1. C Staikou (corresponding author): 1st Department of Anesthesiology, Aretaieio Hospital, Medical School, University of Athens, Fleming 3, Anoixi Attikis, 14569 Greece;
2. E Argyra, A Vadalouca: 1st Department of Anesthesiology, Pain Relief and Palliative Care Unit, Aretaieio Hospital, Medical School, University of Athens, Greece