The study of propofol effect on brain sections under sedation by EEG non-linear analysis

Objective: To study propofol effect on brain sections under epidural anesthesia combined propofol sedation with EEG non-linear monitor, and discuss the clinical values of EEG non-linear monitor. Methods: 20 patients were randomly divided into 2 groups: propofol: 5mg kg^-1 h^-1and propofol: 6mg kg^-1 h^-1group（n=10）. The narcosis was maintained by epidural anesthesia and propofol sedation. The EEG non-linear parameters: approximate entropy （ApEn） and correlation dimension (D₂) were recorded perioperative periods. The BP, HR, SpO₂ were monitored routinely. Results: Comparing to entering room, the EEG activities of frontal and temporal cortices after sedation were restrained more than other cortices. Comparing to the data of entering room EEG non-linear parameters （ApEn, D2） in the two experimental groups, significant differences were found in the data of descending EEG non-linear parameters（ApEn, D2） after sedation in the two experimental groups （P＜0.05）. Comparing to the data of intra-operation in the two experimental groups, the data of EEG non-linear parameters（ApEn, D2） were significantly ascending after resuscitation, awaking in the two experimental groups（P＜0.05）. There were no significant differences between the two experimental groups. After resuscitation, awaking in the two experimental groups, the EEG activities of frontal and temporal cortices were still regaining more intense than other cortices. Conclusions: Under epidural anesthesia and propofol sedation, the EEG restraining activities of different cortices by propofol were not same, more restraining EEG degree in frontal and temporal cortices, more EEG activities in frontal and temporal cortices after resuscitation, awaking.