Membrane Versus Bubbler

Membranes were first conceived in the early 1950's. Development of this type of device seemed the logical approach because of the obvious disadvantage of the bubble oxygenator, namely, the direct contact of gaseous oxygen and blood precipitating considerable blood trauma. Membrane technology has literally raised the method of respiratory exchange from an unphysiologic, mechanical mixing of oxygen and blood to a gentle, molecular exchange of gases across a variety of membrane materials. Our institution's experience with membrane oxygenation spans 12 years. The conclusion that we derived from the accumulation of clinical and investigational data is that membranes lend themselves to a more physiologic treatment of cellular and plasma components without incurring the additional insult of microemboli generation. Time does not permit me to elucidate all the studies that have been reported by other investigators. However, I would like to highlight a few that have addressed some of the more controversial issues. In 1975 Solis1 studied particulate microemboli and in vitro platelet aggregation in patients during cardiac operations with bubblers and membranes using Coulter counter and ultrasound. His results documented a significant increase in the volume of particulate and air emboli in the bubbler over the membrane. In our experience with bubblers, we have never been able to attain an emboli free circuit. In fact,