Taboada Muñiz Manuel, Rodríguez Jaime, Bermúdez María, Valiño Cristina, Blanco Noemi, Amor Marcos, Aguirre Pilar, Masid Ana, Cortes Joaquin, Alvarez Julián, Atanassoff Peter G
Department of Anesthesiology, Hospital Clínico Universitario de Santiago, Travesía da Choupana s/n. 15706 Santiago de Compostela, Spain.
Anesth Analg. 2008 Dec;107(6):2085-8. doi: 10.1213/ane.0b013e318186641d.
Various factors markedly affect the onset time and success rate, of peripheral nerve blockade. This prospective, randomized, double-blind study, compared a dose of mepivacaine 300 mg, in a 20 or 30 mL injection volume for sciatic nerve blockade using Labat's posterior approach.
A total of 90 patients undergoing foot surgery were randomly allocated to receive sciatic nerve block with 20 mL of 1.5% mepivacaine (n = 45) or 30 mL of 1% mepivacaine (n = 45). All blocks were performed with the use of a nerve stimulator (stimulation frequency 2 Hz; intensity 1.5-0.5 mA). In the two groups, appropriate nerve stimulation was elicited at <0.5 mA and the targeted evoked motor response was plantar flexion of the foot. Time required for onset of sensory and motor block in the distribution of the tibial and common peroneal nerves were recorded. A successful block was defined as a complete loss of pinprick sensation in the sciatic nerve distribution with concomitant inability to perform plantar or dorsal flexion of the foot.
A greater success rate was observed with 20 mL of 1.5% mepivacaine (96.6%) than with 30 mL of 1% mepivacaine (68.9%; P < 0.05). Time to onset of complete sensory and motor block was shorter after injection of 20 mL of 1.5% mepivacaine (11 +/- 6 min and 13 +/- 7 min, respectively) than after 30 mL of 1% mepivacaine (17 +/- 8 min and 19 +/- 8 min, respectively, P < 0.05).
In Labat's sciatic nerve blockade, administering a low volume and a high concentration of local anesthetic (1.5% mepivacaine) is associated with a higher success rate and a shorter onset time than a high volume and a low concentration of solution (1% mepivacaine).
多种因素显著影响周围神经阻滞的起效时间和成功率。本前瞻性、随机、双盲研究比较了采用拉巴特后路法进行坐骨神经阻滞时，注射体积为20或30 mL、剂量为300 mg的甲哌卡因的效果。
总共90例接受足部手术的患者被随机分配，分别接受20 mL 1.5%甲哌卡因（n = 45）或30 mL 1%甲哌卡因（n = 45）的坐骨神经阻滞。所有阻滞均使用神经刺激器进行（刺激频率2 Hz；强度1.5 - 0.5 mA）。在两组中，当电流<0.5 mA时引出适当的神经刺激，目标诱发运动反应为足部跖屈。记录胫神经和腓总神经分布区域感觉和运动阻滞起效所需时间。成功的阻滞定义为坐骨神经分布区域针刺感觉完全丧失，同时无法进行足部跖屈或背屈。
观察到20 mL 1.5%甲哌卡因组的成功率（96.6%）高于30 mL 1%甲哌卡因组（68.9%；P < 0.05）。注射20 mL 1.5%甲哌卡因后完全感觉和运动阻滞的起效时间（分别为11 ± 6分钟和13 ± 7分钟）短于30 mL 1%甲哌卡因组（分别为17 ± 8分钟和19 ± 8分钟，P < 0.05）。
在拉巴特坐骨神经阻滞中，与高容量低浓度溶液（1%甲哌卡因）相比，给予低容量高浓度局部麻醉剂（1.5%甲哌卡因）具有更高的成功率和更短的起效时间。
