A novel optical device for end tidal air sampling in breath analysis

The aim of this work is to present a novel breath sampling device, based on tuneable diode laser spectroscopy (TDLS). The proposed system is able to measure CO2 concentrations and flow on expired breath and to precisely separate different fractions from expired breath. The system integrates a flow meter and a CO2 measurement unit based on TDL spectroscopy, allowing the measurement of: either volume and CO2 concentrations, sampling of different breath fractions, breath-by-breath calculation of the volume of anatomical dead space (Fowler's method) and end-tidal CO2 concentration values. The comparison of anatomical dead space estimations in data of single breaths obtained from 10 test subjects is reported in Table 80.1, deviations respect to Fowler's method (calculation by four experts) are <3 %. The proposed system show good perspectives for the development of portable diagnostic instruments based on laser device (TDL spectroscopy) expanding the possibility of observing new species and decreasing costs and can contribute to the common effort to building of common sampling procedures for the analysis of volatile compounds.