Comparative study of epidural anesthesia in dogs by weight or occipito-coccygeal distance

ABSTRACT The effects of volume on lumbosacral epidural block in dogs were evaluated using two different doses of 2% lidocaine. Ten adult dogs, without defined breed, were subjected to two different anesthetic protocols. In the first, the local anesthetic was calculated based on the body weight (GP), wherein 1.0 mL of local anesthetic was used for each 3.5 kg; in the second protocol, the dose was stipulated according to the occipito-coccygeal (DG) distance with 1.5mL of local anesthetic for every 10 cm of distance. The available time, recovery period, extent of block, and rectal temperature were measured. After the analysis of the results, it was possible to verify that there was an increase in the time in GD when compared with GP, due to the greater volume administered in that group. The recovery period remained similar in both groups, despite the use of different doses. Regarding the extent of blockade, there was an increase in GD in relation to GP due to the increase of the local anesthetic dose. On the other hand, the rectal temperature presented a difference between the groups, remaining lower and below the reference values for the species in GD compared with GP at all moments analyzed, possibly due to a sympathetic action triggered by the cranial extension of the epidural block. It could be concluded that when a longer time and a more cranial blockade of epidural anesthesia are desired, the anesthesia volume should be based on the occipito-coccygeal distance, however, observing the rectal temperature.

摘要 本研究以两种不同剂量的2%利多卡因（lidocaine）为受试药物，评估了麻醉容量对犬腰骶硬膜外阻滞（lumbosacral epidural block）效果的影响。选取10只未明确品种的成年犬，开展两种麻醉方案的对照实验。方案一（GP组）中，局麻药（local anesthetic）剂量按体重计算，即每3.5kg体重给予1.0mL局麻药；方案二（DG组）则依据枕尾距（occipito-coccygeal distance）确定给药剂量，即每10cm的枕尾间距给予1.5mL局麻药。本研究记录并测定了有效阻滞时间、恢复时长、阻滞范围以及直肠温度四项指标。经结果分析可知，相较于GP组，DG组的阻滞时间更长，这是由于该组的给药容量更大。尽管两组给药剂量存在差异，但二者的恢复时长并无显著差异。就阻滞范围而言，DG组的阻滞范围较GP组更广，这与局麻药给药剂量的提升直接相关。另一方面，两组的直肠温度存在显著差异：在所有观测时间点，DG组的直肠温度均低于该物种的参考正常值，该现象可能源于硬膜外阻滞向头端扩散所触发的交感神经作用。综上，若需获得更长的阻滞时长与更偏向头端的硬膜外麻醉范围，麻醉容量应依据枕尾距确定，但需同时监测直肠温度。