Stevens R, Mikat-Stevens M, Van Clief M, Schubert A, Weinstein Z
Department of Anesthesiology, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
Reg Anesth. 1989 Jul-Aug;14(4):180-2.
To investigate whether and to what extent air bubbles are present in the epidural space after injections of air, the authors designed an experiment using a chronic dog model. The epidural space was entered at the sixth or seventh lumbar interspace in six mongrel dogs (weight, 20 to 27 kg). Loss-of-resistance (LOR) to saline was tested to identify the epidural space. Three milliliters of air were injected via a Tuohy needle, followed by 5 ml of contrast material (Isovue 300, Squibb Diagnostics). Anterior-posterior (AP) and lateral radiographs were taken on day 1. On days 2, 4, and 8, the procedure was repeated, omitting the air injection. Radiographs were read by a neuroradiologist. Air bubbles were radiographically demonstrated in all six dogs on day 1, and in three of six dogs on day 2. No air was seen on later films. The air bubbles seen were small and few in number but often located near intervertebral spaces. The authors' findings suggest that injection of large volumes of epidural air should be avoided, particularly when N2O is used as part of the anesthetic or when performing diagnostic peridurography since N2O may expand the volume of existing bubbles and interfere with filling of the epidural space by local anesthetics or contrast material.
为了研究注射空气后硬膜外间隙是否存在气泡以及气泡存在的程度，作者设计了一项使用慢性犬模型的实验。在6只杂种犬（体重20至27千克）的第六或第七腰椎间隙进入硬膜外间隙。通过测试对生理盐水的阻力消失（LOR）来确定硬膜外间隙。通过Tuohy针注入3毫升空气，随后注入5毫升造影剂（碘海醇300，施贵宝诊断公司）。在第1天拍摄前后位（AP）和侧位X线片。在第2、4和8天，重复该操作，但不注入空气。X线片由神经放射科医生阅片。在第1天，所有6只犬均在X线片上显示有气泡，在第2天，6只犬中有3只显示有气泡。在随后的片子上未见到气泡。所见到的气泡小且数量少，但常位于椎间隙附近。作者的研究结果表明，应避免注入大量硬膜外空气，尤其是当使用氧化亚氮作为麻醉的一部分或进行诊断性硬膜外造影时，因为氧化亚氮可能会使现有气泡的体积增大，并干扰局部麻醉药或造影剂对硬膜外间隙 的填充。
