Accuracy of tension and saturation-based oxygen indices in the assessment of disease severity and its progress in adults with acute respiratory distress syndrome

Abstract

Objective: The goal of this study was to assess the reliability of different tension and saturation-based oxygen indices with traditional oxygenation index (OI) in the assessment of disease severity and its progress in adult patients with acute respiratory distress syndrome (ARDS) when compared to the standard arterial oxygen tension (PaO 2 )/inspired fraction of oxygen (FiO 2 ) (PF) ratio included in the Berlin definition of ARDS; the primary objective was assessed by the correlation of different OIs to the standard PF index. Design: This was a prospective, observational study. Setting: This study was carried out in Intensive Care Unit (ICU) in a university hospital. Patients and Methods: Sixty adult patients with different grades of ARDS severity according to Berlin definition were enrolled in this study. Measurements: The following indices were measured: (1) PF, (2) OI = FiO 2 × mean airway pressure [MAP] × 100/PaO 2 , (3) oxygen saturation index (OSI) = FiO 2 × MAP × 100/oxygen saturation by pulse oximeter. The primary outcome measurement was the correlation of different OIs to the standard PF index. The secondary outcome measurements were sensitivity and specificity of each index. Results: There were a strong significant negative correlation between OI and OSI with the PF ( r = −0.9 and −0.91, respectively) and a significant positive correlation between OI and OSI ( r = 0.93). Total mortality rate was 36% (22 patients). The PF, OI, and OSI were sensitive and specific (sensitivity: 0.63, 0.77, and 0.81, respectively, and specificity: 0.76, 0.86, and 0.78, respectively). Conclusion: OSI can be used as a noninvasive index for the assessment of ARDS severity in adults as it correlates significantly with PF ratio and OI with high sensitivity and specificity to predict ICU mortality.