[An experimental study of a newly developed silicone coated membrane oxygenator]

The surface of polypropylene hollow fiber is successfully coated with very thin (0.2 micron) silicone layer. Using this fiber, membrane oxygenator was newly developed. To test its reliability biocompatibility and durability, experimental studies were performed using goats. Long-term (6 hours) normothermic cardiopulmonary bypass (CPB) model was applied in 10 animals. A conventional membrane oxygenator (Mera Excelung HPO-15H, MERA, Tokyo) was used in five goats as a control (C-NC group), and a new silicone coated membrane oxygenator, which is the exact same construction of C-NC group, in five (C-SC group). In the both groups, the same roller pump and circuit were used. The pump flow was 64.9 +/- 5.1 ml/kg in C-NC group, and 65.7 +/- 3.1 ml/kg in C-SC group. There were no significant differences between the two groups Hemodynamics changes during pumping in the both groups were similar, and all animals could successfully wean from CPB. The O2 transfer and CO2 removal functions of C-SC group showed the same ranges as compared with that of C-NC group, indicating clinically acceptable values. In the parameters of coagulation, fibrinolytic and complement activations, there were almost no differences between the two groups. As for hemolysis, however, plasma free hemoglobin of C-SC group (56.2 +/- 43.9 mg/dl) was lower than that of C-NC group (125.7 +/- 65.3 mg/dl). In the scanning electron microscopy, much less platelet clots and red blood cell adhesion were observed in C-SC group as compared with C-NC group. Chronic (96 hours) percutaneous cardiopulmonary support (PCPS) model was applied in 6 animals. In this model, a same conventional membrane oxygenator was used in three goats as a control (P-NC group), and a new silicone coated membrane oxygenator, in three (P-SC group). The O2 transfer and CO2 removal functions of the both groups showed the same ranges. Plasma free hemoglobin, the parameters of coagulation and fibrinolysis of P-SC group were lower than that of P-NC group, especially after 72 hours support. In conclusion, this new oxygenator was reliable, biocompatible and durable, and it is suitable not only for CPB, but also for long-term cardiac support.