Randomization
GROUP B
In this study, a total of 459 children undergoing tonsillectomy and adenoidectomy under general anesthesia were recruited, and the children were numbered 1 to 459 in order of surgery, and the random number list generated by Graphpad Prism7 was used for randomization, and finally the A, B, and C corresponding to each number were obtained, and then A, B, and C were sealed in envelopes with corresponding numbers and kept by the study leader. After obtaining written informed consent, the researchers unsealed the envelope to clarify which group the child was assigned to.The trial was conducted on a single-blind basis (i.e., the participants were unaware of the grouping, and the investigators were aware of the child's grouping). The 459 children after OSAS surgery under general anesthesia were randomly divided into three groups, with 153 children in each group. The three groups were Group A: Head-high 0° in right lateral position; Group B: Head-high 15° in right lateral position; Group C: Head-high 30° in right lateral position.