1. Department of Anesthesiology Centre for Anaesthesiological Research Zealand University Hospital Køge Denmark
2. Department of Orthopaedic Surgery and Traumatology Copenhagen University Hospital Bispebjerg and Frederiksberg Copenhagen Denmark
3. Department of Anaesthesia Centre of Head and Orthopaedics, Rigshospitalet Copenhagen Denmark
4. Department of Clinical Medicine University of Copenhagen Copenhagen Denmark
5. Department of Anesthesia and Intensive Care Copenhagen University Hospital Bispebjerg and Frederiksberg Copenhagen Denmark