Patent ID: 8017075

Claim:
An oxygenator comprising: a housing possessing a rectangular parallelepiped form; a hollow fiber membrane bundle positioned in the housing, the hollow fiber membrane bundle comprising a multiplicity of hollow fiber membranes adapted to perform gas exchange, each of the hollow fiber membranes possessing a lumen; the hollow fiber membrane bundle possessing a rectangular parallelepiped form, the hollow fiber membrane bundle possessing an outer surface; a gas-inlet communicating with the lumens at an upstream end of the hollow fiber membranes; a gas-outlet communicating with the lumens at a downstream end of the hollow fiber membranes; a blood passage at an exterior of the hollow fiber membranes along which blood flows during the gas exchange, the blood passage extending between a blood inlet at an upstream end of the blood passage and a blood outlet at a downstream end of the blood passage; and a bubble catching filter member which catches bubbles in the blood flowing towards the blood outlet, the bubble catching filter member being provided on a side of the hollow fiber membrane bundle closer to the blood outlet; wherein the filter member is a flat sheet member and a planar surface of said sheet member directly contacts the outer surface of the hollow fiber membrane bundle.