1. Department of Anaesthesia Hospital Universitario la Paz Madrid Spain
2. Department of Anaesthesia Complutense University of Madrid Hospital Universitario Infanta Leonor Madrid Spain
3. Department of Anaesthesia Hospital Clínico Universitario Lozano Blesa Zaragoza Spain
4. Department of Anaesthesia Örebro University Hospital Örebro Sweden
5. Department of Consultant Preventive Medicine and Public Health Complutense University of Madrid Madrid Spain
6. Department of Colorectal Surgery University of Zaragoza Zaragoza Spain
7. Department of Anaesthesia Complutense University of Madrid Hospital Clínico San Carlos Madrid Spain