Yamamoto K, Nomura T, Shibata K, Ohmura S
Department of Anesthesiology and Intensive Care Medicine, School of Medicine, Kanazawa University, Japan.
Reg Anesth. 1997 Nov-Dec;22(6):557-61.
Unintentional extrasheath injection causes failed axillary brachial plexus block. We wanted to find out if extrasheath injections produce higher plasma concentrations of local anesthetics compared to intrasheath injections. We also studied the incidence of extrasheath injection with radiographs.
Axillary brachial plexus blocks were established using a catheter technique. Fifty milliliters of 1.5% mepivacaine without epinephrine mixed with contrast medium was injected through the catheter. An anteroposterior radiograph was used to determine the distribution of contrast medium. Mepivacaine concentrations in arterial plasma were compared when local anesthetic solution was injected unintentionally outside of the axillary neurovascular sheath (n = 6) and when it was injected correctly into the sheath (n = 6). The incidence of extrasheath injection was studied in a different series of 109 patients.
Arterial plasma mepivacaine concentrations were higher after extrasheath injection [8.0 (6.3-9.7) vs 5.8 (4.5-7.0), microg/mL, means (95% confidence intervals), P < .05]. Pharmacokinetic parameters such as mean residence time and total clearance did not differ between intra- and extrasheath injections. Extrasheath injection was observed in 3.7% (4/109) of cases.
Failed extrasheath injection of 50 mL 1.5% plain mepivacaine produces higher arterial plasma concentration in axillary brachial plexus block.
意外鞘外注射会导致腋路臂丛神经阻滞失败。我们想弄清楚与鞘内注射相比，鞘外注射是否会使局部麻醉药的血浆浓度更高。我们还通过X线片研究了鞘外注射的发生率。
采用导管技术建立腋路臂丛神经阻滞。通过导管注入50毫升不含肾上腺素的1.5%甲哌卡因并混合造影剂。使用前后位X线片确定造影剂的分布。比较当局部麻醉药溶液意外注入腋神经血管鞘外时（n = 6）和正确注入鞘内时（n = 6）动脉血浆中甲哌卡因的浓度。在另一组109例患者中研究鞘外注射的发生率。
鞘外注射后动脉血浆中甲哌卡因浓度更高[8.0（6.3 - 9.7）对5.8（4.5 - 7.0），微克/毫升，均值（95%置信区间），P <.05]。鞘内和鞘外注射之间的药代动力学参数如平均驻留时间和总清除率没有差异。在3.7%（4/109）的病例中观察到鞘外注射。
50毫升1.5%的单纯甲哌卡因鞘外注射失败在腋路臂丛神经阻滞中会产生更高的动脉血浆浓度。
