Associations between oxygen saturation Index and oxygenation index in neonates with congenital diaphragmatic hernia

Objective To explore the relationship between Oxygenation Index (OI) and Oxygen Saturation Index (OSI) among infants with Congenital Diaphragmatic Hernia (CDH), both within the first 24 h after birth and in extended observations in those who survived until their surgical intervention. Methods Seven- years retrospective review of CDH cases at a single Level III neonatal intensive care unit. The correlations of various combinations of OI-OSI pairs were assessed using the Spearman's rho Correlation Coefficient. Additionally, during the initial 24 h, the correlations between admission (first), best (lowest), highest, and mean OI and OSI values were determined. The predictive ability of the first 24 h oxygen and oxygen saturation indices for mortality and other adverse outcomes were assessed using the Area Under the Curve (AUC) analysis. Results Thirty-seven infants with CDH were included in the analysis. A strong correlation was observed between all pairs of OI/OSI (2,289) (Spearman's rho = 0.843), matched pairs of Postductal OI/OSI (1,232 pairs) (Spearman's rho = 0.835) and the unmatched pairs of Postductal OI and Preductal OSI (1,057 pairs) (Spearman's rho = 0.852). Using the regression equations for all pairs, matched and unmatched OI/OSI pairs, we deduced that for clinically pertinent OI thresholds of 10, 15, 20 and 40, the corresponding OSI values were 5, 8, 11, and 23, respectively. Furthermore, in the first 24 h, strong correlations were evident between OI/OSI: at admission (Spearman's rho = 0.783), best OI/OSI (Spearman's rho = 0.848), and highest OI/OSI (Spearman's rho = 0.921). The most robust correlation was observed between the mean OI/OSI with a Spearman's rho of 0.928. First (AUC = 0.849), best (AUC = 0.927), highest (AUC = 0.942) and mean day 1 OI (AUC = 0.946) were all predictive of mortality. Similarly, first (AUC = 1.00), best (AUC = 0.989), highest (AUC = 1.00) and the mean OSI in day 1 (AUC = 0.978) were all predictive of mortality. All of the OIs and OSIs in day 1 except for the admission OSI (AUC = 0.683) were predictive of pulmonary hypertension. Additionally, all of OI and OSI indices in the first 24-hour except for the best day 1 OI (AUC = 0.674) were predictive of the need for rescue HFOV. Conclusion There were a strong correlation between the OI and OSI in infants with CDH. Oxygenation indices and OSI in the first 24 h were predictive of mortality and other adverse outcomes in infants with CDH.