Entropy of EEG in regulating and controlling the depth of general anesthesia

Abstract

Objective To investigate the characteristic and efficacy of Entropy of EEG in regulating and controlling the depth of general anesthesia.Methods One hundred cases who received cholecystectomy under general anesthesia,were included in this study.They were randomly divided into group G and group E( state entropy and response entropy group).In group G,adjustment of simulated concentration of propofol on target-controlled pump was based on the alteration of blood pressure,heart rate and other hemodynamic parameters.In group E,the control of appropriate depth of general anesthesia was through maintaining theentropy indes value between 40 and 60.Intravenous infusion of propofal combined with remifentanil was adopted for anesthesia induction.The simulated target plasma concentration of propofol was setted at 3 μg/ml while remifentanil at 7 ng/ml.Hemodynamics parameter,sober time and extubation time during anesthesia and surgery,anesthetic drug consuption and the entropyindex(SE and RE) were recorded for analysis.Results Baseline values of SE were lower than RE in group E.Both RE and SE decreased after induction,however,SE decreased more significantly compared with RE and was lower than the basic level (P ＜ 0.01 ).Blood pressure declined obviously after induction and was lower than the baseline blood pressure ( P ＜ 0.0l ),and had a strong correlation with the alteration of entropyindex value.The consume of propofol in group G was more than that of group E,the difference was statistically significance (P ＜ 0.05 ).Recovery time in group E significantly reduced compared with group G (P ＜ 0.05 ).Patients in group E can more rapidly recoverspontaneous breathing,had shorter extubation time and promptly recovered orientation.There was good correlation between the entropy index and OAA/S score (P ＜ 0.05 ).All patients had no intraoperative awareness.Conclusions Entropy of EEG can accuratly regulate and controll the depth of general anesthesia and was worthy of clinical use. Key words: Entropy index; State entropy; Response entropy; EEG; Depth of general anesthesia; Target controlled