Introduction
Bedside capillary or arterial blood glucose monitoring is mandatory for ICU patients under tight glycemic control. Point-of-care methods are based on glucose-oxidase (GO) or glucose-dehydrogenase (GD) enzymatic methods whereas the laboratory reference method is hexokinase for measuring the plasma glucose levels.
Methods
In this prospective observational study, blood glucose was simultaneously measured on the Glucocard Arkray (GO, capillary), on the Accu-chek Inform Roche (GD, capillary and arterial) and on the Rapid-Lab 1265 Bayer (GO, arterial), and each value was compared with the reference laboratory result.
Results
A total of 262 matched analyses were done in 60 patients. Biases are defined as the glucose laboratory value minus point-of-care value. The bias, 95% limits of agreement, and numbers of observed discrepancy (d) paired results >20% and >10% are reported in Table 1.
Table 1.
| Point-of care method | Number of comparisons | Bias (mg/dl) | Agreement (mg/dl) | Number >20%d (%) | Number >10%d (%) |
|---|---|---|---|---|---|
| Glucocard, GO capillary | 262 | +8.5 | ± 36 | 32 (12) | 103 (39) |
| Accu-chek, GD capillary | 262 | -6.3 | ± 37 | 40 (15) | 123 (45) |
| Rapid-Lab, GO arterial | 262 | +5.3 | ± 11 | (0) | 21 (8) |
| Accu-chek, GD arterial | 234 | -7.9 | ± 17 | 17 (7) | 67 (29) |
Conclusion
GO methods underestimate while GD methods overestimate all blood glucose levels as compared with plasma glucose levels measured by the reference method of hexokinase. Capillary methods have wider 95% limits of agreement than measures carried out on arterial blood.