Randomization and blinding
nerve block
The enrolled patients were randomly divided into 4 groups by the administrator: A, B, C and D. Group A received ultrasound-guided bilateral superior laryngeal nerve medial branch block (2% lidocaine 3ml on each side) and ultrasound-guided bilateral transversus abdominis plane block (0.375% ropivacaine 15ml on each side). The dosage of sufentanil was 0.4μ g/kg during induction. The nerve block method of group B was the same as that of group A, but the induced dose of sufentanil was 0.2μ g/kg. The nerve block method of group C was the same as that of group A and B, but the induced dose of sufentanil was 0ug/kg; Group D was the control group, which underwent ultrasound-guided bilateral transverse abdominal fascia block (0.375% ropivacaine 15ml per side), but no supralaryngeal nerve block. The dosage of sufentanil was 0.4μg/kg during induction.The administrator who don’t take part in the treatment randomly divided the patients into groups, and generated the random numbers by Excel. Before the start of the experiment, the envelope concealed the random numbers was opened by the anesthesiologist who performed the punctuation and telephone the nurse to dispense the drugs. The anesthesiologist performed anesthesia induction and nerve block under the guidance of ultrasound. Patients in all groups were treated in the postanesthesia care unit and blinded to which treatment they would receive. The outcome assessors, data collectors, and statisticians were blinded to group allocations during the study.