Microvascular flow alterations in critically ill COVID-19 patients: A prospective study

BACKGROUND: Data on microcirculatory pattern of COVID-19 critically ill patients are scarce. The objective was to compare sublingual microcirculation parameters of critically ill patients according to the severity of the disease. METHODS: The study is a single-center prospective study with critically ill COVID-19 patients admitted in ICU. Sublingual microcirculation was assessed by IDF microscopy within 48 hours of ICU admission. Microcirculatory flow index (MFI), proportion of perfused vessel (PPV), total vessel density (TVD), De Backer score (DBS), perfused vessel density (PVD) and heterogeneity index (HI) were assessed. Patients were divided in 2 groups (severe and critical) according to the World health organization definition. FINDINGS: From 19(th) of March to 7(th) of April 2020, 43 patients were included. Fourteen patients (33%) were in the severe group and twenty-nine patients (67%) in the critical group. Patients in the critical group were all mechanically ventilated. The critical group had significantly higher values of MFI, DBS and PVD in comparison to severe group (respectively, PaCO(2): 49 [44–45] vs 36 [33–37] mmHg; p<0,0001, MFI: 2.8 ± 0.2 vs 2.5 ± 0.3; p = 0.001, DBS: 12.7 ± 2.6 vs 10.8 ± 2.0 vessels mm(-2); p = 0.033, PVD: 12.5 ± 3.0 vs 10.1 ± 2.4 mm.mm(-2); p = 0.020). PPV, HI and TVD were similar between groups Correlation was found between microcirculatory parameters and PaCO(2) levels. CONCLUSION: Critical COVID-19 patients under mechanical ventilation seem to have higher red blood cell velocity than severe non-ventilated patients.