连续股神经阻滞超前镇痛对老年患者全膝关节置换术术后早期认知功能的影响

Effects of preemptive analgesia with continuous femoral nerve block after total knee arthroplasty in elderly patients on early postoperative cognitive dysfunction

目的观察连续股神经阻滞（continuous femoral nerve block，CFNB）超前镇痛对老年患者全膝关节置换术（total knee arthroplasty，TKA）术后疼痛程度和早期认知功能的影响。方法60例择期全凭静脉麻醉下行首次TKA的患者，年龄t〉65岁，美国麻醉医师协会（ASA）分级I～Ⅱ级。按随机数字表法分为两组：超前镇痛组和对照组，每组30例。超前镇痛组于手术前施行CFNB，对照组于手术后施行CFNB。收集患者术前一般资料，监测术中循环功能变化和脑电双频指数（bispectral index，BIS），记录术中麻醉用药、手术时间、止血带时间和麻醉时间等。应用简易智能状态量表（mini-mental state examination，MMSE）双盲法测定患者术前1d及术后1、3、5、7d的认知功能，以术后评分和术前1d评分比较下降大于1个标准差即判断发生术后认知功能障碍（postoperative cognitive dysfunction，POCD）。于上述各时间点采用视觉模拟评分（visual analog scale，VAS）评估患者静息和运动时的疼痛程度。结果超前镇痛组术中瑞芬太尼的用量为（1．7±0．4）mg，低于对照组的（1．9±0．3）mg（P〈0．05）；超前镇痛组术后1d和3d运动VAS评分低于对照组（P〈0．01）；两组患者静息VAS评分比较，差异无统计学意义（P〉0．05）；超前镇痛组术后3d POCD的发生率低于对照组（6．7％比26．7％）（P〈0．05）。结论CFNB超前镇痛可促进老年患者TKA术后早期认知功能的恢复，这可能与超前镇痛降低了TKA术后功能锻炼时的疼痛程度有关。

Objective To observe the effects of preemptive analgesia with continuous femoral nerve block（CFNB） after total knee arthroplasty（TKA） in elderly patients on postoperative pain scores and early postoperative cognitive function. Methods Sixty patients aged more than 65 years with American society of anesthesiologists （ASA） physical status Ⅰ -Ⅱ , who were scheduled for elective total knee arthroplasty, were randomly devided into 2 groups （n =30）： preemptive analgesia group and control group. Preemptive analgesia group was implemented CFNB before surgery, while control group was done CFNB after surgery. Patient＇s general information before operation was recorded. The changes of hemodynamics and the value of bispectral index （BIS） were monitored during operation. The doses of all anesthetics, the time of operation, tourniquet and anesthesia were also recorded. Cognitive function was measured on 1 d before surgery, 1, 3, 5 d and 7 d after surgery using mini-mental state examination （MMSE）. The occurrence of postoperative cognitive dysfunction （POCD） was defined when the decreased MMSE score after surgery was more than one standard deviation. The visual analog scale （VAS） at the same days in resting and exercise were recorded to evaluate the degree of postoperative pain. Results The total dosage of remifentanil in preemptive analgesia group （1.7±0.4） mg was less than that in control group（ 1.9±0.3 ） mg（P〈0.05 ）. VAS exercise score in preemptive analgesia group were lower than that of control group （P〈0.01）. VAS resting scores in two groups had no significant significance （P〉0.05）. The incidence of POCD in preemptive analgesia group （6.7%） was lower than in control group （26.7%）（P〈0.05）. Conclusions The preemptive analgesia produced by preoperative CFNB can improve the recovery of early postoperative cognitive function in elderly patients performed TKA. This can be related to the decreasing of the degree of postoperative exercise pain.