Background: Diagnostic criteria for Acute Respiratory Distress Syndrome (ARDS) includes PaO2/FiO2 (PF) ratio and it requires arterial blood gas analysis. Using the PF ratio in the diagnosis and management of treatment may delay or miss the diagnosis of ARDS, especially in conditions where ABG cannot be performed. Besides, clinical identification of ARDS remains poor, clinicians fail to recognize ARDS in 40% of patients. Therefore, a non-invasive measure of oxygenation, SpO2/FiO2 (SF) ratio, may be used as a surrogate for PF ratio. Methods: We enrolled 80 mechanically ventilated adult patients. SpO2, arterial blood gas analysis results, and mechanical ventilation settings were recorded, simultaneously. Firstly, we examined the correlation of SF and PF ratios and determined SF ratios corresponding to PF ratios of ARDS classification. Results: The SF and PF ratios had a linear correlation [SF ratio=109.69+0.642 x (PF ratio)] (%95 CI; p<0.001; r: 0.712). SF ratios corresponds to PF ratios are; 103.2±14.3 for severe ARDS, 220±54.8 for moderate ARDS, 285.4±33.2 for mild ARDS, 308.2±10.2 for non-ARDS patients. Conclusion: SF ratio is a noninvasive and easily available surrogate for PF ratio in mechanically ventilated patients. Using the non-invasive and continuously available SF ratio may help an earlier diagnosis of hypoxia, allowing the utilization of proper treatments. Earlier administration of those therapeutic and supportive strategies in those with milder lung injury may limit the progression into more severe forms of lung injury.
Anahtar Kelimeler: ARDS,PaO2/FiO2 ratio,SpO2/FiO2 ratio, PEEP