Evaluation Of Oxygenation Index In Prognosis Of Acute Respiratory Distress Syndrome Under Standard Ventilation

Objective: To determine the predictive validity of the fraction of inspired oxygen(PaO2/FiO2 ratio)and the variations following standard ventilator setting in the prognosis of patients with acute respiratory distress syndrome(ARDS).Methods: A prospective study was conducted in patients with moderate to severe ARDS from March 2015 to May2016 in Department of Critical Care Medicine,First Affiliated Hospital of Xinjiang Medical University.The patients’ general condition,arterial blood gas,acute physiology and chronic health status score Ⅱ(APACHE Ⅱ)and sequential organ failure estimation score(SOFA)were recorded.After 24 h of mechanical ventilation,the arterial blood gas was measured with ventilation in standard ventilator setting for 30 min.Survival rates were observed at 28 days and were divided into survival and death groups.Results:Twenty-seven patients were enrolled in the study.Among them,22 patients were moderite and 5 patients were severe according to the Berlin criteria.After standard ventilator setting,PaO2/FiO2 was significantly higher than that at study entry [172.83 ± 60.65 vs 140.54 ±41.87(mmHg,1mmHg = 0.133kPa),P = 0.010].There were 8 patients with a200mmHg<PaO2/FiO2≤300mm Hg,and19 patients with a 100 < PaO2/FiO2≤300mm Hg.Twelve patients were dead in 28 days,and the mortality rate was 44.4%.Compared with the death group,the APACHE Ⅱ score was lower in the survival group(22.75 ± 2.6 vs.18.33 ± 3.4,P = 0.010),the SOFA score was lower(9.53 ± 1.9 vs.12.0 ± 2.5,P = 0.034),PO2 / FiO2 was significantly higher after standard ventilator setting [193.79 ± 66.4 vs.146.6 ± 41.5(mmHg),P = 0.010],ant the improvement of PaO2/FiO2 was higher after standard ventilation [62.36 ± 50.39 vs.2.12 ± 70.60(mmHg),P = 0.022].Conclusion:The oxygenation index in standard ventilator setting and its improvement can reflect the condition of ARDS patients and evaluate the prognosis.