The GUARDIAN Pilot Trial

Inclusion Criteria: * ≥45 years old * Scheduled for major noncardiac surgery expected to last at least 2 hours; * Having general endotracheal, neuraxial anesthesia, or the combination; * Expected to require at least overnight hospitalization; * Are designated ASA physical status 2-4 (ranging from mild systemic disease through severe systemic disease that is a constant threat to life); * Chronically taking at least one anti-hypertensive medication; * Expected to have direct blood pressure monitoring with an arterial catheter; * Cared for by clinicians willing to follow the GUARDIAN protocol; * Subject to at least one of the following risk factors: * History of peripheral arterial surgery; * History of coronary artery disease; * History of stroke or transient ischemic attack; * Serum creatinine \>175 µmol/L (\>2.0 mg/dl); * Diabetes requiring medication; * Current smoking or 15 pack-year history of smoking tobacco; * Scheduled for major vascular surgery; * Body mass index ≥35 kg/m2; * Preoperative high-sensitivity troponin T \>14 ng/L or troponin I equivalent; * B-type natriuretic protein (BNP) \>80 ng/L or N-terminal B-type natriuretic protein (NT-ProBNP) \>100 ng/L Exclusion Criteria: * Are scheduled for carotid artery surgery; * Are scheduled for intracranial surgery; * Are scheduled for partial or complete nephrectomy; * Are scheduled for pheochromocytoma surgery; * Are scheduled for liver transplantation; * Require preoperative intravenous vasoactive medications; * Have…