TY - JOUR T1 - Inspiratory muscle constraint during exercise in patients with pulmonary arterial hypertension JF - European Respiratory Journal JO - Eur Respir J VL - 40 IS - Suppl 56 SP - P847 AU - Barbara Joureau-Harasse AU - Gilles Garcia AU - Christian Straus AU - Elise Arnaud Macari AU - Xavier Jaïs AU - David Montani AU - Laurent Savale AU - Olivier Sitbon AU - Gérald Simonneau AU - Marc Humbert AU - Thomas Similowski AU - Pierantonio Laveneziana Y1 - 2012/09/01 UR - http://erj.ersjournals.com/content/40/Suppl_56/P847.abstract N2 - We examined the impact of potential inspiratory muscle constraint on dynamic operating lung volumes response during symptom-limited incremental cardiopulmonary cycle exercise testing (CPET) in patients with pulmonary arterial hypertension (PAH).Thirty-three young non-smoking PAH patients (idiopathic=26; heritable=7) with normal body mass index and no spirometric evidence of obstructive ventilatory defect (FEV1/FVC=115±10% predicted) performed a CPET to limit of tolerance. Ventilatory profile, operating lung volumes [derived from inspiratory capacity (IC) measurements] and inspiratory flow reserve (IFR), an indirect index of inspiratory muscle constraint/fatigue,were assessed throughout CPET.Twenty-two patients (67%) decreased IC (i.e., dynamic hyperinflation) throughout exercise by 0.50L (PAH-H), whereas the remaining patients (33%) increased IC by 0.36L (PAH-NH). V'E and V'O2 at peak exercise were comparable between the two groups. Despite these differences in operating lung volumes response, IFR at peak exercise was not statistically different between PAH-H and PAH-NH (1.9±1.0 vs 2.0±0.8L/s, p=0.7).Both PAH-H and PAH-NH achieved inspiratory tidal flows that approached a similar percentage of the maximal available inspiratory flows (i.e., similar IFR), suggesting that the inspiratory flow-generating reserve of the inspiratory muscles at peak exercise was similar (but occurred at different operating lung volumes). The presence of inspiratory muscle constraint/fatigue and its contribution in modulating the dynamic operating lung volumes response to CPET is unlikely.Support: 1) International Re-integration Grants (IRG), FP7-PEOPLE-2010-RG; 2) PFIZER Investigator-Initiated Research (IIR). ER -