Abstract: Background　Mechanical ventilation is the main treatment of acute respiratory distress syndrome （ARDS）.With further physiological research on ARDS and understanding of ventilator-associated lung injury，lung protection ventilation strategies，such as lung recruitment，small tidal volume and positive end-expiratory pressure （PEEP），are main treatments at present.The treatment of PEEP after lung recruitment is still controversial.Objective　To analyze the effect of optimal PEEP guided by bedside ultrasound on oxygenation index and hemodynamics in patients with ARDS．Methods　A total of 60 patients with ARDS admitted in Bozhou People's Hospital from October 2015 to October 2017 were divided into control group and observation group，each with 30 cases according to PEEP setting after lung recruitment maneuver.Both groups were treated with increasing positive end expiratory pressure，while the control group adopted the maximum oxygen method and the observation group guided by bedside ultrasound to determine the best PEEP.The best PEEP，oxygenation index and dynamic compliance were observed in two groups，and the changes of heart rate （HR），mean arterial pressure （MAP），and central venous pressure （CVP） levels before and 15 minutes，1 and 2 hours after lung recruitment were monitored.Results　The best PEEP in the observation group was （15.5±1.6） cm H2O ，which was higher than that in the control group （13.3±2.4） cm H2O （t=4.103，P<0.001）．Treatment and treatment time had an interaction with oxygenation index and dynamic compliance （P<0.001）．The effect of treatment on dynamic compliance was significant （P<0.05）．The main effects of time on oxygenation index and dynamic compliance were significant （P<0.001）．The oxygenation index and dynamic compliance level of the observation group at 15 min，1 and 2 hours after lung recruitment were all higher than those of the control group （P<0.05）．Treatment and treatment time had an interaction with CVP （P<0.05）．HR and CVP of two groups at 15 min after lung recruitment were higher，and MAP was lower than those before the lung recruitment （P<0.05）；CVP of the observation group was higher than that of the control group at 15 min after lung recruitment （P<0.05）．Conclusion　The best PEEP was determined by bedside ultrasound after lung recruitment maneuver，which has good effect on improving the oxygenation and respiratory system compliance of ARDS patients，and had no significant side effects on hemodynamics of the body.

Key words: Respiratory distress syndrome, adult；Positive-pressure respiration；Ultrasonography；Oxygenation index；Hemodynamics

摘要： 背景　机械通气是急性呼吸窘迫综合征（ARDS）的主要治疗手段，随着临床对ARDS呼吸生理学研究的逐渐深入和对呼吸机相关性肺损伤的认识，目前多选择以肺复张、小潮气量及呼气末正压（PEEP）等为核心内容的肺保护通气策略，但肺复张后PEEP的选择尚存在争议。目的　分析床旁超声导向的最佳PEEP对ARDS患者氧合指数及血流动力学的影响。方法　选取2015年10月—2017年10月亳州市人民医院收治的ARDS患者60例，按照肺复张后PEEP设置方法将其分为对照组和观察组，各30例。两组均采用PEEP递增法进行肺复张，对照组采用最大氧合法，观察组采用床旁超声导向法，以确定最佳PEEP。观察两组最佳PEEP、氧合指数、动态顺应性变化，监测两组肺复张前、肺复张后15 min及1、2 h心率（HR）、平均动脉压（MAP）和中心静脉压（CVP）水平。结果　观察组最佳PEEP为（15.5±1.6）cm H2O，高于对照组的（13.3±2.4）cm H2O（t=4.103，P<0.001）。处理方法与时间对氧合指数、动态顺应性存在交互作用（P<0.001）；处理方法对动态顺应性的影响，主效果显著（P<0.05）；时间对氧合指数、动态顺应性的影响，主效果均显著（P<0.001）。观察组肺复张后15 min及1、2 h的氧合指数、动态顺应性水平均高于对照组（P<0.05）。处理方法与时间对CVP存在交互作用（P<0.05）。两组肺复张15 min后的HR、CVP水平均高于肺复张前，MAP水平低于肺复张前（P<0.05）；观察组肺复张15 min后的CVP水平高于对照组（P<0.05）。结论　肺复张后采用床旁超声确定最佳PEEP，对于改善ARDS患者的氧合指数及动态顺应性具有较好效果，且对机体血流动力学无不良影响。

关键词: 呼吸窘迫综合征, 成人；正压呼吸；超声检查；氧合指数；血流动力学