This trial evaluates the efficacy and safety of surfactant administration with thin catheter technique together with analgesic premedication in comparison with the established INSURE-strategy. It will provide valuable knowledge to improve clinical methodology and enhance lung protective treatment strategies for preterm infants.

To compare two approaches for surfactant administration during CPAP in preterm infants, the INSURE and the LISA technique, using premedication intubation protocols, and investigate aspects of safety, stress and pain, timely administration of the drug, response in oxygenation and pulmonary outcome.

Our study asks whether (P) among infants born <32 weeks' gestation with RDS (I) does surfactant administration with LISA and analgesia premedication (C) versus surfactant administration according to the INSURE protocol (O) improve oxygenation and reduce the rate of respiratory failure and need for intubation and mechanical ventilation (T) within 48 hours of the procedure

Primary outcomes:

1. Positive effect: Oxygenation measured as arterial to alveolar ratio (a/A ratio) at 24 hours post-procedure.
2. Negative effect: Need for mechanical ventilation (MV) within 48 hours post-procedure.

Safety outcomes:

1. Time from meeting the FiO2 or a/A ratio criteria for surfactant treatment until surfactant administration
2. Number of tries before successful intubation/placement of catheter
3. Positive pressure ventilation during the procedure - yes/no/duration (minutes)
4. Stress and pain (changes in heart rate, blood pressure and BIIP-scale)

Inclusion Criteria:

• Infants born before 32 completed weeks of gestation on CPAP, with clinical and radiological signs of RDS and need for surfactant treatment.

Exclusion Criteria:

• Infants requiring surfactant as part of delivery room resuscitation are not eligible.

Infants will be excluded from the final analysis if they have a congenital abnormality or condition that might have an adverse effect on breathing or ventilation, including: congenital diaphragmatic hernia; tracheo-oesophageal fistula or cyanotic heart disease.