For the infant participating the study, ventilator settings and respiratory variables will be recorded every day and exported to a specific computer using the Servo Record Viewer version 1.0 (Maquet Critical Care AB, Getinge, Gothenburg, Sweden). Collected data gives the value for peak inspiratory pressure (PIP), expiratory tidal volume (Vt), peak Edi, minimum Edi, measured respiratory rate (RR), neural respiratory rate (nRR) and percentage of backup breaths for each minute. All the ventilator data will be inspected and compared with the event logs recorded automatically from the ventilator, which includes all the alarm notification, mode and setting changes, cables connection and disconnection data. Data during disconnection of the Edi cable, malfunction or dislocation of Edi catheter will be excluded from the analysis. The mean values during each day will be computed for each ventilatory variables. If there is a change in the ventilatory setting parameters, we will choose the one which was applied for longer duration in the 24-hour time period.

The following clinical characteristics will be collected from medical records: gestational age at birth, birth weight, gender, the time and amount of feeding, medication during the study days, desaturation events, bradycardia events, suction time and methods.

Inclusion Criteria:

• babies who receiving respiratory support with neurally adjusted ventilatory assist
• babies with informed consents from their parents

Exclusion Criteria:

• babies using anesthetic agents

We included preterm infants born before 36 weeks of gestation who received at least 24 hours of ventilatory support with invasive or non-invasive NAVA using a Servo-i or Servo-n ventilator (Getinge, Gothenburg, Sweden).