Study On The Predictive Value Of Diaphragmatic Ultrasound Indicators Combined With Central Venous Oxygen Saturation Change Rate For The Outcome Of Ventilatorweaning

Objective:To investigate diaphragmatic ultrasound indices and the rate of central venous oxygen saturation changes before and after a spontaneous breathing trial（SBT）（ΔScv O₂）on the outcome ofweaning from mechanical ventilation.Methods:Through a prospective observational study.From April 2022 to January 2023,adult patients with invasive mechanical ventilation≥48 hours in the Intensive Care Unit of the First Affiliated Hospital of Gannan Medical University were enrolled in this study.All the enrolled patients were indwelling internal jugular or subclavian venous catheters.The central venous blood was drawn before the start of the SBT test to detect the central venous oxygen saturation（Scv O₂）,and then the ventilator mode was adjusted to PSV mode.The SBT test was routinely performed,and measurement of diaphragmatic excursion（DE）and diaphragmatic thickness fraction（DTF）by bedside diaphragmatic ultrasound.After 2 hours of SBT,central venous blood was drawn again todetect Scv O₂,and the change rate of Scv O₂beforeandafter SBTwas calculated.According to the results of mechanical ventilation weaning,the patients included in the study were divided into a successful weaning group and a failed weaning group.Each index was compared between the two groups to assess the diaphragmatic ultrasound（DE and DTF）andΔScv O₂on the outcome ofweaning from hospital.Results:Finally,47 patients were enrolled in this study through the SBT trial,of which 34 patients weresuccessfully weaned and13 patients failed.（1）There were no statistically significant differences between the weaning success group and the failure group in the general data such as primary etiology,gender,age and APACHE II score（P>0.05）.（2）DE and DTF were significantly lower in the weaning failure group than in the failure group,whereasΔThe Scv O₂was significantly higher in the success group than in the success group（P<0.05）.There was no statistically significant difference between the Scv O₂before SBT test andthe Scv O₂weaning success group and thefailure group after SBT test（P>0.05）.（3）Multivariate logistic regression results:ΔScv O₂was an independent risk factor for weaning failure（OR=1.807,P<0.05）,while DE and DTF could be protective factors（OR=0.647,0.861,P<0.05）.（4）DE,DTF,andΔScv O₂could be used to predict the outcome of weaning from mechanical ventilation,and among them,the optimal cut-off value of DE to predict the outcome of weaning was 13.35mm,which had a sensitivity of 85.30%,specificity of 69.20%,area under the ROC curve of 0.801,positive predictive value of 88.46%,and negative predictive value of 47.62%;The optimal cut-off value of DTF for predicting the outcome of weaning was 27.89%,with a sensitivity of 85.30%,a specificity of 69.20%,an area under the ROC curve of 0.816,a positive predictive value of 81.25%,and a negative predictive value of60.00%;andΔThe optimal cutoff value of 4.80%for Scv O₂to predict the outcome of weaning was 84.60%sensitive,70.60%specific,and the area under the ROC curve was 0.768,with a positivepredictivevalueof 92.31%anda negative predictive valueof 52.38%.（5）Diaphragmatic ultrasound indices combinedΔScv O₂predicts weaning value:DE jointΔScv O₂predicted the outcome of weaning from mechanical ventilation with 79.40%sensitivity,92.30%specificity,and an area under the ROC curve of 0.914;DTF jointΔScv O₂predicted the outcome of weaning from mechanical ventilation with 91.20%sensitivity,76.90%specificity,and an areaunder the ROC curveof 0.851.（6）The accuracy of DE combined withΔScv O₂in predicting weaning outcome was higher than that of DE alone（AUC 0.914 VS 0.801,P<0.05）.However,there was no statistically significant difference in the accuracy of predicting weaning outcome between DTF combinedwithΔScv O₂and DTF（AUC 0.851 VS 0.816,P>0.05）.Conclusion:（1）The diaphragmatic excursion,diaphragm thickening fraction and the change rate of central venous oxygen saturation before and after spontaneous breathing trial can predict the outcome ofmechanical ventilation patients.（2）Compared with diaphragm displacement alone in predicting the outcome of weaning in ICU patients with mechanical ventilation,diaphragm displacement combined with the change rate of central venous oxygen saturation before and after spontaneous breathing trial has higher accuracy in predicting the outcome of weaning,which has higher sensitivity and specificity,and has a good predictive effect on whether thepatient canbe successfully weaned.