Effects of propofol sedation on different areas of cerebral cortex and memory in patients during epidural anesthesia / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of propofol sedation on different areas of cerebral cortex and memory during operation performed under epidural anesthesia using EEG non-linear monitor and determine the critical value of approximate entropy, the EEG non-linear parameter, without implicit memory.Methods Ten ASA I or II patients of both sexes aged 42-56 yr weighing 59-73 kg undergoing elective abdominal or lower limb operation under epidural anesthesia were enrolled in the study. The patients were unpremedicated. After correct placement of epidural catheter was confirmed, a mixture of 2% lidocaine and 0.3% tetracaine 13-15 ml was injected via the catheter. Propofol was then infused i.v. at 6 mg?kg-1?h-1 for sedation. BP, HR and SpO2 were continuously monitored. The EEG non-linear monitor (ZN16E) was used. The sensors were placed on frontal (FP1 , FP2 ) , temporal (T3 , T4 ), parietal (C3 , C4 ) and occipital ( O1 , O2 ) regions. Approximate entropy and topographic map of approximate entropy were recorded before and during propofol infusion. Sedation scores (OAA/S, 1 = deep sleep, 5 = alert) were assessed during operation The patients' explicit and implicit memory scores were estimated by Process Dissociation Procedure during anesthesia sedateon Results The approximate entropy was significantly decreased during propofol sedation compared to the baseline value before sedation. OAA/S score were maintained at 1 during operation. The explicit and implicit memory scores were significantly decreased during propofol sedation compared to the baseline scores before anesthesia sedation( P