Oxygen metabolism markers as predictors of mortality in severe COVID-19

•Hypoxaemia determines mortality in coronavirus disease 2019 (COVID-19).•Oxygen saturation in central venous blood (ScvO2), oxygen consumption (VO2) and oxygen extraction (O2ER) reflect the systemic oxygenation status in patients with severe COVID-19.•ScvO2 124.6 ml/min and O2ER >30.2% appear to be predictive of mortality in patients with COVID-19.•Careful monitoring of oxygen metabolism markers is important in treatment modification in patients with severe COVID-19. To investigate the use of oxygen metabolism markers as predictors of mortality in patients with severe coronavirus disease 2019 (COVID-19). A retrospective analysis was undertaken to compare the medical records of patients with severe COVID-19 (53 deceased patients and 50 survivors). The survivors were selected from 222 records using a random number generator. In addition, 28 individuals who considered themselves to be healthy and who had no history of serious illness were included in the study for comparison. Oxygen saturation in arterial blood, oxygen saturation in central venous blood (ScvO2), arterial partial pressure of oxygen (PaO2), respiratory index (PaO2/fraction of inspired oxygen), oxygen delivery, oxygen consumption (VO2) and oxygen extraction (O2ER) were compared in all participants. The optimal cut-off point for each oxygen metabolism marker in the prediction of mortality was determined based on the maximum value of the Youden Index in receiver operating characteristic curve analysis. Significant differences in all studied oxygen metabolism markers were found between survivors compared with deceased patients (p < 0.001). ScvO2, VO2 and O2ER [area under curve (AUC) 1.0] were the strongest predictors of mortality, and PaO2 was the weakest predictor of mortality (AUC 0.81). ScvO2 124.6 ml/min and O2ER >30.2% were identified as predictors of mortality in patients with COVID-19. ScvO2, VO2 and O2ER are good predictors of mortality in critically ill patients with COVID-19.