Blood purification therapy with a hemodiafilter featuring enhanced adsorptive properties for cytokine removal in patients presenting COVID-19: a pilot study

BACKGROUND: Systemic inflammation in COVID-19 often leads to multiple organ failure, including acute kidney injury (AKI). Renal replacement therapy (RRT) in combination with sequential extracorporeal blood purification therapies (EBP) might support renal function, attenuate systemic inflammation, and prevent or mitigate multiple organ dysfunctions in COVID-19. AIM: Describe overtime variations of clinical and biochemical features of critically ill patients with COVID-19 treated with EBP with a hemodiafilter characterized by enhanced cytokine adsorption properties. METHODS: An observational prospective study assessing the outcome of patients with COVID-19 admitted to the ICU (February to April 2020) treated with EBP according to local practice. Main endpoints included overtime variation of IL-6 and multiorgan function-scores, mortality, and occurrence of technical complications or adverse events. RESULTS: The study evaluated 37 patients. Median baseline IL-6 was 1230 pg/ml (IQR 895) and decreased overtime (p < 0.001 Kruskal-Wallis test) during the first 72 h of the treatment, with the most significant decrease in the first 24 h (p = 0.001). The reduction in serum IL-6 concentrations correlated with the improvement in organ function, as measured in the decrease of SOFA score (rho = 0.48, p = 0.0003). Median baseline SOFA was 13 (IQR 6) and decreased significantly overtime (p < 0.001 at Kruskal-Wallis test) during the first 72 h of the treatment, with the most significant decrease in the first 48 h (median 8 IQR 5, p = 0.001). Compared to the expected mortality rates, as calculated by APACHE IV, the mean observed rates were 8.3% lower after treatment. The best improvement in mortality rate was observed in patients receiving EBP early on during the ICU stay. Premature clotting (running < 24 h) occurred in patients (18.9% of total) which featured higher effluent dose (median 33.6 ml/kg/h, IQR 9) and higher filtration fraction (median 31%, IQR 7.4). No electrolyte disorders, catheter displacement, circuit disconnection, unexpected bleeding, air, or thromboembolisms due to venous cannulation of EBP were recorded during the treatment. In one case, infection of vascular access occurred during RRT, requiring replacement. CONCLUSIONS: EBP with heparin-coated hemodiafilter featuring cytokine adsorption properties administered to patients with COVID-19 showed to be feasible and with no adverse events. During the treatment, patients experienced serum IL-6 level reduction, attenuation of systemic inflammation, multiorgan dysfunction improvement, and reduction in expected ICU mortality rate.