The development of devices that can fix the tidal volume in high-frequency oscillatory ventilation (HFOV) has allowed for a significant improvement in the management of HFOV. At our institution, this had led to the earlier use of HFOV and promoted a change in the treatment strategy involving the use of higher frequencies (above 15 Hz) and lower high-frequency tidal volumes (VThf). The purpose of this observational study was to assess how survival without bronchopulmonary dysplasia grades 2 and 3 (SF-BPD) is influenced by these modifications in the respiratory strategy applied to preterm infants (gestational age < 32 weeks at birth) who required mechanical ventilation (MV) in the first 3 days of life. We compared a baseline period (2012-2013) against a period in which this strategy had been fully implemented (2016-2017). A total of 182 patients were exposed to MV in the first 3 days of life being a higher proportion on HFOV at day 3 in the second period 79.5% (n 35) in 2016-2017 vs 55.4% (n 31) in 2012-2013. After adjusting for perinatal risk factors, the second period is associated with an increased rate of SF-BPD (OR 2.28; CI 95% 1.072-4.878); this effect is more evident in neonates born at a gestational age of less than 29 weeks (OR 4.87; 95% CI 1.9-12.48). Conclusions : The early use of HFOV combined with the use of higher frequencies and very low VT was associated with an increase in the study population's SF-BPD. What is Known: • High-frequency ventilation with volume guarantee improve ventilation stability and has been shown to reduce lung damage in animal models. What is New: • The strategy of an earlier use of high-frequency oscillatory ventilation combined with the use of higher frequencies and lower tidal volume is associated to an increase in survival without bronchopulmonary dysplasia in our population of preterm infants. Keywords High-frequencyventilation. Lung protection. Bronchopulmonary dysplasia. Ventilatory-induced lung injury. Target tidal volume. Preterm infants Abbreviations ΔPhf Delta pressure BPD Bronchopulmonary dysplasia type 2-3 BW Birth weight CMV Conventional mechanical ventilation CRIB Critical index for babies DOL Days of life GA Gestational age HFOV High-frequency oscillatory ventilation Hz Hertz INSURE Intubation-surfactant administration-extubation LISA Less-invasive surfactant administration MV Mechanical ventilation nCPAP Nasal continuous airway pressure NEC Necrotizing enterocolitis Communicated by Daniele De Luca

Objective Parent partnership is a key aspect of neonatal hospital care. However, there is a lack of information regarding parents' perception of neonatal safety. This study explores parents' opinions on safety during their child's hospitalization to identify points for improvement. Study Design We used a questionnaire, validated by the Spanish National Healthcare Authorities, on perception of safety with respect to hospital health care. Results Thirty-seven parents of 20 newborns treated in the neonatal intensive care unit (NICU) and 139 parents of newborns in intermediate care (IC) participated in this study. With regard to overall perception of safety, more than 96% of parents felt “very safe” or “fairly safe.” In the NICU, an area for improvement detected was to ask parents more often their opinion about the care or treatment provided to their child. In IC, three points for improvement were identified from the group of parents whose child was admitted directly to IC: the consistency of the information received, the request for consent for procedures, and the request for an opinion on their child's care and treatment. Only four parents reported that their child suffered an incident. Regarding incident management, parents were not completely satisfied with the information they received. Conclusion To the best of our knowledge, this is the first study of parent perception of patient safety in a neonatal unit using a validated questionnaire. Our findings suggest that parents can provide valuable information on neonatal safety, which can then be used to identify areas for improvement. Key Points