Intervention~Patients will be randomized to either general anesthesia (GA) or HSA + GA.~Spinal group: will receive high spinal anesthesia with hyperbaric bupivacaine (0.3 to 0.6 mgs/kg) + preservative free morphine (3 mcg/kg).~Standard intraoperative monitors will include ECG, pulse oximetry, end-tidal CO2 and anesthetic gas measurement, quantitative EEG monitoring (BIS monitor), arterial line, central venous pressure line and any other monitor as clinically indicated.~Conduct of the general anesthetic will not be protocolized. It will be a pragmatic study. The attending anesthesiologist will attempt to have a BIS score of 20- 40 during the operation.~Intraoperative physiological data (mean blood pressure, end-tidal anesthetic gas concentrations, BIS score) will be recorded and downloaded to a laptop computer using the Trend Face Solo acquisition system for subsequent analysis.~The routine postoperative care map for the postoperative cardiac intensive care unit (ICCS) will be followed.~All patients will be assessed by the study investigator for presence/absence of delirium on postoperative days 1,2 & 3, as well as routine nursing assessment by the delirium assessment tool CAM-ICU, routinely done by nursing staff. Chart reviews will be conducted to confirm any additional incidence of delirium.~All patients will be contacted at one and three months after surgery and asked to complete a ten-minute survey (Postop QoR-15 questionnaire) assessing their quality of recovery.
This is a feasibility study to determine if enough patients undergoing elective or urgent cardiac surgery, can be enrolled in a study where patients are randomized to receive high spinal anesthesia as an adjunct to general anesthesia for their cardiac surgery. The primary clinical outcome will be the incidence of post-operative delirium.