Multicomponent Analysis of Biomarkers in Exhaled Air Using Diode Laser Spectroscopy

Abstract

We have proposed methods of multicomponent spectral analysis of exhaled air based on the use of tunable diode lasers to solve some problems in biomedical diagnostics. Simultaneous laser spectral analysis of CO and CO₂, CO and N₂O pairs near 4.7 µm can be used to examine gas exchange in the studies on the physiology of respiration and cardiovascular diagnostics conducted using various stress tests and for solving problems of anesthesiology and continuous monitoring ventilation–perfusion status. Simultaneous analysis of NO and CO₂ at approximately 5.4 µm can be useful for monitoring the breathing maneuver in studies of inflammatory processes in the distal lungs. Simultaneous detection of NH₃, CO₂, and C₂H₄ near 10.5 µm is promising for studies of general metabolism and major metabolic cycles. Simultaneous analysis of ¹³CO₂ and ¹²CO₂ near 2.05 µm can be used to measure the ratio of ¹³CO₂ to ¹²CO₂ when conducting isotopic breathing tests. The results of the analysis of promising spectral ranges and the relative position of the analytical lines in them are given. The possibility of simultaneous detection of several molecules under study in the proposed spectral regions was experimentally demonstrated, and laser transmission spectra were obtained. The proposed approach can be applied to the analysis of the microcomposition of exhaled air.