Patent Publication Number: US-2023145227-A1

Title: Cannula capture mechanism

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/681,557, filed Nov. 12, 2019, entitled CANNULA CAPTURE MECHANISM, which is a divisional of U.S. patent application Ser. No. 15/461,365, filed Mar. 16, 2017, entitled CANNULA CAPTURE MECHANISM, which claims the benefit of U.S. Provisional Patent Application No. 62/314,262, filed on Mar. 28, 2016, and entitled CANNULA CAPTURE MECHANISM, which are incorporated herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     This disclosure relates generally to vascular access devices and associated methods. More specifically, this disclosure discusses a cannula capture mechanism that is configured to capture a cannula tip in a manner that locks the cannula in a shielded position. The cannula capture mechanism can be used with catheter assemblies. 
     Generally, vascular access devices are used for communicating fluid with the vascular system of patients. For example, catheters are used for infusing fluid (e.g., saline solution, medicaments, and/or total parenteral nutrition) into a patient, withdrawing fluids (e.g., blood) from a patient, and/or monitoring various parameters of the patient&#39;s vascular system. 
     Intravenous (IV) catheter assemblies are among the various types of vascular access devices. Over-the-needle peripheral IV catheters are a common IV catheter configuration. As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. The introducer needle is generally a hypodermic needle coupled to a needle assembly to help guide the needle and to facilitate its cooperation with the catheter. At least the inner surface of the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and, thereby, facilitate insertion of the catheter into the blood vessel. The catheter and the introducer needle are often assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter. Moreover, the catheter and needle are often assembled so that, during insertion, the bevel of the needle faces up, away from the patient&#39;s skin. The catheter and introducer needle are generally inserted at a shallow angle through the patient&#39;s skin into a blood vessel. 
     In order to verify proper placement of the needle and/or catheter in the blood vessel, the operator generally confirms that there is “flashback” of blood into a flashback chamber associated with the needle assembly. Flashback generally entails the appearance of a small amount of blood, which is visible within the needle assembly or between the needle and the catheter. Once proper placement of the distal tip of the catheter into the blood vessel is confirmed, the operator may apply pressure to the blood vessel by pressing down on the patient&#39;s skin over the blood vessel, distal to the introducer needle and the catheter. This finger pressure momentarily occludes the vessel, minimizing further blood flow through the introducer needle and the catheter. 
     The operator may then withdraw the introducer needle from the catheter. The needle may be withdrawn into a needle tip cover or needle cover that extends over the needle&#39;s tip and prevents accidental needle sticks. In general, a needle tip cover includes a casing, sleeve, or other similar device that is designed to trap/capture the needle tip when the introducer needle is withdrawn from the catheter and the patient. After the needle is withdrawn, the catheter is left in place to provide intravenous access to the patient. 
     The separation of the introducer needle assembly from the catheter portions of the catheter assembly presents numerous potential hazards to the operators and others in the area. As indicated above, there is a risk of accidental needle sticks if the needle tip is not secured properly in a needle tip shield. Additionally, because the needle has been in contact with blood in the patient&#39;s vasculature, blood is often present on the needle&#39;s exterior as well as inside the lumen of the needle. As the needle is withdrawn from the catheter, there is a risk that this blood will drip from the needle tip or come into contact with other surfaces to expose people and equipment to blood. Additionally, it has been observed that withdrawing a needle from a catheter assembly often imparts energy to the parts of the needle assembly. For instance, during needle withdrawal, bending forces can be applied (either unintentionally or intentionally) to the needle. Such energy has been observed to cause blood to splatter or spray from the needle when the needle vibrates and shakes as it becomes free from the catheter assembly and releases the stored energy. 
     The present disclosure discusses a cannula capture mechanism that allows a needle to be retracted from an unshielded position to a shielded position in which the cannula feature is trapped. Accordingly, the described capture mechanism is configured to lock the needle in the shielded position to significantly limit or prevent accidental sticks and blood exposure after the needle is withdrawn from a catheter assembly. 
