Point-of-care (POC) testing of lactate in the intensive care patient. Accuracy, reliability, and costs of different measurement systems

Abstract

Background: Point-of-care (POC) monitoring may facilitate diagnostic and therapeutic interventions in the critically ill. In a prospective study reliability and costs of two POC lactate testing devices were compared to the central laboratory lactate monitoring method.

Methods: From arterial whole blood and capillary blood samples of 40 intensive care unit (ICU) patients lactate concentrations were measured using either a battery-powered hand-held lactate analyser (Accusport) or a bench-top blood gas analyser (Chiron 865 series) and compared with lactate measured by the hospital's central laboratory ('reference' method). Measurements were carried out on the day of inclusion in the study ('baseline'), 8 h later, and in the morning of the 1st, 2nd, and 3rd days thereafter. Costs for blood lactate measurements were analysed for each method.

Results: A total of 197 lactate measurements were done with each system. Lactate measured from arterial blood using the Accusport and the central laboratory showed excellent agreement (bias: -0.15 mmol/l; relative error: -2.74%). Lactate measured by the blood gas analyser had also excellent agreement with the reference method (bias: 0.09 mmol/l; relative error: 2.24%) and the hand-held device (bias: -0.24 mmol/l; relative error: -5.06%). Time from blood sampling to availability of data was significantly longer for the central laboratory (85+/-35 min [range: 45-168 min]) than for both POC systems (range: 1-10 min). Total cost for measuring blood lactate was lowest using the Accusport device.

Conclusion: The trend towards miniaturizing laboratory monitoring devices will continue, resulting in greater flexibility of management of the critically ill. Blood lactate can rapidly, easily, accurately, and economically be measured at the bedside with the hand-held monitor apparatus Accusport and the bench-top blood gas analyser.