Acetaminophen-Mannitol Injection and Postoperative Delirium

Inclusion Criteria: * Age ≥ 60 years; * Admitted to ICU after a noncardiac surgical procedure * Signed informed consent form Exclusion Criteria: Patients who meet any of the following criteria will be excluded. * Preoperative medical history: schizophrenia, epilepsy, Parkinson's disease, end stage renal disease, or end stage liver disease. * Inability to communicate preoperatively due to coma, severe dementia, or language disorder. * Patients with traumatic brain injury or undergoing neurosurgical procedures. * Positive screening result for drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, methamphetamine, methadone, or methylenedioxymethamphetamine). * Participation in another clinical study within 30 days prior to surgery, or planned concurrent participation in another clinical study. * Positive preoperative CAM-ICU assessment indicating delirium. * Occurrence of intraoperative or postoperative complications before randomization, and the investigator deems the subject unsuitable for study participation. * Hepatic dysfunction at screening, defined as ALT or AST \>3× the local laboratory upper limit of normal (ULN). * Intolerance or contraindication to acetaminophen or the protocol analgesics.