Hemocompatibility of a miniaturized extracorporeal membrane oxygenation and a pumpless interventional lung assist in experimental lung injury.

Extracorporeal membrane oxygenation (ECMO) is used for most severe acute respiratory distress syndrome cases in specialized centers. Hemocompatibility of devices depends on the size and modification of blood contacting surfaces as well as blood flow rates. An interventional lung assist using arteriovenous perfusion of a low-resistance oxygenator without a blood pump (Novalung, Hechingen, Germany) or a miniaturized ECMO with reduced filling volume and a diagonal blood pump (Deltastream, Medos AG, Stolberg, Germany) could optimize hemocompatibility. The aim of the study was to compare hemocompatibility with conventional ECMO. Female pigs were connected to extracorporeal circulation for 24 h after lavage induced lung injury (eight per group). Activation of coagulation and immune system as well as blood cell damage was measured. A P value <0.05 was considered significant. Plasmatic coagulation was slightly activated in all groups demonstrated by increased thrombin-anti-thrombin III-complex. No clinical signs of bleeding or thromboembolism occurred. Thrombelastography revealed decreased clotting capacities after miniaturized ECMO, probably due to significantly reduced platelet count. These resulted in reduced dosage of intravenous heparin. Scanning electron microscopy of oxygenator fibers showed significantly increased binding and shape change of platelets after interventional lung assist. In all groups, hemolysis remained negligible, indicated by low plasma hemoglobin concentration. Interleukin 8 and tumor necrosis factor-alpha concentration as well as leukocyte count remained unchanged. Both devices demonstrated adequate hemocompatibility for safe clinical application, although a missing blood pump did not increase hemocompatibility. Further studies seem necessary to analyze the influence of different blood pumps on platelet drop systematically.