Evaluation of a Newly Developed, Heparin-Bonded Artificial Lung in Chronic Animal Experiments

Our artificial lung (AL) for long-term extracorporeal membrane oxygenation (ECMO) consists of a special membrane in which micropores on the outer surface of the hollow fibers are blind-ended to eliminate direct blood-gas contact, and the entire blood-contacting surface is treated with covalent heparin binding to promote antithrombogenicity. Chronic performance of the AL was evaluated for gas-exchange function and thromboresistant properties in four goats weighing 28–36 kg, using a venoarterial bypass circuit perfused by means of a pneumatic ventricular assist device for up to 14 days. Serum leakage was completely prevented in all the devices throughout the experimental period. With 3.3–4.21/min of blood flow and 10–151/min of oxygen flow, the AL transferred 166 ± 25ml/min of oxygen and 116 ± 41ml/min of carbon dioxide. Platelet counts and antithrombin III levels significantly decreased during the initial 3 days but rebounded thereafter. Only in one AL was macroscopic thrombus formation observed, presumably related to severe infection. Scanning electron microscopy showed the surface of hollow fibers to be free of thrombus, while fibrin deposits were observed in all devices, mainly on the polyester threads used for weaving the hollow fibers. These results indicate that our new AL can be used for prolonged ECMO, although further improvement in thromboresistant properties should be achieved.