Patients undergoing cardiac surgery were recruited. Baseline characteristics of all subjects were collected. The 3-minute Delirium diagnostic Scale (3D-CAM) was used to screen the POD group and non-POD group from the recruited subjects during the first 7 days after surgery. Peripheral blood samples were collected 1 day before surgery and 2 day after surgery. . Plasma was isolated from peripheral blood for subsequent proteomic analysis.

Patients undergoing noncardiac surgery were recruited. Baseline characteristics of all subjects were collected. The 3-minute Delirium diagnostic Scale (3D-CAM) was used to screen the POD group and non-POD group from the recruited subjects during the first 7 days after surgery. Peripheral blood samples were collected 1 day before surgery and 2 day after surgery. Plasma was isolated from peripheral blood for subsequent proteomic analysis. To study the characteristics of proteins on a large scale, including protein expression levels, post-translational modifications, protein-protein interactions, etc., so as to obtain a comprehensive understanding of disease occurrence, cell metabolism and other processes at the protein level. Assessment of imbalanced protein expression in peripheral blood using protein profiling may allow us to better understand the pathological changes occurring at the molecular level of POD. Early detection of patients at high risk of POD can optimize perioperative management and promote rapid postoperative recovery.

Inclusion Criteria:

• Age ≥65 years old, regardless of gender.
• The patient had clear consciousness and no cognitive impairment, and could cooperate with the investigation and follow-up.
• The ASA classification is I-Ⅲ.

Exclusion Criteria:

• severe neurological or psychiatric disorders.
• drug and alcohol abuse.
• Patients with cognitive impairment caused by various reasons such as neuropsychiatric symptoms.
• Exclusion criteria included incomplete medical records and failure to complete the postoperative follow-up.

Patients undergoing cardiac Surgery.