摘要目的:探讨床旁超声评估膈肌功能、肺部通气，并结合呼吸力学参数气道闭合压P0.1和呼吸浅快指数（rapid shallow breathing index, RSBI）在呼吸衰竭患者撤机结局中的价值。方法:选择2018年9月—2019年12月上海东方医院重症医学科机械通气治疗患者45例，所有患者拔管前均符合自主呼吸实验（spontaneous breathing trial, SBT）的指征，通过30 min SBT后且在撤机前采用超声评估患者膈肌功能和肺部通气，同时记录呼吸力学参数。根据48 h内是否再插管分为成功组和失败组，利用受试者工作特征（receiver operating characteristic, ROC）曲线分析患者肺部超声评分、膈肌移动度、膈肌厚度分数、P0.1与RSBI预测拔管的准确性。结果:45例患者中，25例患者撤机成功。失败组患者的膈肌移动度和膈肌厚度分数低于成功组患者（ P<0.05），失败组患者肺部超声评分、P0.1与RSBI均高于成功组患者（ P<0.05）。ROC曲线分析发现肺部超声评分、膈肌移动度、膈肌厚度分数、P0.1与RSBI预测撤机成功的敏感度分别为85%、80%、96%、70%和90%，特异性分别为72%、80%、60%、76%和68%。以肺部超声评分、膈肌移动度、膈肌厚度分数、P0.1与RSBI ROC曲线的临界值作为预判值，预判失败拔管的数值记1分，预判成功拔管的数值记0分，以上5个预判值得分相加得出预判值总分，其ROC曲线下面积（area under curve, AUC）为0.909，预测撤机成功的敏感度90%，特异性76%。 结论:撤机时结合超声评估肺部通气、膈肌功能及呼吸力学参数能减少呼吸衰竭患者再次插管的风险，在指导撤机方面提供优化方案，以改善撤机结局。

abstractsObjective:To evaluate the application of bedside ultrasound in evaluating diaphragmatic function and pulmonary ventilation, and the outcome of withdrawal of mechanical ventilation in patients with respiratory failure in combination with respiratory mechanical parameters such as airway occlusion pressure (P0.1) and rapid shallow breathing index (RSBI).Methods:A total of 45 patients who underwent mechanical ventilation in Department of Critical Care Medicine, Shanghai East Hospital from September 2018 to December 2019 were selected. All the patients met the indications for spontaneous breathing trail (SBT) before extubation. After SBT for 30 min, ultrasound examination was performed to evaluate diaphragmatic function and pulmonary ventilation before withdrawal of mechanical ventilation, while respiratory mechanical parameters were recorded. According to the presence of re-intubation within 48 h, the patients were divided into two groups: a successful group and a failed group. The receiver operating characteristic (ROC) curve was plotted to analyze pulmonary ultrasound score, diaphragmatic mobility, diaphragmatic thickening fraction, and the accuracy of P0.1 and RSBI in predicting withdrawal.Results:There were 25 out of 45 patients who successfully took off the machine. Patients in the failed group presented decreases in diaphragmatic mobility and diaphragmatic thickening fraction, and increases in pulmonary ultrasound score, P0.1 and RSBI, compared with the successful group ( P<0.05). According to the ROC curve, the sensitivity of pulmonary ultrasound score, diaphragmatic mobility, diaphragmatic thickening fraction, P0.1 and RSBI in predicting successful withdrawal was 85%, 80%, 96%, 70% and 90%, respectively. The specificity of the above five indicators was 72%, 80%, 60%, 76% and 68%. The cut-off values of pulmonary ultrasound score, diaphragmatic mobility, diaphragmatic thickening fraction, P0.1 and RSBI ROC curves were used as predictive values. The predicted failed extubation was scored as 1 point, and the predicted successful extubation was scored as 0 point. The total cut-off values of the above five indicators were added. The area under the ROC curve was 0.909, with a sensitivity of 90% and a specificity of 76%. Conclusions:The combined use of ultrasound during withdrawal of mechanical ventilation to evaluate pulmonary ventilation, diaphragmatic function and respiratory mechanical parameters can reduce the risk of re-intubation in patients with respiratory failure, which provides an optimal scheme in guiding withdrawal of mechanical ventilation to improve the outcome.