Comparative study between general anesthesia and sciatic–femoral–obturator blockade as regards analgesia and incidence of postoperative cognitive dysfunction in elderly patients undergoing unilateral total knee replacement

Objectives The aim of this study was to compare the effect of sevoflurane general anesthesia (GA) and sciatic–femoral–obturator blockade as regards analgesia and incidence of postoperative cognitive dysfunction (POCD) in elderly patients undergoing unilateral total knee replacement. Patients and methods The patients were divided in a randomized manner into two groups: the GA group ( n =40) received maintenance of anesthesia with inhalational sevoflurane, and the peripheral nerve block (PNB) group ( n =40) underwent sciatic nerve block (40 ml), femoral nerve block (20 ml), and obturator nerve block (10 ml) with 0.25% bupivacaine. The following time points were considered: baseline, immediately before induction of anesthesia (T-baseline), immediately after induction of anesthesia (T-induction), at the end of the operation (T-end) and then at 6, 12, 18, and 24 h postoperatively and were represented as T6, T12, T18, and T24, respectively. Results A total of 15 of 40 patients from the GA group developed POCD, whereas six of 38 patients in the PNB group developed POCD at T24. This difference was significant. Moreover, there was a significant decrease in Mini-Mental State Examination score in the GA group after 24 h in comparison with the preoperative value. There was a significantly higher value of Aβ (β-amyloid protein) in the GA group compared with the PNB group 24 h postoperatively. Visual analogue score was significantly lower at T-end, T6, T12, T18, and T24 in the PNB group compared with the GA group. Hemodynamics was significantly lower in the PNB group than in the GA group at T-end, T6, T12, T18, and T24. They were significantly higher in the PNB group than in the GA group at T-induction. Total opioid consumption within 24 h postoperatively and the incidence of nausea were lower in the PNB group compared with the GA group. Induction time was significantly longer in the PNB group than in the GA group. Conclusion The current study demonstrated that PNB with sciatic–femoral–obturator for total knee replacement was accompanied by less POCD, less pain, less nausea, and less opioid consumption within 24 h postoperatively compared with GA with sevoflurane.