Variability of Microcirculatory Measurements in Critically Ill Patients

Introduction: Monitoring the microcirculation may be helpful in guiding resuscitation in patients with circulatory shock. Sublingual side-stream dark field imaging cameras allow for noninvasive, bedside evaluation of the microcirculation, although their use in clinical practice has not yet been validated. The GlycoCheck system automatically analyzes images to determine glycocalyx thickness, red blood cell filling percentage, and vessel density. Although GlycoCheck has been used to study microcirculation in critically ill patients, little is known about the reproducibility of measurements in this population. Materials and Methods: A total of 60 critically ill patients were studied. Three consecutive microcirculation measurements were performed with the GlycoCheck system in 40 of these patients by one of two experienced observers. Twenty patients were assessed by both observers. Intra- and interobserver variability were assessed using intraclass correlation coefficients (ICCs). Results: ICCs of single measurements were poor for glycocalyx thickness and good for filling percentage and vessel density. Reproducibility could be substantially increased for all parameters when three consecutive measurements were performed and averaged. Discussion: GlycoCheck can be used to study microcirculation. However, to obtain reliable results three consecutive measurements should be performed and averaged. The variation of the measurements currently hampers the clinical application in individual patients.