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

Introduction One of diagnostic criteria for Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS) 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 pulse oximetry test may be a reliable non invasive alternative to the PF ratio. Materials and Methods In a cross sectional study we enrolled 105 sample of patients with ALI or ARDS, to determine the Spo2/Fio2 (SF). Pao2 was measured 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.