1 Neonatal Intensive Care Unit, Puerta del Mar University Hospital, Avenida Ana de Viya 11, 11010, Cádiz, Spain. almudena.alonso.sspa@juntadeandalucia.es.
2 Biomedical Research and Innovation Institute of Cádiz (INiBICA), Research Unit, Puerta del Mar University Hospital, Cádiz, Spain. almudena.alonso.sspa@juntadeandalucia.es.
3 Pediatric Intensive Care Unit, Complejo Asistencial Universitario de León, León, Spain.
4 Working Group on Bedside Ultrasound of the Spanish Society of Pediatric Intensive Care (SECIP), Madrid, Spain.
5 Biomedicine Institute of León (IBIOMED), University of León, León, Spain.