BACKGROUND: In unaided caudal epidural block (CEB), incorrect needle insertion has been reported to occur in 15% to 38% of attempts.OBJECTIVE: To statistically analyze the anatomical variables affecting difficult CEB using ultrasonographic measurement.METHODS: Preprocedural ultrasonography was performed and the following measurements were obtained in 146 patients: the distance from the skin to the apex of the sacral hiatus; the depth of the sacral canal at the apex of the sacral hiatus; the length of the sacrococcygeal ligament between the apex of the sacral hiatus and sacral base; the distance from the skin to the apex of the sacral cornu; and the distance between the apexes of bilateral cornua. One clinician, unaware of the ultrasonographic findings, performed the injections using the landmark technique. The procedures were videotaped and were subsequently reviewed by an independent investigator.RESULTS: The means (± SDs) of the abovementioned measurements were 12.1±3.7 mm, 6.1±2.1 mm, 25.9±7.4 mm, 10.0±4.0 mm and 16.4±3.2 mm, respectively. Injections failed in 16 (11%) patients and were defined as difficult in 21 (14.4%) patients. The depth of the sacral canal at the apex of sacral hiatus (P<0.001) and the length of the sacrococcygeal ligament between the apex of the sacral hiatus and sacral base (P=0.001) were significant predictors of difficult CEB. Of all patients, 85.7% and 75.2% were correctly classified as difficult or not difficult, respectively. The cutoff values of the depth of the sacral canal at the apex of the sacral hiatus and the length of the sacrococcygeal ligament between the apex of the sacral hiatus and the sacral base to predict a difficult CEB were 3.7 mm and 17.6 mm, respectively.CONCLUSIONS: Both the depth of the sacral canal at the apex of the sacral hiatus and the length of the sacrococcygeal ligament between the apex of the sacral hiatus and sacral base are significant variables affecting the difficulty of the CEB.

中文翻译：

---

超声评估成年人尾硬膜外注射难度的因素

背景：在无助尾硬膜外阻滞（CEB）中，据报道尝试插入错误的针头发生率为15％至38％。目的：通过超声检查统计分析影响难于CEB的解剖变量。方法：进行术前超声检查并在146例患者中进行了以下测量：从皮肤到the裂顶端的距离；at管裂孔顶端的can管深度; cro骨裂孔顶点与and骨基部之间的sa球韧带的长度；从皮肤到the骨角尖的距离；和双侧角膜顶点之间的距离。一位不知道超声检查结果的临床医生使用界标技术进行了注射。对过程进行录像，然后由独立研究人员进行审查。结果：上述测量的平均值（±SD）为12.1±3.7 mm，6.1±2.1 mm，25.9±7.4 mm，10.0±4.0 mm和16.4±3.2 mm ， 分别。注射失败的有16位（11％）患者，定义为困难的有21位（14.4％）患者。CE骨裂孔顶端的the管深度（P <0.001）以及between骨裂孔顶端和骨基部之间的（球韧带长度（P = 0.001）是困难CEB的重要预测指标。在所有患者中，分别将85.7％和75.2％正确地分类为困难或不困难。