Matched Comparison of Microcirculation Between Healthy Volunteers and Patients with Sepsis

Sepsis-related systemic inflammation resulted in microcirculatory dysfunction. However, information of normal ranges of microcirculatory parameters in the healthy population remain limited. The primary aim of this study was to investigate the differences in microcirculatory parameters between healthy volunteers and patients with sepsis.

This observational study enrolled 45 healthy female and 45 healthy male volunteers, and divided them equally into three age groups: young (20-39 years), middle-age (40-59 years), and elderly (60-79 years). In addition, we enrolled 32 patients with sepsis. Images of sublingual microcirculation were obtained through sidestream dark field videomicroscopy and were analyzed using automated analysis software. Microcirculation parameters, namely the total small vessel density (TSVD), perfused small vessel density (PSVD), proportion of perfused vessel (PPV), microvascular flow index (MFI) score, and heterogeneity index (HI), were evaluated. One-to-one matching between the septic patients and the healthy volunteers was performed on the basis of demographic data including age and gender.

The elderly group had lower MFI scores and a higher HI. Age was positively correlated with the HI (r = 0.38, p < 0.001) and negatively correlated with the PPV and MFI scores (r = -0.26, p = 0.014 and r = -0.37, p < 0.001, respectively). TSVD was higher in female participants than in male participants. Body mass index (BMI) was negatively correlated with TSVD. In multivariate regression analysis, the independent factors associated with PPV are age and sex, however age is the only independent factor associated with MFI and HI. In patients with sepsis, TSVD (17.5 [3.3] vs. 21.7 [3.0]; p = 0.002), PSVD (15.0 [3.0] vs. 21.1 [2.5]; p < 0.001), and MFI score (2.0 [1.6-2.5] vs. 2.9 [2.5-3.0]; p < 0.001) were lower in the 28-day nonsurvivors than in the survivors. Matched comparison revealed that the TSVD (20.7 [3.7] vs. 25.2 [2.3]; p < 0.001), PSVD (19.8 [3.0] vs. 24.3 [2.7]; p < 0.001), and MFI score (2.7 [2.4-3.0] vs. 3.0 [2.7-3.0]; p = 0.019) were lower in the patients with sepsis than in the healthy volunteers.

Age and sex were correlated with microcirculatory parameters of the healthy volunteers. In the patients with sepsis, microcirculatory dysfunction was more severe in the 28-day nonsurvivor group than in the 28-day survivor group. Furthermore, the patients with sepsis exhibited significantly lower TSVD, PSVD, and MFI scores than the healthy volunteers.