Bedside capillary blood glucose measurements in critically ill patients: influence of catecholamine therapy

To evaluate the effects of catecholamine therapy on the accuracy of capillary glucose measurements in hyperglycemic patients.

43 hyperglycemic patients older than 18 years admitted to the intensive care unit of a tertiary medical center were included from December 2005 to March 2006.

This prospective study compares fingerstick and earlobe measurements simultaneously to sampled laboratory venous glucose in patients treated without (group 1) or with (group 2) catecholamine. Three venous samples for serum glucose analysis at three fixed hours and simultaneously two capillary glucose determinations were performed during the two first successive days after inclusion. A difference between the methods of glucose measurements greater than 2.3 mmol/l was considered significant.

The mean difference between the two methods was -0.05 mmol/l in group 1 and +0.29 mmol/l in group 2, while the limits of agreement were +4.03 and -4.13 mmol/l and +5.63 and -5.05 mmol/l in groups 1 and 2, respectively. A difference between paired measurements greater than 2.3 mmol/l was observed in 29% in group 1 and in 40% in group 2 (p=0.038). The alternative site did not improve the accuracy.

In critically ill patients treated with catecholamine capillary fingerstick blood glucose measurement seems inaccurate. Earlobe sampling does not improve accuracy.