Oxygenator

An oxygenator for blood, comprising:

• an elongated hollow housing:
• a bundle of hollow fibers made of a plurality of hollow fibers for gas exchange disposed inside said housing along the longitudinal direction thereof, the ends of said hollow fibers having openings;
• two partition walls respectively supporting the two end portions of the hollow fibers in a liquid tight manner without blocking the openings at the ends of said hollow fibers and defining a gaseous chamber along with the inner wall of the said housing and the outer surfaces of the said hollow fibers;
• inlet and outlet ports for passing gaseous material, said inlet and outlet ports being in communication with the interior of said chamber and extending through a wall of said housing;
• inlet and outlet ports for passing blood, each communicating with the interior spaces of each of said hollow fibers on the outside of the said partition walls;
• an inward projection formed in an intermediate portion of said housing in the longitudinal direction thereof for engaging and fastening said bundle of hollow fibers to said housing and defining chamber portions inside said housing on opposing sides of said inward projection;
• at least one liquid passing groove formed at said inward projection for passing liquid collected at a narrow portion of the said housing defined by said inward projection from one of said chamber portions to the other end of said chamber portions in said housing, said collected liquid flowing down along the inner wall of said one chamber portion of said housing, through said at least one groove, and to said other chamber portion;
• each groove having a cross sectional area of from about 0.005 to 2.9 mm.sup.2 ;
• said grooves having a total cross sectional area S and said hollow fibers of said bundle of hollow fibers having a total membrane area M such that S/M is not less than 2.7.times.10.sup.-7.