Case Series Targeting Cytokine Storm in COVID-19: A Role of Online Hemodiafiltration with Asymmetric Cellulose Triacetate in Maintenance Hemodialysis Patients—A Report of 10 Cases Jos´ e C. De La Flor , 1 Francisco Valga , 2 Alexander Marschall , 3 Tania Monzon , 4 Cristina Albarrac´ ın, 1 Elisa Ruiz, 1 and Miguel Rodeles 1 1 Department of Nephrology, Central Defense Gomez Ulla Hospital, Madrid, Spain 2 Department of Nephrology, Doctor Negr´ ın University Hospital, Las Palmas de Gran Canaria, Spain 3 Department of Cardiology, Central Defense Gomez Ulla Hospital, Madrid, Spain 4 Department of Hemodialysis, Avericum S.L., Las Palmas de Gran Canaria, Spain Correspondence should be addressed to Jos´ e C. De La Flor; josedelaflor81@yahoo.com Received 30 January 2021; Revised 13 February 2021; Accepted 23 February 2021; Published 15 March 2021 Academic Editor: Manel Vera Copyright © 2021 Jos´ e C. De La Flor et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Early reports have suggested that maintenance hemodialysis (MHD) patients could be more susceptible to a severe course of COVID-19. Among the therapeutic approaches, the use of drugs that reduce the cytokine storm characteristic of this disease has been proposed. Some dialyzers, such as the new generation of asymmetric cellulose triacetate (ATA) membranes, could favor the effective elimination of medium-sized molecules and other inflammatory mediators. In this case series, we describe in depth the clinical, analytical, and radiological details, therapeutic aspects, and outcomes of the case series of 10 MHD patients of our dialysis unit, who tested positive for SARS-CoV-2 from 5 October to 30 November 2020. Furthermore, we evaluate the removal of hyperinflammatory parameters with the ATA membrane in postdilution online hemodiafiltration (OL-HDF) in these patients through a variety of biomarkers of systemic inflammation from the diagnosis until stripping. Biochemical blood analysis was carried out at baseline and at days 7 and 14 after diagnosis, respectively. 50% of the patients presented COVID-19 pneumonia and required hospital admission. Median hospitalization time was 21days. A total of 4 patients developed severe pneumonia (3 of them died) and 1 patient developed moderate pneumonia. Patients who died (n � 3) were more likely to present bilateral pneumonia (100% vs 14.3%) at diagnosis and less reduction in interleukin 6 (IL-6) at day 14, as compared to those who survived. e use of the ATA membrane could be considered a therapeutic option, due to its immunomodulatory effect in MHD patients with SARS-CoV-2 infection, especially at the beginning of the disease, where the inflammatory component is predominant. 1. Introduction In early December 2019, a respiratory disease caused by a novel coronavirus, named severe acute respiratory syn- drome coronavirus 2 (SARS-CoV-2), emerged in Wuhan, China. is disease, which the World Health Organization (WHO) denominated coronavirus disease 2019 (COVID- 19), spread rapidly throughout China and worldwide [1]. e WHO declared COVID-19 a pandemic in March 2020 [2]. At the beginning of June 2020, Spain was already re- covering from the high infection rates, after it implemented one of the most draconian COVID-19 lockdowns in Europe. However, two months after lifting the restrictions, the virus spread faster than in any of Spain’s neighboring countries. During the second wave of COVID-19, the therapeutic approach of targeting the virus replication and the hyper- inflammation remains limited and its pathophysiologic basis is not yet not fully understood. Patients with end-stage kidney disease (ESKD), undergoing maintenance hemodi- alysis (MHD), may be more vulnerable to a SARS-CoV-2 infection, due to their suppressed immune system [3, 4]. Prompt identification of SARS-CoV-2 infection, isolation, Hindawi Case Reports in Nephrology Volume 2021, Article ID 5575928, 7 pages https://doi.org/10.1155/2021/5575928