Development of an Integrated Cardiopulmonary Support System

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In this research project, the following studies were conducted :(1) Development of a novel fine silicone hollow fiber for membrane oxygenator suitable for long term application and development of membrane oxygenator using the newly developed silicone hollow fiber(2) Development of a compact centrifugal blood pump system for long term application(3) Design of an integrated cardio-pulmonary support system with the developed system componentsOne of the limitaion of conventional silicone hollow fiber oxygenator is poor gas permeability. However, the silicone hollow fiber is free from plsam leakage, which is the major life limiting factor of the microporous membrane oxygenator. It has been difficult to fabricate a fine, thin hollow fiber for reduction of resistance to gas permeability because of the poor mechanical strength of conventional silicone materials. We have developed a novel silicone material with sufficient mechanical strength and fine silicone hollow fiber with an inner diameter … More of 30 mum and wall thickness of 50 mum which is approximately half of those of a conventional silicone hollow fiber. One of the difficulties in fabricating the oxygenator using the developed silicone hollow fiber is the collapse of the hollow fiber due to external force applied. By controlling the tension applied to the hollow fiber during winding process, we could minimize the collapse of hollow fiber during fabrication process. The oxygen and carbon dioxide transfer rates of the developed membrane oxygenator that have surface area of 2.0 m^2 were 195ml/min and 165ml/min respectively. The novel silicone membrane oxygenator developed in this study can be used for extended duration in such application as extracorporeal membrane oxygenation.In the centrifugal blood pump study the pump head where the impeller was supported by two ceramic pivot bearings was developed that was free from sea-shaft related problems of conventional centrifugal blood pumps. The impeller was driven by magnetically coupled diving system. For application to cardio pulmonary support system a new driver consisting of a compact dc brushless motor was developed. The distance between two coupling magnet could be adjusted to stabilize the motion of impeller utilizing a cam mechanism. The width, length and height of the driver were 134mm, 177mm, and 66.7 mm respectively. The system can generate 31/min against 529 mmHg.We combined the developed pump system and silicone hollow fiber membrane oxygenator and verified the basic performance of the system. At flow rate of 3L/min, the pressure drop across the oxygenator was approximately 35 mmHg. Thus the combined system have enough capability to generate 31/min even if the pressure head required is larger than 300 mmHg due to cardiovascular resistance and cannula resistance. Less