1. Department of Anesthesiology and Pain Medicine, University Health Network, University of Toronto, Toronto, Ontario, Canada
2. Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario, Canada
3. Department of Anesthesiology and Pain Medicine, Toronto Western & Women’ College Hospitals, Toronto, Ontario, Canada
4. Toronto Sleep and Pulmonary Centre, Toronto, Ontario, Canada
5. Department of Anesthesiology, Yale School of Medicine, New Haven, Connecticut
6. Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
7. Division of Pulmonary, Sleep, and Critical Care Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio
8. Department of Anesthesiology, Section on Critical Care Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina
9. Outcomes Research Consortium, Cleveland, Ohio.