Identification of novel sublingual parameters to analyze and diagnose microvascular dysfunction in sepsis: the NOSTRADAMUS study

BackgroundThe availability of handheld, noninvasive sublingual video-microscopes allows for visualization of the microcirculation in critically ill patients. Recent studies demonstrate that reduced numbers of blood-perfused microvessels and increased penetration of erythrocytes into the endothelial glycocalyx are essential components of microvascular dysfunction. The aim of this study was to identify novel microvascular variables to determine the level of microvascular dysfunction in sepsis and its relationship with clinical variables.MethodsThis observational, prospective, cross-sectional study included 51 participants, of which 34 critically ill sepsis patients were recruited from intensive care units of a university hospital. Seventeen healthy volunteers served as controls. All participants underwent sublingual videomicroscopy by sidestream darkfield imaging. A new developed version of the Glycocheck (TM) software was used to quantify vascular density, perfused boundary region (PBR-an inverse variable of endothelial glycocalyx dimensions), red blood cell (RBC) velocity, RBC content, and blood flow in sublingual microvessels with diameters between 4 and 25 mu m.ResultsA detailed analysis of adjacent diameter classes (1 mu m each) of vessels between 4 and 25 mu m revealed a severe reduction of vascular density in very small capillaries (5-7 mu m), which correlated with markers of sepsis severity. Analysis of RBC velocity (V-RBC) revealed a strong dependency between capillary and feed vessel V-RBC in sepsis patients (R-2=0.63, p), which decreased from 7.4 [4.6-8.7] in controls to 1.8 [1.4-2.7] in sepsis patients (p