 However, challenges with the initiation of high-intensity NIV require attention, but do not necessarily have to be solved in-hospital. On the one hand, patients with COPD need higher inspiratory pressures and higher backup breathing frequencies as it is more difficult to correct alveolar hypoventilation in lung parenchyma diseases compared to diseases in which the lungs are not primarily affected, such as in neuromuscular disease. On the other hand, the investigators believe that careful high-intensity NIV initiation and titration should not only focus on maximal improvement in PaCO2 but also on patient comfort. The consequence of high-intensity might be that COPD patients need even more time and attention from caregivers to get used to the high pressures and high backup frequencies before our target can be reached, i.e. improvement in gas exchange and respiratory muscle unloading, before the conditions also for a good long-term compliance can be satisfied. 