1. University of Sherbrooke; Department of Anesthesiology, Faculty of Medicine; Sherbrooke Quebec Canada
2. Peterborough and Stamford Hospitals NHS Foundation Trust; Department of Orthopaedics; Peterborough City Hospital CBU PO Box 211, Bretton Gate Peterborough Cambridgeshire UK PE3 9GZ
3. Peterborough and Stamford Hospitals NHS Foundation Trust; Department of Anaesthesia; Edith Cavell Hospital Bretton Gate Peterborough Cambridgeshire UK PE26 2UA
4. Mayo Clinic College of Medicine; Department of Anesthesiology and Perioperative Medicine; 200 1st St SW Rochester MN USA 55901