SpO2/FiO2 and PaO2/FiO2 for Predicting Intensive Care Admission in Wheezy Children: An Observational Study

To determine the sensitivity of cut-off of SpO2/FiO2 (SF ratio) < 300 at hospital admission for predicting the need for admission in the pediatric intensive care unit (PICU) in wheezy children. Secondary objectives were to determine the sensitivity of cutoff of SF ratio < 300 for predicting in-hospital mortality and that of PaO2/FiO2 (PF ratio) < 200 for predicting intensive care admission and in-hospital mortality. We also ascertained the correlation between SF ratio and PF ratio in the above population.

This prospective observational study was conducted on 315 wheezy children aged 6 months to 12 years requiring admission in the pediatric emergency department. Oxygen saturation (SpO2) and fraction of oxygen in inspired air (FiO2) were recorded at admission while the partial pressure of oxygen (PaO2) was measured using arterial blood gas analysis performed within half an hour of admission. All children were managed as per protocol and followed up during hospital stay. Outcome was defined as the need for admission in the pediatric intensive care unit (PICU) or in-hospital mortality.

Cut-offs of SF ratio < 300 and PF ratio < 200 were able to determine the need PICU admission with a sensitivity of 97.30% and 62.16% respectively. The best cut-off of SF ratio for predicting PICU admission was < 178.79 [AUC (95% CI) 0.841 (0.767, 0.914)], while that for PF ratio was < 201.81 [AUC (95% CI) of 0.849 (0.775, 0.924)]. Cut-offs of < 300 for SF ratio and < 200 of PF ratio, were able to predict in-hospital mortality with sensitivity of 100%, but specificity of only 3.33% and 46.67%, respectively. There was only a moderate correlation between SF ratio and PF ratio (r = 0.44, P < 0.001).

SpO2/FiO2 cut-off of < 300 had a good sensitivity in determining need for PICU admission. SF ratio has only a moderate correlation with PF ratio.