Development of an outside flow membrane oxygenator using a silicone hollow fiber

A new membrane oxygenator was devised and assessed for performance in animal experiments. A silicone fiber membrane oxygenator, heat exchanger, and arterial blood reservoir are the components. The oxygenator is an outside flow type with minimum intrapulmonary resistance and, consequently, gas transfer is by gravity venous drainage. This device was used to conduct normothermic cardiopulmonary bypass (CPB) in 10 sheep over a period of 8 hrs (high flow group: 6 sheep, mean flow, 4.7 + 0.5 L/min; low flow group: 4 sheep, mean flow, 1 L/min). Performance was evaluated with gas transfer capacity, hematologic examination during CPB, and scanning electromicroscopic (SEM) appearance of the membrane after CPB. Blood gas was maintained with high PO2 and acceptable PCO2 levels throughout CPB. Plasma free hemoglobin was significantly low and fibrinogen was also maintained within physiologic levels. Scanning electron microscopy showed no thrombus formation on the membranes of either group. These results indicate this oxygenator to be quite adequate for gas exchange and prevention of blood cell trauma; it is also applicable to pulsatile or separating CPB because of the arterial blood reservoir.