Derivation and validation of Spo2/Fio2 ratio to impute for Pao2/Fio2 ratio in the respiratory component of the Sequential Organ Failure Assessment score.

The Sequential Organ Failure Assessment (SOFA) score is validated to measure severity of organ dysfunction in critically ill patients. However, in some practice settings, daily arterial blood gas data required to calculate the respiratory component of the SOFA score are often unavailable. The objectives of this study were to derive Spo2/Fio2 (SF) ratio correlations with the Pao2/Fio2 (PF) ratio to calculate the respiratory parameter of the SOFA score, and to validate the respiratory SOFA obtained using SF ratios against clinical outcomes.