Dexmedetomidine combined with ropivacaine for continuous femoral nerve block improved postoperative sleep quality in elderly patients after total knee arthroplasty

Abstract

Objective: To investigate the effect of dexmedetomidine adding to ropivacaine for continuous femoral nerve block on the improvement of postoperative sleep quality in elderly patients after total knee arthroplasty. Methods: One hundred and sixty patients aged 60 years or older in Jishuitan Hospital scheduled for single total knee arthroplasty between Nov. 2016 and Jun. 2017 were recruited. All patients received spinal anesthesia and were randomized to receive either combined ropivacaine and dexmedetomidine (0.2% ropivacaine 250 ml and 5 μg/kg dexmedetomidine, at a rate of 5 ml/h or 0.1 μg·kg-1·h-1 dexmedetomidine, dexmedetomidine group) or only ropivacaine (0.2% ropivacaine, at a rate of 5 ml/h, controlled group) for continuous femoral nerve block as postoperative analgesia after surgery. The severity of postoperative pain was assessed with numeric rating scale at 4, 24, and 48 hours after surgery both at rest and with movement. Subjective sleep quality and delirium were evaluated daily during the first 3 days postoperatively. Results: The subjective sleep quality scores were 2(1-4), 2(1-4) and 4(2-8), 4(2-7) in dexmedetomidine group and controlled group respectively on the 1st and 2nd days after surgery. The scores of dexmedetomidine group were much better than those of controlled group (Z=-4.597, -4.183, both P<0.05). The difference was statistically significant. The NRS pain scores at rest were 2(1-2), 2(1-4), and 3(2-5), 3(2-6) in dexmedetomidine group and controlled group respectively at 24 and 48 hours after surgery. The scores of dexmedetomidine group were lower than those of controlled group (Z=-6.671, -4.010, both P<0.05). The difference was statistically significant. The NRS pain scores with movement were 1(1-2), 3(2-4), 3(2-3) and 3(2-4), 5(3-6), 5(4-7)in dexmedetomidine group and controlled group respectively at 4, 24 and 48 hours after surgery. The scores of dexmedetomidine group were lower than those of controlled group (Z=-7.167, -6.824, -7.473, all P<0.05). The difference was statistically significant. The incidence of 3-day delirium was lower in dexmedetomidine group (5%) than that in controlled group (15%) (χ2=4.444, P<0.05). The difference was statistically significant. There were no significant differences between groups regarding the incidences of adverse events. Conclusion: Dexmedetomidine combined with ropivacaine for continuous femoral nerve block may improve subjective sleep quality, postoperative analgesia, and reduce delirium in the elderly after total knee arthroplasty.