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.

BACKGROUND: Patients undergoing major spine surgery, liver transplantation, on-pump cardiac surgery, major vascular surgery, major thoracic surgery, major abdominal surgery, and neurosurgical craniotomy are exposed to substantial perioperative physiologic stress, including hemodynamic instability, blood loss, cardiopulmonary bypass, and procedure-specific periods of altered cerebral perfusion. Quantitative electroencephalography and noninvasive assessments of intracranial dynamics may provide complementary information about brain state and cerebrovascular physiology during these high-risk operations. However, the relationships between monitor-derived features and intraoperative events - including hypotension, anesthetic transitions, major surgical events, and postoperative outcomes - remain incompletely characterized.

DESIGN: Single-center prospective observational cohort study at UT Southwestern Medical Center. SedLine quantitative EEG data are extracted from standard-of-care clinical monitoring for all enrolled subjects. Brain4Care (B4C) noninvasive intracranial dynamics monitoring may additionally be placed as a research device depending on study workflow, patient characteristics, technical feasibility, and clinical context. Either monitoring configuration - SedLine alone or SedLine combined with B4C - constitutes a complete and valid study encounter.

The Moberg Clinical Platform (Moberg Analytics; FDA-cleared multimodal data integration system) serves as the primary data acquisition hub where deployed in the operating room, aggregating synchronized high-resolution physiologic waveforms alongside SedLine and B4C outputs. Where Moberg is unavailable, hemodynamic and physiologic variables are collected retrospectively from the Epic intraoperative anesthesia record.

MONITORING MODALITIES:

Research device placed specifically for this study (where deployed):

- Brain4Care (B4C) extensometry: skull-mounted noninvasive sensor recording cranial compliance-related waveform morphology (P2/P1 ratio, Time to Peak).

Standard-of-care clinical data recorded for research purposes:

• SedLine (Masimo): 4-channel frontal quantitative EEG providing Patient State Index, Spectral Edge Frequency, and exportable raw EDF-format waveforms.
• Moberg Clinical Platform: multimodal physiologic waveform integration including arterial blood pressure, SpO2, ECG, ventilator-derived parameters, temperature, and EtCO2.

DATA MANAGEMENT: Subjects are assigned unique study identifiers. Direct identifiers are removed from analytic datasets. Research data are stored on secure, institutionally approved systems accessible only to IRB-authorized study personnel. De-identified data may be shared with qualified external collaborators under executed data use agreements.

Inclusion Criteria:

• Age 18 years or older
• Scheduled to undergo major spine surgery, liver transplantation, on-pump cardiac surgery, major vascular surgery, major thoracic surgery, major abdominal surgery, or neurosurgical craniotomy at UT Southwestern Medical Center
• Able to provide informed consent (self or legally authorized representative when applicable)
• Safe and feasible placement of SedLine and/or Brain4Care monitoring as determined by the clinical and research teams
• Anticipated availability of perioperative clinical data needed for study analyses

Exclusion Criteria:

• Age younger than 18 years
• Prisoner status
• Pregnancy
• Unable to provide informed consent in English (consent documents available in English only)
• Declining participation
• Lack of subject or legally authorized representative consent when required
• Clinical condition preventing safe or feasible placement of study monitors (e.g., incompatible surgical field location, significant facial or scalp injury, open wounds at intended sensor placement site)
• Operative workflow or clinical urgency precluding reasonable completion of consent and monitor placement prior to start of surgery
• Anticipated clinical data capture insufficient for meaningful analysis

Adult patients age 18 years or older scheduled to undergo major spine surgery, liver transplantation, on-pump cardiac surgery, major vascular surgery, major thoracic surgery, major abdominal surgery, or neurosurgical craniotomy at UT Southwestern Medical Center. These populations were selected because they commonly experience substantial perioperative hemodynamic and physiologic perturbations.