Non-invasive respiratory support is routinely provided to extremely preterm infants following disconnection from mechanical ventilation, in the form of continuous positive airway pressure (CPAP) or non-invasive positive pressure ventilation (NIPPV). However, these modes remain sub-optimal due to lack of synchronization and upper airway defensive mechanisms that potentially hinder their effectiveness. Non-invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA) is a novel mode that may overcome some of these problems but has not been investigated in this population. Investigators hypothesize that there will be significant differences in cardiorespiratory behavior in extremely preterm infants receiving CPAP, NIPPV and NIV-NAVA during the immediate post-extubation period.

A large proportion of extremely preterm infants are mechanically ventilated through the use of endotracheal intubation. However, clinicians try to avoid intubation due to the complications that may arise from being mechanically ventilated such as ventilator associated pneumonia (VAP), pulmonary hemorrhage, air leak etc. In order to the prevent these complications, clinicians accelerate weaning and provide non-invasive respiratory support. The most commonly used type of non-invasive respiratory support following extubation is nasal continuous positive airway pressure (NCPAP). NCPAP has been shown to improve oxygenation, reduce airway resistance, increase tidal volume, stabilize chest wall and maintain functional residual capacity. In addition to NCPAP, nasal intermittent positive pressure ventilation (NIPPV) has become a popular choice as a post-extubation respiratory support mode. However, there is a lack of knowledge regarding the effects of synchronization between the infant's own spontaneous respiratory efforts and ventilator inflations.

Synchronization, especially during non-invasive ventilation, is difficult to achieve in preterm infants due to their rapid respiratory rates, short inspiratory times, periodic breathing, leaks and small tidal volumes. Previous studies have used devices such as an abdominal capsule to allow for synchronization while the infant is receiving NIPPV. The abdominal capsule itself is prone to incorrect placement, time delays and ineffective synchronization. Neurally Activated Ventilatory Assistance (NAVA) is a new technology that can be used during invasive and non-invasive ventilation. In this novel mode, the electrical activity of the diaphragm, called EAdi, is detected be electrodes inserted at the tip of a specialized nasogastric tube. The EAdi represents the patient's inherent neural respiratory drive. The ventilator assists each spontaneous breath by delivering pressure that is linearly proportional to the EAdi. The mechanical breath is initiated at the start of diaphragmatic contraction and maintained until the EAdi is at 60 to 70% of the peak pressure generated. Therefore, the inspiratory time, expiratory time and peak inflation pressure are all controlled and determined by the patient, providing patient-ventilator synchrony.

Inclusion Criteria:

• birth weight under 1250 grams receiving invasive mechanical ventilation

Exclusion Criteria:

• infants with major congenital anomalies, congenital heart defects, neuromuscular disease, diaphragmatic paralysis or palsy, diagnosed phrenic nerve injury, esophageal perforation, hemodynamic instability as well as infants on interpose, narcotics or sedative agents