Patrick J. McCann, Ph.D. Ekips Technologies, Inc. Norman, OK School of Electrical and Computer Engineering University of Oklahoma Norman, OK Exhaled Breath Measured using Tunable Diode Laser Absorption Spectroscopy (TDLAS) ATS Workshop Toronto, Canada December 14,

Tunable Diode Laser Absorption Spectroscopy (TDLAS) Molecules absorb infrared light: Simultaneous NO and CO 2 detection: H 2 O+CO 2 CO 2 NO Vibrational Frequency ( ~ 5.2 µm) Spectral Signals Self-calibrating sensor – Patient’s own CO 2 is the calibration gas 1 Laser ChipDetector 3 Laser ChipDetector 2 Laser ChipDetector 1 2 3

eNO Measurements with TDLAS Single Exhalation Against Resistance (10-20 sec) Results displayed in real-time (video) Laser Light Path (  ~ 5.2  m) Breath Flow Exhaled Breath Flowing through Gas Cell Exhaled Breath Flowing through Gas Cell Laser and Detector Assembly Laser and Detector Assembly

Asthmatic Examples Inflamed Airway Age 14, Male, Mild-Persistent Non-Treated Normal Airway Age 5, Female, Mild-Persistent Corticosteriod Treated

Treatment Monitoring

Air Pollution Effects? Nitric Oxide is a major component of smog. –Automobile exhaust is primary source. –Ambient NO (aNO) concentrations will vary with geography, weather conditions (inversion layers), and time of day. Typical eNO Range (5-70 ppb) Individual Vehicles Group of Vehicles Stopped at Intersection High Emission Vehicles Street Level NO (Norman, OK) Important question for polluted areas

eNO not Affected by aNO Untreated Asthmatic Untreated Asthmatic Untreated Asthmatic Untreated Asthmatic Non- Asthmatic Non- Asthmatic Ambient Air Displaced by Breath Non- Asthmatic Non- Asthmatic Low aNO (2 ppb) High aNO (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 End Consumption Begin Consumption Begin Consumption Measured in breath during and after dinking Molson Golden ™