1. Iberoamerican Cochrane Centre, Biomedical Research Institute Sant Pau (IIB Sant Pau); CIBER Epidemiología y Salud Pública (CIBERESP); Barcelona Spain
2. Service of Anesthesiology; Hospital de la Santa Creu i Sant Pau; Barcelona Spain
3. Iberoamerican Cochrane Centre; Institute of Biomedical Research Sant Pau (IIB Sant Pau), Barcelona; Barcelona Spain
4. Iberoamerican Cochrane Centre - Biomedical Research Institute Sant Pau (IIB Sant Pau); CIBER Epidemiología y Salud Pública (CIBERESP); Barcelona Spain