摘要目的 探讨允许性高碳酸血症机械通气对老年患者脑氧代谢和术后认知功能的影响.方法 择期全麻下腹部手术老年患者120例,年龄65 ～ 80岁,体重45 ～ 66 kg,ASA分级Ⅰ～Ⅲ级,采用随机数字表法,将患者随机分为2组(n=60):常规通气组(R组)和允许性高碳酸血症机械通气组(H组).H组通气参数:VT 6～8ml/kg,RR 12～ 14次/min,吸呼比1:2,维持PaC02 45 ～ 65 mm Hg,pH值＞7.2,R组通气参数:VT10 ～ 12 ml/kg,RR 14～ 16次/min,吸呼比1:2,维持PaCO2 35～ 45 mm Hg.于气管插管即刻(T0)、气管插管后5 min(T1)、15min(T2)、3O min(T3)时经桡动脉、颈内静脉球部采集血样行血气分析,计算动脉-颈内静脉血氧含量差(Da-jvO2)和脑氧摄取率(CERO2).于术前1d、术后24、48 h、1、2周时采用简易智能状态检查表(MMSE)评分评价术后认知功能.结果 与R组相比,H组T1～T3时PET CO2和paCO2升高,pH值、Da-jvO2和CERO2降低,术后MMSE评分升高,术后认知功能障碍发生率降低(P＜ 0.05或0.01);与T0时相比,H组T1～T3时PETCO2和PCO2升高,pH值、Da-jvO2和CERO2降低,2组T1 ～T3时Da-jvO2和CERO2降低,术后24 h～1周MMSE评分降低(P＜0.01).结论 允许性高碳酸血症机械通气可改善老年患者术中脑氧代谢,减轻术后认知功能障碍.

abstractsObjective To investigate the effects of permissive hypercapnia ventilation on cerebral oxygen metabolism and postoperative cognitive function in elderly patients.Methods One hundred and twenty ASA Ⅰ-Ⅲ patients,aged 65-80 yr,undergoing elective lower abdominal surgery under general anesthesia,were randomly divided into 2 groups (n=60 each): routine ventilation group (group R) and permissive hypercapnia ventilation group (group H).In group H,VT=6-8 ml/kg,RR=12-14 bpm,I: E=1: 2,and PaCO2 was maintained at 45-65 mm Hg and pH value ＞ 7.2,while in group R,VT=10-12 ml/kg,RR=14-16 bpm,I:E=1:2,and PaCO2 was maintained at 35-45 mm Hg.Blood samples were taken from the radial artery and jugular bulb for blood gas analyses at 0,5,15 and 30 min after tracheal intubation (T0.3).Cerebral A-V O2 content differences (Da-jvO2)and cerebral O2 extraction rate (CERO2) were calculated at the same time.Cognitive function was assessed by Mini-Mental State Examination (MMSE) at 1 day before operation,and 24 h,48 h,1 week and 2 weeks after operation.Results Compared with group R,PEr CO2 andPaCO2 were significantly increased,and pH value,Da-jvO2 and CERO2 were significantly decreased at T1.3,MMSE score was significantly increased after operation,and the incidence of post-operative cognitive dysfunction was significantly decreased after operation (P ＜ 0.05 or0.01).Compared with the baseline value at T0,Da-jvO2 and CERO2 were significantly decreased at T1-3 in both groups,PETCO2 and PaCO2 were significantly increased,and pH value,Da-jvO2 and CERO2 were significantly decreased at T1-3 in group H,and MMSE score was significantly decreased at 24 h,48 h,1 week and 2 weeks after operation in both groups (P ＜ 0.01).Conclusion Permissive hypercapnia ventilation can improve the cerebral oxygen metabolism during operation,and reduce post-operative cognitive dysfunction in the elderly patients.