1. Department of Anesthesiology, Aretaieion University Hospital, University of Athens Medical School, 11528 Athens, Greece
2. Department of Anaesthetics, St George’s Hospital, Blackshaw Road, London SW17 0QT, UK
3. Second Department of Surgery, Aretaieion University Hospital, University of Athens Medical School, 11528 Athens, Greece
4. Fourth Department of Surgery, Attikon University Hospital, University of Athens Medical School, 12462 Athens, Greece