Study design
A pre-post single-center retrospective study according to STROBE statement checklist was conducted at the CF Centre of Bambino Gesù Pediatric Hospital, from September 2020 to February 2021. Fifty-eight consecutive CF patients with a Pulmonary exacerbation (PE) were enrolled. PE with intravenous (IV) antibiotic need was defined according to standard Fuchs’ criteria with an inadequate/absent clinical response to a standard 14-day oral treatment. We included patients starting from 3 years of age. Exclusion criteria were an advanced lung disease with a FEV1 ≤ 40 % of predicted and chronic Burkholderia cepacia complex and Nontuberculous Mycobacteria (NTM) airways infection. All study participants performed coupled multiple breath washout test and spirometric assessment within 72-hours from hospital admission for pulmonary exacerbation and at the end of IV antibiotic course. IV treatment was conducted entirely in hospital, according to the CF guidelines, providing 14 days of intravenous processing with standard chest daily physiotherapy pulmonary rehabilitation 26. The study protocol was approved by the local ethics committee of Bambino Gesù (2819_OPBG_2022). A written informed consent was obtained from all eligible subjects or from their parents/guardians when necessary.