[Cerebral neuroprotection and ketamine]

Area of Science:

• Anesthesiology
• Neuroscience
• Pharmacology

Context:

• Ketamine is traditionally considered unsuitable for neuroanesthesia due to its effects on intracranial pressure (ICP), cerebral blood flow (CBF), and cerebral metabolic rate for oxygen (CMRO2).
• Emerging evidence suggests potential neuroprotective properties of ketamine, primarily through its interaction with the N-methyl-D-aspartate (NMDA) receptor.

Purpose:

• To critically evaluate the existing literature on ketamine's neuroprotective effects and its suitability for neuroanesthesia.
• To reconcile contradictory findings from experimental rodent studies regarding ketamine's efficacy in various ischemic and traumatic brain injury models.

Summary:

• Meta-analysis of rodent studies indicates ketamine's neuroprotection is context-dependent, offering benefits in specific scenarios like prophylactic/therapeutic administration during complete forebrain ischemia or within 2 hours post-head injury.
• Ketamine does not consistently protect against hypoxic hypoxemia or focal cerebral ischemia.
• Potential neuroprotective mechanisms extend beyond NMDA-receptor antagonism, including free radical scavenging and modulation of dopamine metabolism.

Impact:

• The suitability of ketamine for neuroanesthesia remains questionable, necessitating careful consideration of its complex effects on cerebral hemodynamics and metabolism alongside its neuroprotective potential.
• Further clinical and primate studies are required to validate findings from rodent models and inform clinical practice.