Tight glycemic control increases metabolic distress in traumatic brain injury: A randomized controlled within-subjects trial
Critical Care Medicine, 05/25/2012  Clinical Article

Vespa P et al. – Tight glycemic control results in increased global glucose uptake and an increased cerebral metabolic crisis after traumatic brain injury. The mechanisms leading to the enhancement of metabolic crisis are unclear, but delivery of more glucose through mild hyperglycemia may be necessary after traumatic brain injury.

• The authors performed a prospective, unblinded randomized controlled within–subject crossover trial of tight (80–110mg/dL) vs. loose (120–150mg/dL) glycemic control in patients with severe traumatic brain injury to determine the effects of glycemic control on brain glucose metabolism, as measured by [18F]deoxy–D–glucose brain positron emission tomography.
• Brain microdialysis was done simultaneously.

• Thirteen severely injured traumatic brain injury patients underwent the study between 3 and 8days (mean 4.8days) after traumatic brain injury.
• In ten of these subjects, global brain and gray matter tissues demonstrated higher glucose metabolic rates while glucose was under tight control as compared with loose control (3.2±0.6 vs. 2.4+0.4, p=.02 [whole brain] and 3.8±1.4 vs. 2.9±0.8, p=.05 [gray matter]).
• However, the responses were heterogeneous with pericontusional tissue demonstrating the least state–dependent change.
• Cerebral microdialysis demonstrated more frequent critical reductions in glucose (p=.02) and elevations of lactate/pyruvate ratio (p=.03) during tight glycemic control.