Objective

To develop an ultrasound-guided approach to intercostal nerve injection and to compare the success rate of intercostal nerve injections using blind or ultrasound-guided technique in canine cadavers.

Study design

Prospective, randomized, descriptive, experimental anatomic study.

Animals

A total of 14 mid-sized adult canine cadavers.

Methods

Ultrasound landmarks were identified by dissection of four cadavers and used to develop an ultrasound-guided technique. The remaining 10 cadavers were randomly assigned to blind (five cadavers) or ultrasound-guided (five cadavers) injections of the third to the ninth intercostal nerves bilaterally with 0.03 mL kg^–1 of colorant per injection. The target for intercostal injections was the caudal border of the respective rib, between the internal intercostal membrane and the parietal pleura. Additionally, displacement of the parietal pleura without visible intramuscular distribution was considered the end point for ultrasound-guided injections. For each cadaver, a practitioner in training performed the blocks on one hemithorax, while an experienced practitioner performed the blocks on the opposite hemithorax. Injections were considered successful if ≥1 cm of the target nerve was stained with colorant upon dissection. Success rates and length of nerve staining were analyzed with Fisher’s exact and t tests, respectively. Data were considered statistically different with p < 0.05.

Results

Success rates of blind and ultrasound-guided technique were 57.1% and 91.4%, respectively (p < 0.0001). The length of intercostal nerve staining was 3.1 ± 1.2 cm and 3.6 ± 1.0 cm using blind and ultrasound-guided techniques, respectively (p = 0.02). No differences were observed between the two practitioners for blind (p = 0.33) and ultrasound-guided techniques (p = 0.67).

Conclusions and clinical relevance

Ultrasound guidance improves the accuracy of intercostal nerve injections when compared with blind technique, independently of the level of expertise in regional anesthesia.

中文翻译：

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超声引导对肋间神经注射准确性影响的评价：犬尸体研究

客观的

开发一种超声引导的肋间神经注射方法，并比较使用盲法或超声引导技术对犬尸体进行肋间神经注射的成功率。

学习规划

前瞻性、随机、描述性、实验性解剖学研究。

动物

共有 14 具中型成年犬尸体。

方法

通过解剖四具尸体来识别超声标志，并用于开发超声引导技术。剩余的 10 具尸体被随机分配到盲法（5 具尸体）或超声引导下（5 具尸体）双侧第三至第九肋间神经注射 0.03 mL kg ^–1每次注射的着色剂。肋间注射的目标是相应肋骨的尾缘，位于内肋间膜和壁层胸膜之间。此外，无可见肌内分布的壁层胸膜移位被认为是超声引导注射的终点。对于每具尸体，训练中的从业者在一个侧胸上进行阻滞，而经验丰富的从业者在相反的侧胸上进行阻滞。如果 ≥ 1 cm 的目标神经在解剖时被着色剂染色，则认为注射成功。分别用 Fisher 精确和t检验分析了神经染色的成功率和长度。数据被认为具有统计学差异，p < 0.05。

结果

盲法和超声引导技术的成功率分别为 57.1% 和 91.4% ( p < 0.0001)。使用盲法和超声引导技术的肋间神经染色长度分别为 3.1 ± 1.2 cm 和 3.6 ± 1.0 cm (p  = 0.02)。在盲法 ( p  = 0.33) 和超声引导技术 ( p  = 0.67) 方面，两位从业者之间没有观察到差异。

结论和临床相关性

与盲法相比，超声引导提高了肋间神经注射的准确性，与区域麻醉的专业水平无关。