Dr. Scales graduated from the University of Toronto (UofT) in 1997. Following residencies in Internal Medicine and Critical Care Medicine (UofT), he completed a PhD in Clinical Epidemiology (UofT). He is a Professor of Medicine (UofT), Scientist, and Chief of Critical Care at the Sunnybrook Health Sciences Centre and the Sunnybrook Research Institute.

Dr. Scales conducts epidemiological and health services research examining system-level factors that influence the outcomes of critically ill patients. He has conducted several cluster randomized controlled trials (RCTs) of large-scale quality improvement interventions. He is currently conducting 3 RCTs funded by the Canadian Institute for Health Research: The PITSTOP RCT investigating a prehospital sepsis intervention (PITSTOP; NCT03068741); the NEURO-ETT RCT (NCT02920580) evaluating different airway management strategies for neurologically-impaired ICU patients; and the PROTEST RCT (NCT03559114) evaluating early versus late anticoagulant thromboprophylaxis for patients with traumatic brain injury.