Prospective Observational Multimodal Neuromonitoring in Adult NSICU Patients

BACKGROUND: Patients admitted to the NSICU undergo rapid physiologic changes related to primary neurologic injury, secondary brain injury, sedation, mechanical ventilation, and evolving systemic illness. Cerebral autoregulation (CA) - the brain's intrinsic mechanism for maintaining stable perfusion across a range of systemic arterial pressures - is measurably impaired in aSAH, traumatic brain injury (TBI), intracerebral hemorrhage (ICH), and acute ischemic stroke. In aSAH, CA impairment during the 4-14 day post-rupture window is independently associated with delayed cerebral ischemia (DCI), the leading cause of preventable death and disability in survivors. Approximately 75% of aSAH patients require an external ventricular drain (EVD), which prevents standard ICP-based CA monitoring. B4C extensometry and NIRS-derived CA indices offer EVD-independent monitoring approaches whose feasibility and signal characteristics in aSAH have not been prospectively described.

DESIGN: Single-center prospective observational cohort study at the UT Southwestern NSICU. Eligible subjects may undergo B4C extensometry monitoring (the sole research-specific device under this protocol) and/or have research data recorded from existing standard-of-care clinical monitoring including SedLine qEEG, full-montage long-term monitoring EEG (where clinically ordered), NIRS, invasive ICP/CPP from EVD monitors, transcranial Doppler (TCD; standard of care for aSAH at UT Southwestern), and NeurOptics NPi automated pupillometry. The Moberg Clinical Platform (Moberg Analytics; FDA-cleared) serves as the primary data acquisition hub in the NSICU, aggregating synchronized high-resolution physiologic waveforms from existing bedside monitors without placing any additional research devices.

MONITORING MODALITIES:

Research device placed specifically for research purposes under this protocol:

- Brain4Care (B4C) extensometry: skull-mounted noninvasive sensor recording cranial compliance-related waveform morphology (P2/P1 ratio, Time to Peak), from which surrogate CA indices (nPRx, nCPPopt, nMx) are derived.

Standard-of-care clinical data recorded for research purposes (no additional devices placed):

• SedLine qEEG: clinically placed forehead sensor used for sedation monitoring as standard of care; provides Patient State Index, Spectral Edge Frequency, and raw EDF waveforms.
• Full-montage long-term monitoring EEG: from clinically ordered continuous EEG electrodes for seizure and ADR monitoring where applicable.
• NIRS (near-infrared spectroscopy): regional cerebral oxygenation; CA indices computed include cerebral oximetry index (COx) and total oxygenation reactivity index (TOxA).
• Clinical ICP/CPP waveform data from EVD transducer where present.
• TCD vasospasm surveillance (daily studies as standard of care for aSAH; peak and mean velocities, Lindegaard ratio).
• NeurOptics NPi pupillometry: NPi, constriction velocity, latency, amplitude.
• Moberg Clinical Platform: synchronized arterial blood pressure, ICP, ECG/HRV, SpO2, EtCO2, CVP, ventilator parameters, NIRS.

ASAH PRIORITY ENROLLMENT: For aSAH patients, the protocol prioritizes monitoring through ICU Day 14 to characterize the natural history of B4C-derived and NIRS-derived CA index evolution through the DCI window. An optional 90-day follow-up captures functional and neurological outcomes beyond hospital discharge.

DATA MANAGEMENT: Subjects are assigned unique study identifiers. Direct identifiers are removed from analytic datasets. De-identified data may be shared with qualified external collaborators under executed data use agreements and with applicable IRB approval. De-identified data from this study may be combined with data from the companion NSICU Autonomic Modulation Study for analyses within the approved scope of both protocols.