Coombs D W, Colburn R W, DeLeo J A, Twitchell B B
Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756.
Reg Anesth. 1993 Jul-Aug;18(4):230-7.
The authors report the use of multiple implanted intraspinal port and catheter systems per test animal to study the in vivo functional characteristics and reliability of a new implantable spinal drug delivery port system.
Four ewes were each implanted with two epidural and one subarachnoid silicone elastomer catheters at the lumbar level. Each catheter was connected in series to one of three Therex filtered spinal delivery ports implanted subcutaneously in a similar grid pattern in each ewe to facilitate percutaneous identification. Saline (2 ml) was injected 3 times weekly in each port. The ease of injection and behavioral responses were recorded for 207-213 days of implantation until sacrifice/necropsy.
All ports functioned reliably during the study. However, injection through two of the four subarachnoid catheters resulted in behavioral withdrawal responses intermittently. This behavioral pattern was much less common after epidural port injections. All four subarachnoid and four of eight epidural port and catheter systems were tested with local anesthetic just before sacrifice. Motor block was observed in three of four subarachnoid and three of four epidural port and catheter systems tested. Integrity of the other four epidural ports was tested by injection of methylene blue at sacrifice. This dye did not distribute in the epidural space in one of the latter four epidural ports (not local anesthetic tested) because of a concentric fibrotic reaction about the catheter. Similar fibrotic reactions surrounded the catheters that failed a functional test with local anesthetic.
The implantable intraspinal port system tested functions reliably under repetitive percutaneous access. However, filtering such ports, though desirable to prevent entry of debris into the spinal canal, did not eliminate pericatheter chronic subarachnoid and epidural reaction. The number of test animals required to test 12 ports chronically was reduced by two-thirds without undue trauma to the individual test subject. Chronic percutaneous injection of an implanted subarachnoid system is feasible but may be associated with behavioral effects similar to that seen with chronic epidural systems. Fibrosis around chronic silicone catheters limited functional utility in one-fourth of the implanted test systems. Further study of the potential reactivity of chronic epidural and subarachnoid catheters is indicated.
作者报告了在每只实验动物身上使用多个植入式椎管内端口和导管系统，以研究一种新型可植入式脊柱药物输送端口系统的体内功能特性和可靠性。
对4只母羊在腰椎水平分别植入2根硬膜外和1根蛛网膜下腔硅橡胶弹性体导管。每根导管串联连接到3个Therex过滤式脊柱输送端口中的一个，这些端口以类似的网格模式皮下植入每只母羊体内，以便于经皮识别。每周向每个端口注射3次生理盐水（2毫升）。记录植入207 - 213天直至处死/尸检期间的注射难易程度和行为反应。
在研究期间所有端口功能可靠。然而，通过4根蛛网膜下腔导管中的2根进行注射时，间歇性出现行为退缩反应。硬膜外端口注射后这种行为模式不太常见。在处死前，对所有4根蛛网膜下腔和8根硬膜外端口及导管系统中的4根用局部麻醉剂进行了测试。在测试的4根蛛网膜下腔和4根硬膜外端口及导管系统中，分别有3根观察到运动阻滞。在处死时，通过向另外4根硬膜外端口注射亚甲蓝来测试其完整性。由于导管周围出现同心纤维化反应（未用局部麻醉剂测试），在这4根硬膜外端口中的1根中，染料未在硬膜外间隙扩散。对局部麻醉剂功能测试失败的导管周围也出现了类似的纤维化反应。
所测试的可植入式椎管内端口系统在重复经皮穿刺时功能可靠。然而，过滤此类端口虽然有助于防止碎片进入椎管，但并未消除导管周围慢性蛛网膜下腔和硬膜外反应。在不对个体实验对象造成过度创伤的情况下，将长期测试12个端口所需的实验动物数量减少了三分之二。慢性经皮注射植入式蛛网膜下腔系统是可行的，但可能会产生与慢性硬膜外系统类似的行为影响。在四分之一的植入测试系统中，慢性硅橡胶导管周围的纤维化限制了其功能效用。表明需要进一步研究慢性硬膜外和蛛网膜下腔导管的潜在反应性。
