The purpose of this study was to investigate the effects of different proportions of etomidate/propofol mixture and propofol alone intravenous anesthesia on intraoperative and postoperative physiological indicators and complications, and to find out the optimal use ratio of E/P mixture.

Propofol is one of the most commonly used intravenous anesthesia drugs clinically, the pharmacokinetic characteristics makes it very suitable for total intravenous anesthesia( TIVA), etomidate belongs to intravenous anesthesia with propofol, is a derivative of the imidazoles, its calm performance is strong, work quickly, no obvious respiratory depression, had little effects on the cardiovascular system, which, therefore, to protect the cardiovascular, maintain hemodynamic stability has a certain advantage. Our previous project showed that propofol and etomidate combined application can maintain stable hemodynamics in patients with better, reduce the occurrence of adverse reactions, can be used within 3 h of surgery anesthesia.The purpose of this study is to use propofol or etomidate/propofol mixture in combination with BIS monitoring to perform general anesthesia maintenance for patients, in order to ensure the appropriate depth of anesthesia, better maintain the hemodynamic stability of patients, reduce adverse reactions, and find the appropriate E/P mixture of the best proportion and dose.

Inclusion Criteria:

1. Patients undergoing elective general anesthesia surgery in 3h;
2. American Society of Anesthesiologists gradesⅠ~III;
3. Aged 18 to 65 years, Body Mass Index 18.5 ~ 29.9kg / m2;
4. Hemoglobin 100 ~ 125g / L.
5. In line with the ethics, the patients volunteered to take the test and signed the informed consent

Exclusion Criteria:

1. Identify or suspect abuse or chronic use of narcotic sedatives and analgesics;
2. Heart, or liver, or lung, or kidney dysfunction;
3. Body mass index> 30kg / m2; or <18.5kg / m2
4. Speech, hearing or mental disorders;
5. severe diabetes, hyperkalemia ;
6. participate in other drug clinical researches in four weeks;
7. Poor compliance, can not complete clinical research by research program.
8. Any cerebrovascular accident occurred within 3 months, such as stroke, TIA, etc
9. Unstable angina and myocardial infarction occurred within 3 months;
10. Having contraindications or allergies to experimental drugs and other narcotic drugs;
11. Mental illness, hyperkalemia.