Noninvasive neuromonitoring with rheoencephalography: a case report

Area of Science:

• Neurology
• Biomedical Engineering
• Critical Care Medicine

Background:

• Cerebral blood flow (CBF) autoregulation (AR) monitoring is crucial for managing neurocritical care patients and preventing secondary brain damage.
• Invasive methods like intracranial pressure (ICP) and arterial blood pressure (ABP) are used to calculate the CBF AR index (PRx).
• Rheoencephalography (REG) is an FDA-approved non-invasive technique for measuring CBF.

Observation:

• This study evaluated REG and arm bioimpedance for calculating a novel CBF AR index, termed REGx, in 13 neurocritical care patients across 28 sessions.
• Data acquisition and offline processing were performed using custom-built software on a laptop.
• REG pulse wave morphology was analyzed alongside REGx values and clinical parameters like Glasgow Coma Scale (GCS) and central venous pressure.

Findings:

• REGx successfully quantified CBF AR status, correlating with changes in intracranial compliance (ICC) and clinical status.
• Case studies demonstrated REGx's ability to reflect worsening ICC (Case #1) and improving neurological status (Case #2).
• Rapid changes in REGx and pulse wave morphology were observed within minutes, correlating with hemodynamic shifts (Case #3).

Implications:

• REGx, derived from non-invasive REG and bioimpedance, shows potential as a real-time neuromonitoring tool.
• This non-invasive approach may offer a viable alternative to invasive PRx monitoring in head-injured patients.
• The findings suggest REG-based bioimpedance can provide valuable insights into CBF AR and intracranial compliance, aiding clinical decision-making.