Breath-Analysis Using Mid-Infrared Tunable Laser Spectroscopy

Abstract

Breath analysis is becoming an attractive technique for the noninvasive monitoring of various molecular constituents in exhaled breath. Nitric oxide (NO) is a widely studied biomarker in breath and is known to indicate the lower airway inflammation associated with asthma. A mid-IR laser-based spectroscopic sensor and associated electronics were designed to measure exhaled NO simultaneously with CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . To evaluate the sensor performance, a large observational clinical field study consisting of more than 2200 volunteers was performed over a period of two years. The generated distributions of the measured exhaled NO and CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> levels were found to be log-normal and Gaussian, respectively. In addition, preliminary results of measuring exhaled nitrous oxide (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O) are given as well as suggestions for future applications in infectious disease.