Searching for Biomarkers with Predictive Value in Pediatric Acute Lung Injury : can SpO2/FiO2 be used instead of PaO2/FiO2 as an Index to Predict Outcome?

Pulse oximeter and SpO2/FiO2 (SF) ratio evaluation have become widely used indicators of oxygenation together with arterial blood gas analysis in several clinical settings. Several investigations suggest that the SF ratio method could improve our information in terms of predictive and severity scoring. An interesting study reproposes the use of the SF ratio as an alternative to the PF ratio in the assessment of disease severity and of the Pediatric Index of Mortality. However, the results obtained by this retrospective study raise doubts. There is a need for specifically designed controlled clinical studies. In settings where blood gas analyzers are unavailable, the SF ratio could be used for decision-making and continuous monitoring of critical ventilatory support. Although ventilatory support is generally regarded as a safe and potentially life-saving intervention, there is increasing evidence of its possible harmful effects. In the face of evidence of an association of complications and potentially injurious ventilator settings, several untoward consequelnces could arise, including some of a medico-legal nature.