Effect Of Dexmedetomidine Combined With Ropivacaine Continuous Femoral Nerve Block On Postoperative Analgesia And Delirium In Elderly Patients Undergoing TKA

Objective To investigate the effects of dexmedetomidine combined with ropivacaine continuous femoral nerve block on analgesia and delirium after total knee arthroplasty.Method From June 2018 to December 2019,120 patients who underwent total knee arthroplasty under spinal anesthesia at the People's Hospital of Ningxia Hui Autonomous Region were selected,aged?60 years,with ASA?American Association of Anaesthetists?grades II to III.According to random number table,they were divided into the dexmedetomidine combined with ropivacaine group?DR group?and the ropivacaine group?R group?,with 60 patients in each group.All patients'surgery was performed by the same team of surgeons.Preoperatively,the femoral nerve block was placed under ultrasound guidance.After the surgery,a self-controlled analgesic device was connected.The dr?g formula was 0.25%ropivacaine in R group,0.25%ropivacaine+1?g/kg dexmedetomidine in DR group,and the volumes of both groups were 120ml.The background infusion dose was 2 ml/h and the PCA was 0.5ml each time and the lock-in time was 15 minutes,and the analgesia was continued for48 hours.In this study,the mini-mental state examination?MMSE?was used to screen and exclude cases that did not meet the standard.The visual analogue scale?VAS?was used to determine the pain scores of patients at rest and exercise in 6 hours?T₁?,12hours?T₂?,24 hours?T₃?,and 48 hours?T₄?after surgery.The confusion assessment method?CAM?with a score more than or equal to 22 was defined as postoperative delirium?POD?.The incidence of delirium on the first day?D₁?,the second day?D₂?,and the third day?D₃?were measured.The pittsburgh sleep quality index?PSQI?evaluate the sleep quality of patients on the day before surgery?T₁?,on the night of surgery?T₂?,and 24 hours after surgery?T₃?.The occurrence of postoperative dizziness,nausea and vomiting,bradycardia,respiratory depression,pruritus,hypotension,arrhythmia,and deep vein thrombosis were observed as well.Results1.There was no significant difference in age,gender,BMI,education level,ASA grades,preoperative comorbidities between the two groups?P>0.05?.2.The VAS scores of the DR group in T₂,T₃,and T₄ were lower than those of the R group in rest and exercise status,and the difference was statistically significant?P₂=P₃=P₄=0.00<0.05?,while there was no significant difference in the T₁ VAS score between the two groups in both status?P>0.05?.3.On D₁ and D₂,the incidence of POD of the DR group was lower than those of the R group,but the difference was not statistically significant?P>0.05?.On D₃ there was no POD occurred in all patients.4.The PSQI scores of the DR group in T₂ and T₃ are lower than those of the R group,and the difference was statistically significant?P₂=0.03,P₃=0.004,P<0.05?.And there was no significant difference in the T₁ PSQI score between the two groups?P=0.57>0.05?.5.Comparison of postoperative adverse reactions between the two groups was not statistically significant?P>0.05?.Conclusion1.This study found that dexmedetomidine combined with ropivacaine continuous femoral nerve block enhanced postoperative analgesic effect and improved the sleep quality without significant side effects of patients.2.This study found that dexmedetomidine combined with ropivacaine continuous femoral nerve block did not significantly improve the incidence of delirium after elderly TKA.