Accuracy of glycemic measurements in the critically ill.

Background: Recent evidence emphasizes the importance of maintaining normoglycemia in critically ill patients to reduce morbidity and mortality. Different analytical methods of varying accuracy exist for obtaining and measuring blood glucose in critically ill patients. The purpose of this study was to determine if there were differences in blood glucose values measured by whole blood capillary and arterial samples using three different bedside blood glucose meters and a blood gas analyzer as compared to a reference blood glucose analyzer.
Methods: Sixty subjects were recruited from a university hospital medical/surgical intensive care unit. Matching capillary and arterial samples were analyzed by a clinical blood glucose reference analyzer (YSI, Yellow Springs Instrument, Yellow Springs, OH) and three blood glucose meters (Lifescan [Milpitas, CA] SureStepFlexx, Roche [Indianapolis, IN] Accu-Chek Inform, and Abbott [Alameda, CA] FreeStyle). Additionally, the arterial samples were analyzed by a point-of-care blood gas analyzer (Chiron 865, Bayer, Tarrytown, NY).
Results: Data analysis included repeated-measures analysis of variance, Consensus Error Grid analysis, Bland-Altman plots, and numerical estimates of inaccuracy. With capillary samples there were high numbers of errors as compared to the reference instrument. Measurement of blood glucose with arterial samples demonstrates a higher degree of accuracy. With arterial samples, the Abbott FreeStyle blood glucose meter and the blood gas analyzer glucose exhibited the lowest median and mean relative absolute deviation.
Conclusion: In critically ill adult patients, measurement of blood glucose using arterial samples is recommended. Using arterial blood, the Abbott FreeStyle blood glucose meter and the point-of-care blood gas analyzer (Bayer Chiron 865) were shown to be highly accurate instruments to measure arterial blood glucose.