Depth of Anesthesia on Postoperative Delirium and Cognitive After Surgery

The goal of this clinical trial (Balanced-2 study) is to compare light to deep general anesthesia using widely available brain monitors, to see if 'light' anesthesia could reduce rates of delirium, cognitive decline, and disability in older adults undergoing major surgery. Delirium is the most common serious surgical complication, occurring in an estimated one in four older adults undergoing major surgery. Delirium causes significant distress to patients and family, and is associated with prolonged hospital stay, physical disability, progression to dementia-like illnesses, and discharge to long-term care. Between 10 - 30% of adults aged 70 years and above have surgery every year, and preserving brain health and wellbeing is an important priority during this time. Older adults (aged ≥65 years, or Indigenous, Pacific patients aged ≥55 years) undergoing major surgery with general anesthes