Step needle for intraosseous access device
An apparatus and method for a stepped needle for an intraosseous device that uses the outer surface of the bone cortex as a reference point. Since the thickness of the bone cortex does not vary significantly between patients, the accuracy of needle placement can be improved. The device includes a needle with a stepped increase in outer diameter disposed along the needle shaft. The abrupt change in outer diameter provides a substantial increase in insertion force. The stepped increase prevents any further insertion into the bone cortex. Embodiments can include a tapered needle lumen for medullary access confirmation and an overtube that is rotatably and slidably engaged to protect surrounding tissues and prevent needle stick injuries. Further, a needle hub can be rotatable or slidable, and can transition an overtube to an extended position to prevent accidental needle stick injuries.
1 . A needle assembly for an intraosseous access system, comprising:
a needle hub; and
a needle coupled to the needle hub, the needle comprising:
a distal tip;
an outer surface defining a stepped increase in diameter at a predetermined distance from the distal tip, the stepped increase in diameter configured to penetrate a skin surface and abut against a bone cortex; and
a lumen comprising:
a first needle lumen diameter distal of the stepped increase in diameter; and
a second needle lumen diameter proximal of the stepped increase in diameter, the second needle lumen diameter greater than the first needle lumen diameter.
2 . The needle assembly according to claim 1 , wherein the predetermined distance is configured to allow the distal tip to extend through the bone cortex and into a medullary cavity of a bone.
3 . The needle assembly according to claim 1 , wherein the stepped increase in diameter is formed integrally with the needle.
4 . The needle assembly according to claim 1 , wherein a distal surface of the stepped increase in diameter extends perpendicular to a longitudinal axis of the needle.
5 . The needle assembly according to claim 1 , wherein a distal surface of the stepped increase in diameter extends at an angle to a longitudinal axis of the needle to define a tapered shape.
6 . The needle assembly according to claim 1 , wherein the lumen of the needle further comprises a third needle lumen diameter proximal of the second needle lumen diameter, the third needle lumen diameter less than the second needle lumen diameter to define a bulged portion in the needle.
7 . The needle assembly according to claim 6 , further comprising an obturator disposed within the lumen of the needle, an outer diameter of the obturator being equal to, or less than, the first needle lumen diameter.
8 . The needle assembly according to claim 1 , further including an overtube engaged with the outer surface of the needle, a distal tip of the overtube defining a portion of the stepped increase in diameter.
9 . The needle assembly according to claim 8 , wherein a longitudinal length of the overtube is less than a longitudinal length of a shaft of the needle, and wherein the overtube is adhered to the outer surface of the needle to form a collar.
10 . The needle assembly according to claim 8 , wherein the overtube is slidably or rotatably engaged with the needle.
11 . The needle assembly according to claim 8 , wherein the overtube includes a material selected from the group consisting of a metal, an alloy, a plastic, a polymer, a composite, and a carbon-based composite.
12 . The needle assembly according to claim 8 , wherein the overtube includes a first material and a second material different from the first material, wherein the first material is a relatively softer material and can elastically or plastically deform, and wherein the second material is a harder material and can be resistant to any elastic or plastic deformation.
13 . The needle assembly according to claim 12 , wherein the overtube is formed of concentric tubes comprising:
a first tube formed of one of the first material or the second material, the first tube disposed adjacent the needle; and
a second tube formed of one of the first material or the second material, the second tube disposed on an outer surface of the first tube.
14 . The needle assembly according to claim 12 , wherein the overtube is formed of adjacent tubes including a first tube formed of the first material disposed distally of a second tube formed of the second material.
15 . The needle assembly according to claim 12 , wherein a first portion of the overtube is formed of the first material and extends annularly about the needle between 1° and 359°, and wherein a second portion of the overtube is formed of the second material and extends annularly about the needle between 1° and 359°.
16 . The needle assembly according to claim 8 , wherein the distal tip of the overtube is configured to blunt and increase in diameter on contact with a surface of the bone cortex.
17 . The needle assembly according to claim 8 , wherein a proximal end of the overtube abuts against the needle hub to prevent further longitudinal movement of the distal tip of the needle.
18 . The needle assembly according to claim 8 , wherein the overtube is slidably engaged with the needle between a retracted position and an extended position, and wherein the distal tip of the overtube extends distally of the distal tip of the needle in the extended position.
19 . The needle assembly according to claim 18 , further comprising:
a locking mechanism configured to retain the overtube in the retracted position when in a locked configuration; and
an actuator configured to transition the locking mechanism between the locked configuration and an unlocked configuration, wherein the actuator is configured for rotating or sliding a proximal housing relative to a distal housing.
20 . The needle assembly according to claim 18 , further comprising an overtube biasing member configured to bias the overtube toward the extended position.
21 . The needle assembly according to claim 20 , wherein the overtube biasing member is configured to prevent the overtube from transitioning from the extended position to the retracted position.
22 . The needle assembly according to claim 18 , further including an abutment configured to engage the overtube in the extended position and prevent the overtube transitioning from the extended position to the retracted position.
23 . The needle assembly according to claim 8 , wherein one of the needle or the overtube includes graduated markings.
24 . The needle assembly according to claim 1 , wherein the needle hub includes a proximal housing slidably or rotatably engaged with a distal housing, and wherein the needle hub includes a biasing member configured to bias the distal housing toward a proximal position relative to the proximal housing.
25 . The needle assembly according to claim 24 , wherein the distal housing includes a distal face configured to engage the skin surface.