Objective: To observe the clinical effect of lower limb warming blanket combined with dexmedetomidine (DEX) in preventing postoperative delirium (POD) and chills in elderly patients undergoing spinal surgery. Methods: A total of 160 elderly patients undergoing posterior spinal surgery under general anesthesia were selected and divided into control group (group N), heating group (group T), DEX group (group D) and heating combined with DEX group (group TD) according to the random number table method, 40 cases in each group. T group and TD group routine insulation and lower limb heating blanket. DEX was injected in group D and group TD. The dosage of anesthetics, the changes of body temperature and heart rate at different time points during operation, and the occurrence of postoperative chills and POD were compared among the groups.

Inclusion Criteria:

• Age: between 65-80 years old;
• American Society of Anesthesiologists (ASA) grade II-III;
• Normal body temperature before operation;
• the operation time was 2-4 hours

Exclusion Criteria:

• Preoperative fever or hypothermia (body temperature≥37.5 ℃ or≤35.5℃ on the day of operation);
• Body mass index (BMI) >30 kg/m2;
• The existence of heart, brain, lung, kidney and other important organs and circulatory system, respiratory system, immune system, central nervous system diseases;
• Patients who had taken antipsychotic drugs or β-blockers before surgery would have a greater impact on intraoperative body temperature and other patients who could not effectively cooperate with this study;
• Patients with operation time more than 5 hours