     BRIEF SUMMARY OF THE INVENTION 
     The present application relates to a cannula capture mechanism. In some embodiments, the capture mechanism may include a cannula, an inner housing, and an outer housing. In some embodiments, the inner housing may include multiple arms, which may extend distally from a proximal end of the inner housing. In some embodiments, when the cannula is exposed from a distal end of the inner housing, the multiple arms of the inner housing may be splayed radially outward. In some embodiments, when the cannula is retracted proximally within the inner housing, the outer housing may be configured to move from a compressed state to an decompressed state (“decompressed state” as used herein may refer to a state in which the outer housing is less compressed than when the outer housing is in the compressed state and does not necessarily refer to a state without any compression of the outer housing). In some embodiments, when the outer housing is in the decompressed state, the outer housing may bias the arms of the inner housing together, which may securely close the distal end of the inner housing and prevent the cannula from exiting the distal end of the inner housing. 
     In some embodiments, when the cannula is retracted proximally within the inner housing, the cannula may be prevented from exiting the distal end of the inner housing as well as a proximal end of the inner housing. Thus, the cannula may be bi-directionally trapped within the inner housing when the cannula is retracted proximally within the inner housing. For example, in some embodiments, the cannula may include a cannula feature. In some embodiments, when the cannula is retracted proximally within the inner housing, the cannula feature may be configured to contact the proximal end of the inner housing to prevent the cannula from exiting the proximal end of the inner housing. 
     In some embodiments, a compressible portion of the outer housing may be compressed when the outer housing is in the compressed state and decompressed when the outer housing is in the decompressed state. In some embodiments, the compressible portion may include a spring, an elastomer, or another compressible member. In some embodiments, the compressible portion may be baffled or accordion-shaped. In some embodiments, the compressible portion may be compressible along an axis aligned with a longitudinal axis of the cannula. 
     In some embodiments, movement of the outer housing to the decompressed state may cause a distal end of the outer housing, which may be radially rigid and/or coupled with the compressible portion, to slide distally over a distal portion of the inner housing, which may bias the arms of the inner housing together and seal or close the distal end of the inner housing. The distal portion of the inner housing may include at least a portion of the arms and may have a first outer diameter when the cannula is exposed from the distal end of the inner housing and a second outer diameter when the cannula is retracted proximally within the inner housing. In some embodiments, the second outer diameter may be approximately equal to an inner diameter of the distal end of the outer housing and may be smaller than the first outer diameter. 
     In some embodiments, the cannula capture mechanism may be secured to one or more of the following when the cannula is exposed from the distal end of the inner housing: a catheter adapter, a side port of the catheter adapter, a non-luer accessible port of the catheter adapter, a septum activator, and a septum. In some embodiments, an inner surface of the catheter adapter may be configured to secure the inner housing within the catheter adapter when the cannula is exposed from the distal end of the inner housing. In some embodiments, the inner surface of the catheter adapter may also be configured to separate from the inner housing to release the inner housing from the catheter adapter when the cannula is retracted proximally within the inner housing. 
     In further detail, an outer surface of the inner housing may include one or more interlock components that may interact with one or more interlock surfaces formed in the inner surface of the catheter adapter. In some embodiments, contraction of the inner housing radially inward, in response to retraction of the cannula proximally within the inner housing, may cause the one or more interlock components to be separated from the one or more interlock surfaces, which may allow removal of the cannula capture mechanism from the catheter adapter, a distal tip of the cannula being shielded inside the inner housing. 
