1. Department of Anaesthesiology and Intensive Care , Haukeland University Hospital , Bergen , Norway
2. Department of Clinical Medicine , University of Bergen , Bergen , Norway
3. Department of Orthopaedic Surgery , Haukeland University Hospital , Bergen , Norway
4. Centre for Clinical Research , Haukeland University Hospital , Bergen , Norway
5. Department of Heart Disease , Haukeland University Hospital , Bergen , Norway
6. Department of Clinical Science , University of Bergen , Bergen , Norway