Abstract
BACKGROUND: Pathologically low brain glucose levels, referred to as neuroglucopenia, are associated with unfavorable outcomes in neurocritical care patients. We sought to investigate whether an increase in serum glucose levels would be associated with a reduction of neuroglucopenia. METHODS: In this retrospective analysis of prospectively collected data, we included 55 consecutive patients with spontaneous subarachnoid hemorrhage who underwent cerebral microdialysis (CMD) monitoring. Neuroglucopenia was defined as CMD-glucose levels < 0.7 mmol/l. We identified systemic glucose liberalization events, defined as a day with median serum glucose levels < 150 mg/dl, followed by a day with median serum glucose levels > 150 mg/dl, and compared concentrations of cerebral metabolites between these days. Unfavorable outcome was defined as modified Rankin Scale score ≥ 3 at 3 months after the bleeding. RESULTS: Episodes of neuroglucopenia were more frequent in patients with unfavorable outcome (19.8% [19.3-20.3%] vs. 10.9% [10.4-11.5%], p = 0.007). Sixty-nine systemic glucose liberalization events were identified in 40 patients. Blood glucose levels increased from 141.2 (138.7-143.6) mg/dl to 159.5 (157.0-162.2) mg/dl (p < 0.001), CMD-glucose levels increased from 1.44 (1.39-1.50) mmol/l to 1.68 (1.62-1.75) mmol/l (p = 0.001), and the frequency of neuroglucopenia decreased from 24.7% (22.9-26.5%) to 20.2% (18.7-21.8%) (p = 0.002) during these events. Liberalization was not associated with changes in CMD-lactate, CMD-pyruvate, CMD-lactate-to-pyruvate ratio, CMD-glutamate, or CMD-glycerol. CONCLUSIONS: In conclusion, the liberalization of serum glucose concentrations to levels between 150 and 180 mg/dl was associated with a significant reduction of neuroglucopenia.