Patent Publication Number: US-2023141587-A1

Title: Blood collection devices, systems, and methods facilitating blood flashback

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/998,592, filed Aug. 20, 2020, and entitled BLOOD COLLECTION DEVICES, SYSTEMS, AND METHODS FACILITATING BLOOD FLASHBACK, which claims the benefit of U.S. Provisional Patent Application No. 62/901,631, filed Sep. 17, 2019, and entitled BLOOD COLLECTION DEVICES, SYSTEMS, AND METHODS FACILITATING BLOOD FLASHBACK, which are incorporated herein in their entirety. 
    
    
     BACKGROUND 
     Intravenous catheters are commonly used for a variety of infusion therapies. For example, intravenous catheters may be used for infusing fluids, such as normal saline solution, various medicaments, and total parenteral nutrition, into a patient. Intravenous catheters may also be used for withdrawing blood from the patient. 
     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 subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some implementations described herein may be practiced. 
     SUMMARY 
     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 1 mm/s and 2 mm/s. In some embodiments, a velocity of blood travelling within the channel may between 0.22 mm/s and 2 mm/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 1 s for blood to move from one end of the channel to the other. For example, it may take between 5 s and 20 s 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 10 mL. In some embodiments, the channel may be disposed on a top of the flow control plug, as illustrated, for example, in  FIG.  1 A , 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. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Example embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG.  1 A  is an upper perspective view of an example catheter system, according to some embodiments; 
         FIG.  1 B  is an exploded view of the catheter system of  FIG.  1 A , according to some embodiments; 
         FIG.  1 C  is an upper perspective view of an example flow control plug, according to some embodiments; 
         FIG.  1 D  is an upper perspective view of another example flow control plug, according to some embodiments; 
         FIG.  1 E  is a cross-sectional view of the catheter system of  FIG.  1 A , according to some embodiments; 
         FIG.  1 F  is an enlarged cross-sectional view of a portion of the catheter system of  FIG.  1 A , according to some embodiments; 
         FIG.  1 G  is a cross-sectional view of the catheter system of  FIG.  1 A  along the line  1 G- 1 G of  FIG.  1 A , according to some embodiments; 
         FIG.  2 A  is an upper perspective view of another example flow control plug, according to some embodiments; 
         FIG.  2 B  is a cross-sectional view of the flow control plug of  FIG.  2 A  coupled to the catheter system of  FIG.  1 A , according to some embodiments; 
         FIG.  2 C  is an upper perspective view if the flow control plug of  FIG.  2 A  coupled to an example needle assembly, according to some embodiments; 
         FIG.  2 D  is a transverse cross-sectional view along the line  2 D- 2 D of  FIG.  2 C , according to some embodiments; 
         FIG.  3 A  is an upper perspective view of another example flow control plug, according to some embodiments; 
         FIG.  3 B  is a cross-sectional view of the flow control plug of  FIG.  3 A  coupled to the catheter system of  FIG.  1 A , according to some embodiments; 
         FIG.  3 C  is a transverse cross-sectional view of the flow control plug of  FIG.  3 A  coupled to the catheter system of  FIG.  1 A , according to some embodiments; 
         FIG.  4 A  is an upper perspective view of another catheter system, according to some embodiments; 
         FIG.  4 B  is a cross-sectional view of the catheter system of  FIG.  4 A , according to some embodiments; 
         FIG.  4 C  is an upper perspective view of an example needle hub of the catheter system of  FIG.  4 A , according to some embodiments; 
         FIG.  4 D  is an enlarged cross-sectional view of an example pocket, according to some embodiments; 
         FIG.  4 E  is an enlarged upper perspective view of an example microgroove, according to some embodiments; 
         FIG.  4 F  is an upper perspective view of an example inner barrel, according to some embodiments; 
         FIG.  5 A  is a cross-sectional view of another example catheter system, according to some embodiments; 
         FIG.  5 B  is an upper perspective view of the catheter system of  FIG.  5 A , illustrating an example outer barrel removed, according to some embodiments; 
         FIG.  5 C  is a cross-sectional view of a proximal end of the catheter system of  FIG.  5 A , according to some embodiments; 
         FIG.  5 D  is an enlarged cross-sectional view of an example pocket of the catheter system of  FIG.  5 A , according to some embodiments; 
         FIG.  5 E  is a transverse cross-sectional view of the catheter system of  FIG.  5 A , according to some embodiments; 
         FIG.  6 A  is a cross-sectional view of an example needle hub being inserted into an example barrel, according to some embodiments; 
         FIG.  6 B  is an enlarged cross-sectional view of a portion of the needle hub of  FIG.  6 A , according to some embodiments; 
         FIG.  6 C  is an upper perspective view of the needle hub of  FIG.  6 A , according to some embodiments; and 
         FIG.  6 D  is a lower perspective view of a portion of the needle hub of  FIG.  6 A , according to some embodiments. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     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 spirit and scope of the invention. 
