Hollow fiber-type artificial lung

Claim 1

A hollow fiber-type artificial lung, comprising: an axially extended housing; a hollow fiber bundle including a multiplicity of hollow fibers accommodated within and along the axial direction of said housing, said hollow fibers forming blood channels between outer wall surfaces of neighboring ones of said fibers, and being arranged within said housing in such a manner that neighboring blood channels are brought into substantial communication; first and second walls each having cylindrically concave faces for liquid-tightly supporting said hollow fibers at both end portions of said fibers within said housing; gas inlet means provided on an outer side of at least one of said first and said second walls for communicating with the hollow interior of said hollow fibers; the concave faces of said first and second walls, the inner wall of said housing and the outer wall surfaces of said hollow fibers defining a blood chamber, wherein the centers of the cylindrically concave faces of said first and second walls define extreme axial end locations of said blood chamber; blood inlet and outlet means communicating with said blood chamber; the inner surface of said housing in the vicinity of said blood inlet means being flared outwardly relative to the inner surface of the intermediate portion of the housing, for forming a first annular blood flow passage in said blood chamber at a portion adjacent to said first wall between the outer periphery of said hollow fiber bundle and the inner surface of the flared housing, wherein the flared inner surface of said housing in the vicinity of said blood inlet means is off-centered with respect to said hollow fiber hundle to increase the distance between said blood inlet means and said hollow fiber bundle and thus enlarge the flow area of said first blood flow passage facing said blood inlet means while gradually diminishing the flow area of said first blood flow passage with increasing distance from said blood inlet means, so that the amount of blood entering said first blood flow passage from said inlet means is substantially uniform circumferentially of said hollow fiber bundle and the flow rate of blood traveling axially of the housing within said blood chamber tends to be made uniform, said first blood flow passage communicates with said blood inlet means and surrounds said hollow fiber bundle circumferentially at the end portion retained by said first wall, and said housing forming a second blood flow passage at a portion adjacent to said second wall, said second flow passage communicating with said blood outlet means and surrounding said hollow fiber bundle circumferentially at the end portion retained by said second wall; the inner surface of said housing in the vicinity of said blood outlet means being flared outwardly relative to the inner surface of the intermediate portion of said housing, for forming said second blood flow passage in an annular shape between the outer periphery of said hollow fiber bundle and the inner surface of said housing: the flared inner surface of said housing in the vicinity of said blood outlet means is off-centered with respect to said hollow fiber bundle to increase the distance between said blood outlet means and said hollow fiber bundle and thus enlarge the flow area of said second blood flow passage facing said blood outlet means while gradually diminishing the flow area of said second blood flow passage with increasing distance from said blood outlet means so that the amount of blood entering said second blood flow passage is substantially uniform circumferentially of said hollow fiber bundle and the flow rate of blood traveling axially of said housing becomes uniform in relation to the circumferential direction of said hollow fiber bundle; said housing having an inner diameter of minimum value at the vicinity of the central region of said housing axially thereof for constricting said hollow fiber bundle, and a gradually larger value in the direction toward the ends of the housing for varying the cross-sectional area of said blood channels formed between neighboring fibers to narrow said blood channels toward the axial center region of said hollow fiber bundle from both of its ends; and gas venting means communicating with the interior of said blood chamber in the vicinity of the center of the concave face of said second wall so that said gas venting means can be situated at substantially the highest location of said blood chamber when said housing is vertically oriented when the artificial lung is in use.