Utility of SF Ratio and OI to OSI for Predicting Outcomes in Children with Acute Hypoxemic Respiratory Distress

A new study compared the PaO2/FiO2 (PF ratio) to SpO2/FiO2 (SF ratio) and the oxygenation index (OI) to the oxygenation saturation index (OSI) for predicting short-term outcomes, such as – mortality, progression to ventilation, and ventilator-free days (VFD). It also examined trends in S/F and OSI for predicting early mortality in children with acute hypoxemic respiratory distress.

This was a prospective observational study that included 200 consecutive children with acute hypoxemic respiratory distress. Serial PF and SF ratios were calculated at 0, 6, 24, and 48 hours and compared for predicting 28-day mortality. The same approach was used for ventilated patients using OI and OSI.

The SF ratio at admission had a 72% sensitivity and 60% specificity for predicting mortality, while the PF ratio had a 78% sensitivity and 75% specificity. The area under the curve (AUC) for the SF ratio was 0.82. Serial SF ratios accurately predicted mortality. OI had a sensitivity of 92% and specificity of 95% in predicting 24- and 48-hour mortality. OSI had 95% sensitivity and 92% specificity for predicting mortality – with an AUC of 1.000 at 24- and 48-hours post-ventilation. Increasing OI and OSI trends are inversely correlated with VFDs.

From the findings, it was inferred that the SF ratio is a reliable substitute for the PF ratio and a useful predictor of the need for ventilation and survival at discharge. OSI is an effective marker for worsening hypoxia and mortality in ventilated patients.

Source: Shah N, Sarangi BU, Shankar GH, et al. Indian Journal of Pediatrics. 2024 Jun 7:1-7.