White J L, Stevens R A, Beardsley D, Teague P J, Kao T C
Department of Anesthesiology, Georgetown University Hospital, Washington, DC.
Reg Anesth. 1994 Sep-Oct;19(5):335-8.
It is well established that spinal anesthesia results in a differential block to the sensations of pinprick and cold temperature discrimination. However, the existence of differential block during epidural anesthesia has not always been accepted. Recently, it has been shown that lumbar epidural anesthesia with chloroprocaine and lidocaine produces a differential block to pinprick and cold sensation. The purpose of this study was to determine if the choice of local anesthetic used for epidural anesthesia has any influence on the relative levels of anesthesia, analgesia, and cold sensation.
The authors studied nine healthy subjects; each was studied three times and received one of three local anesthetics (0.75% bupivacaine, 2% lidocaine, and 3% chloroprocaine) via an epidural catheter placed into the second or third lumbar epidural space. The authors tested the following modalities compared to an unblocked dermatome: anesthesia, loss of sensation to pinprick; analgesia, loss of an equally sharp sensation to pinprick; and cold sensation, loss of cold sensation to alcohol.
Twenty minutes after injection of the local anesthetic, zones of differential sensory block existed for all three agents tested. Anesthesia and analgesia were the most caudad and cephalad, respectively, while loss-to-cold sensation was found to be between these two levels. There was no significant difference in the dermatomal level achieved among the three local anesthetics tested. Sensory testing data observed 10 minutes later showed that no significant change had occurred.
This study reaffirms the existence of differential sensory block during epidural anesthesia and establishes that the observed differential block appears to be independent of the local anesthetic used.
脊髓麻醉对针刺觉和冷温度辨别觉产生不同程度的阻滞，这一点已得到充分证实。然而，硬膜外麻醉期间是否存在不同程度的阻滞一直未被完全认可。最近有研究表明，用氯普鲁卡因和利多卡因进行腰段硬膜外麻醉会对针刺觉和冷觉产生不同程度的阻滞。本研究的目的是确定用于硬膜外麻醉的局部麻醉药的选择是否会对麻醉、镇痛和冷觉的相对水平产生影响。
作者对9名健康受试者进行了研究；每名受试者接受3次研究，通过置于第二或第三腰椎硬膜外间隙的硬膜外导管接受三种局部麻醉药（0.75%布比卡因、2%利多卡因和3%氯普鲁卡因）中的一种。与未阻滞的皮节相比，作者测试了以下几种感觉模式：麻醉，针刺觉丧失；镇痛，对同样尖锐的针刺觉丧失；冷觉，对酒精冷觉丧失。
注射局部麻醉药20分钟后，所有三种受试药物均存在不同程度的感觉阻滞区域。麻醉和镇痛分别在最尾端和最头端，而冷觉丧失区域位于这两者之间。三种受试局部麻醉药所达到的皮节水平无显著差异。10分钟后观察到的感觉测试数据显示未发生显著变化。
本研究再次证实了硬膜外麻醉期间存在不同程度的感觉阻滞，并确定观察到的不同程度阻滞似乎与所用局部麻醉药无关。
