The prognostic value of continuous dynamic monitoring of intrapulmonary shunt in patients with acute respiratory distress syndrome / 中华危重病急救医学

ABSTRACT

Objective To investigate the predictive value of continuous dynamic monitoring of intrapulmonary shunt (Qs/Qt) in patients with acute respiratory distress syndrome (ARDS).Methods A prospective observational study was conducted.The adult patients with ARDS undergoing mechanical ventilation admitted to intensive care unit (ICU) of Tianjin Third Central Hospital from June 2014 to December 2015 were enrolled.Baseline characteristics,demographic data and relevant physiologic data were recorded.All patients were divided into survivors and non-survivors according to the outcome of patients within 28 days.Artery and mixed venous blood was collected immediately after admission for blood gas analysis,and daily Qs/Qt within 7 days was continuously monitored in ARDS patients.The receiver operating characteristic curve (ROC) was used to evaluate the prognosis accuracy of Qs/Qt.Results In 46 enrolled ARDS patients,20 died,and 26 survived.During the first 7 days of ARDS,the mean Qs/Qt in survivors showed an increasing tendency [(23 ± 6)％,(27 ± 6)％,(28 ± 9)％,respectively,at 1-3 days] and a downtrend tendency from 4 days [(27 ± 5)％,(25 ± 4)％,(19 ± 4)％,(16 ± 2)％,respectively,at 4-7 days].However,a rising tendency of Qs/Qt in non-survivors was found at 1-7 days [(28 ± 7)％,(30 ± 3)％,(33 ± 6)％,(33 ± 11)％,(34 ± 5)％,(33 ± 6)％,(35 ± 6)％,respectively],and Qs/Qt from the 5th day in non-survivors was significantly higher than that in survivors (all P ＜ 0.05).The fluctuation of oxygenation index (PaO2/FiO2) within 1 week in both groups was small,and PaO2/FiO2 (mmHg,1 mmHg =0.133 kPa) at 1-7 days in survivors was 167.37±43.98,180.55±39.90,174.27±35.47,188.64±39.74,252.54±49.22,239.35±25.63,248.93±45.64,respectively,and it was 168.65±35.54,182.31 ± 32.36,159.80 ± 34.39,176.97 ± 31.75,200.69 ± 45.33,185.98 ± 36.47,and 175.43 ± 30.98 in non-survivors respectively.PaO2/FiO2 was significantly lower in non-survivors than survivors from 5 days (all P ＜ 0.05).It was shown by ROC curve that area under ROC curve (AUC) for Qs/Qt evaluating the prognosis on the 5th day was 0.958,and 95％ confidence interval (95％CI) was 0.777-0.999 (P ＜ 0.000 1,Z =13.13).When the cut-off value of Qs/Qt was 28％,sensitivity and specificity were 83.3％ and 90.0％,respectively.AUC for PaO2/FiO2 evaluating the prognosis on the 5th day was 0.790,and 95％CI was 0.577-0.928 (P =0.002 1,Z =3.08).When the cut-off value of PaO2/FiO2 was 223 mmHg,sensitivity and specificity were 69.2％ and 81.8％,respectively.Conclusion Dynamic Qs/Qt surveillance can help physician to analyze the changes of the patient's condition,and it was better than PaO2/FiO2,and can be an important evaluation indicator of prognosis for ARDS patients.