Schwender D, Klasing S, Faber-Züllig E, Pöppel E, Peter K
Institut für Anaesthesiologie, Ludwig-Maximilians-Universität München.
Anaesthesist. 1991 Nov;40(11):583-93.
The possibility of processing sensory information during general anesthesia and the ability to recall it postoperatively is of major ethical, medical and even theoretical importance. Auditory stimuli especially are perceived intraoperatively and remembered postoperatively. Neuropsychological experiments indicate that sensory information can be processed and recalled both at a conscious and at an unconscious level. Therefore, we have to distinguish between explicit and implicit memory. Explicit memory is characterized by an active and conscious recall of space- and time-related events, i.e., episodes in a person's life. In contrast, implicit memory recalls passively and unconsciously without being related to space and time, i.e., language and general knowledge. Experimental results from amnesic patients indicate that these two memory systems work independently from each other. Even when explicit memory is grossly impaired the function of the implicit memory may still be completely preserved. Various studies on intraoperative awareness show that explicit memory is widely eliminated during general anesthesia. The incidence of conscious awareness that can be actively recalled postoperatively is reported to be 1-3%. In contrast, the implicit memory function can be partially preserved. When implicit memory tasks or hypnosis are employed, traces of unconscious memory of intraoperative auditory information can be shown in 20-30% of the patients. These observations are of important clinical relevance, because the unconsciously recalled information about the intraoperative procedure may have a negative influence on the patient's postoperative recovery and well-being. So far it is still not known which anesthetics most reliably suppress auditory perception and conscious and unconscious memory during the intraoperative period. Therefore, future studies should focus on several different points. The anesthetic state should be defined exactly and the functional state of the auditory modality should be monitored when auditory information is presented to the patients. The recollection of intraoperative events should be investigated using implicit memory tests, because these are regarded as more sensitive than explicit memory tests.
在全身麻醉期间处理感觉信息以及术后回忆这些信息的可能性具有重大的伦理、医学乃至理论意义。尤其是听觉刺激在术中会被感知且术后会被记住。神经心理学实验表明，感觉信息能够在有意识和无意识层面得到处理与回忆。因此，我们必须区分显性记忆和隐性记忆。显性记忆的特点是主动且有意识地回忆与空间和时间相关的事件，即一个人生活中的片段。相比之下，隐性记忆则是被动且无意识地回忆，与空间和时间无关，比如语言和常识。失忆症患者的实验结果表明，这两种记忆系统相互独立运作。即便显性记忆严重受损，隐性记忆功能仍可能完全保留。关于术中知晓的各种研究表明，在全身麻醉期间显性记忆会被广泛消除。据报道，术后能够主动回忆起的有意识知晓的发生率为1% - 3%。相比之下，隐性记忆功能可能会部分保留。当采用隐性记忆任务或催眠时，20% - 30%的患者会显示出对术中听觉信息的无意识记忆痕迹。这些观察结果具有重要的临床意义，因为术中过程的无意识回忆信息可能会对患者术后恢复和身心健康产生负面影响。到目前为止，仍不清楚哪种麻醉剂在术中能最可靠地抑制听觉感知以及有意识和无意识记忆。因此，未来的研究应聚焦于几个不同要点。应精确界定麻醉状态，在向患者呈现听觉信息时监测听觉模态的功能状态。应使用隐性记忆测试来研究术中事件的回忆情况，因为这些测试被认为比显性记忆测试更敏感。
