Trial procedures
Participants were randomly assigned to receive open-label nebulized surfactant or no intervention in a 3:2 ratio using an internet-based block randomization service (ALEA tool for clinical trials, FormsVision BV). As patients were unable to consent, consent was obtained from a personal legal representative (PerLR) or professional legal representative (ProfLR) prior to randomisation. Once regained capacity, all participants were approached for their consent for continued participation. The trial steering committee designed the protocol, and the oversight was provided by independent data and safety monitoring board (DSMB) and an external contract research organization (PHARMExcel). The trial protocol was previously published and registered in ClinicalTrials.gov (NCT04362059). All relevant data were collected and analyzed by the investigators. All the authors assume responsibility for the accuracy and completeness of trial data and the trial fidelity to the protocol and statistical analysis plan.