IL6 and Cognitive impairment: In this study, the efficacy and safety of Ulinastatin in elderly patients with general anesthesia POCD will be evaluated by the incidence of postoperative cognitive impairment, mini mental state examination (Mini-Mental State Examination [MMSE]), visual regeneration, associative memory score, S100 β protein, tumor necrosis factor α (TNF- α), interleukin 6 (IL-6), IL- 10 inflammatory factors and the incidence of adverse reactions.