From Macrohemodynamic to the Microcirculation

Table 1

Parameters for the evaluation and scoring of the microcirculation.

Microcirculation parameter	Information provided	Measurement
Microvascular flow index (MFI)	Perfusion quality (for small, medium, and large vessels*)	The image is divided into four quadrants; a number is assigned for each quadrant according to the predominant type of flow (0 = no flow; 1 = intermittent; 2 = sluggish; 3 = continuous). The MFI results from the averaged values.
De Backer score (n/mm)	Vessel density	The image is divided by 3 vertical and 3 horizontal lines; the De Backer score is calculated as the number of vessels crossing the lines divided by the total length of the lines
Total vessel density (mm/mm^2)	Vessel density (for small, medium, and large vessels*)	Total length of vessels is divided by the total surface of the analyzed area
Perfused vessel density (mm/mm^2)	Functional vessel density (for small, medium, and large vessels*)	Total length of perfused vessels (sluggish or continuous) is divided by the total surface of the analyzed area
Proportion of perfused vessels (%)	Perfusion quality (for small, medium, and large vessels*)	100* number of perfused vessels is divided by the total number of vessels
Flow heterogeneity index (FHI)	Perfusion heterogeneity	The difference between the highest MFI and the lowest MFI is divided by the mean MFI. MFI is intended as the averaged MFI of each site

∗Vessel diameter classification: <20 𝜇 = small; 20–50 𝜇 = medium; 50–100 𝜇 = large.
Three or five sites are evaluated. MFI of small vessels can be calculated separately.