Systemic glucose and brain energy metabolism after subarachnoid hemorrhage

Background Brain energy metabolic crisis (MC) and lactate-pyruvate ratio (LPR) elevations have been linked to poor outcome in comatose patients. We sought to determine if MC and LPR elevations after subarachnoid hemorrhage (SAH) are associated with acute reductions in serum glucose. Methods Twenty-eight consecutive comatose SAH patients that underwent multimodality monitoring with intracranial pressure and microdialysis were studied. MC was defined as lactate/pyruvate ratio (LPR) ≥ 40 and brain glucose < 0.7 mmol/l. Time-series data were analyzed using a multivariable general linear model with a logistic link function for dichotomized outcomes. Results Multimodality monitoring included 3,178 h of observation (mean 114 ± 65 h per patient). In exploratory analysis, serum glucose significantly decreased from 8.2 ± 1.8 mmol/l (148 mg/dl) 2 h before to 6.9 ± 1.9 mmol/l (124 mg/dl) at the onset of MC (P < 0.001). Reductions in serum glucose of 25% or more were significantly associated with new onset MC (adjusted odds ratio [OR] 3.6, 95% confidence interval [CI] 2.2-6.0). Acute reductions in serum glucose of 25% or more were also significantly associated with an LPR rise of 25% or more (adjusted OR 1.6, 95% CI 1.1-2.4). All analyses were adjusted for significant covariates including Glasgow Coma Scale and cerebral perfusion pressure. Conclusions Acute reductions in serum glucose, even to levels within the normal range, may be associated with brain energy metabolic crisis and LPR elevation in poorgrade SAH patients.