Inclusion Criteria:  Patients aged 18-80 years old without restriction of gender, race, religion, creed or nationality; Surgery with general anesthesia operation with estimated operation time of at least 2 hours; Patients and/or their family members know and agree to participate in the trial.  Exclusion Criteria:  Local anesthesia surgery; Being admitted to ICU immediately after surgery; Pregnant or breastfeeding; History of solid organ or bone marrow transplantation; Diseases that may affect immune-related indicators, including autoimmune diseases (rheumatoid arthritis and systemic lupus erythematosus, etc.), and malignant hematological tumours (leukaemia and lymphoma, etc.); Acute brain injury, including traumatic brain injury, subarachnoid hemorrhage, acute ischemic stroke, acute intracranial hemorrhage and acute intracranial infection; Chronic nephrosis; Acute myocardial infarction or severe heart failure (NYHA: Grade 4); Severe chronic liver disease (child-Pugh: Grade C); Deafness, aphasia, mental illness or severe cognitive impairment; Endotracheal intubation could not be removed within 24 hours after surgery Patients and/or their family members refuse to participate in the trial.