The same investigators who carried out the study in the previous Figure^[8] also looked at 2 years of home-based nocturnal NIV in addition to rehabilitation in patients with hypercapnic COPD.^[9] This Figure shows the results of this randomized crossover trial, showing changes of blood gases over time, and again it is clear that blood gases in the patients receiving nocturnal NIV in addition to pulmonary rehabilitation improved significantly more than in the control group.