We will develop an integrated blood pump-membrane oxygenator/heat exchanger suitable for cardiopulmonary bypass in patients < 5 kg body weight. This device will feature Nimbus' new pediatric/neonatal centrifugal blood pump system. Effective blood oxygenation and heat transfer will be accomplished via a microporous hollow fiber network containing an integral heat exchanger. The current prototype integrated unit has 0.5M2 membrane surface area and a priming volume of only 85 ml; approximately one-half the priming volume of separate blood pump, oxygenator, and interconnecting tubing found in conventional infant bypass systems. Other virtues of the Nimbus package are its compact size and portability, allowing for placement adjacent to the patient. Phase I will demonstrate the feasibility of this innovative concept. The aims of this program are to design and fabricate six prototype units and to perform in vitro and in vivo trials to evaluate system performance and suitability of this concept for neonatal cardiopulmonary bypass. If successful, we believe that the new Nimbus product would gain wide acceptance by pediatric perfusionists both in the U.S. and overseas.National Heart, Lung, and Blood Institute (NHLBI)