Patent Description:
Common types of intravenous catheter are peripheral IV catheters ("PIVCs"), peripherally inserted central catheters ("PICCs"), and midline catheters. Intravenous catheters may include "over-the needle" catheters, which may be mounted over a needle having a sharp distal tip. The sharp distal tip may be used to pierce skin and the vasculature of the patient. Insertion of the intravenous catheter into the vasculature may follow the piercing of the vasculature by the needle. The needle and the intravenous catheter are generally inserted at a shallow angle through the skin into the vasculature of the patient with a bevel of the needle facing up and away from the skin of the patient.

In order to verify proper placement of the introducer needle and/or the intravenous catheter in the vasculature, a user generally confirms that there is flashback of blood, which may be visible to the user. In some instances, the introducer needle may include a notch disposed towards a distal end of the introducer needle, and in response to the distal tip of the introducer needle being positioned within the vasculature, blood may flow proximally through a needle lumen, exit the needle lumen through the notch, and then travel proximally between an outer surface of the introducer needle and an inner surface of the intravenous catheter.

Accordingly, where the intravenous catheter is at least partially transparent, the user may visualize a small amount of blood "flashback" and thereby confirm placement of the intravenous catheter within the vasculature. Presence of a vasculature entrance indicator, such as flashback, may facilitate successful placement of intravenous catheters. Once placement of the introducer needle within the vasculature has been confirmed, the user may temporarily occlude flow in the vasculature and withdraw the introducer needle, leaving the intravenous catheter in place for future blood withdrawal and/or fluid infusion.

The present disclosure generally relates to blood collection devices, systems, and methods to facilitate blood flashback. In some embodiments, a catheter system may include a catheter adapter which may include a distal end, a proximal end, and a lumen extending through the distal end and the proximal end. In some embodiments, the catheter system may include a catheter extending distally from the distal end of the catheter adapter. In some embodiments, the catheter system may include a needle hub, which may include a distal end and a proximal end. In some embodiments, the distal end of the needle hub may be coupled to the proximal end of the catheter adapter.

In some embodiments, the catheter system may include a peripheral intravenous catheter system, such as, for example, the BD NEXIVA™ Closed IV Catheter system, the BD CATHENA™ Catheter system, the BD VENFLON™ Pro Safely Shielded IV Catheter system, the BD NEOFLON™ IV Cannula system, the BD INSYTE™ AUTOGUARD™ BC Shielded IV Catheter system, or another suitable peripheral intravenous catheter system. In some embodiments, the catheter system may include a PICC system or a midline catheter system.

In some embodiments, the catheter system may include a needle, which may include a distal end and a proximal end. In some embodiments, the needle may include an introducer needle, which may include a sharp distal tip. In some embodiments, the needle may be secured within the needle hub. In some embodiments, the catheter system may include a flow control plug, which may be coupled to the proximal end of the needle hub. In some embodiments, the flow control plug may block a proximal opening of the needle hub such that blood does not exit the proximal opening of the needle hub. In some embodiments, the flow control plug may include one or more vents, which may include a porous membrane or microgrooves that may vent air while containing blood.

In some embodiments, the catheter system may include a flashback pathway disposed between an outer surface of the flow control plug and an inner surface of the needle hub. In some embodiments, the needle hub may be constructed of a clear or transparent material, which may facilitate observation blood within the flashback pathway. In some embodiments, the needle hub may include a lens, which may facilitate observation of blood within the flashback pathway. In some embodiments, the flow control plug may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway.

In some embodiments, the outer surface of the flow control plug may include a channel. In some embodiments, the flashback pathway may extend through the channel between the channel and the inner surface of the needle hub. In some embodiments, the channel may provide a high area-to-volume ratio and may include a small height compared to its width. In some embodiments, a velocity of blood travelling within the channel may be between <NUM>/s and <NUM>/s. In some embodiments, a velocity of blood travelling within the channel may between <NUM>/s and <NUM>/s, which may create a continuous motion indicative of vein access in a real-time or near real-time manner. In some embodiments, it may take greater than <NUM> for blood to move from one end of the channel to the other. For example, it may take between <NUM> and <NUM> for blood to move through the channel.

