1. Department of Anaesthesiology; Copenhagen University Hospital; Nordsjaellands Hospital; Hillerød Denmark
2. Copenhagen Trial Unit; Centre for Clinical Intervention Research; Copenhagen University Hospital; Rigshospitalet; Copenhagen Denmark
3. Department of Anaesthesiology; Aarhus University Hospital; Aarhus C Denmark
4. Department of Anaesthesiology; Juliane Marie Centre; Copenhagen University Hospital; Rigshospitalet; Copenhagen Denmark