Fig. 42: This Figure reports results from a randomized crossover trial that assessed whether NIV applied directly during walking is associated with improvements of exercise capacity.^[22] The upper portion of the Figure shows the 6-min walking distance (6MWD) with supplemental oxygen alone.  It can be seen that although supplemental oxygen was applied during walking, the patients experienced exercise-induced deoxygenation and hypercapnia. The bottom portion of the Figure shows the results of the same 6MWD with NIV in addition to supplemental oxygen, where use of NIV clearly increased PaO₂ after the 6MWD and prevented exercise-induced hypercapnia. Furthermore, patients with NIV walked longer and had less dyspnea.

Thus this randomized crossover trial demonstrated that NIV applied directly during walking in stable hypercapnic COPD patients is associated with improvements in exercise capacity and exercise-induced dyspnea.