     Referring now to  FIG.  1 A- 1 G , in some embodiments, a catheter system  10  may include a catheter adapter  12  which may include a distal end  14 , a proximal end  16 , and a lumen  18  extending through the distal end  14  and the proximal end  16 . In some embodiments, the catheter system  10  may include a catheter  20  extending distally from the distal end  14  of the catheter adapter  12 . In some embodiments, the catheter system  10  may include a needle hub  22 , which may include a distal end  24  and a proximal end  26 . In some embodiments, the distal end  24  of the needle hub  22  may be coupled to the proximal end  26  of the catheter adapter  12 . 
     In some embodiments, the catheter system  10  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  10  may include a PICC system or a midline catheter system. 
     In some embodiments, the catheter system  10  may include a needle  28  which may include a distal end  30  and a proximal end  32 . In some embodiments, the needle  28  may include an introducer needle, which may include a sharp distal tip. In some embodiments, the needle  28  may be secured within the needle hub  22 . In some embodiments, the catheter system  10  may include a flow control plug  34 , which may be coupled to the proximal end  26  of the needle hub  22 . In some embodiments, the flow control plug  34  may block a proximal opening  36  of the needle hub  22  such that blood does not exit the proximal opening  36  of the needle hub  22 . In some embodiments, the flow control plug  34  may include one or more vents  38 , which may include a porous membrane or a microgroove that may vent air while containing blood. In some embodiments, a cap  35  may be coupled to a proximal end of the flow control plug  34 . 
     In some embodiments, the catheter system  10  may include a flashback pathway  40  disposed between an outer surface of the flow control plug  34  and an inner surface of the needle hub  22 . In some embodiments, the needle hub  22  may be constructed of a clear or transparent material, which may facilitate observation blood within the flashback pathway  40 . In some embodiments, the needle hub may include a lens  42 , which may facilitate observation of blood within the flashback pathway  40 . In some embodiments, the flow control plug  34  may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway  40 . 
     In some embodiments, the lens  42  may be disposed above a proximal end  32  of the needle  28 . In some embodiments, the lens  42  may be integrated within the needle hub  22 . In some embodiments, the lens  42  may be convex or another suitable shape. In some embodiments, an outer surface of the lens  42  may generally conform to a shape of an outer surface of the needle hub  22 . 
     In some embodiments, the outer surface of the flow control plug  34  may include a channel  44 . In some embodiments, the flashback pathway  40  may extend through the channel  44  between the channel  44  and the inner surface of the needle hub  22 . In some embodiments, the channel  44  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  44  may be between 1 mm/s and 2 mm/s. In some embodiments, a velocity of blood travelling within the channel  44  may between 0.22 mm/s and 2 mm/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 1 s for blood to move from one end of the channel  44  to the other. For example, it may take between 5 s and 20 s for blood to move through the channel  44 . In some embodiments, the channel  44  may be axially aligned with a longitudinal axis of the catheter system  10 . 
     In some embodiments, the flashback pathway  40  may provide an unobstructed, sharp-contrast visualization of a small volume of blood. In some embodiments, the catheter system  10  may provide an effective signal for vein confirmation with a small amount of blood, such as approximately 10 mL. In some embodiments, the channel  44  may be disposed on a top of the flow control plug  34 , as illustrated, for example, in  FIG.  1 A , to ease visibility of the flashback pathway  40 . A bevel of the sharp distal tip of the needle  28  may face toward a top of the catheter system  10  when the catheter system  10  is in an insertion position, ready for insertion into a patient, as illustrated, for example, in  FIG.  1 A . 
     In some embodiments, the outer surface of the flow control plug  34  may include a pocket  46  proximate the channel  44 . In some embodiments, the proximal end  32  of the needle  28  may be disposed within the pocket  46 . In some embodiments, the pocket  46  may be deeper than the channel  44 . Blood travelling through the flashback pathway  40  may be forced from the pocket  46  to an outside of the flow control plug  34 , which may improve visibility of the blood within the flashback pathway  40  to the clinician. 