In some embodiments, the flashback pathway may provide an unobstructed, sharp-contrast visualization of a small volume of blood. In some embodiments, the catheter system may provide an effective signal for vein confirmation with a small amount of blood, such as approximately <NUM>. In some embodiments, the channel may be disposed on a top of the flow control plug, as illustrated, for example, in <FIG>, to ease visibility of the flashback pathway.

In some embodiments, the outer surface of the flow control plug may include a pocket proximate the channel. In some embodiments, the proximal end of the needle may be disposed within the pocket. In some embodiments, the pocket may be deeper than the channel. Blood travelling through the flashback pathway may be forced from the pocket to an outside of the flow control plug, which may improve visibility of the blood within the flashback pathway to the clinician.

In some embodiments, the channel may be formed by multiple side walls, which may extend from a bottom of the channel to the inner surface of the needle hub and may contact the inner surface of the needle hub. Thus, blood may be contained within the channel as it travels proximally through the channel. In some embodiments, the vent may be disposed proximate the channel, such as at a proximal end of the channel. In some embodiments, the vent may be disposed at an interface between the proximal end of the needle hub and the flow control plug.

In some embodiments, the distal end of the flow control plug may include a male luer. In some embodiments, the male luer may include a slip male luer or a threaded male luer. In some embodiments, a tip of the male luer may include a generally planar surface, which may extend across the tip such that a shape of the flashback pathway is generally semi-circular.

In some embodiments, the outer surface of the flow control plug may include multiple channels, and the flashback pathway may extend through the channels between the channels and the inner surface of the needle hub. In some embodiments, the outer surface of the flow control plug may include one or more grooves extending from the channels inwardly towards a longitudinal axis of the flow control plug. In some embodiments, a proximal end of each of the channels may be formed by a proximal wall. In some embodiments, the proximal wall may include one or more microgrooves configured to allow air but not blood to pass. In some embodiments, the proximal wall may interfere with an inner surface of the needle hub, which may prevent blood from exiting the proximal end of the channel.

In some embodiments, a catheter assembly of the catheter system may include the catheter adapter and the catheter. In some embodiments, a needle assembly of the catheter system may include one or more of the following: the needle hub, the needle, an inner barrel, and an outer barrel. In some embodiments, the inner barrel may surround the needle hub. In some embodiments, the needle hub may be secured within the inner barrel. In some embodiments, the flashback pathway may be disposed between an outer surface of the needle hub and an inner surface of the inner barrel. In some embodiments, the flow control plug may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway.

In some embodiments, the outer barrel may surround the inner barrel. In some embodiments, the inner barrel and the needle hub may be configured to move proximally within the outer barrel to retract the needle. In some embodiments, the needle assembly may include a button and/or a spring. In some embodiments, the inner barrel and the needle hub may move proximally within the outer barrel in response to depression of the button and actuation of the spring.

In some embodiments, the needle hub may include a channel, and the flashback pathway may extend through the channel between the channel and the inner surface of the inner barrel. In some embodiments, the needle hub may include a pocket proximate the channel. In some embodiments, the proximal end of the needle may be disposed within the pocket. In some embodiments, the pocket may be deeper than the channel. In some embodiments, a proximal end of the channel may be formed by a proximal wall of the needle hub. In some embodiments, the proximal wall may include one or more microgrooves configured to allow air but not blood to pass. In some embodiments, the proximal wall may interfere with an inner surface of the inner barrel. In some embodiments, the inner surface of the inner barrel may include one or more alignment ridges. In some embodiments, the outer surface of the needle hub may include one or more other alignment ridges, which may contact the alignment ridges.

In some embodiments, the needle assembly may include a middle barrel. In some embodiments, the inner barrel may include a hole and/or the middle barrel may include a hole aligned with the hole of the inner barrel. In some embodiments, the flashback pathway may include the first hole and the second hole and may extend between an outer surface of the middle barrel and an inner surface of the outer barrel. In some embodiments, the pocket may be proximate the first hole. In some embodiments, the inner barrel and the needle hub may be configured to move proximally within the middle barrel to retract the needle. In some embodiments, the inner barrel and the needle hub may move proximally in response to depression of the button and actuation of the spring.

