Influence of nerve block combined with general anesthesia on cognitive function and postoperative pain in patients undergoing knee joint replacement

Objective: To investigate the influence of nerve block combined with general anesthesia on the cognitive function and postoperative pain of patients undergoing knee joint replacement and analyze the risk factors of postoperative cognitive dysfunction. Methods: A retrospective analysis was conducted on 104 elderly patients undergoing knee joint replacement in our hospital between January 2018 and January 2021. The control group (n=50) received laryngeal mask anesthesia, while the observation group (n=54) received ultrasound-guided nerve block combined with laryngeal mask anesthesia. The visual analogue scale (VAS) was adopted for scoring the pain intensity of both groups, and the Mini-Mental State Examination (MMSE) was used for evaluating changes in cognitive function before and after operation. The self-rating anxiety scale (SAS) and self-rating depression scale (SDS) were adopted for scoring patientsbefore and after operation. Additionally, the time to spontaneous breathing recovery, time to wake up, time to open eyes when ordered, and extubation time of the two groups were recorded. The changes in serum IL-6, cortisol (Cor), and IL-10 before and after operation were compared. The two groups were compared in the dosage of used analgesic drugs, the first getting out-of-bed time, treatment expense, and hospitalization time. The correlation between VAS score and IL-6, Cor and IL-10 before and after treatment was analyzed. The adverse reactions of the two groups were also compared. Logistic regression was used to analyze risk factors for cognitive dysfunction. Results: After operation, the observation group experienced shorter spontaneous breathing recovery time, time to wake up, time to open eyes when ordered, and extubation time, than the control group (P<0.05). The observation group also consumed less sufentanil than the control group (P<0.05). Additionally, the observation group had lower VAS and MMSE scores than the control group at 6 and 12 h after operation (P>0.05) and lower SAS and SDS scores than the control group (P<0.05). Moreover, at 6 h after operation, the control group showed higher levels of IL-6, Cor and IL-10 than the observation group (P<0.05), and the control group experienced later first getting out-of-bed time and a longer hospitalization time than the observation group (P<0.05). There was a positive correlation between VAS score and IL-6 as well as Cor before and after treatment (P<0.05). The two groups were similar in treatment expense (P>0.05) and the incidence of adverse reactions (P>0.05). Age and anesthesia scheme were risk factors for postoperative cognitive dysfunction. Conclusion: Nerve block combined with general anesthesia can effectively improve the cognitive function and analgesic effect of elderly patients undergoing knee joint replacement, and accelerate recovery time, without increasing f adverse reactions, and can also accelerate recovery of their cognitive function.