1 Centre for Perioperative Medicine and Critical Care Charing Cross Hospital Intensive Care Unit, Imperial College NHS Trust, Fulham Palace Road, W6 8RF, London, UK. frubulotta@hotmail.com.
2 Interdepartmental Division of Critical Care and Department of Medicine, University of Toronto, Sunnybrook Health Sciences Centre, Toronto, Canada.
3 Perelman School of Medicine at the University of Pennsylvania, Philadelphia, USA.