Stduy On Evaluation Method Of Anesthesia Consciousness Level Based On High Density Eeg

General anesthesia can change consciousness reversiblely,which plays an important role in an operation.There are many types of anesthetics in clinical practice,and different anesthetics affect consciousness by different mechanisms,which becomes a big problem in evaluating the level of consciousness during surgery.Therefore,the research on the mechanisms of different anesthetic drugs can provide a scientific basis for clinical surgical safety and provide guidance for intraoperative drug delivery.This study analyzed the highdensity EEG signals under propofol,dexmedetomidine and ketamine anesthesia,researched the method of evaluating the level of consciousness by calculating the changes of different indicators before and after anesthesia.Firstly,this study introduced the methods of collecting and preprocessing EEG data,and used spectral analysis on the processed data.The results found that the power changes in different frequency bands after three anesthetics induction but in the θ frequency band,the EEG power under the three drugs increased after no response.It showed that spectrum can reflect changes in the level of consciousness and the three drugs have different effects on different frequency bands,and may have similar effects in the θ frequency band.Secondly,we analyzed these data from the perspective of functional connection and information integration theory.In the phase-amplitude coupling based on functional connection,we calculated the coupling mode and intensity between the low-frequency oscillation and the α-oscillation,and it was found that there was no obvious mode transition when the state changed,but the change in the coupling intensity was significant,especially in frontal lobe(P<0.001).The weighted phase lag index of the three drugs based on functional connection was also different before and after anesthesia.This study also proposed permutation cross mutual information method based on the information integration theory to analyze the changes before and after the three drugs anesthesia.The values of ketamine in all frequency bands increased after no response,which was opposite to the other two drugs,and the changes of the three drugs in different frequency bands are not the same.These three methods also reflected changes in the level of consciousness,but had drug relevance.Finally,this study analyzed the node characteristics and global network changes of the data under different drugs before and after anesthesia from the perspective of the brain network.By using the method of graph theory,the node clustering coefficient,node efficiency,normalized average clustering coefficient and normalized average path length of the permutation cross mutual information of the data under the three drugs was calculated.It was found that the changes of the node characteristic brain network under the three drugs in different frequency bands were different.While the changes of the normalized average clustering coefficient and normalized average path length of the permutation cross mutual information under the three drugs were almost the same,which reflected a decline in connectivity of the global network.In conclusion,the spectrum,functional connection,information integration and brain network can reflect changes in the level of consciousness,and there are drug-independent in some frequency bands.