1. Nordsjaellands Hospital; Department of Anaesthesiology; Hillerød Denmark 3400
2. University of Aarhus; Research Center for Emergency Medicine; Aarhus Denmark
3. Herlev Hospital, University of Copenhagen; Department of Anaesthesiology; Herlev Denmark
4. Herlev and Gentofte Hospital, University of Copenhagen; The Cochrane Anaesthesia, Critical and Emergency Care Group; Herlev Ringvej Herlev Denmark 2730
5. Gentofte Hospital; Department of Anaesthesiology and Intensive Care; Kildegårdsvej 28 Hellerup Copenhagen Denmark 2900
6. Department 7812, Rigshospitalet, Copenhagen University Hospital; Copenhagen Trial Unit, Centre for Clinical Intervention Research; Blegdamsvej 9 Copenhagen Denmark DK-2100