DEVELOPMENT OF A MEMBRANE-OXYGENATOR FOR LONG-TERM RESPIRATORY SUPPORT AND ITS EXPERIMENTAL EVALUATION IN PROLONGED ECMO

The authors developed a new membrane oxygenator (MO) for long-term res piratory support and evaluated its performance in animal experiments f or as long as 336 hr. The MO, with a membrane area of 1.2 m(2) and pri ming volume of 140 ml, is compact and designed to be interposed in a v entricular assist system (VAS) conduit. It is made with a novel hollow fiber membrane, in which micropores are blind-ended so that serum lea kage can be prevented during prolonged use. The blood contacting surfa ce of the MO is heparinized with a newly developed covalent bonding te chnique that ensures good thrombus resistance. In vivo evaluation with five adult goats was performed by installing the MO into a venoarteri al or venovenous bypass circuit. No systemic anticoagulant therapy was used, except for a heparin-added fluid infusion to keep the pressure monitoring lines open (2-3 U/kg/hr). Throughout the experiments, no pl asma leakage was observed, and gas transfer rates were maintained in a satisfactory range. Platelet counts did not decrease to less than 60% of levels before bypass, and hemolysis was negligible. The levels of coagulation parameters including fibrinogen, fibrin degradation produc ts (FDP), antithrombin III (AT III), antiplasmin, prothrombin time (PT ) and activated partial thromboplastic time (APTT) remained within phy siologic ranges and relatively constant. At the end of the evaluation, no thrombus formation was noted in three of five MOs. These results s uggest that this MO is a promising device for long-term respiratory su pport.