The investigators assessed POD by the Confusion Assessment Method for the ICU twice daily for 7 days after surgery. Participants' cognitive function was assessed with neuropsychological battery tests. The tests included digit span (forward and backward), Corsi block, paired associate verbal learning, digit symbol test, trail-making test and so on.The investigators make a CPSP diagnosis based on the 11th revision of the International Classification of Diseases.
Postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) occur in 11-51% of patients after surgery, and its prevalence increases with age. The occurrence of delirium is associated with increased morbidity and mortality, prolonged hospital stay, worse functional recovery. Orthopedic procedures and specifically joint replacements have been considered as a major risk for development of chronic postsurgical pain (CPSP). Approximately 13-44% of patients will develop CPSP after knee or hip arthOpioid abuseroplasty. CPSP may cause the discomfort, distress, disability and opioid abuse. Mounting evidence has revealed that inflammation triggered by surgical trauma plays a key role in POD, POCD and CPSP. Recent studies found that vagus nerve stimulation showed the suppression of inflammation. In this study, the effect of perioperative transauricular vagus nerve stimulation on the prognosis of patients undergoing arthroplasty will be investigated, providing potential solutions for the prevention and treatment of postoperative cognitive dysfunction, postoperative delirium and chronic postsurgical pain.