Methods
Before surgery, the parents/guardians of the participants were advised to routinely fast their children for 6 h, avoid breastfeeding for 4 h and feed them with light food for 2 h. The patients and their guardians were escorted to the operating room 60 min before surgery. The patient’s preoperative status was assessed by the anesthesiologist in a single-blind manner, including ASA classification, heart rate monitoring, non-invasive blood pressure, saturation of peripheral oxygen (SpOWe confirmed that all methods were performed following the relevant guidelines and regulations.