Effects Of Peripheral Nerve Block On Postoperative Cognitive Function In Obese Patients Undergoing Laparoscopic Sleeve Gastrectomy

Objective:To investigate the effects of peripheral neural blocks on postoperative cognitive function and inflammation in morbidly obese patients undergoing laparoscopic sleeve gastrectomy,and its association with inflammation.Methods:A total of 75 patients were included in this clinical trial after screening from November 2020 to August 2021,who were morbidly obese and planned to undergo laparoscopic sleeve gastrectomy at the Second Affiliated Hospital of Anhui Medical University.Informed consent was obtained from all individual participants included in the study.Patients were randomly assigned in a 1:1:1 ratio to a general anesthesia（GA）group,a general anesthesia combined with transabdominal plane block（TAPB）group,and a general anesthesia combined with quadratus lumborum block（QLB）group.All demographic and clinical characteristics were collected with case report form by a doctor who was blinded to the randomization and interventions.Neuropsychological assessments were conducted with Mini-mental State Examination（MMSE）,Montreal Cognitive Assessment（Mo CA）,Auditory Verbal Learning Test（AVLT）,Digital Span Test（DST）,and Stroop Color Word Test（SCWT）.Bilateral TAPB or QLB was performed（0.33%ropivacaine with dexmedetomidine 1μg/kg）before the standardized general anesthesia.The same surgeon team performed all the surgical procedures by using five ports technique.The patients were admitted to the Anesthesia Intensive Care Unit（AICU）for monitoring.Cognitive test battery was completed before LSG and in 1-month and 3-month follow-up.The levels of peripheral inflammatory cytokines were determined at equivalent time points.One-way analysis of variance,chi-square tests,or Kruskal–Wallis H tests were used to compare demographic data between groups as appropriated.Linear mixed models were used to evaluate the changes in cognitive function and inflammatory cytokines in postoperative 3 months.Multiple comparisons with（?）idák adjustment were conducted to further investigate the changes in cognitive functions and inflammatory cytokines at different time points and in different groups.Pearson correlations were conducted to test the association between changes in inflammatory cytokines and standard cognitive scores in postoperative 3 months.P<0.05 was considered statistically significant.Results:A total of 75 patients were recruited,25 in each group were randomly assigned,and a total of 10 were lost to follow-up.Final analysis included 23 patients in the GA group,and 21 patients in the other two groups.Demographic information including age,gender composition ratio,height,weight,body mass index（BMI）,ASA grade,and the occurrence status of comorbidities were similar in the three groups（P>0.05）.The results of the mixed linear models indicated that the cognitive function of the three groups improved significantly after bariatric surgery(P_time<0.001),in which the patients in the QLB group had significantly higher postoperative Mo CA scores than those in the GA group（β=0.56,95%CI:0.08,1.05）.However,the results of the inflammatory cytokines showed that the levels of peripheral IL-6,IL-8 and hs-CRP were significantly altered in all three groups of patients(P_group<0.05).We further found that in the QLB group,IL-6 was a negative correlated with the scores of MMSE and Mo CA,while positive correlated with AVLT-DR.Conclusion:The application of peripheral nerve blocks may further enhance the effect of laparoscopic sleeve gastrectomy in improving cognitive function among obese patients,and this may be related to the level of inflammation.