Table 3.

Pathophysiologic Types of Cerebral Shock (adapted from Brain Shock-Toward Pathophysiologic Phenotyping in Traumatic Brain Injury [78]). Brain tissue oxygen (PbtO2); lactate/pyruvate ratio (LPR); cerebral blood flow (CBF); cerebral perfusion pressure (CPP); intracranial pressure (ICP); cortical spreading depression (CSD). If a neuromonitoring result is not listed, it is either unchanged or unpredictable.

Pathophysiologic Type	Neuromonitoring Result	Underlying Pathophysiology and Management
Flow Dependent	↓: PbtO2, glucose, pyruvate ↑: lactate, LPR	Suboptimal CBF → optimize hemodynamic parameters and CPP
Flow Independent Oxygen Diffusion Limitation	↓: PbtO2 ↑: lactate, LPR	Intracellular/interstitial edema → appropriately manage cerebral edema
Flow Independent Energy Production (Mitochondrial) Failure	↓: lactate, LPR, possibly pyruvate ↑: glucose	Management is unclear
Flow Independent Microvascular Shunting	↓: PbtO2 (from ↑CBF) ↑: glucose, lactate	Microvascular shunting → appropriately manage ICP
Low Extraction	↓: PbtO2, pyruvate ↑: lactate, LPR	Hypoxemic, anemic or high-affinity hypoxia → treat appropriate underlying cause to improve oxygenation
Hypermetabolic	↓: PbtO2, glucose, pyruvate ↑: lactate, LPR Similar profile to flow dependent	Increase in metabolic demand → Avoid hyperthermia, seizures, CSD; consider sedation if appropriate