TY - JOUR T1 - Expiratory capnography in brown Norway rat: Feasibility and effect of acute bronchoconstriction JF - European Respiratory Journal JO - Eur Respir J VL - 40 IS - Suppl 56 SP - P864 AU - Mathieu Guilbart AU - Loïc Degrugilliers AU - Franck Robidel AU - Françoise Rogerieux AU - François Marchal AU - Bruno Chenuel AU - Sam Bayat Y1 - 2012/09/01 UR - http://erj.ersjournals.com/content/40/Suppl_56/P864.abstract N2 - RATIONALE: The phase III slope of the expiratory volumetric capnogram (S3v)has been shown to increase with bronchoconstriction in asthmatics (ERJ 1994;7:318-323), however, the mechanisms involved remain speculative. We assessed the feasibility of expiratory capnographic slope analysis during acute bronchoconstriction in an experimental model in rat.METHODS: Rats undergoing a separate study were divided into 2 groups: sensitized to ovalbumin (OVA) and exposed either to air or to NO2, 10 ppm, 6h/d, 5d/wk for 4 weeks. 24h after exposure, animals were anesthetized and mechanically ventilated. Respiratory mechanics were measured using multiple linear regression at baseline and after infusion of methacholine (MCH) (15 µg/kg/min (γ)). Exhaled capnograms were recorded during tidal breathing using a rapid CO2 analyzer. The S3v was computed and averaged in a minimum of 10 respiratory cycles in each condition.RESULTS: Respiratory system resistance (Rrs) and elastance (Ers) significantly increased in response to MCH. Similarly, S3v increased during MCH infusion. This increase was significantly larger in NO2-exposed animals.View this table:CONCLUSIONS: Measurement of S3v is feasible in rat, and significantly increases following bronchoconstriction. This new experimental model will allow further study of the mechanisms associated with the increase in S3v. ER -