OBJECTIVE: Regarding the use of lung ultrasound (LU) in neonatal intensive care units (NICUs) across Europe, to assess how widely it is used, for what indications and how its implementation might be improved. DESIGN AND INTERVENTION: International online survey. RESULTS: Replies were received from 560 NICUs in 24 countries between January and May 2023. LU uptake varied considerably (20%-98% of NICUs) between countries. In 428 units (76%), LU was used for clinical indications, while 34 units (6%) only used it for research purposes. One-third of units had <2 years of experience, and only 71 units (13%) had >5 years of experience. LU was mainly performed by neonatologists. LU was most frequently used to diagnose respiratory diseases (68%), to evaluate an infant experiencing acute clinical deterioration (53%) and to guide surfactant treatment (39%). The main pathologies diagnosed by LU were pleural effusion, pneumothorax, transient tachypnoea of the newborn and respiratory distress syndrome. The main barriers for implementation were lack of experience with technical aspects and/or image interpretation. Most units indicated that specific courses and an international guideline on neonatal LU could promote uptake of this technique. CONCLUSIONS: Although LU has been adopted in neonatal care in most European countries, the uptake is highly variable. The main indications are diagnosis of lung disease, evaluation of acute clinical deterioration and guidance of surfactant. Implementation may be improved by developing courses and publishing an international guideline.

2 Department of Neonatology Neonatal Biophysical Monitoring and Cardiopulmonary Therapies Research Unit Poznan University of Medical Sciences Poznan Poland

Amsterdam Reproduction and Development Amsterdam The Netherlands

Department of Neonatology Centro Hospitalar Universitário de São João Porto Portugal

Department of Neonatology Copenhagen University Hospital Rigshospitalet Copenhagen Denmark

Department of Neonatology Emma Children's Hospital Amsterdam UMC Amsterdam The Netherlands

Department of Neonatology George Emil Palade University of Medicine Pharmacy Science and Technology of Targu Mures Targu Mures Romania

Department of Neonatology Lithuanian University of Health Sciences Kaunas Lithuania

Department of Neonatology University Children's Hospital Basel Switzerland

Department of Paediatrics and Adolescence Medicine University Hospital of North Norway Tromso Norway

Department of Paediatrics University of Patras Patras Greece

Department of Pediatrics and Adolescent Medicine University Hosptial of Turky and Turku University Turku Finland

Department of Pediatrics University of California San Francisco San Francisco California USA

Department of Physiology Jessenius Faculty of Medicine Comenius University Bratislava Slovakia

Department of Women's and Children's Health Uppsala Universitet Uppsala Sweden

Division of Neonatology and Pediatric Intensive Care Medicine Department of Pediatrics and Adolescent Medicine University Medical Center Ulm Ulm Germany

Division of Neonatology Department of Obstetrics and Gynecology General Faculty Hospital and 1st Faculty of Medicine Charles University Prague Czechia

Division of Neonatology Department of Pediatrics and Adolescent Medicine Paracelsus Medical University University Hospital Salzburg Salzburg Austria

Division of Neonatology Saint Luc University Hospital UCLouvain Brussels Belgium

Divivion of Paediatric and Neonatal Critical Care Hôpital Antoine Béclère Clamart France

Health Sciences University Başaksehir Cam and Sakura City Hospital Istanbul Turkey

National Perinatal Epidemiology Unit Oxford Population Health Medical Sciences Division University of Oxford Oxford UK

Neonatal Intensive Care Unit Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico Milan Italy

Neonatal Intensive Care Unit Hospital Universitario Puerta del Mar Cadiz Spain

Neonatal Unit National Maternity Hospital Dublin Ireland

Neonatology Division Mayanei Hayeshua Medical Center Bnei Brak Tel Aviv Israel

Newborn Services Southmead Hospital North Bristol Trust Bristol UK

Paediatric Research Group Faculty of Health Sciences UiT The Arctic University of Norway Tromso Norway

Research Unit Puerta del Mar University Hospital Biomedical Research and Innovation Institute of Cádiz Cadiz Spain

School of Medicine University College Dublin Ireland

Tel Aviv University Tel Aviv Israel

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