Neuromonitoring with microdialysis in severe traumatic brain injury patients.

BACKGROUND: Neuromonitoring with microdialysis has the potential for early detection of metabolic derangements associated with TBI.

METHODS: 1,260 microdialysis samples from 12 TBI patients were analyzed for glucose, -lactate, pyruvate, lactate/pyruvate ratio (LPR), and lactate/glucose ratio (LGR). Analytes were correlated with the Glasgow Coma Scale (GCS) before surgery and with the Glasgow Outcome Scale (GOS) at the time of discharge. The patients were divided into two groups for GCS: 3-6 and 7-9, and for GOS 1-3 and 4-5. Chi-squared test was performed for correlations.

RESULTS: Glucose, lactate levels, and LGR were high in TBI patients with GCS 3-6 (p < 0.0001). Pyruvate level was lower in patients with GCS 7-9 (p < 0.001). LPR was higher in patients with GCS 3-6 (p < 0.05). High glucose, lactate level (p < 0.001), and LPR (p < 0.01) was observed in patients with GOS 1-3. Pyruvate level was low in patients with GOS 1-3 (p < 0.001). LGR was higher in patient with better outcome (GOS 4-5).

CONCLUSION: After craniotomy extracellular glucose and lactate were good "biomarkers" of cerebral damage in TBI patients. We consider that high extracellular lactate and low glucose is an indicator of severe neurological damage and poor outcome, because of impaired brain metabolism.