Sconzo J M, Moscicki J C, DiFazio C A
Department of Anesthesiology, University of Virginia Health Sciences Center, Charlottesville 22901.
Reg Anesth. 1990 Jan-Feb;15(1):37-40.
Smooth emergence from general endotracheal anesthesia is frequently complicated by coughing induced by stimulation from an endotracheal tube. Lidocaine and other local anesthetics have been shown to anesthetize important rapidly adpating stretch receptors in the dog trachea. With the aim of providing a reservoir for continuous lidocaine release to adjacent tracheal tissue, we examined the ability of clinically used concentrations of lidocaine to diffuse across a commonly used endotracheal tube cuff. Cuffs were filled with either 2% or 4% lidocaine and placed in a 200 mL bath with samples drawn at time intervals up to 360 minutes. Samples were then analyzed for lidocaine concentration. Another set of endotracheal tube cuffs were prefilled for one or 2.5 hours with 2% or 4% lidocaine, emptied, and then refilled with 2% lidocaine. They were then bathed and sampled as above. Cuffs exposed to 4% lidocaine during the prefilling or the diffusion stages resulted in significantly higher concentrations of lidocaine in the baths throughout the time course of the experiment, although all groups demonstrated a rise in the concentration of lidocaine in the baths with time. The highest concentration obtained was 17.49 +/- 2.03 micrograms/mL after 360 minutes. We conclude lidocaine diffuses across endotracheal tube cuffs in a fashion that may enable the cuff to serve a potentially useful role as a reservoir for local anesthetic. This in turn appears to have the potential to smooth emergence from general endotracheal anesthesia in those patients in whom tracheal stimulation may be a complicating factor.
全身气管内麻醉平稳苏醒常常因气管内导管刺激引发咳嗽而变得复杂。利多卡因和其他局部麻醉药已被证明可麻醉犬气管中重要的快速适应性牵张感受器。为了提供一个持续向相邻气管组织释放利多卡因的储库，我们研究了临床常用浓度的利多卡因透过常用气管导管套囊扩散的能力。将套囊填充2%或4%的利多卡因，置于200毫升浴槽中，在长达360分钟的时间间隔抽取样本，然后分析样本中的利多卡因浓度。另一组气管导管套囊预先用2%或4%的利多卡因填充1或2.5小时，排空后再用2%的利多卡因重新填充，然后按上述方法进行浴洗和采样。在预填充或扩散阶段接触4%利多卡因的套囊，在整个实验过程中浴槽中的利多卡因浓度显著更高，尽管所有组的浴槽中利多卡因浓度均随时间升高。360分钟后获得的最高浓度为17.49±2.03微克/毫升。我们得出结论，利多卡因以一种可能使套囊作为局部麻醉药储库发挥潜在有用作用的方式透过气管导管套囊扩散。这反过来似乎有可能使那些气管刺激可能成为复杂因素的患者全身气管内麻醉平稳苏醒。
