Evaluating glycocalyx
FRAGILITY
Visualizing human glycocalyx directly in vivo is highly challenging due to its fragility. The region where it is partially accessible to flowing red blood cells at its luminal side is called the perfused boundary region (PBR) [An SDF video microscope attached to a glycocalyx measurement system (GlycoCheck ICU®; Maastricht University Medical Center, Maastricht, the Netherlands) was employed to assess sublingual microcirculation. Ten image sequences of forty frames were recorded in different areas, and PBR was automatically calculated. The RBC column was automatically measured in 3000 vascular segments. For each segment, 840 radial intensity profiles were captured to measure the RBC column width, and the PBR was automatically estimated. The vessel segments were classified into 1 μm wide diameter classes. PBR values were determined for each diameter class before calculating the average PBR over a set of diameters ranging from 5 to 25 μm. As described above, vessel diameters were categorized into groups of small (5–9 μm), medium (10–19 μm), and large (20–25 μm) to facilitate further analysis [