Non-invasive ventilation (NIV) reduces carbon dioxide in hypercapnic respiratory failure by unloading the respiratory muscles. Spontaneous modes of NIV are usually being used in these situations. Spontaneous modes have the disadvantage, that the patient has to trigger the ventilator. The work to activate the trigger (WT) is estimated to be as high as up to 50% of the total work of breathing dependent on the underlying disease. Elimination of WT would increase the degree of respiratory muscle unloading.