1 Department of Anesthesia, University Children's Hospital, University of Zurich, Zurich, Switzerland.
2 Department of Pediatric Anesthesia Hallerwiese Hospital/Cnopf'sche Children's Hospital Nuremberg, Nuremberg, Germany.
3 Department of Anesthesia & Intensive Care, Pediatric Section, Odense University Hospital, Odense, Denmark.
4 School of Medicine and Dentistry, University of Aberdeen, Royal Aberdeen Children's Hospital, Aberdeen, Scotland AB25 2ZN, UK. Electronic address: t.engelhardt@nhs.net.