1. Department of Anesthesia; University of Pisa; Pisa; Italy
2. University Department of Anaesthesiology and Pain Therapy; Inselspital; Berne; Switzerland
3. Epidemiology and Biostatistics Unit's Research; Department of Experimental Pathology M.B.I.E.; University of Pisa; Pisa; Italy
4. Department of Anesthesia; McGill University Health Centre; Montreal; QC; Canada