Bernards C M, Hill H F
Department of Anesthesiology, University of Washington, Seattle 98195.
Anesthesiology. 1991 Nov;75(5):827-32. doi: 10.1097/00000542-199111000-00015.
It has been frequently suggested that the spinal nerve root sleeve is a preferred route for redistribution of drugs from the epidural space to the spinal cord. To determine if this supposition is true, the authors measured the rate at which morphine, fentanyl, and lidocaine diffuse through dog and monkey meningeal specimens with and without a root sleeve. Two meningeal specimens of intact dura-arachnoid-pia mater were removed from each animal and placed in separate temperature-controlled diffusion cells. One specimen included a spinal nerve root sleeve; the other did not. The permeability of the tissues to each drug was then determined by placing the study drug in one of the reservoirs of the diffusion cell and measuring the rate at which the drug diffused through the tissue and accumulated in the second reservoir. There was no difference in permeability between specimens with and without a nerve root sleeve for any drug in either species. Lidocaine was found to diffuse through the tissue significantly faster than fentanyl in both the dog and monkey even though fentanyl is nearly 48 times more lipid soluble than lidocaine. Morphine diffused through the tissue significantly slower than both lidocaine and fentanyl. The authors conclude that the spinal nerve root sleeve is not a preferred route of entry for drugs moving from the epidural space to the spinal cord. In addition, despite hypotheses to the contrary, lipid solubility does not appear to be the overriding determinant of meningeal permeability.
经常有人提出，脊神经根袖是药物从硬膜外腔重新分布到脊髓的首选途径。为了确定这一假设是否正确，作者测量了吗啡、芬太尼和利多卡因在有和没有神经根袖的狗和猴脑膜标本中的扩散速率。从每只动物身上取下两个完整的硬脑膜-蛛网膜-软脑膜的脑膜标本，并将其置于单独的温度控制扩散池中。一个标本包括一个脊神经根袖；另一个则没有。然后通过将研究药物放入扩散池的一个储液器中，并测量药物通过组织扩散并在第二个储液器中积累的速率，来确定组织对每种药物的通透性。在两个物种中，对于任何药物，有和没有神经根袖的标本之间的通透性没有差异。在狗和猴中，都发现利多卡因通过组织的扩散速度明显快于芬太尼，尽管芬太尼的脂溶性几乎是利多卡因的48倍。吗啡通过组织的扩散速度明显慢于利多卡因和芬太尼。作者得出结论，脊神经根袖不是药物从硬膜外腔进入脊髓的首选途径。此外，尽管有相反的假设，但脂溶性似乎并不是脑膜通透性的首要决定因素。
