In Project 2, the aim is to demonstrate that administration of NAVA with invasive (endotracheal intubation) or non-invasive interface (nasal prongs) is equally efficient in terms of triggering and cycling-off. The hypothesis is that with NAVA, non-invasive ventilation with nasal prong is equally efficient as invasive ventilation. In premature infants deemed ready for extubation, NAVA will be implemented prior to and post-extubation (with single nasal prong). We anticipate that ventilatory assist will be delivered with full synchrony regardless of invasive or non-invasive delivery of assist, and that there should be no difference in the delays between the onset of EAdi and ventilatory assist and in the delays between peak of EAdi and cycling-off. We also expect that due to less airway resistance during non-invasive ventilation, peak applied pressures and diaphragm activation levels will be lower.