How should I approach evaluating a glucose meter for use in the ICU?
The answer to this question has both patient care and regulatory considerations. For patient care purposes, the choice of sample type may be as important as the choice of device: arterial whole blood offers the most accurate measurement in the ICU, while capillary sampling may lead to erroneous results in patients with poor tissue perfusion. Venous catheter sampling can lead to overestimation of glucose at higher concentrations depending on meter technology. The ideal approach to evaluating a meter is to collect nearly simultaneously whole blood glucose meter samples and plasma or serum laboratory samples. Using the actual end users to perform bedside measurement—and the intended sample type from ICU patients—allows observation of the variables most likely to impact glucose meter accuracy, such as hematocrit effect, medication interferences, and user errors.
To complement a patient-based assessment of meter accuracy, residual serum or plasma specimens can be spiked with medications used in the ICU to detect interferences. While accuracy (bias) and interferences are the most important factors, meter precision at normal, high, and low glucose concentrations is also important. Fortunately, precision of most hospital-use glucose meters is quite good, with a coefficient of variation <5%.
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Image: Drahomira Springer