全麻机械通气下俯卧位对患者肺换气功能的影响

Effects of prone position on pulmonary gas exchange during mechanical ventilation under general anesthesia

目的 评价全麻机械通气下俯卧位对患者肺换气功能的影响.方法 根据体位分为择期全麻下行俯卧位腰椎手术患者组（俯卧位组,n=30）和行仰卧位手术患者组（仰卧位组,n=30）,年龄30～ 64岁,性别不限,BMI 19～ 30 kg/m^2,ASA分级Ⅰ或Ⅱ级.全麻诱导气管插管后行机械通气,采用全凭静脉麻醉维持,2组分别于预充氧前10 min（T0）、插入气管导管后10 min（仰卧位变为俯卧位即刻）（T1）、45 min（T2）、90 min（T3）、拔除气管导管前5 min（俯卧位变为仰卧位前即刻）（T4）及拔除气管导管后15 min（T5）时,采集桡动脉血样行血气分析,记录PaO2和PaCO2,计算肺泡-动脉血氧分压差（A-aDO2）;并于T1、T4和T5时,行胸部数字X线摄影,观察肺部改变.结果 与仰卧位组比较,俯卧位组T1-4时PaO2升高,A-aDO2降低（P＜0.05）;2组患者PaCO2及T0和T5时上述各指标比较差异无统计学意义（P＞0.05）;2组不同时点肺部数字X线摄影未见肺不张.结论 全麻机械通气下,俯卧位肺换气功能优于仰卧位.

Objective To evaluate the effects of the prone position on pulmonary gas exchange during mechanical ventilation under general anesthesia.Methods Thirty patients scheduled for elective spine surgery in the prone position under general anesthesia （group prone,n =30）,30 patients scheduled for elective spine surgery in the supine position under general anesthesia （group supine,n=30）,aged 30-64 yr,with body mass index of 19-30 kg/m^2,of ASA physical status Ⅰ or Ⅱ,were enrolled in the study.After induction of general anesthesia,the patients were mechanically ventilated.Anesthesia was maintained with total intravenous anesthesia.At 10 min before pre-oxygenation （T0）,10 min after intubation （immediately after the patients were moved from the supine to the prone position） （T1）,45 and 90 min after intubation （T2,3）,5 min before extubation （immediately before supine position to the prone position） （T4）,and 15 min after extubation （T5）,arterial blood samples were taken for blood gas analysis,and PaO2 and PaCO2 were recorded.Alveolar-arterial oxygen difference （A-aDO2） was calculated.Digital radiography was performed and the changes of the lung were observed.Results Compared with supine group,PaO2 was significantly increased and A-aDO2 was decreased at T1-4 in prone group.There was no significant difference in PaCO2,and PaO2 and A-aDO2 at T0 and T5 between the two groups.The results of digital radiography showed no atelectasis at different time points in either group.Conclusion Pulmonary gas exchange in the prone position is superior to that in the supine position during mechanical ventilationunder general anesthesia.