Relationship Between Lidocaine and Serum Orphanin FQ (N/OFQ)

Inclusion Criteria: * ASA I-II * Patients undergoing elective abdominal surgery with anesthesia duration less than 1-2h Exclusion Criteria: * It is estimated that patients with difficulty in tracheal intubation (poor head and neck mobility, history of airway surgery, history of OSAHS, nail to chin distance\<6cm, Malampati grade 3 and above, mouth opening\<2.5cm, obesity (BMI\>30kg · m-2), etc.) * Hypertension patients (clinically diagnosed as hypertension), coronary heart disease patients (with typical symptoms of angina pectoris and exclusion of aortic valve disease, clear history of old myocardial infarction, clear history of acute myocardial infarction) * Patients with diabetes and central nervous system diseases * Patients with long-term use of sedatives or antidepressants * Patients with a history of alcoholism or drug dependence * Asthma or reactive airway disease * Shock, severe hypotension, severe arrhythmia and other adverse events occurred during the operation