Bispectral Index And Cerebral State Index Monitor Levels Of Sedation With Midazolam Plus TCI Of Propofol During Induction In Elderly

Objective:To investigate the effectiveness of cerebral state index (CSI)and bispectral index(BIS)in measuring the levels of sedation during midazolam plus target controlled infusion(TCI)of propofol induced in the elderly without surgery stimulation.Methods:40 ASA Physical status 1～II elderly Patients(age≥60 years old)undergoing general anesthesia were divided into four groups with 10 Patients in each group:controlled group(M1)-without midazolam premedication of propofol TCI;trial group(M2)- midazolam 0.02 mg/kg premedication;trial group(M3)- midazolam 0.03 mg/kg premedication;trial group(M4)- midazolam 0.04 mg/kg premedication; The level of sedation was assessed using OAA/S scale.Anesthesia was induced with midazolam and TC1 of propofol.The target effect-site concentration was set initially at 0.5μg/ml,followed by increments of 0.5μg/ml every 5 min until 5min after the patients lost consciousness and did not respond to pain stimulation(OAA/S=0).CS1 and BIS were recorded,sedation level were recorded every 20s during stepwise increase(target-controlled infusion,0.5μg/ml)of propofol until the patients lost response.BP,HR,SP0₂ were monitored and recorded at each effect-site concentration(Ce)before incubation.Spearman correlation coefficient were calculated for sedation levels with CSI and BIS.Ce50, BIS50 and CSI50 were calculated at each end-point(loss of verbal contact and loss of consciousness)based on recordings of CSI and BIS values.Results:Four groups were comparable with respect to age,sex(M/Fratio),bodyweight,bodyweight index,liver and renal function.MAP decreased in all groups compared with consciousness and deceased dramatically in M1 and M4 groups while more stable with midazolam 0.02mg/kg and 0.03mg/kg premedication groups.BIS and CSI values decreased as Ce increased.CSI changes rapidly than BIS when sedation level changed.CSI and BIS correlates good with sedation levels,but no significant differences of values with CS1 and BIS between groups were found.In the same Ce value,the BIS,CSI,OAA/S scale decreased accompanied with midalozam premedication increases as the same as the cost of induction.Ce50,BIS50 and CSI50 between groups were respectively 1.5μg/ml,1.2μg/ml,0.9μg/ml,0.6μg/ml; 74.8,75.6,66.6,73.6;65.9,68.2,68.2,67.2 at end-Point of loss of verbal contact(LVC),and 2.3μg/ml,2.0μg/ml,,1.6μg/ml,,1.4μg/ml;70.7,66.2,62.8,63.1;58.6,56.7,60.6,63.4 at end- point of loss of consciousness(LOC).The effective site between groups decreased compared with midazolam increased but no significant differences with BIS and CSI value between groups.Conclusions:(1)midazolam premedication plus TCI of propofol support more stable condition for ansthesia induction and less cost effect in elderly patients.(2)BIS and CSI highly correlates with sedation levels. BIS and CSI can distinguish the level of sedation effectively and promptly.The ability of BIS and CSI to measure the depth of sedation is the same with or without midazolam.CSI appears to be more sensitive when sedation level changes.