1. Intensive Care Unit, Department of Anaesthesiology, Pharmacology and Intensive Care, University Hospitals of Geneva, 4 Rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland
2. Faculty of Medicine, University of Geneva, 4 Rue Gabrielle-Perret-Gentil, 1211 Geneva 14, Switzerland
3. Division of Clinical Epidemiology (Biostatistics), University Hospitals of Geneva, 4 Rue Gabrielle-Perret-Gentil 1211 Geneva 14, Switzerland