Validity of Spo2/Fio2 Ratio in Detection of Acute Lung Injury and Acute Respiratory Distress Syndrome

Abstract

Introduction: One ofdiagnostic criteria for Acute Lung Injury and Acute Respiratory Distress Syndrome is pao2/fio2 (PF) ratio 300 for ALI or 200 for ARDS. This criteria requires invasive arterial sampling. Measurement of Spo2/Fio2 (SF) ratio by pulseoximetry may be a reliable non invasive alternative to the PF ratio. Methods and Materials: In a cross sectional study we enrolled 105 sample of patients with ALI or ARDS, to determine the Spo2/Fio2 (SF). Pao2 wasmeasured through arterial blood sampling and Spo2 measured with pulse oximetry and documented within 5 minutes of each other. Results The relationship between SF and PF ratio was described by the following equation: SF=57+0/61PF (P<0/001). Spo2/Fio2 (SF) ratios of 181 and 235 can be substituted pao2/fio2 (PF) ratio of 200 and 300 in ARDS and ALI respectively. The ALI SF cutoff of 235 had 57% sensitivity and 100% specificity, and ARDS, SF cutoff of 181 had 71% sensitivity and 82% specificity. Conclusion Spo2/Fio2 (SF) ratio is a reliable noninvasive marker to determine children with ALI or ARDS and can be used instead of it.