Department of Anesthesiology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
Anesth Analg. 2010 Mar 1;110(3):951-7. doi: 10.1213/ANE.0b013e3181ca134b. Epub 2009 Dec 10.
Surgical anesthesia for reconstructive ankle surgery requires sensory and motor block of all the terminal nerve distributions of the sciatic nerve. In this prospective observational study, we investigated the value of sensory and motor testing of the foot, after local anesthetic injection, for predicting complete sciatic nerve blockade and the duration of testing required for identifying incomplete anesthesia.
Sciatic nerve blocks (n = 180) using the infragluteal-parabiceps approach were performed in patients undergoing reconstructive ankle surgery. Levobupivacaine 0.625% with epinephrine 1:300,000 (0.4 mL/kg) was injected after obtaining an elicited motor response at <0.4 mA of plantar flexion or inversion. Pinprick sensory assessments were performed at intervals by an observer unaware of the elicited motor response in the distal cutaneous distributions of the superficial peroneal nerve, deep peroneal nerve, posterior tibial nerve, and sural nerve. Motor block was assessed using foot (plantar flexion and dorsiflexion) movement and toe movement. A complete block was defined as sensory and motor loss in all distributions of the sciatic nerve within 25 minutes of local anesthetic injection. The optimal sensitivity and specificity of various cutoff times of sensory and motor testing were determined by receiver operating characteristic analysis. The area under the curves was compared for equivalence using nonparametric methods. The cutoff times were determined as the point of intersection of the lines of sensitivity and specificity.
The elicited evoked motor response before sciatic nerve block was plantar flexion in 87 patients and inversion in 93. Eighty-eight of 93 patients (94.6%) who had an elicited motor response of inversion and 49 of 87 (55.7%) who had an elicited motor response of plantar flexion achieved complete sciatic nerve block at 25 minutes. Area under the curves were not different among testing paradigms. Receiver operating characteristic analysis identified optimal testing times of 4 minutes for the sural and 6 minutes for the posterior tibial nerve with an elicited motor response of inversion and 6 minutes with an elicited motor response of plantar flexion. No subject with an incomplete block achieved sural anesthesia by 10 minutes.
Sural anesthesia assessed at the lateral heel and the lateral aspect of the foot and the fifth toe identified within 4 to 6 minutes demonstrated a similar posttest predictive value as anesthesia in the distributions of the posterior tibial and peroneal nerves or motor movement of the foot at later intervals. In addition, failure to achieve sural anesthesia within 10 minutes was predictive of block failure.
重建踝关节手术的外科麻醉需要感觉和运动阻滞所有坐骨神经的末梢神经分布。在这项前瞻性观察研究中，我们研究了局部麻醉注射后足部感觉和运动测试预测完全坐骨神经阻滞的价值，以及确定不完全麻醉所需的测试持续时间。
对接受重建踝关节手术的患者采用臀下肌-肱二头肌入路行坐骨神经阻滞（n=180）。在获得<0.4 mA 跖屈或内翻的诱发运动反应后，注射 0.625%左布比卡因加肾上腺素 1:300,000（0.4 mL/kg）。通过观察者在间隔时间内进行针刺痛觉评估，而不了解在浅表腓总神经、深腓总神经、胫后神经和腓肠神经的远端皮肤分布中诱发的运动反应。使用足部（跖屈和背屈）运动和脚趾运动评估运动阻滞。完全阻滞定义为局部麻醉注射后 25 分钟内坐骨神经所有分布的感觉和运动丧失。通过接收者操作特征分析确定各种感觉和运动测试截止时间的最佳敏感性和特异性。使用非参数方法比较曲线下面积的等效性。截止时间确定为敏感性和特异性线的交点。
在坐骨神经阻滞前，87 例患者出现跖屈，93 例患者出现内翻的诱发运动反应。93 例内翻诱发运动反应的患者中有 88 例（94.6%）和 87 例跖屈诱发运动反应的患者中有 49 例（55.7%）在 25 分钟时达到完全坐骨神经阻滞。测试方案之间的曲线下面积没有差异。接收者操作特征分析确定了在出现内翻诱发运动反应时，最佳测试时间为 4 分钟用于腓肠神经和 6 分钟用于胫后神经，而在出现跖屈诱发运动反应时为 6 分钟。在 10 分钟内，没有不完全阻滞的患者达到腓肠神经麻醉。
在 4 至 6 分钟内评估外侧足跟和足部外侧以及第五脚趾的腓肠神经麻醉与胫后神经和腓总神经的麻醉或足部的运动在较晚的时间间隔具有相似的术后预测价值。此外，在 10 分钟内未能达到腓肠神经麻醉预示着阻滞失败。
