[Effect of continuous blood purification on immunity and endothelial cell function in patients with sepsis]

To explore the effect of continuous blood purification (CBP) on the immunity and endothelial cell function of patients with sepsis.

A prospective study was conducted. The patients aged ≥ 18 years old and meeting the diagnostic criteria of sepsis admitted to the department of critical care medicine of Binzhou Medical University Hospital from March 2019 to October 2020 were selected as the research subjects, and the patients were divided into standard treatment group and CBP treatment group according to random number table method. Both groups were given standard treatment including initial fluid resuscitation, infection source control and antibiotics according to the 2016 international guidelines for the management of sepsis and septic shock. CBP treatment group was additionally given continuous veno-venous hemofiltration (CVVH) at a dose of 25-30 mL×kg^-1×h^-1 and blood flow rate of 150-200 mL/min for more than 20 hours a day for 3 days. The clinical data of patients including blood lactic acid (Lac), procalcitonin (PCT), lymphocyte count (LYM), acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure assessment (SOFA) score were recorded before treatment and 1 day and 3 days after treatment. At the same time, the venous blood was collected, and the immune function related indexes [interleukins (IL-4, IL-7), programmed death receptor-1 (PD-1), programmed death ligand-1 (PD-L1), interferon-γ (IFN-γ)] and endothelial cell injury related markers [soluble thrombomodulin (sTM), angiopoietin-2 (Ang-2), von Willebrand factor (vWF), heparan sulfate (HS), syndecan-1 (SDC-1)] levels in serum were determined by enzyme-linked immunosorbent assay (ELISA). The length of intensive care unit (ICU) stay of patients in the two groups was recorded, and the outcomes of patients in the two groups were followed up for 28 days.

Finally, 20 patients were enrolled in the standard treatment group, and 19 patients were enrolled in the CBP treatment group. There were no significant differences in gender, age and infection site between the two groups. The length of ICU stay in the standard treatment group was (10±5) days, and 5 patients died and 15 patients survived after 28 days. The length of ICU stay in the CBP treatment group was (9±4) days, and 8 patients died and 11 patients survived after 28 days. There were no significant differences in the length of ICU stay and number of patients who died within 28 days between the two groups (both P > 0.05). There were no significant differences in the Lac, PCT, LYM, APACHE II score, SOFA score and immune function and endothelial cell injury related indexes before treatment and 1 day after treatment between the two groups. After 3 days of treatment, the Lac, PCT, APACHE II score and SOFA score of the CBP treatment group were significantly lower than those before treatment, and pro-inflammatory and anti-inflammatory cytokines such as IFN-γ and IL-4, apoptosis-related indicators such as PD-1 and IL-7, and endothelial injury related factors such as sTM, SDC-1 and HS were significantly improved compared with the pre-treatment, the improvement degree of the above indicators was more obvious than that of the standard treatment group, and LYM was significantly higher than that of the standard treatment group (×10⁹/L: 1.3±0.3 vs. 0.9±0.4, P < 0.05), IL-4, IFN-γ, IFN-γ/IL-4 ratio, IL-7, PD-1, sTM, SDC-1, HS, and Ang-2 were significantly lower than those of the standard treatment group [IL-4 (ng/L): 2.8 (1.5, 3.2) vs. 3.3 (2.7, 5.2), IFN-γ (ng/L): 6.3 (5.4, 106.5) vs. 217.9 (71.4, 517.1), IFN-γ/IL-4 ratio: 3.7 (1.8, 70.3) vs. 59.1 (18.3, 124.9), IL-7 (ng/L): 4.6 (3.2, 5.1) vs. 6.3 (5.2, 8.0), PD-1 (μg/L): 0.04 (0.03, 0.06) vs. 0.08 (0.05, 0.12), sTM (μg/L): 4.9 (4.3, 7.4) vs. 8.7 (6.0, 10.8), SDC-1 (μg/L): 0.6 (0.3, 1.1) vs. 0.9 (0.8, 2.5), HS (ng/L): 434.8 (256.2, 805.0) vs. 887.9 (620.1, 957.3), Ang-2 (ng/L): 934.0 (673.3, 1 502.1) vs. 2 233.9 (1 472.5, 3 808.4)], the differences were statistically significant (all P < 0.05).

CBP treatment can eliminate the patient's immunosuppressive state, reduce a variety of endothelial injury markers and the degradation of glycocalyx, but cannot decrease the 28-day death risk or shorten the length of ICU stay.