Abstract: Objective To evaluate the effects of different loading doses of Sketamine on postoperative cognitive dysfunction in elderly patients with hip replacement.Methods This was a prospective case control study.120 patients who underwent hip replacement surgery from September 2020 to September 2021 were randomly divided into three groups(n=40) by random number table method:low load dose Sketamine(group L,0.3mg/kg),highload dose of Sketamine(group H,0.5mg/kg) and control group(group C),After the level of anesthesia was stabilized,each group was given intravenous injection of corresponding doses of drugs.At the beginning of operation,both group L and group H were given 0.1mg/(kgoh) Sketamine by pump,and group C was given 0.1ml/(kgoh) normal saline pump until the end of the operation.To evaluate the patients' preoperative and postoperative Mini mental Status Examination(MMSE) scores,postoperative 3minute Delirium Diagnostic Scale(3D CAM) scores,sleep scores,intraoperative sedation assessment scale(RASS) scores and ICU non verbal communication patient pain assessment scale(COPT) score,assess patients for the occurrence of POCD.Results Compared with group C,the incidence of POCD and the analgesia score at 24 hours after operation were decreased in groups L and H(P<0.05).The incidence of POCD:13 cases in group C,5 cases in group L,and 4 cases in group H,analgesia scores:group C(3.15±0.81),group L(2.1±0.96),group H(1.9±0.96)(P<0.05);the incidence of adverse reactions in group H(13 cases) was higher than group C(5 cases) and group L(3 cases)(P<0.05).Conclusion The application of low dose Sketamine in elderly hip replacement patients can improve there postoperative cognitive cognition,reduce the occurrence of postoperative complications.

Key words: Sketamine, postoperative cognitive dysfunction, postoperative delirium, hip replacement surgery, neuroinflammation