1. Pain Unit, Department of Anesthesiology and Critical Care, University Hospital “Puerta del Mar”, Avenida Ana de Viya 21, 11009 Cádiz, Spain
2. Preventive Medicine and Health Public Area, University of Cádiz, Avenida Ana de Viya 52, 11009 Cádiz, Spain
3. Surgery Department, University of Cádiz, Plaza Fragela 9, 1003 Cádiz, Spain