1. Department of Intensive Care Medicine; University Hospitals Birmingham National Health Service Foundation Trust; Queen Elizabeth Hospital Birmingham; University of Birmingham; UK
2. Medical Statistics Department; London School of Hygiene and Tropical Medicine; London UK
3. Department of Anaesthesia, Pharmacology and Intensive Care Medicine; Geneva University Hospitals; Genève Switzerland
4. Department of Cardiothoracic Anaesthesia and Intensive Care Medicine; Royal Papworth Hospital National Health Service Foundation Trust; Cambridge UK
5. Research and Development Department; Royal Papworth Hospital National Health Service Foundation Trust; Cambridge UK
6. Department of Anaesthesia and Intensive Care; Royal Papworth Hospital National Health Service Foundation Trust; Cambridge UK