Evoked Spinal Cord Potential (ESP) for Detection and Prevention of Spinal Cord Ischemia During Aortic Cross-Clamping.

为了及时发现和预防胸主动脉阻断术中脊髓缺血引起的截瘫，对脊髓诱发电位（ESP）进行了记录和分析。(1)实验：材料和方法：成年犬在主动脉阻断前、阻断中、阻断后连续监测ESP。将刺激电极放置在L-1附近的硬膜外腔中，将传感电极放置在T-3和T-5之间的椎间盘中。将5至100个响应取平均值以构建%e% sP。结果如下：主动脉阻断后的ESP反应可分为3种类型：主动脉阻断时ESP消失（1型）、主动脉阻断时ESP无变化（2型）和主动脉阻断时ESP短暂下降和恢复（3型）。所有1型反应的犬均表现出截瘫，而2型反应的犬均未表现出截瘫。一些3型反应的犬表现出痉挛性截瘫。另一组1型犬在ESP达到20%后10分钟解除钳夹，但未能阻止截瘫的发生，组织学检查显示截瘫犬T-8以下脊髓灰质梗死，钳夹时选择性肋间动脉灌注和主动脉内输注血管扩张剂似乎有希望防止脊髓缺血性损伤。(2)在30例接受胸主动脉手术的患者中监测ESP，23例患者显示2型反应。4例患者ESP轻度降低。3例患者表现为1型反应，1例患者重新建立了临时旁路，另外2例患者在ESP丧失后几分钟内可释放交叉夹。我们发明了一种特殊的旁路管，在脊髓切开术中灌注肋间动脉，以防止持续的1型反应，这强烈提示脊髓缺血。

Evoked spinal cord potential (ESP) was recorded and analyzed in order to detect and prevent the paraplegia caused by spinal cord ischemia during thoracic aortic cross-ciamping.(1) Experiment.Material and Methods: Adult dogs underwent continuous monitoring of ESP before, during, and after aortic cross-clamping. Stimulating electrodes were placed in the epidural space near L-1, sensing electrodes were placed in the intervertebral disc between T-3 and T-5. 5 to 100 responses were averaged to construct %e%sP..Results: ESP responses to aortic cross-clamping were categorized into three types: loss of ESP during aortic cross-clamp (type 1),'no change in ESP during cross- clamp (type 2), and transient depression and return of ESP during cross-clamp (type 3). All dogs of type 1 response demonstrated paraplegia, where-as no dog of type 2 response showed paraplegia. Some dogs of type 3 response demonstrated spastic paraplegia. Although cross-clamp was removed 10 minutes after ESP became 20% of the previous amplitude in another series of type 1 dogs, paraplegia was not prevented.Histological examination revealed infarction of the grey matter of the spinal cord below T-8 in the dogs with paraplegia.Selective perfusion of the intercostal arteries furing cross-clamping and intraaortic infusion of vasodilators seemed promising to prevent spinal cord ischemic injury.(2) PracticeESP was monitored in 30 patients who underwent thoracic aortic surgery.23 patients showed type 2 response. ESP was slightly depressed in 4 patients. 3 patients demonstrated type 1 response; temporary bypass was re-established in one case, cross-clamp could be released within a few minutes after ESP loss in other two cases. No paraplegia was experienced.We have invented a special bypass tube to perfuse intercostal arteries during aortotomy in case of prolonged type 1 response which strongly suggests spinal cord ischemia.