It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the invention, as claimed. It should be understood that the various embodiments are not limited to the arrangements and instrumentality shown in the drawings. It should also be understood that the embodiments may be combined, or that other embodiments may be utilized and that structural changes, unless so claimed, may be made without departing from the scope of the various embodiments of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense.

All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the scope of the invention.

Referring now to <FIG>, in some embodiments, a catheter system <NUM> may include a catheter adapter <NUM> which may include a distal end <NUM>, a proximal end <NUM>, and a lumen <NUM> extending through the distal end <NUM> and the proximal end <NUM>. In some embodiments, the catheter system <NUM> may include a catheter <NUM> extending distally from the distal end <NUM> of the catheter adapter <NUM>. In some embodiments, the catheter system <NUM> may include a needle hub <NUM>, which may include a distal end <NUM> and a proximal end <NUM>. In some embodiments, the distal end <NUM> of the needle hub <NUM> may be coupled to the proximal end <NUM> of the catheter adapter <NUM>.

In some embodiments, the catheter system <NUM> may include a peripheral intravenous catheter system, such as, for example, the BD NEXIVA™ Closed IV Catheter system, the BD CATHENA™ Catheter system, the BD VENFLON™ Pro Safely Shielded IV Catheter system, the BD NEOFLON™ IV Cannula system, the BD INSYTE™ AUTOGUARD™ BC Shielded IV Catheter system, or another suitable peripheral intravenous catheter system. In some embodiments, the catheter system <NUM> may include a PICC system or a midline catheter system.

In some embodiments, the catheter system <NUM> may include a needle <NUM> which may include a distal end <NUM> and a proximal end <NUM>. In some embodiments, the needle <NUM> may include an introducer needle, which may include a sharp distal tip. In some embodiments, the needle <NUM> may be secured within the needle hub <NUM>. In some embodiments, the catheter system <NUM> may include a flow control plug <NUM>, which may be coupled to the proximal end <NUM> of the needle hub <NUM>. In some embodiments, the flow control plug <NUM> may block a proximal opening <NUM> of the needle hub <NUM> such that blood does not exit the proximal opening <NUM> of the needle hub <NUM>. In some embodiments, the flow control plug <NUM> may include one or more vents <NUM>, which may include a porous membrane or a microgroove that may vent air while containing blood. In some embodiments, a cap <NUM> may be coupled to a proximal end of the flow control plug <NUM>.

In some embodiments, the catheter system <NUM> may include a flashback pathway <NUM> disposed between an outer surface of the flow control plug <NUM> and an inner surface of the needle hub <NUM>. In some embodiments, the needle hub <NUM> may be constructed of a clear or transparent material, which may facilitate observation blood within the flashback pathway <NUM>. In some embodiments, the needle hub may include a lens <NUM>, which may facilitate observation of blood within the flashback pathway <NUM>. In some embodiments, the flow control plug <NUM> may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway <NUM>.

In some embodiments, the lens <NUM> may be disposed above a proximal end <NUM> of the needle <NUM>. In some embodiments, the lens <NUM> may be integrated within the needle hub <NUM>. In some embodiments, the lens <NUM> may be convex or another suitable shape. In some embodiments, an outer surface of the lens <NUM> may generally conform to a shape of an outer surface of the needle hub <NUM>.

In some embodiments, the outer surface of the flow control plug <NUM> may include a channel <NUM>. In some embodiments, the flashback pathway <NUM> may extend through the channel <NUM> between the channel <NUM> and the inner surface of the needle hub <NUM>. In some embodiments, the channel <NUM> may provide a high area-to-volume ratio and may include a small height compared to its width. In some embodiments, a velocity of blood travelling within the channel <NUM> may be between <NUM>/s and <NUM>/s. In some embodiments, a velocity of blood travelling within the channel <NUM> may between <NUM>/s and <NUM>/s, which may create a continuous motion indicative of vein access in a real-time or near real-time manner. In some embodiments, it may take greater than <NUM> for blood to move from one end of the channel <NUM> to the other. For example, it may take between <NUM> and <NUM> for blood to move through the channel <NUM>. In some embodiments, the channel <NUM> may be axially aligned with a longitudinal axis of the catheter system <NUM>.

