Relation between brain interstitial and systemic glucose concentrations after subarachnoid hemorrhage.

Area of Science:

• Neuroscience
• Metabolism
• Critical Care Medicine

Background:

• Subarachnoid hemorrhage (SAH) can disrupt brain energy metabolism.
• Understanding brain glucose dynamics is crucial for managing SAH patients.

Purpose of the Study:

• To investigate the relationship between brain interstitial and systemic blood glucose concentrations in acute SAH.
• To assess the impact of insulin administration on brain energy metabolism post-SAH.

Main Methods:

• Intracerebral microdialysis (MD) was used to monitor brain glucose, lactate, pyruvate, glutamate, and glycerol in 19 SAH patients for 7 days.
• Plasma glucose and MD glucose concentrations were correlated.
• The effects of insulin on brain metabolism were evaluated.

Main Results:

• A positive correlation (r=0.27) was observed between plasma and brain interstitial glucose, with significant individual variability.
• Brain glucose and the brain/plasma glucose ratio decreased, while lactate and pyruvate increased, suggesting increased glucose consumption.
• Insulin administration lowered brain glucose and pyruvate, sometimes below safe levels despite adequate plasma glucose.

Conclusions:

• Brain and plasma glucose are correlated after SAH, but with high individual variation.
• A shift towards increased cerebral glucose consumption occurs in the first week post-SAH.
• Insulin therapy may impair brain glucose supply in SAH patients, necessitating careful monitoring.