The Study Of The Interaction Between The Inhalation Concentration Of Sevoflurane And The Degree Of Muscle Relaxation Of Rocuronium On The Entropy Index

Purpose:Spectral entropy is informative test for evaluation of depth of anaesthesia in comparison with BIS(bispectral index).Muscle relaxation might affect EEG(electroencephalogram)monitoring by causing the inhibition of frontal muscle activity.The use of muscle relaxants could attenuate the effect from noxious stimulation on electroencephalogram.However,there are no data available on the effects of different degrees of NMB(neuromuscular blockade)on spectral entropy during sevoflurane anaesthsia.The aim of this study was to demonstrate the different degrees of neuromuscular blockages on the SE(state entopy)and RE(response entropy)values during several levels of sevoflurane anesthesia(expressed as MAC,minimum alveolar concentration).Material and Methods:81 female patients were enrolled in the present study.All patients were randomly divided into nine groups containing nine each,according to the concentration of sevoflurane inhalation(0.6MAC,0.8MAC,1.0MAC)and the degree of neuromuscular blockage(50%,75%,100%).Response entropy and state entropy were monitored.The evoked train-of-four response was continuously recorded by TOF-watch SX.Noxious stimulation was applied to the ulnar nerve by cutaneous tetanic electrical stimulation of 80 mA at 100 Hz for 5 s.RE and SE were recorded as a mean of 10s(three consecutive readings)at the following time points:awake(Ta,awake RE and awake SE),after a 20 min equilibrium period before the TET(Tb),60 s after the TET(Tc).The RE-SE difference was calculated by subtracting the SE value from the simultaneous RE value.Results:The spectral entropy values was negatively correlated with the sevoflurane concentrations.Without noxious stimulation,no significant effects of interactions on RE,SE and RE-SE were found between sevoflurane concentrations and NMB(P>0.05),while sevoflurane concentrations showed a significantly main effect on the spectral entropy(P<0.05).After noxious stimulation,significant effects of interactions on changes of RE,changes of SE and changes of RE-SE were found between sevoflurane concentrations and NMB.Conclusions:The response entropy and state entropy values decreased with increases in sevoflurane concentration.NMB did not affect spectral entropy without noxious stimulation obviously.With noxious stimulation,muscle relaxants could reduced the changes of spectral entropy significantly and there were significant effects of interactions on spectral entropy between NMB and sevoflurane.Purpose:The tracheal intubation is a kind of intense injury stimulation,which can induce a series of stress reactions including elevated blood pressure and tachycardia,which affects EEG.Induction intubation by sevoflurane inhalation was induced rapidly,with less adverse reactions,good cardiovascular stability and light respiratory inhibition.The addition of sedatives and opioids can make the induction more stable,reduce the blood flow,and reduce the harmful stimulation during intubation.However,the effect of sevoflurane induction on the spectral entropy is not very clear.Muscle relaxants can reduce the response of EEG,and patients who use muscle relaxants are more likely to have intraoperative knowledge than those who do not.The aim of this study was to investigate the effect of tracheal intubation on the spectral entropy and hemodynamics under different degrees of neuromuscular blockages during several levels of sevoflurane anesthesia.Material and Methods:54 female patients were enrolled in the present study.All patients were randomly divided into six subgroups containing nine patients each(groupl A,1B,2A,2B,3A and 3B),according to the concentration of sevoflurane inhalation(1.0MAC,1.5MAC,2.0MAC)and the degree of neuromuscular blockage(75%,100%)under tracheal intubation.Spectral entropy and train-of-four response were monitored.HR(heart rate),MAP(mean arterial pressure),RE and SE were recorded at the following time points:awake(Ta),after a 15 min equilibrium period of concentration sevoflurane inhalation under mask ventilation(Tb),when the fourth or first twitch of the TOF disappeared after rocuronium administration(Tc),and 0 and 2 min following tracheal intubation(Td and Te,respectively).The RE-SE difference was calculated by subtracting the SE value from the simultaneous RE value.Results:HR and MAP decreased significantly at Tb and Tc compared with Ta.(P<0.05).Following tracheal intubation,HR and MAP significantly increased compared with Tb and Tc in group 1A,1B,2A and 2B.(P<0.05)RE,SE RE-SE decreased significantly at Tb and Tc compared with Ta(P<0.05).Following tracheal intubation,RE and SE were significantly increased at Td compared with Tc in group 1A,1B,2A and 2B(P<0.05).In group 3A and 3B,SE didn't change significantly at each time point expect Ta.(P>0.05).In group 1B,2B,3A and 3B,RE-SE didn't change significantly at each time point expect Ta.(P>0.05)Conclusions:The tracheal intubation could significantly increase HR,MAP,RE and SE under the 1.0MAC-1.5MAC sevoflurane inhalation concentration.When the tracheal intubation was performed at the time of the 100%neuromuscular blockade,,RE-SE-was not significantly changed compared with before the intubation.After the inhalation of 2.0MAC sevoflurane to the steady state,the muscle relaxants caused by the injection of rocuronium did not cause the change in the entropy index.The use of 2.0MAC sevoflurane in combination with usage of muscle relaxant can inhibit the stress response and entropy changes caused by tracheal intubation.