Patent ID: 7749435

Claim:
An oxygenator comprising: a housing having an interior; a blood inlet port in the housing through which blood is adapted to flow, the blood inlet port opening to outside the housing and communicating with the interior of the housing to introduce the blood into the interior of the housing; a hollow fiber membrane bundle positioned in the interior of the housing and comprised of a multiplicity of integrated hollow fiber membranes configured to subject the blood introduced into the housing to gas exchange; the hollow fiber membranes each possessing a lumen extending between opposite ends of the hollow fiber membrane forming a gas passage for passage of gas; a gas inlet port in the housing through which gas is adapted to flow, the gas inlet port opening to outside the housing and communicating with the gas passages of the hollow fiber membranes to introduce the gas into the gas passages; a gas outlet port in the housing through which gas is adapted to flow, the gas outlet port opening to outside the housing and communicating with the gas passages of the hollow fiber membranes to discharge the gas in the gas passages; a blood outlet port in the housing through which blood which has been subjected to the gas exchange is adapted to flow, the blood outlet port opening to outside the housing and communicating with the interior of the housing to discharge from the housing the blood which has been subjected to the gas exchange, the blood flowing in a downstream direction through the hollow fiber membrane bundle toward the blood outlet port; a filter member positioned in the housing at a position downstream of the hollow fiber membrane bundle with respect to the direction of blood flow so that the blood flows through the hollow fiber membrane bundle and is subjected to gas exchange before passing through the filter member, the filter member being constructed to catch bubbles in the blood which has been subjected to the gas exchange; a blood passage downstream of the filter member into which flows the blood which has passed through the filter member, the blood passage being defined by a gap having a predetermined width between an outer surface of the filter member and an inner surface of the housing; and a passage enlargement between the blood passage and the blood outlet port, the passage enlargement having an enlarged width defined between the outer surface of the filter member and the inner surface of the housing, the enlarged width being greater than the predetermined width of the blood passage such that the passage enlargement provides an increased passage cross-sectional area relative to the blood passage so that blood which has passed through the filter member toward the blood outlet port is decelerated in the passage enlargement.