Randomization
Patients were randomly divided into the magnesium sulfate group (M group) and the control group (C group) by internet-based randomization software with a 1:1 ration, and the information of each patient was sealed in an envelope. On the day of surgery, the anesthesia nurse randomly selected an envelope to determine whether the patient in the M or C group. Data collection was performed by an anesthetic technician who did not participant in the study. Participants and investigators were blinded to group allocation.