George Stavrou1, Georgia Tsaousi2, Katerina Kotzampassi3. 1. York Teaching Hospital NHS Foundation Trust, York, YO318HE, UK. 2. Department of Anesthesiology, Aristotle University Thessaloniki, University Campus, 54006, Thessaloníki, Greece. tsaousig@otenet.gr. 3. Department of Surgery, Aristotle University Thessaloniki, University Campus, 54006, Thessaloníki, Greece.