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Home > Teams > LAsers, Molecules and Environment > Themes > Analysis of gas traces

Exhaled air analysis

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Optical-Feedback Cavity-Enhanced Absorption Spectroscopy (OF-CEAS) is a very promising laser spectroscopy technique for breath analysis. Real-time and non-invasive measurements are performed with extreme sensitivity and selectivity for the species to be measured. This point is of particular importance as hundreds of compounds are present in exhaled air. Furthermore, OF-CEAS offers additional advantages for medical diagnostic: it does not require any calibration with certified gas mixtures, its response time is faster than a single respiratory cycle and it allows the realization of compact and robust instruments that can be operated by non-specialized personnel in a medical setting.

Resolving respiratory cycles : Breath analysis at Bichat Claude Bernard Hospital (Paris)

Simultaneous to spirometric measurements on patients, OF-CEAS measurements of CO and CH4 were performed (figure 1). The fast analyser response allows to monitor the different expiratory phases (figure 1).

Figure 1: (a) Lung volume recorded with a spirometer during different ventilatory phases (breathing in the tidal volume is followed by a slow deep exhalation, a deep inhalation, and a forced fast and complete exhalation).
(b) CO and CH4 concentrations measured by OF-CEAS.

Lung graft evaluation (collaboration with TIMC-IMAG at Grenoble Hospital and Foch Hospital at Suresnes)
The goal of our research is to establish new markers for the re-habilitation of pulmonary grafts initially rejected for transplant. OF-CEAS measurements of endogenous gas production (CO and NO) are performed on isolated lung in an Ex Vivo Lung Perfusion (EVLP) device. Initial studies are performed on an animal model (pig, figure 1). We could then enter a new phase by measuring endogenous production of CO by human lung grafts during EVLP before their transplant at Foch hospital.

Figure 2: Real time measurements of air breathed in and out by a mechanically ventilated pig, monitored with two OF-CEAS analyzers in series.


  • TIMC-IMAG (CHU de Grenoble), Dr R. Briot
  • Hôpital Foch (Suresnes), Pr E. Sage
  • AP-HP Hôpital Bichat Claude Bernard (Paris), Pr Ch. Clerici

  • ANR "BreathDiag" 2015-2020 (ANR-15-CE18-0006-01). Portée par le LIPhy en collaboration avec les médecins de TIMC-IMAG et du CIC-IT pour le CHUGA de Grenoble, ainsi que l’entreprise AP2E.

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