Self-occluding intravascular cannula assembly

Claim 1

A self-occluding cannula assembly comprising: a generally tubular cannula sheath having a proximal end, a distal end and an inner lumen extending axially therethrough; a connecting hub formed on the proximal end of said cannula sheath, said connecting hub having an axial bore formed therein, said axial bore being fluidly consistent with the inner lumen of said cannula sheath; and an occluding means comprising: a generally frusto conical dilator projection formed within the bore of said connecting hub; an elastomeric valving member having a peripheral portion and a mid-portion, said elastomeric valving member being positioned transversely within the bore of said connecting hub, proximal to said dilator projection, with the peripheral portion thereof being axially compressed so as to cause the exertion of radially inward pressure toward the mid-portion thereof; and an elastically openable and closable aperture extending axially through the mid-portion of said valving member; said peripherally compressed valving member being alternately movable between an "occluding" position wherein said openable and closable aperture remains closed so as to substantially preclude fluid flow through said cannula lumen; and a "non-occluding" position wherein the mid-portion of said valving member is advanced over at least a portion of said dilator projection such that the dilator projection exerts sufficient pressure against said valving member to cause said openable and closable aperture to assume an open configuration thereby allowing fluid flow through said cannula lumen; and said valving member, when in said "non-occluding" position being sufficiently resilient to automatically return to said "occluding" position when said distally directed pressure is removed therefrom.