P Diéguez1, M Fajardo2, S López3, P Alfaro2. 1. Department of Anesthesia, Hospital Abente y Lago, Complexo Hospitalario Universitario A Coruña, A Coruña, Spain. Electronic address: pauladieguez@yahoo.com. 2. Department of Anesthesia, Hospital Universitario de Móstoles, Madrid, Spain. 3. Department of Anesthesia, Hospital Abente y Lago, Complexo Hospitalario Universitario A Coruña, A Coruña, Spain.