CPC A61B 17/3403 (2013.01) [A61B 8/0841 (2013.01); A61B 17/3415 (2013.01); A61B 17/3417 (2013.01); A61B 17/3423 (2013.01); A61B 2017/3413 (2013.01); A61B 90/39 (2016.02); A61B 2090/3925 (2016.02)] | 12 Claims |
1. A needle assembly, comprising:
an echogenic cannula having an echogenic longitudinal shaft of a given length that is echogenic along the entire given length, the shaft defined by a circumferential wall having an outer wall surface and an inner wall surface defining an axial bore that has a distal end and a proximal end connected to a cannula hub, the outer wall surface and the inner wall surface each are smooth along the entire length of the echogenic cannula; and
a needle having a shaft defining a through passage extending distally from a needle hub having an end connector adapted to be connected to a fluid store such that fluid can be conveyed through the passage of the shaft to a patient end of the needle, the shaft having a longitudinal axis, an outer circumferential wall and a sharp tip at the patient end, the needle having an echogenic feature that includes at least one continuous groove spirally wound about the outer circumferential wall of the shaft from at least adjacent the sharp tip to a predetermined distance away from the sharp tip, the one groove having two walls orthogonal to each other formed onto the outer circumferential wall along the predetermined distance of the shaft such that the orthogonal walls each are formed at an angle (α) tilted toward the proximal end of the shaft, one of the walls is formed at an angle (β) relative to the longitudinal axis of the shaft, the angle (β) resulting from subtraction of the angle (α) from a would be neutral position of the walls wherein the walls each are angled at approximately 45° from the longitudinal axis, the needle adapted to be inserted into a body at an insertion angle (Δ) offset from emitted ultrasound waves by the angle (β) such that ultrasound waves directed toward the needle are reflected in a reverse direction by at least one of the walls of the groove, the needle slidably extending along the axial bore of the cannula such that the needle hub and the cannula hub are engaged to each other and the sharp tip and at least a portion of the echogenic feature of the needle extend beyond the distal end of the cannula when the needle assembly is to be inserted into the body;
wherein the portion of the echogenic feature that extends beyond the distal end of the cannula and the echogenic cannula are both visible under ultrasonic observation during placement of the needle assembly into the body, the echogenic feature that extends beyond the distal end of the cannula adapted to guide insertion movement of the needle assembly into a desired location in the body, wherein the echogenic cannula is configured to remain in the body after the placement of the needle assembly to the desired location in the body such that the location of the echogenic longitudinal shaft of the cannula in the body is confirmable under ultrasonic observation after the needle is removed from the cannula.
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