1. Hvidovre Hospital, University of Copenhagen; Department of Anaesthesiology and Intensive Care Medicine; Kettegård Alle 30, Hvidovre Denmark 2650
2. Department 7812, Rigshospitalet, Copenhagen University Hospital; Copenhagen Trial Unit, Centre for Clinical Intervention Research; Blegdamsvej 9 Copenhagen Denmark DK-2100
3. Herlev and Gentofte Hospital, University of Copenhagen; Cochrane Anaesthesia, Critical and Emergency Care Group; Herlev Ringvej Herlev Denmark 2730
4. Rigshospitalet, Copenhagen University Hospital; Juliane Marie Centre - Anaesthesia and Surgical Clinic Department 4013; Copenhagen Denmark