A VAD and Novel High Performance Compact Oxygenator for Long-Term ECMO with Local Anticoagulation

A novel method of long-term ECMO was designed and evaluated experimentally. Special features of this ECMO method include: 1. using a pneumatic diaphragm type VAD with excellent blood compatibility as a pump system; 2. using a newly developed, high performance, compact oxygenator, with a novel gas exchange membrane in which micropores are blind at the blood contacting surface; 3. regional anticoagulation within the ECMO circuit with short-acting protease inhibitor FUT-175; and 4. right heart bypass with direct cannulation through a thoracotomy. Four goats implanted with a VAD between the right atrium and the pulmonary artery underwent ECMO by interposing a compact oxygenator in the return cannula for as long as 14 days. Blood clotting was regulated with continuous infusion of FUT-175 from the inflow cannula of the ECMO circuit. In this system, 2 to 4 L/min of bypass flow, 80 to 120 ml/min of O2, and 40 to 80 ml/min of CO2 gas exchange were obtained. Serum leakage in the oxygenator did not occur, and various blood chemical and hematologic parameters were maintained within the normal range. Regional anticoagulant therapy was successfully achieved with a significant difference of activated clotting time between the blood samples from the systemic circulation and those from the ECMO circuit. These results indicate that this method overcomes several problems with ECMO, and has the capacity for long-term respiratory assistance.