TY - JOUR T1 - Resting ventilation distribution abnormalities predict exercise impairment in mild to end-stage COPD JF - European Respiratory Journal JO - Eur Respir J VL - 44 IS - Suppl 58 SP - P4877 AU - J. Alberto Neder AU - Conor O'Donnell AU - Julia Cory AU - Casey Ciavaglia AU - Daniel Langer AU - Katherine Webb AU - Denis O'Donnell Y1 - 2014/09/01 UR - http://erj.ersjournals.com/content/44/Suppl_58/P4877.abstract N2 - Total lung capacity (TLC) is underestimated by single-breath inert gas dilution techniques compared with body plethysmography in COPD. The degree of TLC underestimation provides an index of ventilation distribution inequalities and might be related to more severe mechanical-ventilatory and gas exchange disturbances in these patients. Two-hundred and seventy-six COPD patients distributed across GOLD grades 1 to 4 and 67 healthy controls were evaluated. The “poorly-communicating fraction” (PCF) of the TLC was estimated as the ratio (%) of TLC to alveolar volume (VA) from the single-breath lung diffusing capacity measurement. Healthy subjects showed significantly lower PCF values compared to GOLD grades 1 to 4 (10 ± 3 % vs. 17 ± 8 % vs. 27 ±10 % vs. 37 ± 10 % vs. 56 ± 11 %, respectively; p<0.05). Pulmonary gas exchange impairment, mechanical ventilatory constraints and ventilation-corrected dyspnea scores gradually worsened across PCF tertiles (p<0.05). Of note, GOLD grades 1 and 2 patients with the highest PCV values had pronounced exercise ventilatory inefficiency and dyspnea as a limiting symptom. In fact, dyspnea was a significant contributor to exercise limitation across the whole sample in those with “moderate” or “extensive” PCF (p<0.05). A ROC curve analysis revealed that PCF was a better predictor of severely-reduced maximal exercise capacity than traditional pulmonary function indexes including FEV1 (area under the curve (95% confidence interval)= 0.85 (0.81-0.89); p<0.01). In conclusion, PCF is a readily-available functional marker of gas exchange and mechanical abnormalities relevant to breathlessness and exercise intolerance across the COPD grades. ER -