TY - JOUR T1 - Alterations in static lung volumes during methacholine challenge (MCH) tests, assessed by whole-body plethysmography using the aerosol provocation system (APS) JF - European Respiratory Journal JO - Eur Respir J VL - 40 IS - Suppl 56 SP - 4720 AU - Richard Kraemer AU - Gaby Giger AU - Thomas Sigrist AU - Martin Frey Y1 - 2012/09/01 UR - http://erj.ersjournals.com/content/40/Suppl_56/4720.abstract N2 - Rationale. Airway hyperreactivity (AHR) is a characteristic feature of asthma, and methacholine challenge tests (MCT) are well established in asthma diagnostics and research, to quantitate AHR. Cut points have arbitrarily been selected, defining a fall of 20% in FEV1 as PC20. By this technical approach, however, changes in end-expiratory resting level cannot be detected. MCT using APS technology integrated in the Jaeger whole-body plethysmograph features the possibility to evaluate changes of airway dynamics concomitantly with changes of lung volumes [1].Objectives. We aimed to assess changes of FRCpleth, IC, ERV and hence RV and TLC during MCT, and comparing changes of effective specific airway conductances (sGeff, sG0.5, sGtot) in relation to changes effected to FEV1 and MEF50.Methods. We retrospectively analysed data from our hospital database including 140 test persons (asthmatics and controls; 59 males; 81 females; age: 11 to 82 y), in whom MCT have been performed. Methacholine was administered during 3 consecutive cumulative challenge levels (P1:0.2 mg; P2:1.0 mg; P3:2.2 mg) computerized by the APS system.Results. During MCT not only airway mechanics, but also static lung volumes (FRCpleth, IC) changed consistently.Conclusions. In the assessment of AHR by MCT sGeff and and sGtot qualified as most sensitive target parameter, taking into account changes of airway dynamics concomitantly with changes of lung volumes. Comparison between volume-time and flow-volume parameters with plethysmographically assessed sGeff, sG0.5 during MCT is presented in abstract 850930.[1]. Matthys H, et al.: Respiration: 1975;32(2):121-134. ER -