Microcirculatory, Endothelial and Inflammatory Responses in Critically Ill Patients with COVID-19 Are Distinct from Those Seen in Septic Shock: A Case Control Study

Abstract

Background: Critically ill patients with COVID-19 infection frequently exhibit a hyperinflammatory response and develop organ failures, however the underlying mechanisms are unclear. We investigated the microcirculatory, endothelial and inflammatory responses in critically ill COVID-19 patients and compared them to a group of patients with septic shock. Methods: Prospective observational case control study. 30 patients with COVID-19 admitted to the ICUs of a tertiary hospital were compared to 33 patients with septic shock. Measurements of sublingual microcirculatory flow were performed using Incident Dark Field (IDF) video-microscopy and serial measurements of IL-6 and Syndecan-1 levels were made. Findings: COVID-19 patients had significantly less vasoactive drug requirement and lower plasma lactate than those with septic shock. Microcirculatory flow was significantly worse in septic patients than those with COVID-19 (MFI 2.6 v 2.9 p 0.02, PPV 88 v 97% p <0.001). IL-6 was higher in patients with septic shock than COVID-19 (1653 v 253 pg/ml, p 0.03) IL-6 levels in COVID 19 patients were not elevated compared to healthy controls except on the day of ICU admission. Syndecan-1 levels were not different between the 2 pathological groups. Interpretation: Compared to patients with bacterial sepsis an overt shock state with tissue hypoperfusion does not appear typical of COVID-19 infection. There was no evidence of significant sublingual microcirculatory impairment, widespread endothelial injury or marked inflammatory cytokine release in this group of critically ill COVID-19 patients. COVID-19 may have a different pathogenesis to bacterial induced septic shock. Funding Statement: Royal Centre for Defence Medicine (UK Ministry of Defence), 2019; European Society of Intensive Care Medicine Point of Care Ultrasound award, 2019. Declaration of Interests: All authors declare that they have no conflicts of interest. Ethics Approval Statement: Yorkshire and Humber (Leeds East) and North West Research Ethics committees (18/YH/0371and 19/NW/0750).