1. Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
2. Harvard T.H. Chan School of Public Health, Harvard University, MA, USA
3. Division of Respiratory Medicine, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
4. Department of Anesthesia, Pharmacology and Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
5. Department of Critical Care Medicine, Surrey Memorial Hospital, Surrey, British Columbia, Canada