| Objective: To investigate the effect of tourniquet on postoperative delirium in elderly patients undergoing unilateral total knee arthroplasty and its possible mechanism.Methods: A total of 184 patients(44 males and 140 females,aged≥65 years)who underwent unilateral total knee arthroplasty under general anesthesia in the First Affiliated Hospital of Chongqing Medical University from March 2019 to June 2020 were selected.Preoperative ASA grade I-III,Preoperative MMSE score≥27 points was performed.The patients were divided into two groups by random number method: the tourniquet group and the non-tourniquet group,with 92 patients in each group.The tourniquet group was used at the beginning of operation.When the time exceeded 90 min,the tourniquet was relaxed for 10 min,and the tourniquet pressure was 25-30 KPa.Unilateral knee replacement was performed in the non-tourniquet group without tourniquet.Patients in both groups were treated with combined static and aspiration anesthesia during operation.Postoperative analgesia was performed using ultrasound-guided femoral nerve block at the surgical side and connected with PCNA pump.Cognitive function of patients was evaluated by the confusion assessment method(CAM)day 1,day 2 and day 3 respectively after surgery(POD was considered if scores≥20 points).Visual analogue pain score(VAS)was used to evaluate patients day 1,day 2 and day 3 after surgery,and VAS score at rest and activity was recorded(A score of >4 at any time is considered postoperative pain).The suprapatellar girth on the surgical side of the patient was measured and recorded day 1,day 2 and day 3 after surgery(the increase of >3cm compared with 1 day before surgery was considered as the limb swelling on the affected side).The main outcome measures were CAM scores day 1,day 2 and day 3 after surgery,and inflammatory indicatorsday day 1 and day 3 after surgery(including WBC,Neut %,CRP,IL-6 and ESR).Secondary outcome measures were intraoperative blood loss,postoperative opioid use,postoperative nausea and vomiting,postoperative Alb and Hb levels day 1,day 2 and day 3 after surgery.The suprapatellar girth on the surgical side day 1 and day 3 after surgery,resting and active VAS scores day 1,day 2 and day 3 after surgery.Results: There were no significant differences in gender,age,BMI,educational level,ASA classification,preoperative MMSE score,preoperative complications and intraoperative medication(including anesthetic drugs and other drugs)between the two groups(P> 0.05).The amount of intraoperative blood loss in T1 group was significantly lower than that in T2 group(P<0.05).The incidence of POD within 3 days after operation in T1 group was significantly higher than that in T2 group,15.20% and 5.40%,respectively(P<0.05).The Hb and Alb of T1 and T2 groups on the 1st and3 rd day after surgery were significantly lower than those on the 1st day before surgery(P<0.05),the Hb of T2 group on the 1st day and 3rd day after surgery was significantly lower than that of T1 group(P<0.05),and the Alb of T1 group on the 3rd day after surgery was significantly lower than that of T2 group.WBC,ESR,Neut %,CRP and IL-6 in T1 and T2 groups on the 1st and 3rd day after surgery were significantly higher than those in T2 group(P<0.05).WBC and CRP in T1 group on the 3rd day after surgery,Neut % and IL-6 in T1 group on the 1st and 3rd day after surgery were significantly higher than those in T2 group(P<0.05).The number of postoperative limb swelling in T1 group was significantly higher than that in T2 group(P<0.05).The resting VAS scores and active VAS scores on the 1st and 2nd days after operation in the T1 group were significantly higher than those in the T2 group(P<0.05),and the number of patients with oral opioids after operation in the T1 group was significantly higher than that in the T2 group(P<0.05).Conclusion: The use of tourniquets during unilateral TKA in elderly patients may aggravate postoperative systemic inflammation,aggravate postoperative limb pain,increase the demand for oral opioids and decrease the value of albumin,which may lead to the increase of postoperative POD. |
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