1. Centre for Anaesthesiological Research, Department of Anaesthesiology Zealand University Hospital Køge Denmark
2. Department of Anaesthesiology Næstved, Slagelse and Ringsted Hospitals Slagelse Denmark
3. Department of Anaesthesia and Intensive Care, Bispebjerg and Frederiksberg Hospital Copenhagen University Hospital Denmark
4. Department of Orthopaedic Surgery and Traumatology, Bispebjerg and Frederiksberg Hospital Copenhagen University Hospital Denmark
5. Department of Anaesthesiology Copenhagen University Hospital, North Zealand Hospital Hillerød Denmark
6. Department of Orthopaedic Surgery, Trauma Unit Zealand University Hospital Køge Denmark
7. Department of Anaesthesia, The Juliane Marie Centre Copenhagen University Hospital, Rigshospitalet Copenhagen Denmark