More than 20% of patients over 60 years old develop postoperative delirium following non-cardiac surgery . Delirium increases morbidity and mortality , and may lead to long-term cognitive impairment . The underlying mechanisms behind delirium are not understood , endothelial dysfunction and disruption of the blood brain barrier (BBB ) caused by perioperative systemic inflammation may play a important role in the development of delirium . This study intends to evaluate the relationship between neuroinflammation and postoperative delirium in elderly non-cardiac surgery patients . The results of the study are to identify risk factors and explore the biomarkers most closely linked to each step of the proposed pathway .

The investigators do the neuropsychological tests , Mini-Mental score examination (MMSE ) , Charlson Comorbidity Index (CCI ) , Quality of Recovery Score - 40 (QoR-40 ) 1 day before the surgery（baseline ) . Serum of the patients was collected before operation and at POD1 , and then detect the concentration change of biomarkers of endothelial dysfunction , blood brain barrier disruption and neuronal injury . Also , the patients were interviewed once before discharge from PACU and twice on postoperative days 1-3 by the Confusion Assessment Method and then divided them into POD and non-POD groups . Meanwhile , the severity of pain (Numerical Rating Scale（NRS )) was evaluated at the same time and QoR-40 at 1 day after surgery .

Inclusion Criteria:

1. Patients undergoing selective major noncardiac surgery and general anesthesia;
2. Age 60-90 yrs;
3. Anesthesia Society of American (ASA) Scale II~III;
4. Anticipated surgery time 2-6 hrs
5. Written informed consent;

Exclusion Criteria:

1. decline to participate
2. Dementia patients（Mini-mental state examination< 20）
3. Factors existed that affect cognition assessment such as language,visual,and auditory dysfunction.

Patients aged ≥60 years undergoing elective non-cardiac major surgery under general anesthesia were investigated.