Point-of-care glucose testing - Effects of critical care variables, influence of reference instruments, and a modular glucose meter design

Objective.-To assess the clinical performance of glucose meter systems when used with critically ill patients. Design.-Two glucose meter systems (SureStepPro and Precision G) and a modul ar adaptation (Immediate Response Mobile Analysis-SureStepPro) were assesse d clinically using arterial samples from critically ill patients. A biosens or-based analyzer (YSI 2700) and a hospital chemistry analyzer (Synchron CX -7) were the primary and secondary reference instruments, respectively. Patients and Setting.-Two hundred forty-seven critical care patients at the University of California, Davis, Medical Center participated in this study . Outcome Measures.-Error tolerances of +/-15 mg/dL for glucose levels less t han or equal to 100 mg/dL and +/-15% for glucose levels >100 mg/dL were use d to evaluate glucose meter performance; 95% of glucose meter measurements should fall within these tolerances. Results.-Compared to the primary reference method, 98% to 100% of SureStepP ro and 91% to 95% of Precision G measurements fell within the error toleran ces. Paired differences of glucose measurements versus critical care variab les (P-O2, pH, P-CO2, and hematocrit) were analyzed to determine the effect s of these variables on meter measurements. P-O2 and P-CO2 decreased Precis ion G and SureStepPro measurements, respectively, but not enough to be clin ically significant based on the error tolerance criteria. Hematocrit levels affected glucose measurements on both meter systems. Modular adaptation di d not affect test strip performance. Conclusions.-Glucose meter measurements correlated best with primary refere nce instrument measurements. Overall, both glucose meter systems showed acc eptable performance for point-of-care testing. However, the effects of some critical care variables, especially low and high hematocrit values, could cause overestimated or underestimated glucose measurements.