Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation that uses the diaphragm's normal electrical activity to deliver a mechanically supported breath. The amount of support provided is determined in part by the NAVA level, where a higher NAVA level will provide higher level of support and unload more of the work of the diaphragm. The purpose of this study is to compare the optimal NAVA level in neonates while on mechanical ventilation while intubated and after being extubated.