In this study, the EEG information of patients was collected by different BIS electrodes, in order to compare the quality of EEG signals obtained by subdermal needle electrodes and the original BIS sensors, and try to use primitive EEG signals to develop a new calculation of needle electrode to monitor the depth of anesthesia.

After the patient enters the room, non-invasive BP, HR, end-tidal CO2, SPO2 and other routine monitoring are performed, and the corresponding BIS electrodes are worn to the patient. The anesthesiologist decides whether to perform invasive hemodynamic monitoring, such as invasive arterial blood pressure monitoring, central venous pressure monitoring, etc., depending on the patient's condition and surgical requirements. The induction and maintenance of anesthesia is the routine scheme in the Second Affiliated Hospital of Zhejiang University , and the medication and dose are based on the judgment of the main anesthesiologist . After induction, endotracheal intubation was performed and mechanical ventilation was given. After anesthesia induction, install subcutaneous needle electrode to the patient. BIS values were collected using two BIS monitoring systems, one using the original BIS sensor and the other connected to the needle electrodes.During the operation, the anesthesiologist adjusted the depth of anesthesia according to the original BIS value, and propofol was used to improve the depth of sedation if the BIS value was greater than 60. In this study, surface acoustic wave electronic nose was used to monitor the exhaled propofol concentration of patients undergoing general anesthesia.The BIS value, hemodynamic information, exhaled propofol concentration and plasma propofol concentration were recorded.

Inclusion Criteria:

• ASAⅠ~Ⅲ
• Over 18 years old
• Patients undergoing General Anesthesia surgery requiring BIS Monitoring
• Obtained informed consent

Exclusion Criteria:

• Patients who have mental disorders and unable to answer
• Patients who have taken anti-epileptic drugs and psychotropic drugs for a long time
• Patients who are pregnant
• Patients who refuse to participate in this trial
• Patients considered by the investigator to be unsuitable for inclusion in the trial

General anesthesia patients undergoing non-cardiac surgery