TY - JOUR T1 - Mechanical determinants of dyspnoea in asthma JF - European Respiratory Journal JO - Eur Respir J VL - 42 IS - Suppl 57 SP - P2029 AU - Alessandro Gobbi AU - Andrea Antonelli AU - Emanuele Crimi AU - Michele Baroffio AU - Carlo Gulotta AU - Roberto Torchio AU - Raffaele Dellaca AU - Giorgio Scano AU - Vito Brusasco AU - Riccardo Pellegrino Y1 - 2013/09/01 UR - http://erj.ersjournals.com/content/42/Suppl_57/P2029.abstract N2 - Background. Bronchial asthma is characterized by episodes of airway narrowing with dyspnoea. This is described as chest tightness, inspiratory effort, unrewarded inspiration or expiratory difficulty.Aims. To examine if dyspnoea or its descriptors reflect different mechanical changes during bronchoconstriction.Methods. Eighty-four mild asthmatics were challenged with methacholine. Symptoms were scored as Borg units. Lung function measurements included: 1) compression-free partial flow at 40% of vital capacity, residual volume, functional residual capacity, inspiratory resistance (R5) and reactance (X5) at 5 Hz; 2) changes in R5 and X5 with deep breath and velocity of recovery; 3) difference in resistance between 5 and 19 Hz (R5-19); 4) interquartile range (IQR) of R5, R5-19, and X5; 5) difference between inspiratory and expiratory X5 (ΔX5), as an index of expiratory flow limitation. Relationships between variables were assessed by ordinal logistic regression analysis and expressed as Odds Ratio (OR).Results. At 25% FEV1 fall, dyspnoea was related to increased X5-IQR (OR: 8.55), inspiratory effort to ΔX5 (OR: 2.27), unrewarded inspiration to deep-breath inability to attenuate X5 fall (OR: 4.58) and expiratory difficulty to a blunted increase in R5-19-IQR (OR: 0.017). No relationships were observed between functional data and chest tightness.Conclusions. The increments in dyspnoea, inspiratory effort and unrewarded inspiration reflect the ease with which the airways close over time, occurrence of expiratory flow limitation, and reduced recruitment of closed airways with deep breaths. The increase in expiratory difficulty appears to reflect the inability of the open peripheral airways to take different configurations with breathing. ER -