Jürg Hammer1, Daniel Trachsel1, Thomas Nicolai2, Markus Weiss3, Ernst Eber4. 1. Division of Respiratory and Critical Care Medicine, University Children's Hospital Basel, Switzerland. 2. Department of Pediatrics, Dr. von Hauner Children's Hospital, Ludwig-Maximilians-University, Munich, Germany. 3. Department of Anesthesia, University Children's Hospital Zurich, Switzerland. 4. Division of Pediatric Pulmonology and Allergology, Department of Pediatrics and Adolescent Medicine, Medical University of Graz, Austria.