1 Department of Paediatrics, Division of Paediatric Intensive Care, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Internal Postal Code CA 62, P.O. Box 30.001, 9700 RB, Groningen, the Netherlands. r.g.t.blokpoel@umcg.nl.
2 Department of Paediatrics, Division of Paediatric Intensive Care, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Internal Postal Code CA 62, P.O. Box 30.001, 9700 RB, Groningen, the Netherlands.
3 Faculty of Science and Technology, University of Twente, Enschede, the Netherlands.
4 Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
5 Critical care, Anesthesiology, Peri-operative and Emergency medicine (CAPE), University of Groningen, Groningen, the Netherlands.