COMPARISON OF THE SPO2/FIO2 RATIO AND THE PAO2/FIO2 RATIO IN PATIENTS WITH ACUTE LUNG INJURY AND ACUTE RESPIRATORY DISTRESS SYNDROM

Diagnostic criteria for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) requires acute onset of disease، chest radiograph demonstrating bilateral pulmonary infiltrates، lack of significant left ventricular dysfunction and Pao2/Fio2 (PF) ratio 300 for ALI or 200 for ARDS. And the latter one requires invasive arterial sampling. Measurement spo2 by pulse oxi metry and calculation spo2/Fio2 (SF) ratio may be a reliable non invasive alternative to the PF ratio.

In this cross sectional study، 70 patient diagnosed for ALI or ARDS admitted in Tabriz children’s hospital PICU were enrolled. Then spo2، Fio2، Pao2 charted within 5 minutes were measured and the ratio of SF and PF were calculated and compared. SF threshold the values were determined to replacement PF ratio for diagnose ARDS and ALI.

The relationship between SF and PF ratio was described by the following regression equation SF=57+0/61PF (P<0/001). SF ratios of 181 and 235 corresponded of PF ratio 300 and 200. The ALI SF cutoff of 235 had 57% sensitivity and 100% specificity، and ARDS، SF cutoff of 181 had 71% sensitivity and 82% specificity.

SF ratio is a reliable noninvasive marker for PF ratio to identify children with ALI or ARDS. A nd can be replaced pulse oximetry by arterial blood sampling.