The thromboresistant mechanism of Heparin surface and its application to membrane oxygenator

我们与瑞典Karolinska研究所合作，对肝素表面的抗血栓机制及其在膜式氧合器中的应用进行了研究。我们得到的结果如下：1.肝素涂层本身不吸收或发挥因子Xa抑制作用。随着抗凝血酶III（AT）吸附在高和低亲和力肝素上，表面具有抑制暴露于表面的Xa因子的能力。结果表明，AT在高亲和力和低亲和力肝素上的密度决定了Xa因子的抑制能力，而AT在高亲和力位点上的量限制了反应速率. Xa因子和凝血酶抑制能力在低壁剪切率段中相似，这是通过压缩一段表面肝素化动静脉分流术获得的。在高壁剪切率段，凝血酶抑制能力降低，表明AT介导的丝氨酸蛋白酶抑制依赖于壁剪切率.研究表明，在犬中，使用表面肝素化膜式氧合器的体外动静脉旁路循环可以在不进行任何全身肝素化的情况下进行至少24小时。证实了在上述相同的实验条件下也可以进行体外静脉-静脉转流循环。因此，我们得出结论，表面肝素化体外循环膜式氧合器是治疗呼吸衰竭患者的有效和有用的呼吸支持系统，该系统也适用于呼吸困难的围手术期患者.在气管切除和重建的情况下，我们准备了该系统用于呼吸支持，但由于没有必要使用该系统，我们将其备用。

We have conducted research work on the thromboresistant mechanism of Heparin surface and its application to membrane oxygenator in collaboration with the Karolinska Institute in Sweden. The results we have obtained are as follows;1. The heparin coating did not take up or exert Factor Xa inhibition by itself. With antithrombin III(AT) adsorbed on both high and low affinity heparin the surface had the capacity to inhibit Factor Xa exposed to the surface. It was demonstrated that the density of AT on both high and low affinity heparin determines the Factor Xa inhibition capacity whereas the amount of AT on high affinity sites limits the rate of the reaction.2. The Factor Xa and thrombin inhibitory capacity were similar in low wall shear rate segments which were obtained by compressing a segment of the surface-heparinized arterio-venous shunts. In high wall shear rate segments, the thrombin inhibitory capacity was decreased, thus indicating that the AT-mediated inhibition of the serine protease is dependent upon the wall shear rate.3. It was demonstrated that an extracorporeal arterio-venous bypass circulation with surface-heparinized membrane oxygenator can be performed for at least 24 hours without any systemic heparinization in dogs.4. It was confirmed that an extracorporeal veno-venous bypass circulation call be done as well under the same experimental conditions as above.5. Consequently we have concluded that the surface-heparinized extracorporeal circuit with membrane oxygenator is an effective and useful system for tile respiratory support in the treatment of the patients with respiratory failure and this system is also applicable for the perioperative patients with difficult airways.6. In the case of the tracheal resection and reconstruction we prepared this system for the respiratory support, but as it was unnecessary to use the system we kept it standby.