Outcome measurements
After the patient entered the operating room, vital signs were monitored and baseline SBP, DBP, MAP, and HR (T1) were recorded. SBP, DBP, MAP, and HR were recorded at the first TOF=0 (T2), 30s after inflation of the tracheal tube cuff (T3), and 5min after inflation of the tracheal tube cuff (T4), The grading of tracheal intubation was also recorded according to the Cooper grading system (