Novel oxygenation and saturation indices for mortality prediction in Covid-19 ARDS patients: the impact of driving pressure and mechanical power

Abstract

Background: The oxygenation index (OI) and oxygen saturation index (OSI) are proven mortality predictors in pediatric and adult patients, traditionally using mean airway pressure (P-mean). We introduce novel indices, replacing P-mean with DP (Delta P-insp), MPdyn, and MPtot, assessing their potential for predicting COVID-19 acute respiratory distress syndrome (ARDS) mortality, comparing them to traditional indices. Methods: We studied 361 adult COVID-19 ARDS patients for 7 days, collecting Delta P-insp, MPdyn, and MPtot, OI-Delta P-insp, OI-MPdyn, OI-MPtot, OSI-Delta P-insp, OSI-MPdyn, and OSI-MPtot. We compared these in surviving and non-surviving patients over the first 7 intensive care unit (ICU) days using Mann-Whitney U test. Logistic regression receiver operating characteristic (ROC) analysis assessed AUC and CI values for ICU mortality on day three. We determined cut-off values using Youden's method and conducted multivariate Cox regression on parameter limits. Results: All indices showed significant differences between surviving and non-surviving patients on the third day of ICU care. The AUC values of OI-Delta P-insp were significantly higher than those of P/F and OI-P-mean (P values .0002 and <.0001, respectively). Similarly, AUC and CI values of OSI-Delta P-insp and OSI-MPdyn were significantly higher than those of SpO(2)/FiO(2) and OSI-P-mean values (OSI-Delta P-insp: P < .0001, OSI-MPdyn: P values .047 and .028, respectively). OI-Delta P-insp, OSI-Delta P-insp, OI-MPdyn, OSI-MPdyn, OI-MPtot, and OSI-MPtot had AUC values of 0.72, 0.71, 0.69, 0.68, 0.66, and 0.64, respectively, with cut-off values associated with hazard ratios and P values of 7.06 (HR = 1.84, P = .002), 8.04 (HR = 2.00, P <= .0001), 7.12 (HR = 1.68, P = .001), 5.76 (HR = 1.70, P <= .0001), 10.43 (HR = 1.52, P = .006), and 10.68 (HR = 1.66, P = .001), respectively. Conclusions: Critical values of all indices were associated to higher ICU mortality rates and extended mechanical ventilation durations. The OI-Delta P-insp, OSI-Delta P-insp, and OSI-MPdyn indices displayed the strongest predictive capabilities for ICU mortality. These novel indices offer valuable insights for intensivists in the clinical management and decision-making process for ARDS patients.