Randomization
A computer-generated block randomization was designed to provide each site with a blinded randomized sequence assigning the PEEP level during HCPAP therapy. An initial sequence of 50 patients was sent to the study coordinator at each site, with an equal number of patients in each group at all sites. The subsequent planned blocks were not sent after study interruption. After patients were randomly assigned to the study groups and achievement of informed consent, the PEEP level enrollment group was revealed, and it was open to all caregivers due to the impossibility of blinding it.