老年患者认知功能损伤对麻醉的影响

The Effects of Cognitive Impairment on Anaesthetic Requirement in the Elderly

目的:比较认知功能损伤和正常的老年患者在麻醉诱导期间的脑电双频指数(bispectral index score,BIS)和丙泊酚需求量有无差异,进一步评估老年患者认知功能损伤对手术期间及麻醉苏醒期麻醉药物消耗量的影响。方法:选择ASA1-2级、年龄≥65岁、择期行全髋关节置换术的老年患者92例,根据简易精神状态检查(Mini Mental State Examination,MMSE)评分分组:第1组≥25,第2组≤21。所有患者泵注瑞芬太尼0.5μg kg-1 min-1后静注丙泊酚0.5mg/kg,分次追加丙泊酚使意识丧失后以75μg kg-1 min-1的速度泵注。调节丙泊酚和瑞芬太尼的速度使BIS值维持在45-60。记录术前和术后24hMMSE评分、麻醉药使用量、平均动脉压、心率和BIS值。结果:术前第1组和第2组基础MMSE分别是(26.8±1.6)和(16.6±4.2),术后24h是(26.6±1.5)和(15.6±4.3),诱导前第1组有4例(8.9%)基础BIS值<93,第2组有13例(27.7%)基础BIS值<93(P=0.02),在诱导前、意识丧失期、停药后3、5min和拔管前第2组平均BIS值均低于第1组(P<0.05),第2组丙泊酚诱导量低于第1组(P=0.02),第2组睁眼时间长于第1组(P=0.03)。结论:认知功能损伤患者基础BIS值低于正常患者,诱导时丙泊酚减少和苏醒时睁眼时间延长,认知功能正常患者全麻时推荐的目标BIS值并不一定适合认知功能损伤患者。

Objective To compare the bispectral index score（BIS） and the dose of propofol required for induction in patients suffering from cognitive impairment with that in those who had normal cognitive function.This study also evaluated the effects of cognitive impair ment in the elderly on anaesthetic agent consumption during surgery and on emergence from anaesthesia.Methods Patients over 65 years of age,ASA I-II and scheduled for femoral head replacement were allocated to one of two groups.Interventions Patients（n=92） were allocated according to their Mini Mental State Examination（MMSE） score： 25 or higher（group 1） or 21 or less（group 2）.All patients received propofol 0.5mg/kg following the commencement of a remifentanil infusion at 0.5μg kg-1 min-1.After incremental doses of pro pofol up to loss of consciousness,a propofol infusion was started at 75μg kg-1 min-1.Propofol and remifentanil infusion doses were ad justed to keep the BIS value between 45 and 60 during surgery.MMSE score was evaluated 24 h before and after surgery.The anaesthet ic consumption,mean arterial pressure,HR and BIS values of the patients were recorded.Results Before surgery,mean Mini Mental State Examination scores were 26.8±1.6 and 16.6±4.2 in group 1 and 2,respectively.These returned to baseline value 24 h after surgery in group 1 （26.6±1.5） and group 2 （15.6±4.3）. Before induction, 4 of 45 patients （8.9%） in group 1 had a BIS value less than 93 com- pared with 13 of 47 （27.7%） in group 2 （P=0.02）. The mean BIS value was significantly lower in group 2 than in group 1 before induction, during loss of consciousness, 3 and 5 min after discontinuation of the anaesthetic agents and before extubation {P〈O.05 ） . The induc- tion dose of propofol was lower in group 2 than in group 1 （P=0.02） . The eye opening time was significantly longer in group 2 than in group 1 { P=0.03 } . Conclusion The baseline BIS value was lower in patients with cognitive inlpairment than in those with normal cog- nitive function. The former received less propofol during induction and eye opening time was longer. So the recommended target BIS val- ue for adequate anaesthesia in the general population is inappropriate for patients with cognitive impairment.