 5, Female, Mild-Persistent Corticosteriod Treated Normal Airway Age 14, Male, Mild-Persistent Non-Treated Inflamed Airway
Treatment Monitoring
Air Pollution Effects? • Nitric Oxide is a major component of smog. – Automobile exhaust is primary source. – Ambient NO (a. NO) concentrations will vary with geography, weather conditions (inversion layers), and time of day. Street Level NO (Norman, OK) Important question for polluted areas Group of Vehicles Stopped at Intersection High Emission Vehicles Individual Vehicles Typical e. NO Range (5 -70 ppb)
e. NO not Affected by a. NO Untreated Asthmatic Non. Asthmatic Low a. NO (2 ppb) Untreated Asthmatic Non. Asthmatic Ambient Air Displaced by Breath High a. NO (24 ppb)
Other Molecules • TDLAS can rapidly measure many different small heteronuclear molecules. – Compounds measured by the OU/Ekips team in the last 3 years: CO, COF 2, NO, N 2 O, NH 3, CH 4, C 2 H 2, CS 2, SO 2, H 2 O, HDO, H 2 O 2, 12 CO 2, 13 CO 2, C 7 H 8 (toluene), C 6 H 6 (benzene), CH 2 O (formaldehyde), C 2 H 4 O (acetaldehyde), C 6 H 6 O (phenol), C 3 H 6 O (acetone), and CH 2 Cl 2 (methylene chloride) Acetaldehyde is an alcohol metabolite End Consumption Begin Consumption Measured in breath during and after dinking Molson Golden™
- Slides: 8