In some embodiments, the flashback pathway <NUM> may provide an unobstructed, sharp-contrast visualization of a small volume of blood. In some embodiments, the catheter system <NUM> may provide an effective signal for vein confirmation with a small amount of blood, such as approximately <NUM>. In some embodiments, the channel <NUM> may be disposed on a top of the flow control plug <NUM>, as illustrated, for example, in <FIG>, to ease visibility of the flashback pathway <NUM>. A bevel of the sharp distal tip of the needle <NUM> may face toward a top of the catheter system <NUM> when the catheter system <NUM> is in an insertion position, ready for insertion into a patient, as illustrated, for example, in <FIG>.

In some embodiments, the outer surface of the flow control plug <NUM> may include a pocket <NUM> proximate the channel <NUM>. In some embodiments, the proximal end <NUM> of the needle <NUM> may be disposed within the pocket <NUM>. In some embodiments, the pocket <NUM> may be deeper than the channel <NUM>. Blood travelling through the flashback pathway <NUM> may be forced from the pocket <NUM> to an outside of the flow control plug <NUM>, which may improve visibility of the blood within the flashback pathway <NUM> to the clinician.

In some embodiments, the channel <NUM> may be formed by multiple side walls <NUM>, which may extend from a bottom of the channel <NUM> to the inner surface of the needle hub <NUM> and may contact the inner surface of the needle hub <NUM>. Thus, blood may be contained within the channel <NUM> as it travels proximally through the channel <NUM>. In some embodiments, the vents <NUM> may be disposed proximate the channel <NUM>, such as at a proximal end of the channel <NUM>. In some embodiments, the vents <NUM> may be disposed at an interface between the proximal end <NUM> of the needle hub <NUM> and the flow control plug <NUM>.

In some embodiments, the side walls <NUM> may include elongated ribs. In some embodiments, a height of the side walls <NUM> from a bottom of the channel <NUM> and/or a width of the channel <NUM> from one of the side walls <NUM> to the an opposite of the side walls <NUM> may increase with an increased gauge size of the catheter <NUM>. For example, the flow control plug <NUM> illustrated in <FIG> may be used with a larger gauge catheter than the flow control plug <NUM> illustrated in <FIG>. As another example, the flow control plug <NUM> illustrated in <FIG> may be used with a larger gauge catheter than the flow control plug <NUM> illustrated in <FIG>. In some embodiments, the distal end of the flow control plug <NUM> may include a male luer. In some embodiments, the male luer may include a slip male luer or a threaded male luer.

Referring now to <FIG>, in some embodiments, the outer surface of the flow control plug <NUM> may include multiple channels <NUM>, and the flashback pathway <NUM> may extend through the channels <NUM> between the channels <NUM> and the inner surface of the needle hub <NUM>. In some embodiments, a number of the channels <NUM> may vary. In some embodiments, the outer surface of the flow control plug <NUM> may include one or more grooves <NUM> extending from the channels <NUM> inwardly towards a longitudinal axis of the flow control plug <NUM>. In some embodiments, the grooves <NUM> may be generally perpendicular to the channels <NUM>.

In some embodiments, a proximal end of each of the channels <NUM> may be formed by a proximal wall <NUM>. In some embodiments, the proximal wall <NUM> may include one or more microgrooves configured to allow air but not blood to pass. In some embodiments, the proximal wall <NUM> may interfere with an inner surface of the needle hub <NUM>, which may prevent blood from exiting the proximal end of the channel <NUM>.

In some embodiments, the needle hub <NUM> may be constructed of a clear or transparent material, which may facilitate observation blood within the flashback pathway <NUM>. In some embodiments, the needle hub <NUM> may include one or more lenses, which may facilitate observation of blood within the flashback pathway <NUM>. In some embodiments, the flow control plug <NUM> may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway <NUM>.

Referring now to <FIG>, in some embodiments, a tip <NUM> of the male luer may include a generally planar surface <NUM>, which may extend across the tip <NUM> such that a shape of the flashback pathway <NUM> is generally semi-circular. In some embodiments, the flow control plug <NUM> illustrated in <FIG> may be used with an <NUM> or <NUM> gauge catheter or another suitable size catheter.

