Patent ID: 8585679

Claim:
A single-lumen, multi-stage cannula comprising: a first stage comprising a longitudinal tubular tip having a first plurality of fenestrations disposed at a distal end of the tip for supplying fluid from a first region outside the cannula to provide an axial flow at a proximal end of the tip; a second stage coaxial with the first stage comprising a nozzle section having an outer lumen wall and an inner annular wall, wherein a central passage is disposed within the inner annular wall, wherein the central passage continues the axial flow from the first stage, wherein a plurality of outer passages are disposed between the outer lumen wall and the inner annular wall so that the inner annular wall isolates the central passage from the outer passages, wherein the outer lumen wall includes a plurality of second fenestrations, wherein each second fenestration supplies fluid from a second region outside the cannula to a respective outer passage, and wherein the outer passages have respective outlets arranged to provide an injected flow substantially parallel to the axial flow; and a proximal tube coaxial with the second stage and having a central lumen, wherein an initial portion of the central lumen continues the axial flow and receives the injected flow annularly injected around and substantially parallel with the axial flow, and wherein a proximal end of the central lumen delivers a drainage output of the cannula comprising the axial flow and injected flow together.