RT Journal Article SR Electronic T1 Inspiratory muscle constraint during exercise in patients with pulmonary arterial hypertension JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P847 VO 40 IS Suppl 56 A1 Barbara Joureau-Harasse A1 Gilles Garcia A1 Christian Straus A1 Elise Arnaud Macari A1 Xavier Jaïs A1 David Montani A1 Laurent Savale A1 Olivier Sitbon A1 Gérald Simonneau A1 Marc Humbert A1 Thomas Similowski A1 Pierantonio Laveneziana YR 2012 UL http://erj.ersjournals.com/content/40/Suppl_56/P847.abstract AB 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).