Referring now to <FIG>, in some embodiments, a catheter assembly <NUM> of a catheter system <NUM> may include the catheter adapter <NUM> and the catheter <NUM>. In some embodiments, the catheter system <NUM> may include or correspond to the catheter system <NUM> of one of more of <FIG>. In some embodiments, a needle assembly <NUM> of the catheter system <NUM> may include one or more of the following: the needle hub <NUM>, the needle <NUM>, an inner barrel <NUM>, and an outer barrel <NUM>. In some embodiments, the inner barrel <NUM><NUM> may surround the needle hub <NUM>. In some embodiments, the needle hub <NUM> may be secured within the inner barrel <NUM>. In some embodiments, the flashback pathway <NUM> may be disposed between an outer surface of the needle hub <NUM> and an inner surface of the inner barrel <NUM>. In some embodiments, the flow control plug <NUM> may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway <NUM>.

In some embodiments, the outer barrel <NUM> may surround the inner barrel <NUM>. In some embodiments, the inner barrel <NUM> and the needle hub <NUM> may be configured to move proximally within the outer barrel <NUM> to retract the needle <NUM>. In some embodiments, the needle assembly <NUM> may include a button <NUM> and/or a spring <NUM>. In some embodiments, the inner barrel <NUM> and the needle hub <NUM> may move proximally within the outer barrel <NUM> in response to depression of the button <NUM> and actuation of the spring <NUM>. In some embodiments, a needle retraction mechanism of the catheter system <NUM> may operate similar to the BD INSYTE™ AUTOGUARD™ BC Shielded IV Catheter System or another suitable catheter system.

In some embodiments, the inner barrel <NUM> may include a generally hour-glass shape so that its medial portion has a smaller diameter than either end. This shape facilitates engagement between an opening <NUM> in the button <NUM> and the inner barrel <NUM>. In some embodiments, when the button <NUM> or activation latch is not depressed or is "up" in a non-activated position, a projection <NUM> may be located inside the catheter adapter <NUM>. Thus, when the catheter <NUM> is still located on the needle <NUM> with the catheter adapter <NUM>, the projection <NUM> may prevent the button <NUM> from being moved "down" into the activated position.

When the catheter <NUM> is moved off the needle <NUM> so the catheter adapter <NUM> is not adjacent to the projection <NUM>, the button <NUM> may be moved "down," i.e. activated, because the catheter adapter <NUM> no longer interferes with the movement of the projection <NUM>. In this position, the opening <NUM> is larger than a maximum diameter of inner barrel <NUM>. The spring <NUM> can thus force the needle hub <NUM> and the inner barrel <NUM> to a proximal end of the outer barrel <NUM> and withdraw the the distal end <NUM> of the needle <NUM> into the outer barrel <NUM>. In some embodiments, the inner barrel <NUM> and the needle hub <NUM> may be integrally formed or monolithically formed as a single unit.

In some embodiments, the needle hub <NUM> may include a channel <NUM>, and the flashback pathway <NUM> may extend through the channel <NUM> between the channel <NUM> and the inner surface of the inner barrel <NUM>. In some embodiments, the needle hub <NUM> may include a pocket <NUM> proximate the channel <NUM>. In some embodiments, the proximal end of the needle <NUM> may be disposed within the pocket <NUM>. In some embodiments, the pocket <NUM> may be deeper than the channel <NUM>. In some embodiments, a proximal end of the channel <NUM> may be formed by a proximal wall <NUM> of the needle hub <NUM>. In some embodiments, the proximal wall <NUM> may include one or more vents, which may include a microgroove configured to allow air but not blood to pass. In some embodiments, the proximal wall <NUM> may interfere with an inner surface of the inner barrel <NUM>. In some embodiments, the inner surface of the inner barrel <NUM> may include one or more alignment ridges <NUM>. In some embodiments, the outer surface of the needle hub <NUM> may include one or more other alignment ridges <NUM>, which may contact the alignment ridges <NUM> to facilitate orientation of the needle hub <NUM> with respect to the inner barrel <NUM>.

