Comparison of PaO2/FiO2 (PF ratio) to SpO2/FiO2 (SF ratio) and OI to OSI for Predicting Short Term Outcomes in Children with Acute Hypoxemic Respiratory Distress: A Prospective Observational Study.

ABSTRACT

OBJECTIVES: To compare PaO2/FiO2 (PF ratio) to SpO2/FiO2 (SF ratio) and oxygenation index (OI) to oxygenation saturation index (OSI) for predicting short term outcomes [mortality, progression to ventilation and ventilator free days (VFD)] and compare trends of S/F and OSI in predicting early mortality in children with acute hypoxemic respiratory distress. METHODS: This prospective observational study included 200 consecutive children with acute hypoxemic respiratory distress. Serial PF and SF ratios calculated at 0, 6, 24 and 48 h were compared and their trends were utilized for prediction of 28 d mortality. Same was done in ventilated patients using OI and OSI. RESULTS: SF ratio at admission had a 72% sensitivity and 60% specificity while PF had a sensitivity of 78% and a specificity of 75% for prediction of mortality. The area under the curve (AUC) for SF ratio was 0.82 (CI 0.688-0.915). Serial SF ratios accurately predicted mortality. OI had sensitivity of 92% and specificity of 95% in predicting 24 and 48 h mortality. OSI had 95% sensitivity and 92% specificity in predicting mortality with AUC 1.000 (CI- 1.00-1.00) at 24 and 48 h post ventilation. Serially increasing OI and OSI trends had an inverse correlation with VFDs (p <0.01). CONCLUSIONS: SF is a reliable surrogate for PF and a useful predictor of progression to ventilation and survival at discharge while OSI is a useful marker of worsening hypoxia and mortality in ventilated patients.