[Relationship between PAO2/FIO2 and SATO2/FIO2 with mortality and duration of admission in critically ill children]

Objectives: The aim of this study is to analyse the relationships and the association between PaO(2)/FiO(2) and SatO(2)/FiO(2with) the duration of admission in Paediatric Intensive Care Units (PICU) and mortality, and to study the relationships between both ratios.

Material and methods: A retrospective study was conducted on PICU patients in whom a gas analysis was performed in the first twenty-four hours of admission. Demographic, clinical and ventilation variables were collected, and the relationship between PaO(2)/FiO(2) and SatO(2)/FiO(2) with days of admission and mortality was determined. Finally, the best cut-off points of SatO(2)/FiO(2) were determined for PaO(2)/FiO(2) values greater and less than 200.

Results: Of 512 patients admitted during one year, a gas analysis was performed on 358, 65% of those in arterial blood. The median duration of hospitalization was two days and there were 11 patient deaths. There was a low negative correlation between the values of PaO(2)/FiO(2) and SatO(2/)FiO(2) on admission to PICU and with duration of admission, and an inverse association with mortality (P<.01). This association was stronger for the PaO(2)/FiO(2) ratio in patients with heart disease, those undergoing invasive mechanical ventilation, and for arterial blood samples. PaO(2)/FiO(2) and SatO(2)/FiO(2) ratios were significantly correlated with each other. A cut-off of 200 for SatO(2)/FiO(2) had a sensitivity of 97.5% for classifying patients with PaO(2)/FiO(2) values lower or higher than 200.

Conclusions: PaO(2)/FiO(2) and SatO(2)/FiO(2) index are markers of severity in critically ill patients. In patients who do not have an arterial line, SatO(2)/FiO(2) index can be used for assessment of oxygenation as an indicator of severity in children in critical condition.