Referring now to <FIG>, in some embodiments, the needle assembly <NUM> may include a middle barrel <NUM>. In some embodiments, the inner barrel <NUM> may include a first hole <NUM> and/or the middle barrel <NUM> may include a second hole <NUM> aligned with the first hole <NUM> of the inner barrel <NUM>. In some embodiments, the flashback pathway <NUM> may include the first hole <NUM> and the second hole <NUM> and may extend between an outer surface of the middle barrel <NUM> and an inner surface of the outer barrel <NUM>.

In some embodiments, a pocket <NUM> may be proximate the first hole <NUM>. In some embodiments, the inner barrel <NUM> and the needle hub <NUM> may be configured to move proximally within the middle barrel <NUM> to retract the needle <NUM>. In some embodiments, the inner barrel <NUM> and the needle hub <NUM> may move proximally in response to depression of the button <NUM> and actuation of the spring <NUM>.

In some embodiments, the outer surface of the middle barrel <NUM> may include a channel <NUM>, and the flashback pathway <NUM> may extend through the channel <NUM> between the channel <NUM> and the inner surface of the inner barrel <NUM>. In some embodiments, the needle hub <NUM> may include a pocket <NUM> proximate the channel <NUM>. In some embodiments, the proximal end <NUM> of the needle <NUM> may be disposed within the pocket <NUM>. In some embodiments, a proximal end of the channel <NUM> may be formed by a proximal wall <NUM> of the middle barrel <NUM>. In some embodiments, the proximal wall <NUM> may include one or more vents, which may each include a microgroove configured to allow air but not blood to pass. In some embodiments, the proximal wall <NUM> may interfere with an inner surface of the outer barrel <NUM>.

In some embodiments, the channel <NUM> may be formed by multiple side walls <NUM>, which may extend from a bottom of the channel <NUM> to the inner surface of the outer barrel <NUM> and may contact the inner surface of the outer barrel <NUM>. Thus, blood may be contained within the channel <NUM> as it travels proximally through the channel <NUM>.

Referring now to <FIG>, the needle hub <NUM> is illustrated being inserted into the inner barrel <NUM> during assembly of a catheter system. The catheter system may include or correspond to the catheter system <NUM> of <FIG> and/or <FIG>. In some embodiments, the proximal end <NUM> of the needle <NUM> may contact and be secured within the needle hub <NUM>, but a remaining portion of the needle <NUM> may not contact the needle hub <NUM> and/or any portion of the catheter system. In some embodiments, the proximal end <NUM> of the needle <NUM> may be pinched and/or glued within the needle hub <NUM>, as illustrated, for example, in <FIG>.

Referring now to <FIG>, in some embodiments, the vents <NUM> may be disposed on a bottom of the needle hub <NUM>, which may facilitate better fluid containment. In some embodiments, flashback may flow proximally through the channel <NUM> and then down one or more sides of the needle hub <NUM> to a location proximate the vents <NUM>. In some embodiments, a proximal end of the needle hub <NUM> may include a seal <NUM>, which may include a rib and/or may extend from one side of the vents <NUM> to the other.

Claim 1:
A catheter system (<NUM>, <NUM>), comprising:
a catheter assembly (<NUM>), comprising:
a catheter adapter (<NUM>), comprising a distal end, a proximal end, and a lumen extending through the distal end and the proximal end; and
a catheter (<NUM>) extending distally from the distal end of the catheter adapter (<NUM>); and
a needle assembly, comprising:
a needle hub (<NUM>);
a needle (<NUM>), comprising a distal end and a proximal end, wherein the needle (<NUM>) is secured within the needle hub (<NUM>);
an inner barrel (<NUM>) surrounding the needle hub (<NUM>), wherein the needle hub (<NUM>) is secured within the inner barrel (<NUM>), wherein the inner barrel (<NUM>) comprises a first hole (<NUM>);
characterized by
a middle barrel (<NUM>) surrounding the inner barrel (<NUM>), wherein the middle barrel (<NUM>) comprises a second hole (<NUM>) aligned with the first hole (<NUM>);
an outer barrel (<NUM>) surrounding the middle barrel (<NUM>); and
a flashback pathway (<NUM>) comprising the first hole (<NUM>) and the second hole (<NUM>) and
extending between an outer surface of the middle barrel (<NUM>) and an inner surface of the outer barrel (<NUM>).