Weitz S R, Drasner K
Department of Anesthesia, University of California, San Francisco 94143-0648, USA.
Anesthesiology. 1995 Jul;83(1):96-100. doi: 10.1097/00000542-199507000-00012.
When local anesthetic is used to produce epidural anesthesia intraoperatively, epidural catheter placement is confirmed. However, when epidural catheters are placed intraoperatively only to provide postoperative opioid analgesia, correct catheter placement may not be confirmed by administration of a local anesthetic. The current study tests the hypothesis that the extent of sensory blockade produced by a 10-ml dose of 1.5% lidocaine can be used to predict the adequacy of epidural opioid analgesia.
Forty-nine patients undergoing major abdominal surgery in whom a lumbar epidural catheter was placed intraoperatively were studied, but no more than 3 ml 1% lidocaine had been injected. Placement of the epidural catheter was assessed in the postanesthesia care unit by administration of a 10-ml dose of 1.5% lidocaine. The extent of sensory blockade was determined using the pinprick technique: All dermatomes, T2 and below, were assessed and scored using 1 point per dermatome per side from L1 to T2 to a maximum of 24 points. Scores were arbitrarily divided into three groups, where group 1, 0-7 points; group 2, 8-15 points; and group 3, 16-24 points. Epidural morphine infusion was initiated independently of the extent of the sensory blockade and adjusted using predetermined guidelines. Adequacy of opioid-induced analgesia was determined using the visual analog scale.
Significantly lower visual analog scale scores for pain at rest and with movement from epidural morphine infusion were associated with sensory blockade score of 16-24 points. Seven patients failed to obtain a detectable sensory block. No patient requested alternative analgesia. None of the epidural catheters was removed because of inadequate pain relief, even in patients who failed to obtain a detectable sensory block.
Extensive sensory block from 10 ml 1.5% lidocaine was associated with excellent epidural opioid analgesia. Extent of analgesia after a 10-ml test dose of 1.5% lidocaine can be used to predict the adequacy of analgesia resulting from an epidural opioid infusion. The failure of a local anesthetic dose to produce sensory blockade does not necessarily predict a failure to produce analgesia from an epidural opioid infusion, as indicated by the presence of analgesia in several patients without detectable sensory block.
术中使用局部麻醉药进行硬膜外麻醉时，硬膜外导管的位置可得到确认。然而，当术中放置硬膜外导管仅用于术后阿片类药物镇痛时，通过给予局部麻醉药可能无法确认导管位置是否正确。本研究检验了以下假设：10毫升1.5%利多卡因产生的感觉阻滞范围可用于预测硬膜外阿片类药物镇痛的充分性。
对49例行腹部大手术且术中放置了腰段硬膜外导管的患者进行研究，这些患者术中注入的1%利多卡因不超过3毫升。在麻醉后护理单元，通过给予10毫升1.5%利多卡因来评估硬膜外导管的位置。使用针刺技术确定感觉阻滞范围：评估T2及以下所有皮节，从L1到T2每侧每个皮节计1分，最高24分。分数被任意分为三组，其中第1组，0 - 7分；第2组，8 - 15分；第3组，16 - 24分。硬膜外吗啡输注独立于感觉阻滞范围开始，并根据预定指南进行调整。使用视觉模拟评分法确定阿片类药物诱导镇痛的充分性。
硬膜外吗啡输注后静息和活动时疼痛的视觉模拟评分显著较低与感觉阻滞评分为16 - 24分相关。7例患者未获得可检测到的感觉阻滞。没有患者要求使用其他镇痛方法。即使在未获得可检测到感觉阻滞的患者中，也没有因为镇痛效果不佳而拔除任何硬膜外导管。
10毫升1.5%利多卡因产生的广泛感觉阻滞与良好的硬膜外阿片类药物镇痛相关。10毫升1.5%利多卡因试验剂量后的镇痛范围可用于预测硬膜外阿片类药物输注产生的镇痛充分性。局部麻醉药剂量未能产生感觉阻滞不一定预示硬膜外阿片类药物输注不能产生镇痛效果，如几名没有可检测到感觉阻滞的患者存在镇痛效果所示。
