To explore the effect of perioperative ulinastatin on postoperative delirium in elderly patients undergoing hip arthroplasty.

A total of 120 elderly patients undergoing elective hip arthroplasty were recruited in the study, aged 65 to 90 years old, American Society of Anesthesiologists (ASA) I to II, without neurological or psychiatric diseases, no history of sedative or antidepressant drugs; with good communication and postoperative follow-up. The random number table method was divided into four groups: ulinastatin groups (group U₁, U₂, U₃) and control group (group C), 30 cases in each group, and the patients were used by Intraoperative intravenous inhalation combined with general anesthesia. Before the operation, the patients were given 2 500 U/kg ulinastatin in group U₁, 5 000 U/kg in group U2, 10 000 U/kg in group U₃ for 1 h, and continued intravenous infusion the same doses of ulinastatin on the first and second day after the operation. Group C received saline intravenously at the same time. The information including the time of consciousness recovery, visual analogue scale (VAS), the improved observer's assessment of alertness/sedation scale (OAA/S) and the confusion assessment method (CAM) score after operation, the number of delirium cases after operation, and the changes o interleukin-6 (IL-6)f, S-100 calcium binding protein beta subunit (S-100β) and brain-derived neurotrophic factor (BDNF)at different time points before and after the operation, were recorded. General condition, extubation time and consciousness recovery quality score data were analyzed by one-way analysis of variance. The CAM score, IL-6, S-100β and BDNF data were analyzed by repeated measures data analysis. The number of postoperative delirium cases was calculated by chi-square test.

After extubation, the agitation scores in U₂ group and the U₃ group were lower than the group C and U₁(F=34.41, P <0.05), the recovery time of consciousness was shorter(F=8.45, P=0.008), and the postoperative modified OAA/S scale were lower( F=7.33, P <0.05). Three days after surgery, CAM score of ulinastatin groups were higher than group C (F=8.61, P<0.05); there were more cases of delirium in group C after the operation(χ²=8.76, P<0.05). After 6 h to 24 h, IL-6 concentration in group U₁, U₂, and U₃ were significantly lower than group C (F=16.84, P<0.05), S-100β group U₁, U₂, and U₃ were lower than group C (F=7.613, P<0.05). After surgery to 12h, serum BDNF concentration in group U₁, U₂, and U₃ were significantly higher than that in group C (F =38.54, P<0.05).

The use of 5, 000 U/kg and 10 000 U/kg ulinastatin in the perioperative period of hip arthroplasty can shorten the recovery time of consciousness and reduce the occurrence of agitation after extubation. It may be that the application of ulinastatin affects inflammation. Factor IL-6, which reduces S-100β and maintains BDNF concentration, is associated with the reduction of spasticity after hip arthroplasty in the elderly.