Tierexperimentelle Untersuchungen zu Praktikabilität und Hämokompatibilität einer miniaturisierten extrakorporalen Membranoxygenierung

During treatment on an intensive care unit a severe complication of shock, sepsis or pneumonia is the development of ARDS (acute respiratory distress syndrome). An aggressive ventilation strategy is necessary to prevent hypoxemia but causes further damage to the lungs. The ventilator-induced lung injury leads to irreversible lung damage and increases mortality. With extracorporeal membrane oxygenation using capillary membrane oxygenators specialized centers have the possibility to provide sufficient gas exchange in severe ARDS with life-threatening hypoxemia despite optimal conservative treatment. The standard device used for ECMO is accompanied by several problems, for example large foreign surfaces and priming volumes as well as plasma leakage of membrane oxygenators. In order to improve biocompatibility and practical use of ECMO therapy, a miniaturized ECMO system was developed. It is composed of a portable DeltaStream® blood pump and a polymethyl-pentene membrane oxygenator (HILITE7000LT®) with reduced risk of plasma leakage. In the conducted study a heparin-coated miniaturized ECMO system was compared to the standard ECMO system over 24 hours. For that purpose, after inducing an experimental lung injury, eight pigs were joined to the conventional and to the miniaturized system, respectively. After starting extracorporeal circulation combined with lung protective ventilation, data regarding hemodynamics, gas exchange, ventilation, hematology, coagulation, blood pump and membrane oxygenator were collected at certain times. The main result is that the miniaturized ECMO system allowed sufficient oxygenation and deoxygenation over the complete period of time. Two main disadvantages were found: First, the cannulas of the miniaturized system limited blood flow through the ECMO circuit. Second, hemocompatibility of the miniaturized system was reduced compared to the conventional system, since a decrease in platelet count and an activation of the plasmatic coagulation system occurred. In general, the miniaturized ECMO system has proved reliable in the animal model. The lower priming volume and reduced risk of plasma leakage combined with simplified use outweigh the described problems and justify application of the new system in man. Further studies are necessary to clarify if the different heparin-coating, the blood pump or the membrane oxygenator is responsible for the increased activity of the coagulation system. Beyond that, the cannulas of the miniaturized system ought to be optimized