     In some embodiments, the channel  44  may be formed by multiple side walls  48 , which may extend from a bottom of the channel  44  to the inner surface of the needle hub  22  and may contact the inner surface of the needle hub  22 . Thus, blood may be contained within the channel  44  as it travels proximally through the channel  44 . In some embodiments, the vents  38  may be disposed proximate the channel  44 , such as at a proximal end of the channel  44 . In some embodiments, the vents  38  may be disposed at an interface between the proximal end  26  of the needle hub  22  and the flow control plug  34 . 
     In some embodiments, the side walls  48  may include elongated ribs. In some embodiments, a height of the side walls  48  from a bottom of the channel  44  and/or a width of the channel  44  from one of the side walls  48  to the an opposite of the side walls  48  may increase with an increased gauge size of the catheter  20 . For example, the flow control plug  34  illustrated in  FIG.  1 D  may be used with a larger gauge catheter than the flow control plug  34  illustrated in  FIG.  1 C . As another example, the flow control plug  34  illustrated in  FIG.  3 A  may be used with a larger gauge catheter than the flow control plug  34  illustrated in  FIGS.  1 C and  1 D . In some embodiments, the distal end of the flow control plug  34  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  FIGS.  2 A- 2 D , in some embodiments, the outer surface of the flow control plug  34  may include multiple channels  44 , and the flashback pathway  40  may extend through the channels  44  between the channels  44  and the inner surface of the needle hub  22 . In some embodiments, a number of the channels  44  may vary. In some embodiments, the outer surface of the flow control plug  34  may include one or more grooves  50  extending from the channels  44  inwardly towards a longitudinal axis of the flow control plug  34 . In some embodiments, the grooves  50  may be generally perpendicular to the channels  44 . 
     In some embodiments, a proximal end of each of the channels  44  may be formed by a proximal wall  52 . In some embodiments, the proximal wall  52  may include one or more microgrooves configured to allow air but not blood to pass. In some embodiments, the proximal wall  52  may interfere with an inner surface of the needle hub  22 , which may prevent blood from exiting the proximal end of the channel  44 . 
     In some embodiments, the needle hub  22  may be constructed of a clear or transparent material, which may facilitate observation blood within the flashback pathway  40 . In some embodiments, the needle hub  22  may include one or more lenses, which may facilitate observation of blood within the flashback pathway  40 . In some embodiments, the flow control plug  34  may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway  40 . 
     Referring now to  FIGS.  3 A- 3 C , in some embodiments, a tip  54  of the male luer may include a generally planar surface  56 , which may extend across the tip  54  such that a shape of the flashback pathway  40  is generally semi-circular. In some embodiments, the flow control plug  34  illustrated in  FIG.  3 A  may be used with an 18 or 20 gauge catheter or another suitable size catheter. 
     Referring now to  FIGS.  4 A- 4 D , in some embodiments, a catheter assembly  58  of a catheter system  60  may include the catheter adapter  12  and the catheter  20 . In some embodiments, the catheter system  60  may include or correspond to the catheter system  10  of one of more of  FIGS.  1 A- 3 C . In some embodiments, a needle assembly  62  of the catheter system  60  may include one or more of the following: the needle hub  22 , the needle  28 , an inner barrel  64 , and an outer barrel  66 . In some embodiments, the inner barrel  6   4  may surround the needle hub  22 . In some embodiments, the needle hub  22  may be secured within the inner barrel  64 . In some embodiments, the flashback pathway  40  may be disposed between an outer surface of the needle hub  22  and an inner surface of the inner barrel  64 . In some embodiments, the flow control plug  34  may be constructed of a white material, which may provide a sharp contrast when blood flows into the flashback pathway  40 . 
     In some embodiments, the outer barrel  66  may surround the inner barrel  64 . In some embodiments, the inner barrel  64  and the needle hub  22  may be configured to move proximally within the outer barrel  66  to retract the needle  28 . In some embodiments, the needle assembly  62  may include a button  68  and/or a spring  70 . In some embodiments, the inner barrel  64  and the needle hub  22  may move proximally within the outer barrel  66  in response to depression of the button  68  and actuation of the spring  70 . In some embodiments, a needle retraction mechanism of the catheter system  60  may operate similar to the BD INSYTE™ AUTOGUARD™ BC Shielded IV Catheter System or another suitable catheter system. 
     In some embodiments, the inner barrel  64  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  71  in the button  68  and the inner barrel  64 . In some embodiments, when the button  68  or activation latch is not depressed or is “up” in a non-activated position, a projection  73  may be located inside the catheter adapter  12 . Thus, when the catheter  20  is still located on the needle  28  with the catheter adapter  12 , the projection  73  may prevent the button  68  from being moved “down” into the activated position. 
