Table 2 Clinical variables to be collected for infants enrolled in the study

Antenatal and maternal variables

Mother age, parity, complications during pregnancy, maternal medications, intra-uterine growth restriction, mode of delivery, multiple birth, use of antenatal steroids, rupture of membranes, use of antibiotics during labor, histological chorioamnionitis.

Infant characteristics pre-extubation

Gender, birth weight, gestational age, Apgar scores (1, 5 and 10 min), cord blood gases, use of surfactant (age, dose), use of antibiotics and caffeine administration prior to extubation (age and dose).

Infant characteristics at time of extubation

Weight at extubation, age and post-conceptional age at extubation, ventilator mode, peak inflation pressure, positive end-expiratory pressure, mean airway pressure, tidal volume, set inspiratory time, ventilator rate, fraction of inspired oxygen (FiO₂), oxygen saturation and blood gas

Infant characteristics post-extubation

Type of non-invasive respiratory support, interface used, settings, FiO₂ and blood gas

Primary extubation outcome

Fulfilling extubation failure criteria within 72 h from extubation

Secondary extubation outcomes

- Fulfilling extubation failure criteria up to 14 days after extubation

- Need for reintubation at any time point from extubation until death or discharge (including timing and reasons for reintubation)

Other outcome variables

Total duration (in days) of mechanical ventilation, non-invasive respiratory support and of oxygen supplementation, intraventricular hemorrhage, patent ductus arteriosus, necrotizing enterocolitis, postnatal infection (defined as positive culture from the blood, urine or cerebrospinal fluid), need for postnatal steroids, bronchopulmonary dysplasia at 36 weeks post conceptual age (classified as none, mild, moderate or severe), upper airway complications, diuretics at discharge, retinopathy of prematurity and death occurring anytime in the NICU (including timing and cause).