The effect of non-invasive ventilation (NIV) during exercise on inspiratory capacity (IC) and endurance time (Tlim) in patients with severe COPD

Background: Dynamic hyperinflation (DH) can occur during exercise in people with stable COPD and is associated with increased dyspnoea and reduced exercise capacity. While NIV during exercise can improve endurance time, the effect of NIV on IC (a DH marker) is unclear. Objective: To determine the effect of NIV on IC and Tlim in patients with COPD during constant load cycle exercise. Method: 20 patients with severe COPD (FEV1:32±4%pred, RV/TLC:163±29%) and who showed DH during a peak cycle test, in one day, performed three cycle endurance tests at 75% peak work rate to exhaustion, in random order: no NIV, standard NIV (expiratory positive airway pressure (EPAP) 5cmH2O), titrated NIV (individualised EPAP to maximise IC at rest). Metabolic variables, breathing pattern, oxygen saturation (SpO2), transcutaneous carbon dioxide (TcCO2), heart rate and muscular oxygenation (SmO2) (via NIRS) were measured continuously. IC and dyspnoea were measured each minute. Results: Tlim and isotime change in IC (∆IC) were significantly increased (Table 1) with standard and titrated NIV during exercise vs no NIV. In both NIV tests, TcCO2, SpO2 and SmO2 were significantly improved. There were no differences between NIV tests. Conclusion: When using NIV compared to no NIV, stable patients with severe COPD had clinically improved exercise endurance time and significantly reduced DH at isotime