Intensive insulin therapy reduces microdialysis glucose values without altering glucose utilization or improving the lactate/pyruvate ratio after traumatic brain injury.
OBJECTIVE
To determine that intensive glycemic control does not reduce microdialysis glucose concentration brain metabolism of glucose.


METHODS
Prospective monitoring followed by retrospective data analysis of cerebral microdialysis and global brain metabolism.


METHODS
Single center, academic neurointensive care unit.


METHODS
Forty-seven moderate to severe traumatic brain injury patients.


METHODS
A nonrandomized, consecutive design was used for glycemic control with loose insulin (n=33) for the initial 2 yrs or intensive insulin therapy (n=14) for the last year.


RESULTS
In 14 patients treated with intensive insulin therapy, there was a reduction in microdialysis glucose by 70% of baseline concentration compared with a 15% reduction in 33 patients treated with a loose insulin protocol. Despite this reduction in microdialysis glucose, the global metabolic rate of glucose did not change. However, intensive insulin therapy was associated with increased incidence of microdialysis markers of cellular distress, namely elevated glutamate (38+/-37% vs. 10+/-17%, p<.01), elevated lactate/pyruvate ratio (38+/-37% vs. 19+/-26%, p<.03) and low glucose (26+/-17% vs. 11+/-15%, p<.05, and increased global oxygen extraction fraction. Mortality was similar in the intensive and loose insulin treatment groups (14% vs. 15%, p=.9), as was 6-month clinical outcome (p=.3).


CONCLUSIONS
Intensive insulin therapy results in a net reduction in microdialysis glucose and an increase in microdialysis glutamate and lactate/pyruvate without conveying a functional outcome advantage.
Vespa
Paul
P
UCLA Division of Neurosurgery, Los Angeles, CA, and Barrows Neurologic Institute, Phoenix, AZ, USA.
Boonyaputthikul
Robert
R
McArthur
David L
DL
Miller
Chad
C
Etchepare
Maria
M
Bergsneider
Marvin
M
Glenn
Thomas
T
Martin
Neil
N
Hovda
David
D
D000328:Adult; D001921:Brain / Q000378:metabolism*; D001930:Brain Injuries / Q000150:complications*; D018849:Controlled Clinical Trials as Topic; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006943:Hyperglycemia / Q000209:etiology / Q000517:prevention & control*; D007003:Hypoglycemia / Q000139:chemically induced / Q000503:physiopathology; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000009:adverse effects; D007262:Infusions, Intravenous; D007328:Insulin / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D012189:Retrospective Studies
D007004:Hypoglycemic Agents; D007328:Insulin; D005947:Glucose