RT Journal Article SR Electronic T1 The prevalence of ventilatory limitation at peak exercise in pulmonary arterial hypertension JF European Respiratory Journal JO Eur Respir J FD European Respiratory Society SP P2160 VO 44 IS Suppl 58 A1 James Tadjkarimi A1 Stephen Thomson A1 Martin Johnson YR 2014 UL http://erj.ersjournals.com/content/44/Suppl_58/P2160.abstract AB Patients with Pulmonary Arterial Hypertension (PAH) have severely impaired exercise capacity on incremental cardiopulmonary exercise tests (CPET.) The disease process is characterised by a cardiovascular pattern of limitation with abnormalities in both oxygen transport /delivery and gas exchange. If ventilatory limitation is present, it is thought to strongly suggest the presence of concomitant lung disease. However, reaching ventilatory limitation depends upon the balance between ventilatory capacity and demand. Since ventilatory efficiency is reduced in PAH and hence demand increased, in severe cases it is theoretically possible for patients with PAH and without lung disease to exhibit a ventilatory pattern of limitation.The aim of this study was to determine the prevalence of ventilatory limitation in PAH subjects with normal resting spirometry and normal CT appearance of the lungs. CPET results from patients with PAH tested between 2008 and 2013 were retrospectively examined for the presence of ventilatory limitation defined as end-exercise ventilation > 85% of maximum voluntary ventilation (MVV) and a breathing reserve of < 15 l/min. MVV was calculated by multiplying resting FEV1 by 40.Of 38 patients satisfying the inclusion criteria, three showed evidence of ventilatory limitation (7.9% CI: 1.8, 8.8). In these 3 subjects mean Ve/VCO2 at anaerobic threshold and PetCO2 were 55.7 and 19.7 mmHg respectively (cf 54.5 and 20.7 mmHg in PAH subjects with no ventilatory limitation).In conclusion, ventilatory limitation does occur on CPET testing in PAH subjects without lung disease, but its prevalence is low.