Influence Of Vecuronium And Succinylcholine On Sedation Index During Propoful Anesthesia

Background:Depth of anesthesia and patients consciousness statues often be covered up or become difficult to judge becanse of combining usage of muscle relaxants and analgetic agents.How to judge and to control the anesthesia depth on a suitable level is becoming an urgent problem to be solved.As the newly developed monitor index for depth of anesthesia,Bispectral index(BIS)and entropy are both on account of electroencephalogram.Many researches conformed that both indexes have good relationship to the commonly used anesthetics which can effectually reflex the transition of conscious status,help to decrease the emergence time and improve the emergence quality.Bruhn et al.reported the first two cases in which BIS values reflected EMG activity but not the depth of anesthesia in 2000.From then on,the possible influence of EMG variance on the monitoring index of anesthesia depth becomes the hot studies.Therefore,the aim of this study is to investigate the influence of muscle relaxants vecuronium and succinylcholine on BIS and entropy during propofol anesthesia.Methods:Ninety patierts(ASAⅠorⅡgrade)undergoing elective surgery under general anesthesia were randomly allocated into six groups(n=15).Anesthesia was induced with propofol in TCI manner.The target effect-site concentration(Ce)was set as 4.0μg/ml.When the OAA/S score is equal to or below one,a laryngeal mask was inserted.Ventilation parameters were adjusted to target an end-tidal carbon dioxide tention between 35 and 45 mmHg.The Ce of propofol was maintained at 2.0μg/ml or 3.0μg/ml.5 minutes later,vecuronium of 0.1mg/kg(groups V2.0 and V3.0), succinylcholine of 1mg/kg(groups S2.0 and S3.0),or normal saline with same volume(groups C2.0 and C3.0)was injected intravenously.BIS,response entropy (RE),status entropy(SE),MAP and HR were recorded before induction,before and just after laryngeal mask insertion,before injection of muscle relaxants(baseline),at 1～5 minute after vecuronium injection and 1～10 minute after succinylcholine or saline injection.The times from injection to that TOF ratio reached 0 and recovered 100%were also recorded.Results BIS,RE,SE decreased significantly after neuromuscular blockers or saline injection in groups V2.0,S2.0 and C2.0(P＜0.05),but no change of all monitoring indexes was observed in groups V3.0,S3.0 and C3.0(P＞0.05).RE and SE, not BIS,rose markedly at the second minute after succinylcholine injection(P＜0.05). The difference between RE and SE(RE-SE)increased significantly only at the first minute after injection in groups S2.0 and S3.0(P＜0.05).No differences were found during recovery from paralysis caused by succinylcholine.Compared with control group,no difference was found in BIS and SE in all patients with injection of muscle relaxant(P＞0.05),and only RE enhanced obviously at the second minute after succinylcholine injection(P＜0.05)in groups S2.0 and S3.0.Conclusion Neuromuscular blockers altered the BIS and entropy score in moderately sedated patients but not in deeply sedated patients.The influence of muscle relaxants on sedation index is independent of their kinds.Entropy is better than BIS and furthenmore,RE is better than SE in reflecting the change of EMG signal. RE-SE is expected to be an index of monitoring the change of EMG signal.