Relation between brain interstitial and systemic glucose levels after subarachnoid hemorrhage

• Objects: The optimal blood glucose level after acute brain injury is not known. The aim of the present investigation was to study the relation between brain interstitial and systemic blood glucose levels during the acute phase after SAH. We also studied the effects of insulin administration on local brain energy metabolism. Methods: 19 patients with spontaneous SAH were monitored with intracerebral microdialysis (MD). The relation between plasma (P)-glucose and interstitial MD-glucose levels and the temporal pattern of MD-metabolites was studied seven days after SAH. With a target P-glucose of 5-10 mmol/L, the effect of insulin injection on brain energy metabolites (MD-glucose, lactate, pyruvate) and glutamate was evaluated. Results: The mean correlation coefficient between P-glucose and MD-glucose was 0.27 ± 0.27, (p=0.0005) with a high degree of individual variation. MD-glucose, MD/P-glucose ratio and MD-glutamate levels decreased in parallel with a gradual increase in MD-pyruvate and MD-lactate levels. There were no significant changes of MD-L/P ratio or MD-glycerol. Insulin administration induced a statistically significant decrease in MD-glucose and MD-pyruvate. Conclusion: After SAH, there was a positive correlation between P-glucose and MD-glucose levels with a high degree of individual variation. A gradual decline of MD-glucose and MD/P-glucose ratio and an increase of MD-pyruvate and MD-lactate levels during the first week after SAH could suggest a transition to a hyperglycolytic state with increased cerebral glucose consumption. Administration of insulin was related to lowering of MD-glucose and MD-pyruvate, often to critically low levels even though plasma glucose values remained above 6 mmol/L. Thus, P-glucose should not be low in the acute phase after SAH and administration of insulin should be done with caution, even more crucial when the cerebral glucose metabolism has recovered and an increased energy demand is developing in the injured, repairing brain.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kirurgi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Surgery (hsv//eng)

Nyckelord

Brain glucose

Blood glucose

Insulin

Microdialysis

Subarachnoid hemorrhage

Neurosurgery

Neurokirurgi

Neurosurgery

Neurokirurgi

Publikations- och innehållstyp

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