Objective

To determine whether the addition of bupivacaine or contrast medium to methylene blue dye would affect dye distribution following ultrasound (US)-guided transversus abdominis plane (TAP) injections.

Study design

Prospective, randomized, blinded cadaveric study.

Animals

A total of 29 fresh Beagle dog cadavers.

Methods

Each hemiabdomen (n = 58) was randomized into one of three groups: group M, 1% methylene blue; group MB, 50:50 mixture of 1% methylene blue and 0.5% bupivacaine; group MC, 25:75 mixture of 1% methylene blue and contrast agent (iohexol). TAP injections (0.5 mL kg^–1) were performed bilaterally by a trained individual followed by dissection of the abdominal walls. Craniocaudal and dorsoventral spread along tissue planes was measured. Staining of branches of the thoracic and lumbar spinal nerves was considered successful when dye on the nerve was >10 mm. One-way anova with post hoc Tukey test was used to compare craniocaudal and dorsoventral spread and Kruskal–Wallis test to compare incidence of nerve staining among groups.

Results

TAP injections were successful in 52 out of 58 hemiabdomens. Dorsoventral spread was greater for group M (60 ± 10 mm) compared with MC (49 ± 9 mm; p = 0.01) but not MB (52 ± 9 mm; p = 0.09). No difference was found in craniocaudal spread or number of nerves stained among groups.

Conclusion and clinical relevance

The significant difference found in spread of tissue staining between methylene blue alone and methylene blue mixed with contrast in the TAP blocks should be kept in mind when interpreting dye-based cadaveric regional anesthesia studies.

中文翻译：

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对比和局麻药对犬尸体横腹平面注射后染料扩散的影响。

目的

为了确定向美甲蓝染料中添加布比卡因或造影剂是否会影响超声（US）引导的腹横肌平面（TAP）注射后的染料分布。

学习规划

前瞻性，随机，盲法尸体研究。

动物

总共29只新鲜的比格犬尸体。

方法

每个半腹（n  = 58）随机分为三组之一：M组，1％亚甲蓝；MB组：1％亚甲蓝和0.5％布比卡因的50:50混合物；MC组，1％亚甲蓝和造影剂（碘己醇）的25∶75混合物。TAP注射（0.5 mL kg ^–1）由受过训练的人员双向进行，然后解剖腹壁。测量了沿组织平面的颅尾和背腹的扩散。当神经上的染料> 10 mm时，认为对胸和腰椎神经的分支进行染色是成功的。单向方差分析和事后Tukey检验用于比较颅尾和背腹扩散，Kruskal-Wallis检验用于比较各组之间神经染色的发生率。

结果

在58个半腹部中有52个TAP注射成功。与MC（49±9 mm; p  = 0.01）组相比，M组（60±10 mm）的背腹展宽更大，而MB（52±9 mm; p  = 0.09）不如。各组之间的颅尾扩散或神经染色数量均无差异。

结论与临床意义

在解释基于染料的尸体区域麻醉研究时，应牢记在单独的亚甲基蓝和在TAP嵌段中混有对比度的亚甲基蓝之间在组织染色扩散中发现的显着差异。