1. Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
2. Division of Respirology, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
3. Division of Otolaryngology, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada
4. Clinical Research Unit, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
5. Clinical Epidemiology, Ottawa Hospital Research Institute
6. Department of Epidemiology and Community Medicine, University of Ottawa
7. Department of Anesthesia, University Hospital, Coventry, UK
8. Division of Anesthesiology, University of Ottawa, Children's Hospital of Eastern Ontario, Ottawa, Ontario, Canada