RT Journal Article SR Electronic T1 Expiratory capnography in brown Norway rat: Feasibility and effect of acute bronchoconstriction JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P864 VO 40 IS Suppl 56 A1 Mathieu Guilbart A1 Loïc Degrugilliers A1 Franck Robidel A1 Françoise Rogerieux A1 François Marchal A1 Bruno Chenuel A1 Sam Bayat YR 2012 UL http://erj.ersjournals.com/content/40/Suppl_56/P864.abstract AB 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.