The investigators intend to recruit 600 participants to see if alpha power during anesthesia is influenced by analgesic medication and associated with a reduction of delirium following surgery.
Adults aged 60 years or over
Has capacity to provide informed consent
Undergoing elective non-cardiac surgery, which does not involve the head or neck, with planned volatile-based general anesthesia of expected duration of at least 2 hours
Chronic pain with opioid requirement or concurrent use of enzyme inducers, e.g. carbamazepine, phenytoin,
Illicit substance use or excessive alcohol intake
Refusal by patient or case anesthesiologist responsible for patient's care