中潜伏期听觉诱发电位与意识状态和认知功能的关系

 目的 本研究的目的是观察在一定的麻醉深度下中潜伏期听觉诱发电位与意识状态和认知功能的关系。方法 120例择期全麻下行上腹部手术的病人，随机分为6组，每组20例。维持脑电双频指数（bispectral index, BIS）<40（C1组和T1组）、40～60（C2组和T2组）及>60（C3组和T3组）,稳定15min后观察病人对指令的反应，然后给病人听10min录音。病人完全清醒2h后检测其外显记忆和内隐记忆。结果 BIS<40和40～60的病人未对指令作出反应;BIS>60以后，病人对指令作出反应时Pa潜伏期平均值为20.12ms。所有病人未检测出外显记忆。T1组未检测到内隐记忆的存在，T2组中有6个病人检测出内隐记忆；T3组有9个病人检测出内隐记忆。有内隐记忆的病人MLAEP波形类似于清醒状态，Pa潜伏期在基础值上延长小于15ms。结论 随着麻醉深度逐渐加深，MLAEP潜伏期逐渐延长，波幅逐渐减小。 Na、Pa潜伏期显著延长的病人，意识和认知功能受到抑制。

A study of the relationship among midlatency auditory evoked potentials and consciousness and cognitive functions

Objective To observe the relationship between midlatency auditory evoked potentials(MLAEP) and consciousness,cognitive functions during general anesthesia. Methods There were 120 patients scheduled for elective upper abdominal surgery under general anesthesia.The patients were randomly divided into six groups: BIS<40(group C1 and group T1),BIS 40-60(group C2 and group T2),BIS>60(group C3 and group T3).Fifteen minutes later,patients'response to command was assessed.Then the patients were exposed to the acoustic stimuli for 10 min.Explicit and implicit memory were assessed 2 hours after fully awake.All experimental evaluations were conducted under double-blind conditions. Results No patient responded to verbal command in groups of BIS<40 and BIS 40-60.All patients in group of BIS>60 responded to verbal command while mean value of Pa latency was 20.12ms.No implicit memory was detected in group T1.Six patients had implicit memory of the tape message in group T2.Nine patients had implicit memory in group T3.No explicit memory was detected in all patients.In the patients with implicit memory,MLAEP were similar to that of the awake state with a Pa latency increase less than 15ms. Conclusions Our study showed that when the anesthesia got deeper,the latency of Na and Pa decreased significantly.The function of cognitive and consciouseness are inhibited in patients with the prolonged latency of Na and Pa.