Neurally Adjusted Ventilatory Assist (NAVA) is a new form of partial support wherein the machine applies positive pressure throughout inspiration in proportion to the electrical activity of the diaphragm (EAdi), as assessed by trans-esophageal electromyography. To test the hypothesis that NAVA could provide better patient-ventilator synchrony during NIV delivered by nasal-facial mask as compared to conventional flow-triggered PSV in infants with Acute Respiratory Failure.