Continuous renal replacement therapy using a cellulose triacetate hemofilter for severe coronavirus disease

In patients with severe coronavirus disease (COVID-19), the use of acrylonitrile hemofilters can reduce cytokine concentrations. However, acrylonitrile hemofilters can easily coagulate, and the effect of hemofilters on improvement in patient prognosis remains unclear. Therefore, we aimed to investigate the changes in serum cytokine concentrations, alleviation of organ damage, and improvement in patient prognosis with continuous renal replacement therapy (CRRT) using a cellulose triacetate (CTA) filter with excellent anticoagulation property in patients with severe COVID-19.

This was a retrospective, single-center study conducted by the Advanced Critical Care Center in Sapporo Medical University Hospital, Japan. Seven patients with severe COVID-19 between March 01 and June 30, 2020, were included. The patients were under mechanical ventilation and received continuous blood purification therapy with a CTA filter. We summarized the CRRT status and patient prognosis and measured their serum cytokine (interleukin [IL]-1β, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-α, and interferon-γ) and serum marker levels, before and after CRRT. In addition, we evaluated the changes in their respiratory status, hemodynamics, and organ dysfunction scores. The average age of the patients was 61.5 years, and five patients were male. Extracorporeal membrane oxygenation was used in five patients. The treatment outcome included three deaths.

The median CRRT duration was 7 days. The hemofilter was replaced once a day. After CRRT, the IL-6 concentration decreased from 393 to 85 pg/mL (p = 0.016), the Krebs von den Lungen-6 concentration decreased from 554 to 350 U/mL, and the PaO₂/FiO₂ ratio increased significantly from 90 to 248, and therefore, oxygenation improved. In addition, the norepinephrine dose and lactate level decreased, and the circulation tended to improve; however, the renal function and Sequential Organ Failure Assessment score did not change.

The serum IL-6 level decreased, and the respiratory status improved upon CRRT using a CTA filter in patients with severe COVID-19.