Patent ID: 6979317

Claim:
A medical device comprising: a needle having a lumen; and an inner cannula positioned within the needle lumen and movable longitudinally in the needle lumen, the inner cannula having a lumen for delivering a first fluid to the patient and the needle lumen arranged for delivering a second fluid to a patient, the inner cannula having a cannula tip configured to detach a mass from the needle when the inner cannula is moved from an extended position at which the cannula tip extends from a distal end of the needle to a withdrawn position at which the cannula tip is within the needle lumen; and further comprising an injection hub connected to the needle and the inner cannula and configured to deliver the first fluid though the lumen of the inner cannula and the second fluid between an inner surface of the needle and an outer surface of the inner cannula, wherein the injection hub includes a fluid activated piston connected to the inner cannula and, wherein the injection of the first fluid into the injection hub activates the piston.