Oxygen Debt as Predictor of Mortality and Multiple Organ Dysfunction Syndrome in Severe COVID-19 Patients: A Retrospective Study

Abstract

Background: Oxygen debt (DEOx) represents the disparity between resting and shock oxygen consumption (VO₂) and is associated with metabolic insufficiency, acidosis, severity, and mortality. This study aimed to assess the reliability of DEOx as an indirect quantitative measure for predicting multiple organ dysfunction syndrome (MODS) and 28-day mortality in patients admitted to the intensive care unit (ICU) with respiratory syndrome severe acute coronavirus type 2 (SARS-CoV-2) infection, in comparison to the Acute Physiology and Chronic Health Evaluation II (APACHE II), sepsis-related organ failure assessment (SOFA), and 4C scores. Methods: A retrospective cohort study was conducted, including ICU patients with SARS-CoV-2 infection between 2020 and 2021. Clinical data were extracted from the EPIMED Monitor Database®. APACHE II, SOFA, and 4C scores were calculated upon ICU admission, and their accuracy in predicting 28-day mortality and MODS was compared to DEOx. Multivariate logistic regression analysis was performed to analyze the outcome variables. Results: 708 patients were included, with a mortality rate of 44.4%. DEOx value was 11.16 ml O2/kg. The mean age was 58.7 years. Multivariate analysis showed that DEOx was independently associated with mortality, intubation, and renal injury. Each point increase in creatinine was associated with a higher risk of MODS. To determine the precision of the scores, area under the receiver operating characteristic curves (AUROC) analysis was performed with weak discrimination and similar behavior for the primary outcomes. The most accurate scale for mortality and MODS was 4C with an AUC of 0.683 and APACHE II with an AUC of 0.814, while that of the AUROC of DEOx was 0.612 and 0.646, respectively. Conclusions: DEOx showed similar predictive value to established scoring systems in critically ill patients with SARS-CoV-2 infection. The correlation of DEOx with these scores may facilitate early intervention in critically ill patients.