Postoperative delirium (POD) refers to an acute neurocognitive disorder that occurs within 1 week after surgery or before discharge. Old age is one of the important risk factors for postoperative delirium. The incidence rate of the elderly is high, and the life span of human beings is increasing. Postoperative delirium has adverse effects on both short-term and long-term outcomes, including mortality, ability to work, and dependence on society.

Low-density lipoprotein (LDL) is a key molecule in the cholesterol transport mechanism and is easily oxidized to oxidized low-density lipoprotein (OxLDL). Oxidized low density lipoproteins are immunogenic and are also cytotoxic to endothelial cells. Some studies have shown that increased oxidative stress is one of the earliest changes in disease, and similar signs can be detected in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI), such as protein oxidation and lipids. An increase in the quality of the peroxidation index. For the study of anesthesiology, oxidative stress theory has long been recognized as one of the mechanisms of postoperative delirium. We have a hypothesis that plasma oxidized low-density lipoprotein levels are associated with postoperative delirium and can be used as an early warning marker for disease occurrence.

Based on clinical research data, we conducted a prospective cohort study to explore the correlation between plasma oxidized low-density lipoprotein levels and postoperative sputum, providing clinical prediction and diagnostic value.

Inclusion Criteria:

• Surgical treatment was performed in our hospital under standard anesthesia.
• Patients in orthopedics, urology and general surgery.

Exclusion Criteria:

• Patients with mental illness or taking psychotropic substances before surgery.
• Preoperative dementia or cognitive dysfunction.
• Unable to communicate and cooperate with patients due to coma, language barrier or end-stage disease before surgery.
• ASA greater or equal to 4.
• Patients who have undergone neurosurgery and cardiac vascular surgery.

Patients in orthopedics, urology and general surgery .