Randomization and blinding
The participants were randomly assigned (1:2) using a computer-generated randomization system to receive saline (Control group) or a single intravenous dose of penehyclidine 0.5 mg (PHC group) (Chengdu Lisite Pharmaceutical Co., Ltd., Chengdu, China) after enrollment into the trial. The random allocation sequence was sealed in opaque envelopes. Participants, care providers, and investigators were all blinded to treatment allocation. For safety reasons, the anesthesiologists responsible for administering the anesthetic were aware of the grouping. However, they were not responsible for the postoperative assessment and data collection.