Casati A, Baciarello M, Di Cianni S, Danelli G, De Marco G, Leone S, Rossi M, Fanelli G
Department of Anaesthesia and Pain Therapy, University of Parma, Ospedale Maggiore di Parma, via Gramsci 14, 43100 Parma, Italy.
Br J Anaesth. 2007 Jun;98(6):823-7. doi: 10.1093/bja/aem100. Epub 2007 May 3.
We tested the hypothesis that ultrasound guidance may reduce the minimum effective anaesthetic volume (MEAV50) of ropivacaine 0.5% required to block the femoral nerve compared with nerve stimulation guidance.
After standard premedication and sciatic nerve block were given, 60 patients undergoing knee arthroscopy were randomly allocated to receive a femoral nerve block with ropivacaine 0.5% using either nerve stimulation (group NS, n = 30) or ultrasound (group US, n = 30) guidance. The volume of the injected solution was varied for consecutive patients based on an up-and-down staircase method according to the response of the previous patient. The initial volume was 12 ml. A double-blinded observer evaluated the occurrence of complete loss of pinprick sensation in the femoral nerve distribution, with concomitant block of the quadriceps muscle: positive or negative responses within 30 min after the injection determined a 3 ml decrease or increase for the next patient, respectively.
The mean (sd) MEAV50 for femoral nerve block was 15 (4) ml (95% CI, 7-23 ml) in group US and 26 (4) ml (95% CI, 19-33 ml) in group NS (P = 0.002). The effective dose in 95% of cases (ED95) calculated with probit transformation and logistic regression analysis was 22 ml (95% CI, 13-36 ml) in group US, and 41 ml (95% CI, fs 24-66 ml) in group NS.
Ultrasound guidance provided a 42% reduction in the MEAV of ropivacaine 0.5% required to block the femoral nerve as compared with the nerve stimulation guidance.
我们检验了这样一个假设，即与神经刺激引导相比，超声引导可能会降低0.5%罗哌卡因阻滞股神经所需的最小有效麻醉剂量（MEAV50）。
在给予标准的术前用药和坐骨神经阻滞后，60例行膝关节镜检查的患者被随机分配，分别采用神经刺激（NS组，n = 30）或超声（US组，n = 30）引导，接受0.5%罗哌卡因的股神经阻滞。根据前一位患者的反应，采用上下阶梯法为连续的患者调整注射溶液的体积。初始体积为12 ml。一名双盲观察者评估股神经分布区针刺感觉完全丧失的情况，以及股四头肌的伴随阻滞情况：注射后30分钟内的阳性或阴性反应分别决定下一位患者的注射体积减少或增加3 ml。
US组股神经阻滞的平均（标准差）MEAV50为15（4）ml（95%可信区间，7 - 23 ml），NS组为26（4）ml（95%可信区间，19 - 33 ml）（P = 0.002）。经概率转换和逻辑回归分析计算，95%病例的有效剂量（ED95）在US组为22 ml（95%可信区间，13 - 36 ml），在NS组为41 ml（95%可信区间，24 - 66 ml）。
与神经刺激引导相比，超声引导使阻滞股神经所需的0.5%罗哌卡因的MEAV降低了42%。
