Hawkins I F, Wilcox C S, Kerns S R, Sabatelli F W
Division of Angio/Interventional Radiology, University of Florida College of Medicine, Gainesville 32610-0374.
Am J Kidney Dis. 1994 Oct;24(4):685-94. doi: 10.1016/s0272-6386(12)80232-0.
Although the new nonionic contrast agents are safer than ionic agents, renal insufficiency and even death still occur occasionally. Therefore, we have explored the use of carbon dioxide (CO2) as an alternative angiographic contrast agent used in combination with digital subtraction angiography. Clinical observations have been made in over 800 patients. The images obtained are of equivalent diagnostic quality compared with those using conventional iodinated contrast agents. Recent advances in imaging, including "stacking," provide images comparable with iodinated contrast. Very small vessels, equivalent to third-order branches of the renal artery, can be imaged satisfactorily with CO2. Occasional studies with CO2 yield information not apparent with iodinated contrast agents, including excellent visualization of arteriovenous shunts, collateral circulations, malignant tumors, and minute amounts of arterial bleeding. Many of the advantages and disadvantages of CO2 derive from its special physical and chemical properties. The advantages include no allergic potentiation and no renal metabolism of CO2, because CO2 is cleared by the lungs and does not recirculate. Other advantages include delivery by very small catheters because of the low viscosity of CO2, minimal discomfort on injection, and very low cost. However, the low-density and compressibility of CO2 poses some special problems. Imaging requires digital subtraction angiography with electronic enhancement and injections require an experienced investigator and, ideally, a dedicated CO2 injector. The dedicated CO2 injector provides calculated, controlled dosing and rates for injection, while excluding the possibility of air contamination. The buoyancy of CO2 inhibits good filling of dependent vessels. Accordingly, CO2 does not normally produce good nephrographic images, although proximal renal arteries are normally shown clearly. Experimental studies in dogs, whose renal arteries have been injected repeatedly with very large doses of CO2, demonstrate only transient changes in renal blood flow and no endothelial cell damage. However, these studies also showed clearly that renal ischemia can occur due to a "vapor lock" phenomenon if the kidney is positioned vertically above the injection site, and recurrent injections are given without time for absorption of the arterially delivered CO2 boluses. Uncontrolled studies in over 800 patients have confirmed that CO2 likely has a very low renal toxicity. At the University of Florida, CO2 is the radiologic contrast agent of choice in patients with renal insufficiency, especially those with diabetes mellitus, and in those with pre-existing allergy to iodinated contrast agents. Further controlled clinical studies are required to define the true clinical utility and safety of CO2 compared with conventional radiologic contrast agents.
尽管新型非离子型造影剂比离子型造影剂更安全，但肾功能不全甚至死亡仍偶尔发生。因此，我们探索了使用二氧化碳（CO₂）作为与数字减影血管造影联合使用的替代血管造影剂。已对800多名患者进行了临床观察。与使用传统碘化造影剂获得的图像相比，所获得的图像具有同等的诊断质量。包括“叠加”在内的成像技术的最新进展提供了与碘化造影相当的图像。非常小的血管，相当于肾动脉的三级分支，可以用CO₂满意地成像。偶尔使用CO₂进行的研究可获得碘化造影剂无法显示的信息，包括动静脉分流、侧支循环、恶性肿瘤和微量动脉出血的良好可视化。CO₂的许多优缺点都源于其特殊的物理和化学性质。优点包括无过敏增强作用，且CO₂不经肾脏代谢，因为CO₂由肺清除且不会再循环。其他优点包括由于CO₂粘度低，可用非常小的导管输送，注射时不适最小，且成本非常低。然而，CO₂的低密度和可压缩性带来了一些特殊问题。成像需要带有电子增强功能的数字减影血管造影，注射需要经验丰富的研究人员，理想情况下还需要专用的CO₂注射器。专用的CO₂注射器可提供计算得出的、可控的剂量和注射速率，同时排除空气污染的可能性。CO₂的浮力会抑制下垂血管的良好充盈。因此，尽管肾动脉近端通常能清晰显示，但CO₂通常不会产生良好的肾造影图像。对犬进行的实验研究中，其肾动脉被反复注射非常大剂量的CO₂，结果仅显示肾血流有短暂变化，且无内皮细胞损伤。然而，这些研究也清楚地表明，如果肾脏垂直位于注射部位上方，且在动脉输送的CO₂团块没有时间吸收的情况下进行反复注射，可能会因“气锁”现象导致肾缺血。对800多名患者进行的非对照研究证实，CO₂的肾毒性可能非常低。在佛罗里达大学，CO₂是肾功能不全患者，尤其是糖尿病患者以及对碘化造影剂已有过敏反应患者的首选放射学造影剂。与传统放射学造影剂相比，需要进一步进行对照临床研究来确定CO₂的真正临床效用和安全性。