     When the catheter  20  is moved off the needle  28  so the catheter adapter  12  is not adjacent to the projection  73 , the button  68  may be moved “down,” i.e. activated, because the catheter adapter  12  no longer interferes with the movement of the projection  73 . In this position, the opening  71  is larger than a maximum diameter of inner barrel  64 . The spring  70  can thus force the needle hub  22  and the inner barrel  64  to a proximal end of the outer barrel  66  and withdraw the distal end  30  of the needle  28  into the outer barrel  66 . In some embodiments, the inner barrel  64  and the needle hub  22  may be integrally formed or monolithically formed as a single unit. 
     In some embodiments, the needle hub  22  may include a channel  44 , and the flashback pathway  40  may extend through the channel  44  between the channel  44  and the inner surface of the inner barrel  64 . In some embodiments, the needle hub  22  may include a pocket  46  proximate the channel  44 . In some embodiments, the proximal end of the needle  28  may be disposed within the pocket  46 . In some embodiments, the pocket  46  may be deeper than the channel  44 . In some embodiments, a proximal end of the channel  44  may be formed by a proximal wall  52  of the needle hub  22 . In some embodiments, the proximal wall  52  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  52  may interfere with an inner surface of the inner barrel  64 . In some embodiments, the inner surface of the inner barrel  64  may include one or more alignment ridges  74 . In some embodiments, the outer surface of the needle hub  22  may include one or more other alignment ridges  76 , which may contact the alignment ridges  74  to facilitate orientation of the needle hub  22  with respect to the inner barrel  64 . 
     Referring now to  FIGS.  5 A- 5 E , in some embodiments, the needle assembly  62  may include a middle barrel  78 . In some embodiments, the inner barrel  64  may include a first hole  80  and/or the middle barrel  78  may include a second hole  82  aligned with the first hole  80  of the inner barrel  64 . In some embodiments, the flashback pathway  40  may include the first hole  80  and the second hole  82  and may extend between an outer surface of the middle barrel  78  and an inner surface of the outer barrel  66 . 
     In some embodiments, a pocket  46  may be proximate the first hole  80 . In some embodiments, the inner barrel  64  and the needle hub  22  may be configured to move proximally within the middle barrel  78  to retract the needle  28 . In some embodiments, the inner barrel  64  and the needle hub  22  may move proximally in response to depression of the button  68  and actuation of the spring  70 . 
     In some embodiments, the outer surface of the middle barrel  78  may include a channel  44 , and the flashback pathway  40  may extend through the channel  44  between the channel  44  and the inner surface of the inner barrel  64 . In some embodiments, the needle hub  22  may include a pocket  46  proximate the channel  44 . In some embodiments, the proximal end  32  of the needle  28  may be disposed within the pocket  46 . In some embodiments, a proximal end of the channel  44  may be formed by a proximal wall  52  of the middle barrel  78 . In some embodiments, the proximal wall  52  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  52  may interfere with an inner surface of the outer barrel  66 . 
     In some embodiments, the channel  44  may be formed by multiple side walls  48 , which may extend from a bottom of the channel  44  to the inner surface of the outer barrel  66  and may contact the inner surface of the outer barrel  66 . Thus, blood may be contained within the channel  44  as it travels proximally through the channel  44 . 
     Referring now to  FIGS.  6 A- 6 B , the needle hub  22  is illustrated being inserted into the inner barrel  64  during assembly of a catheter system. The catheter system may include or correspond to the catheter system  60  of  FIGS.  4 A- 4 F  and/or  FIGS.  5 A- 5 E . In some embodiments, the proximal end  26  of the needle  28  may contact and be secured within the needle hub  22 , but a remaining portion of the needle  28  may not contact the needle hub  22  and/or any portion of the catheter system. In some embodiments, the proximal end  26  of the needle  28  may be pinched and/or glued within the needle hub  22 , as illustrated, for example, in  FIG.  6 B . 
     Referring now to  FIGS.  6 C- 6 D , in some embodiments, the vents  38  may be disposed on a bottom of the needle hub  22 , which may facilitate better fluid containment. In some embodiments, flashback may flow proximally through the channel  44  and then down one or more sides of the needle hub  22  to a location proximate the vents  38 . In some embodiments, a proximal end of the needle hub  22  may include a seal  84 , which may include a rib and/or may extend from one side of the vents  38  to the other. 
     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 spirit and scope of the invention.