Association of Intraoperative Blood Pressure Excursions Below Cerebral Autoregulatory Boundaries With Organ Injury Following Major Noncardiac Surgery

"Main study (all patients): Continuous bilateral frontal cerebral near-infrared spectroscopy (NIRS) monitoring will be performed in all patients for the duration of general anesthesia. Intraoperative parameters including NIRS and invasive blood pressure will be collected and recorded in real-time using the software ICM+.~Postoperative hemodynamics substudy (facultative): Cerebral NIRS monitoring will be continued postoperatively in a subset of patients being admitted to the ICU."

"Main study (all patients): Creatinine, high-sensitivity troponin (T hs-cTnT), Growth/Differentiation Factor-15 (GDF-15), Hemoglobin~Neurological injury substudy (facultative): Neurofilament Light Chain (NFL) and C-reactive protein (CRP)"

Main study (all patients): Telephone follow-up (1-year outcomes).

Tissue perfusion substudy (facultative): Continuous somatic NIRS monitoring of an extremity (i.e. on skin of leg or arm) will be performed intraoperatively and postoperatively in a subset of patients being admitted postoperatively to the ICU.

Processed EEG substudy to explore the relationship between processed EEG-derived depth of anesthesia metrics and cerebral autoregulatory function.