1. Paediatric Intensive Care Unit, Hospital Universitario de Burgos, Burgos, Spain;
2. Department of Neonatology, Hospital Universitario de Burgos, Burgos, Spain;
3. Chemical Engineering Division, Department of Biotechnology and Food Science, Universidad de Burgos, Burgos, Spain;
4. Department of Investigation Unit, Hospital Virgen de la Concha, Escuela Universitaria de Enfermería de Zamora, Zamora, Spain