关键词: 超声检查；胸部；通气机, 机械；脓毒症；撤机

Abstract: Background　Weaning from mechanical ventilation is associated with a high failure rate in sepsis patients.Although in recent years，ultrasound has been widely used in the management of critically ill patients before weaning from mechanical ventilation，such as evaluating the cardiac function，chest ultrasound is rarely used in the process of weaning from mechanical ventilation in patients with sepsis.Objective　To investigate the value of chest ultrasound in predicting the outcome of weaning from mechanical ventilation in patients with sepsis.Methods　A prospective study was conducted.Sixty-five patients with sepsis who underwent continuous mechanical ventilation for more than 48 hours in the ICU，Cixi Hospital Affiliated to WenZhou Medical University from June 2017 to December 2018 were enrolled.For those meeting the screening criteria of weaning from mechanical ventilation，spontaneous breathing trial（SBT） was performed using low level pressure support ventilation，and chest ultrasound was implemented before and 30 minutes after SBT，and parameters including lung ultrasound score（LUS），diaphragmatic excursion，diaphragmatic thickness at end-inspiration and diaphragmatic thickness at end-expiration as well as calculated rapid shallow breathing index（RSBI），diaphragmatic rapid shallow breathing index（D-RSBI） and diaphragmatic thickening fraction（DTF） were collected.Weaning from mechanical ventilation was performed in the eligible cases，and the aforementioned parameters were compared between those with successful and failed weaning（good weaning outcome was defined as successful weaning）.ROC curve analysis was conducted to evaluate the values of chest ultrasound parameters in predicting the outcome of weaning from mechanical ventilation.Results　Fifty cases were finally enrolled，including 35 with successful weaning，and 15 with failed weaning.There were significant differences in mean levels of post-SBT LUS，pre-SBT DTF，post-SBT DTF as well as post-SBT D-RBSI between the two groups（P<0.05）.The mean LUS level increased significantly after SBT than before in those with failed weaning（P<0.05）.The mean DTF level showed an obvious increase after SBT before in both groups（P<0.05）.In predicting the outcome of weaning from mechanical ventilation，the AUC of post-SBT LUS was 0.819，and a good outcome may be estimated when the cutoff point was determined as less than 15.5 scores with a sensitivity of 0.730 and a specificity of 0.800.The AUC of post-SBT D-RSBI was 0.895，and a good outcome may be estimated when the cutoff point was determined as less than 1.41 times?min-1?mm-1 with a sensitivity of 0.867 and a specificity of 0.829.The AUC of pre-SBT DTF was 0.738，and a good outcome may be estimated when the cutoff point was determined as greater than 22.9% with a sensitivity of 0.866 and a specificity of 0.667.The AUC of post-SBT DTF was 0.891，and a good outcome may be estimated when the cutoff point was determined as greater than 33.2% with a sensitivity of 0.886 and a specificity of 0.867.Conclusion　Chest ultrasound has predictive value for the result of weaning in patients with sepsis.Post-SBT LUS<15.5 scores in combination with post-SBT D-RSBI<1.41?min-1?mm-1 and post-SBT DTF>33.2% predicts high rate of successful weaning.

Key words: Ultrasonography；Thorax；；Ventilators, mechanical；Sepsis；；Weaning