Fiedler M A
University of Alabama at Birmingham, USA.
AANA J. 1997 Oct;65(5):451-9.
In Part A of this two-part Journal course, issues of safety during subarachnoid and epidural blocks were examined (see the August 1997 issue of the AANA Journal). Part B deals with the effectiveness of spinal and epidural blocks. Although the overall failure rate for subarachnoid and epidural blocks is low, regional anesthesia is not always effective. Knowing the failure rates for various types of regional blocks and the factors that influence the rate of failure is useful for planning anesthetic care and choosing the most effective techniques. Combined spinal and epidural techniques offer the quick onset of a spinal with the continuous dosing and controllability of an epidural. The combined spinal and epidural technique is somewhat more complicated to perform especially in regard to test dosing. Opioids and vasoconstrictors enhance the density and duration of spinal and epidural blocks. In addition, opioids can be used to provide postoperative analgesia after the block has worn off. While opioid induced respiratory depression was a significant hazard during the initial development of spinal and epidural opioid techniques, refinements in dosing and monitoring of these patients have reduced the incidence of this complication to a low level. While alpha agonists, such as epinephrine, do prolong the duration of some types of blocks, they also introduce or exacerbate problems, such as urinary retention, itching, and even hypotension. Whatever technique is used, careful patient selection, allowing adequate time for the block to set up, and administering small doses of a systemic analgesic or sedative if needed may make the difference between the success or failure of a well-performed block.
在这个分为两部分的《麻醉护理杂志》课程的A部分中，探讨了蛛网膜下腔阻滞和硬膜外阻滞期间的安全问题（见《麻醉护理协会杂志》1997年8月刊）。B部分讨论脊髓阻滞和硬膜外阻滞的有效性。尽管蛛网膜下腔阻滞和硬膜外阻滞的总体失败率较低，但区域麻醉并不总是有效。了解各种类型区域阻滞的失败率以及影响失败率的因素，对于规划麻醉护理和选择最有效的技术很有帮助。腰麻-硬膜外联合技术兼具脊髓阻滞起效快和硬膜外阻滞持续给药及可控性的优点。腰麻-硬膜外联合技术的操作稍微复杂一些，尤其是在试验剂量方面。阿片类药物和血管收缩剂可增强脊髓阻滞和硬膜外阻滞的密度和持续时间。此外，在阻滞消退后，阿片类药物可用于提供术后镇痛。虽然在脊髓和硬膜外阿片类技术最初发展期间，阿片类药物引起的呼吸抑制是一个重大危险，但对这些患者给药和监测方法的改进已将这种并发症的发生率降低到了很低的水平。虽然肾上腺素等α受体激动剂确实能延长某些类型阻滞的持续时间，但它们也会引发或加重诸如尿潴留、瘙痒甚至低血压等问题。无论使用何种技术，仔细选择患者、留出足够时间让阻滞起效以及在需要时给予小剂量全身镇痛药或镇静剂，可能是一次实施良好的阻滞成功或失败的关键。
