Research article

Screening for hypoglycemia at the bedside in the neonatal intensive care unit (NICU) with the Abbott PCx glucose meter

Cynthia Balion^1,2 , Vijaylaxmi Grey^2,3 , Afisi Ismaila^4,5 , Susan Blatz⁶ and Wendy Seidlitz⁶

¹  Department of Laboratory Medicine, Hamilton Health Sciences, Hamilton, Ontario, Canada

²  Department of Pathology & Molecular Medicine, McMaster University, Hamilton, Ontario, Canada

³  Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada

⁴  Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada

⁵  McMaster University Evidence-based Practice Center (EPC), McMaster University, Hamilton, Ontario, Canada

⁶  Department of Pediatrics, Hamilton Health Sciences, Hamilton Ontario, Canada

author email corresponding author email

BMC Pediatrics 2006, 6:28doi:10.1186/1471-2431-6-28

Published:	3 November 2006

Abstract

Background

Point of care (POC) glucose meters are routinely used as a screening tool for hypoglycemia in a neonatal setting. Glucose meters however, lack the same accuracy as laboratory instruments for glucose measurement. In this study we investigated potential reasons for this inaccuracy and established a cut off value for confirmatory testing.

Methods

In this prospective study, all patients in the neonatal intensive care unit who had a plasma glucose test ordered were eligible to participate. Demographic information, sample collection information (nine variables) and a recent hematocrit value were recorded for each sample. Glucose measurements were taken at the bedside on the glucose meter (RN PCx) as well as in the laboratory on both the glucose meter (LAB PCx) and the laboratory analyzer (PG). Data were analyzed by simple and mixed-effects regression analysis and by analysis of a receiver operator characteristics (ROC) curve.

Results

There were 475 samples analyzed from 132 patients. RN PCx values were higher than PG values (mean = 4.9%), while LAB PCx results were lower (mean = -5.2%) than PG values. Only 31% of the difference between RN PCx – PG and 46% of the difference for LAB PCx – PG could be accounted for by the variables tested. The largest proportion of variance between PCx and PG measurements was explained by hematocrit (about 30%) with a greater effect seen at glucose concentrations ≤4.0 mmol/L (≤72 mg/dL)(48% and 40% for RN PCx and LAB PCx, respectively). The ROC analysis showed that for detection of all cases of hypoglycemia (PG < 2.6 mmol/L)(PG < 47 mg/dL) the PCx screening cut off value would need to be set at 3.8 mmol/L (68 mg/dL) requiring 20% of all samples to have confirmatory analysis by the laboratory method.

Conclusion

The large difference between glucose results obtained by PCx glucose meter compared to the laboratory analyzer can be explained in part by hematocrit and low glucose concentration. These results emphasize that the glucose meter is useful only as a screening device for neonatal hypoglycemia and that a screening cut off value must be established.