Nitric oxide breath testing by tunable-diode laser absorption spectroscopy: application in monitoring respiratory inflammation

Abstract

We used a high-resolution mid-IR tunable-laser absorption spectroscopy (TLAS) system with a single IV-VI laser operating near 5.2 microm to measure the level of exhaled nitric oxide (eNO) in human breath. A method of internal calibration using simultaneous eNO and exhaled CO2 measurements eliminated the need for system calibration with gas standards. The results observed from internally calibrating the instrument for eNO measurements were compared with measurements of eNO calibrated to gas standards and were found to be similar. Various parameters of the TLAS system for eNO breath testing were examined and include gas cell pressure, exhalation time, and ambient NO concentrations. A reduction in eNO from elevated concentrations (approximately 44 parts in 10(9)) to near-normal levels (<20 parts in 10(9)) from an asthmatic patient was observed after the patient had received treatment with an inhaled glucocorticoid anti-inflammatory medication. Such measurements can help in evaluating airway inflammation and in monitoring the effectiveness of anti-inflammatory therapies.

Simultaneous Gas-phase Detection of Nitric Oxide (NO) and Nitrous Oxide (N2O) from the Decomposition of Angeli's Salt (Na2N2O3) at Different pHs Using Tunable-diode Laser Absorption Spectroscopy

“…We have shown previously that a direct linear correlation exists between absorption intensity and NO concentrations in the 0-500 ppb range [25]. A similar direct linear correlation exists for N 2 O up to 10 ppm (using the smaller doublet peaks at 2198.995/2199.016 cm -1 ; Figure 2).…”

Detection of Gas Concentration by Correlation Spectroscopy Using a Multi-Wavelength Fiber Laser

“…Using the Beer-Lambert law, gas concentration can be easily measured with a single-mode tunable laser which scans in a continuous wavelength range including some absorption peaks of the target gas. When using a tunable diode laser, it has a common gas measurement technique called TDLAS (tunable diode laser absorption spectroscopy) [4][5][6][7]. Its measurement precision is limited by the unstableness of a laser mode and the presence of interfering gases.…”

Detection of disease markers in human breath with laser absorption spectroscopy

“…Using this spectral range nitric oxide has been already detected with sensitivity up to the ppb levels. The techniques as MUPASS -WMS [46][47][48], ICOS [49,50], and CALOS [51] were demonstrated. Our experiment with nitric oxide detection in the N 2 was performed using CEAS technique.…”