Discrepancies between capillary glucose measurements and traditional laboratory assessments in both shock and non-shock states after trauma.

The purpose of this study was to analyze the accuracy of capillary blood glucose (CBG) against laboratory blood glucose (LBG) in critically ill trauma patients during the shock state.All critically ill trauma patients admitted to the Surgical Intensive Care Unit at the Los Angeles County + University of Southern California Medical Center requiring blood glucose monitoring from January 2007 to December 2008 were included. Accuracy of CBG was compared against LBG during shock and non-shock states. Shock was defined as either systolic blood pressure <90 mm Hg or mean arterial pressure <70 mm Hg and the need for vasopressor therapy. The Bland-Altman method was used to determine the agreement between CBG and LBG during shock and non-shock states. CBG values were considered to disagree significantly with LBG values when the difference exceeded 15%.During the 2-y study period, a total of 1215 patients were admitted to the Surgical Intensive Care Unit. Overall, the mean age was 38.4 ± 20.9 y, 79.6% (967) were male, and 75.0% (911) sustained blunt trauma. A total of 1935 paired samples of CBG and LBG were included in this analysis (367 during shock and 1568 during non-shock). During shock, the mean difference between CBG and LBG levels was 13.4 mg/dL (95% CI, -15.4 to 42.2 mg/dL), and the limits of agreement were -27.1 and 53.9 mg/dL. A total of 136 CBG values (37.1%) differed from the LBG values by more than 15%. During non-shock, the mean difference between CBG and LBG levels was 12.6 mg/dL (95% CI, -19.9 to 32.5 mg/dL), and the limits of agreement were -20.6 and 45.8 mg/dL. A total of 639 CGB values (40.8%) differed from the LBG values by more than 15%. Agreement was lowest among hypoglycemic readings in both shock and non-shock states.There is poor correlation between the capillary and laboratory glucose values in both shock and non-shock states.