Abstract
This study aims to investigate the association between oxygenation saturation index (OSI) and the outcome of acute respiratory distress syndrome (ARDS) patients, and assess the predictive performance of OSI for ARDS patients’ mortality. This study was conducted at one regional hospital with 66 adult intensive care unit (ICU) beds. All patients with ARDS were identified between November 1 2016 and May 31 2018, and their clinical information was retrospectively collected. The lowest PaO2/FiO2 ratio and SpO2/FiO2 ratio and highest mean airway pressure (MAP) were recorded on the first day of ARDS; and oxygen index (OI) and OSI were calculated as (FiO2 × MAP × 100)/PaO2, and (FiO2 × MAP × 100) /SpO2 accordingly. During the study period, a total of 101 patients with ARDS were enrolled, and their mean age was 69.2 years. The overall in-ICU and in-hospital mortality rate was 57.4% and 61.4%, respectively. The patients with in-ICU mortality had higher APACHE II score than the survivors (31.6 ± 9.8 vs. 23.0 ± 9.1, p < 0.001). In addition, mortalities had lower SpO2, and SpO2/FiO2 ratios than the survivors (both p < 0.05). In contrast, survivors had lower OI, and OSI than the mortalities (both p = 0.008). Both OSI (area under curve (AUC) = 0.656, p = 0.008) and OI (AUC = 0.654, p = 0.008) had good predictive performance of mortality among ARDS patients using receiver-operating characteristics (ROC) curves analysis. In addition, the AUC of SpO2/FiO2 (AUC = 0.616, p = 0.046) had better performance for mortality prediction than PaO2/FiO2 (AUC = 0.603, p = 0.08). The patients with OSI greater than 12 had a higher risk of mortality than OSI < 12 (adjusted OR, 5.22, 95% CI, 1.31–20.76, p = 0.019). In contrast, OI, PaO2/FiO2, and SpO2/FiO2 were not found to be significantly associated with increased mortality. OSI is significantly associated with the increased mortality of ARDS patients and can also be a good outcome predictor.
Highlights
Acute respiratory distress syndrome (ARDS) is an acute catastrophic lung condition that can be associated with high mortality [1,2,3]
We found that oxygenation saturation index (OSI) was significantly associated with increased mortality of ARDS patients
It had a similar performance for mortality prediction to oxygen index (OI), but better than the other two oxygenation parameters—PaO2/FiO2, and SpO2/FiO2
Summary
Acute respiratory distress syndrome (ARDS) is an acute catastrophic lung condition that can be associated with high mortality [1,2,3]. In 1994, the American and European Consensus Conference (AECC) established specific clinical criteria for ARDS and acute lung injury (ALI), including acute and sudden onset of severe respiratory distress, bilateral infiltrates on chest radiography, the absence of cardiogenic pulmonary edema, and severe hypoxemia [4]. No matter which criterion is applied for ARDS, severe hypoxemia remains the hallmark of ARDS. Accurate analysis of oxygenation relies on the arterial blood gas measurement, and this test requires repeated arterial blood gas sampling. The concerns about the complications of arterial blood gas tests, including excess blood draws, increasing medical cost, and the implementation of arterial lines are raised. If we want to obtain accurate oxygenation measurement and avoid the arterial blood gas-associated complications, pulse oximetric measurement of oxygenation saturation (SpO2) may provide a solution
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