Protocol for the Electroencephalography Guidance of Anesthesia to Alleviate Geriatric Syndromes (ENGAGES-CANADA) Study: a Pragmatic, Randomized Clinical Trial

ENGAGES CANADA is a parallel study to the ENGAGES study which has been published in JAMA, DOI:10.1001/jama.2019.5161. Due to the difference in practice models and types of anesthesia principles, ENGAGES CANADA is an important study. Delirium is a relatively common postoperative complication in the geriatric population, affecting 20% to 70% of surgical patients over the age of 60. Delirium manifests as confusion, inattention and the inability to think logically, and may affect the patient's postoperative healing and rehabilitation. It is associated with persistent cognitive decline, longer hospital stay, increased incidence of injurious falls, and increased mortality. Patients undergoing major cardiac surgery are at a significant risk of postoperative delirium. To date, there is no proven method to prevent postoperative delirium in this patient population and often delirious events remain unrecognized. Randomized controlled studies in diverse surgical patient populations suggest that intraoperative electroencephalography (EEG) guidance during general anesthesia may decrease postoperative delirium and adverse postoperative outcomes. Patients who experience postoperative delirium report persistently decreased quality of life and it is a risk factor for incident psychiatric disorders and psychotropic medication use. One potential key mechanism in the relationship between delirium and incident psychiatric illness may be the experience of dissociation (disturbed awareness, impaired memory, or altered perceptions) in the perioperative period in those who are delirious. The co-occurrence of psychiatric illness and delirium can put older adults at greater risk of negative long terms effect such as functional decline. This study will compare the effectiveness of two anesthetic protocols in reducing postoperative delirium and postoperative health-related quality of life in a high risk population.We expect that EEG-guided anesthetic management of patients during their operative procedure will result in improved health-related outcomes, specifically decreased incidence of postoperative delirium and improved postoperative mental and physical health outcomes.