Abstract: Background　Mechanical ventilation （MV） is an important means to rescue patients with respiratory failure，but it can lead to atrophy and functional decline in diaphragm.Studies have found that diaphragmatic atrophy occurred at the early stage of MV，but the correlation between early diaphragmatic atrophy and  MV duration and prognosis is still unclear.Objective　To investigate the relationship of the changes in diaphragmatic thickness at the end of expiration （DTee） during respiratory cycles scanned by bedside color Doppler ultrasound with MV duration and length of stay in the ICU in mechanically ventilated patients.Methods　The enrolled 60 cases of MV were from the Intensive Care Unit，Shenzhen People's Hospital between January 2016 and September 2017.All of them received routine treatment.We collected their data about sex，age，primary disease，baseline APACHE Ⅱ score and high-sensitivity C-reactive protein （hs-CRP），MV duration，length of stay in ICU，DTee at baseline，during 5-day MV and immediately before weaning from MV，and the difference between DTee after MV and MV before （ΔDTee） during 5-day MV and immediately before weaning from MV （detected by a kind of color Doppler diagnostic ultrasound produced by SonoScape）． They were divided into diaphragm atrophy group （n=21） and normal diaphragm thickness group （n=39） based on the DTee detected on the 3rd of MV.Results　The DTee decreased with the MV duration （F=108.95，P<0.001）． In all patients，the mean baseline DTee was higher than that measured on the 3rd，4th，5th days of MV，and immediately before weaning from MV，as was the mean DTee measured on the 1st day of MV when compared with that measured on the 4th，5th days of MV，and immediately before weaning from MV，and the mean DTee measured on the 2nd day of MV when compared with that measured immediately before weaning from MV（P<0.05）． ΔDTee tended to increase with MV duration（F=263.10，P<0.001）． The mean ΔDTee between the DTee at baseline and on the 1st of MV was found to be lower than other 4 subsequently measured ΔDTee（P<0.05）． The mean ΔDTee between the DTee on the 3th day of MV was lower than immediately before weaning from MV（P<0.05）.Compared with normal diaphragm thickness group，diaphragm atrophy group demonstrated higher mean hs-CRP level，longer MV duration and length of stay in ICU （P<0.05）． Moreover，the ΔDTee from the 1st day to the 3rd day of MV was positively associated with MV duration （r=0.266，P=0.04）． Conclusion　DTee gradually decreased with the MV duration in mechanically ventilated patients，which was particularly obvious in the first 3 days.The extent of early diaphragm atrophy was related with MV duration and length of stay in ICU.

Key words: Mechanical ventilation, Diaphragmatic thickness at the end of expiration, Prognosis, Ultrasonography

摘要： 背景　机械通气（MV）是抢救呼吸衰竭患者的重要手段，但其本身会导致膈肌出现萎缩和功能下降。研究发现膈肌萎缩在MV的早期就已出现，然而早期膈肌萎缩与患者MV的时间及预后的相关性如何目前尚不清楚。目的　采用床边彩超观察MV患者早期呼气末膈肌厚度（DTee）的变化趋势，并探讨其与MV时间和重症医学科（ICU）住院时间的关系。方法　选取2016年1月—2017年9月深圳市人民医院ICU收治的MV患者60例，根据第3天的DTee将患者分为膈肌萎缩组（21例）和膈肌厚度正常组（39例），均进行常规治疗，入院时收集性别、年龄、原发疾病、急性生理与慢性健康状况评分系统Ⅱ（APACHE Ⅱ），检测超敏C反应蛋白水平，记录患者MV时间及ICU住院时间，采用SonoScape超声检查仪测量MV前、MV后5 d及撤机前的DTee及MV后DTee与MV前的差值（ΔDTee）。结果　MV患者的DTee随MV时间的延长呈下降趋势（F=108.95，P<0.001）；其中，第3、4、5天及撤机前的DTee均低于MV前，第4、5天及撤机前的DTee均低于第1天，撤机前的DTee低于第2天（P<0.05）。MV患者的ΔDTee随MV时间的延长呈增长趋势（F=263.10，P<0.001）；其中，第2、3、4、5天及撤机前的ΔDTee均高于MV前、第1天，撤机前的ΔDTee高于第3天（P<0.05）。膈肌萎缩组的超敏C反应蛋白水平、MV时间、ICU住院时间均高于膈肌厚度正常组（P<0.05）。第1~3天的ΔDTee与MV时间呈正相关（r=0.266，P=0.04）。结论　MV患者的DTee随MV时间的延长逐渐下降，以前3 d下降的速度最明显，且早期DTee与MV时间、ICU住院时间有相关性。

关键词: 机械通气, 呼气末膈肌厚度, 预后, 超声检查