Hypoglycemia Aggravates Critical Illness-Induced Neurocognitive Dysfunction

OBJECTIVE - Tight glycemic control (TGC) in critically ill patients is associated With in increased risk of hypoglycemia. Whether those short episodes of hypoglycemia are associated with adverse morbidity and mortality is a matter of discussion. Using a case-control study design, we investigated whether hypoglycemia under TGC causes permanent neurocognitive dysfunction in patients surviving critical illness. RESEARCH DESIGN AND METHODS - From our Patient data management System, we identified adult survivors treated for >72 h in our surgical intensive care unit (ICU) between 2004 and 2007 (n = 4,635) without a history of neurocognitive dysfunction or structural brain abnormalities who experienced at least one episode of hypoglycemia during treatment (hypo group) (n = 37). For each hypo group patient, one patient stringently Matched for demographic and disease-related data were identified as a control subject. We performed a battery of neuropsychological tests investigating five areas of cognitive functioning in both groups at least I year after ICU discharge. Test results were compared With data from healthy control subjects and between groups. RESULTS - Critical illness caused neurocognitive dysfunction in all tested domains in both groups. The dysfunction was aggravated in hypo group patients in one domain, namely that of visuospatial skills (P < 0.01). Besides hypoglycemia, both hyperglycemia (r = -0.322; P = 0.005) and fluctuations of blood glucose (r = -0.309; P = 0.008) were associated with worse test results in this domain. CONCLUSIONS - Hypoglycemia was found to aggravate critical illness-induced neurocognitive dysfunction to a limited, but significant, extents however, an impact of hyperglycemia and fluctuations of blood glucose on neurocognitive function cannot be excluded.