This is a prospective observational cohort study of adult patients undergoing high-risk surgery at UT Southwestern Medical Center. The study acquires synchronized multimodal neuromonitoring data - including SedLine quantitative EEG (qEEG) extracted from standard-of-care clinical monitoring and, where deployed, Brain4Care (B4C) noninvasive intracranial dynamics data - and links these data to perioperative hemodynamic, medication, laboratory, procedural, and outcome variables. No alteration of routine clinical care occurs. The primary goal is to characterize associations between monitor-derived features and perioperative clinical variables, and to establish a multimodal dataset supporting future analyses of perioperative brain health in high-risk surgical populations.