Point accuracy and reliability of an interstitial continuous glucose-monitoring device in critically ill patients: a prospective study

Roosmarijn TM van Hooijdonk, Jan Hendrik Leopold, Tineke Winters, Jan M Binnekade, Nicole P Juffermans, Janneke Horn, Johan C Fischer, Edmée C van Dongen-Lases, Marcus J Schultz

IntroductionThere is need for continuous glucose monitoring in critically ill patients. The objective of this trial was to determine the point accuracy and reliability of a device designed for continuous monitoring of interstitial glucose levels in intensive care unit patients.MethodsWe evaluated point accuracy by comparing device readings with glucose measurements in arterial blood using blood gas analyzers. Analytical and clinical accuracy was expressed in Bland¿Altman plots, glucose prediction errors, and Clarke error grids. We used a linear mixed model to determine which factors affect the point accuracy. In addition, we determined the reliability, including duration of device start¿up and calibration, skips in data acquisition, and premature disconnections of sensors.ResultsWe included 50 patients in whom we used 105 sensors. Five patients from whom we could not collect the predefined minimum number of four consecutive comparative blood draws were excluded from the point accuracy analysis. Therefore, we had 929 comparative samples from 100 sensors in 45 patients (11 (7 to 28) samples per patient) during 4,639 hours (46 (27 to 134) hours per patient and 46 (21 to 69) hours per sensor) for the accuracy analysis. Point accuracy did not meet the ISO14971 standard for insulin dosing accuracy, but improved with increasing numbers of calibrations, and was better in patients who did not have a history of diabetes. Out of 105 sensors, 60 were removed prematurely for a variety of reasons. The device start¿up time was 49 (43 to 58) minutes. The number of skips in data acquisition was low, resulting in availability of real¿time data during 95 (89 to 98) % of the connection time per sensor.ConclusionsThe point accuracy of a device designed for continuous real¿time monitoring of interstitial glucose levels was relatively low in critically ill patients. The device had few down times, but one third of the sensors were removed prematurely because of unresolved sensor ¿ or device related problems.Trial registration numberNetherlands Trial Register, NTR3827. 30 January 2013.