1. Children\'s Hospital, University Hospital of Cologne, Cologne, Germany
2. FOM University of Applied Science for Economics & Management, Essen, Germany
3. General Pediatrics, Neonatology and Pediatric Cardiology, University Hospital of Düsseldorf, Düsseldorf, Germany
4. Department of Neonatology, Children\'s Hospital, University Hospital of Cologne, Cologne, Germany