Early Initiation of Extracorporeal Blood Purification Using the AN69ST (oXiris®) Hemofilter as a Treatment Modality for COVID-19 Patients: a Single-Centre Case Series

Abstract Introduction: Severe coronavirus disease 2019 (COVID-19) is characterised by hyperinflammatory state, systemic coagulopathies, and multiorgan involvement, especially acute respiratory distress syndrome (ARDS). We here describe our preliminary clinical experience with COVID-19 patients treated via an early initiation of extracorporeal blood purification combined with systemic heparinisation and respiratory support. Methods: Fifteen patients were included; several biomarkers associated with COVID-19 severity were monitored. Personalised treatment was tailored according to the levels of interleukin (IL)-6, IL-8, tumour necrosis factor alpha, C-reactive protein (CRP), neutrophil-to-lymphocyte ratio, thrombocyte counts, D-dimers, and fibrinogen. Treatment consisted of respiratory support, extracorporeal blood purification using the AN69ST (oXiris®) hemofilter, and 300 U/kg heparin to maintain activation clotting time ≥ 180 seconds. Results: Ten patients presented with severe to critical disease (dyspnoea, hypoxia, respiratory rate > 30/min, peripheral oxygen saturation < 90%, or > 50% lung involvement on X-ray imaging). The median intensive care unit length of stay was 9.3 days (interquartile range 5.3-10.1); two patients developed ARDS and died after 5 and 26 days. Clinical improvement was associated with normalisation (increase) of thrombocytes and white blood cells, stable levels of IL-6 (< 50 ng/mL), and a decrease of CRP and fibrinogen. Conclusion: Continuous monitoring of COVID-19 severity biomarkers and radiological imaging is crucial to assess disease progression, uncontrolled inflammation, and to avert irreversible multiorgan failure. The combination of systemic heparin anticoagulation regimens and extracorporeal blood purification using cytokine-adsorbing hemofilters may reduce hyperinflammation, prevent coagulopathy, and support clinical recovery.