participants are excluded from the study if any of the following criteria apply: any contraindications to surfactant administration e.g., pulmonary hemorrhage and pneumothorax) weight < 40kg stage 4 severe chronic kidney disease (i.e., egfr < 30) pregnancy administration of any nebulized surfactant in the 48 hours before the first poractant alfa administration

participants are excluded from the study if any of the following criteria apply: any contraindications to surfactant administration e.g., pulmonary hemorrhage and pneumothorax) weight < 40kg stage 4 severe chronic kidney disease (i.e., egfr < 30) pregnancy administration of any nebulized surfactant in the 48 hours before the first poractant alfa administration

participants are excluded from the study if any of the following criteria apply: 1. any contraindications to surfactant administration e.g., pulmonary hemorrhage and pneumothorax) 2. weight < 40kg 3. stage 4 severe chronic kidney disease (i.e., egfr < 30) 4. pregnancy 5. administration of any nebulized surfactant in the 48 hours before the first poractant alfa administration

participants are excluded from the study if any of the following criteria apply: 1. any contraindications to surfactant administration e.g., pulmonary hemorrhage and pneumothorax) 2. weight < 40kg 3. stage 4 severe chronic kidney disease (i.e., egfr < 30) 4. pregnancy 5. administration of any nebulized surfactant in the 48 hours before the first poractant alfa administration

participants are excluded from the study if any of the following criteria apply: 1. any contraindications to surfactant administration e.g., pulmonary hemorrhage and pneumothorax) 2. weight < 40kg 3. stage 4 severe chronic kidney disease (i.e., egfr < 30) 4. pregnancy 5. administration of any nebulized surfactant in the 48 hours before the first poractant alfa administration 6. extracorporeal membrane oxygenation* * [exclusion criterion not applicable for patients eligible for the ecmo-cohort]

participants are excluded from the study if any of the following criteria apply: 1. any contraindications to surfactant administration e.g., pulmonary hemorrhage and pneumothorax) 2. weight < 40kg 3. stage 4 severe chronic kidney disease (i.e., egfr < 30) 4. pregnancy 5. administration of any nebulized surfactant in the 48 hours before the first poractant alfa administration 6. extracorporeal membrane oxygenation* * [exclusion criterion not applicable for patients eligible for the ecmo-cohort]