The GUARDIAN Trial

Eligibility 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 disease;
• * 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14 ng/L or troponin I equivalent; defined as ≥15 ng/L (Abbott assay),73 19 ng/L (Siemens assay, \[Borges, unpublished\]), or 50% of the 99% percentile for other assays; B-type natriuretic protein (BNP) \>80 ng/L or N-terminal B-type natriuretic protein (NT-ProBNP) \>200 ng/L
• * 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 or kidney transplantation;
• * Require preoperative intravenous vasoactive medications;
• * Have a condition that precludes routine or tight blood pressure management such as surgeon request for relative hypotension;
• * Require beach-chair positioning;
• * Have a documented history of dementia;
• * Have language, vision, or hearing impairments that may compromise cognitive assessments;
• * Have contraindications to norepinephrine or phenylephrine per clinician judgement;
• * Have previously participated in the GUARDIAN trial.