     In some embodiments, an inner surface of the side port, the septum activator, and/or the septum may be similarly configured to secure the cannula capture mechanism within the catheter adapter when the cannula is exposed from the distal end of the inner housing and/or to separate from the inner housing when the cannula is retracted proximally within the inner housing. For example, the one or more interlock components of the outer surface of the inner housing may interact with one or more interlock surfaces formed in the inner surface of the side port, the septum activator, and/or the septum. Contraction of the inner housing radially inward, in response to retraction of the cannula proximally within the inner housing, may cause the one or more interlock components to be separated from the one or more interlock surfaces of the side port, the septum activator, and/or the septum, which may allow removal of the cannula capture mechanism from the catheter adapter, a distal tip of the cannula being shielded inside the inner housing. In some embodiments, the septum may be configured to move distally over a fixed septum activator, and the outer surface of the inner housing may interact with one or more interlock surfaces formed in the inner surface of the septum. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE FIGURES 
       In order that the manner in which the above-recited and other features and advantages of the invention will be readily understood, a more particular description of the cannula capture mechanism briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the appended Figures. Understanding that these Figures depict only typical embodiments and are not, therefore, to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying Figures in which: 
         FIG.  1    illustrates a partial cut-away view of a representative embodiment of a catheter device that includes a cannula capture mechanism in which a cannula is exposed from the catheter device; 
         FIG.  2 A  illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is exposed from a distal end of an inner housing; 
         FIG.  2 B  illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is retracted within the inner housing; 
         FIG.  3 A  illustrates a cross sectional view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is exposed from the distal end of the inner housing; 
         FIG.  3 B  illustrates a cross sectional view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is retracted within the inner housing; 
         FIG.  4 A  illustrates an exploded view of a representative embodiment of an outer housing and an inner housing of the cannula capture mechanism of  FIG.  1   ; 
         FIG.  4 B  illustrates the outer housing and the inner housing of the cannula capture mechanism of  FIG.  1    coupled together; 
         FIG.  5 A  illustrates an exploded view of a representative embodiment of an outer housing and an inner housing of another cannula capture mechanism; 
         FIG.  5 B  illustrates the outer housing and the inner housing of the cannula capture mechanism of  FIG.  5 A  coupled together; 
         FIG.  6 A  illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is exposed from the inner housing, and the cannula capture mechanism is secured to a septum activator; 
         FIG.  6 B  illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is retracted within the inner housing, and the cannula capture mechanism is separated from the septum activator; 
         FIG.  7 A  illustrates a cross sectional view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which a distal tip is partially exposed from the inner housing; 
         FIG.  7 B  illustrates a cross sectional view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the distal tip is disposed in a square-edged sleeve; and 
         FIG.  7 C  illustrates a cross sectional view of a representative embodiment of another cannula capture mechanism in which a first arm and a second arm of the inner housing are different lengths; 
         FIG.  8    illustrates a partial cut-away view of a representative embodiment of a catheter device that includes another cannula capture mechanism; 
         FIG.  9    illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    in which the cannula is exposed from the inner housing, and the cannula capture mechanism is secured to a septum; 
         FIG.  10 A  illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    disposed in an integrated catheter; and 
         FIG.  10 B  illustrates a partial cut-away view of a representative embodiment of the cannula capture mechanism of  FIG.  1    disposed in the integrated catheter, the cannula being partially retracted. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The presently preferred embodiments of the described invention will be best understood by reference to the Figures, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the bi-directional cannula feature capture mechanism, as represented in  FIGS.  1  through  7   , is not intended to limit the scope of the invention, as claimed, but is merely representative of some presently preferred embodiments of the invention. 
     Generally, this application relates to a cannula capture mechanism. In other words, this application discusses a cannula capture mechanism that allows a cannula to be moved from an unshielded position to a shielded position in which the cannula is prevented from moving distally out of the capture mechanism. In some embodiments, the cannula is bi-directionally trapped and also prevented from moving proximally out of the capture mechanism. As used herein, the term “unshielded” may refer to circumstances in which the cannula&#39;s distal tip is exposed from the inner housing of the capture mechanism. Conversely, the term “shielded” may refer to circumstances in which the cannula&#39;s tip is covered, shielded, or otherwise protected by the inner housing of the capture mechanism. In some embodiments, because the capture mechanism allows the cannula to be locked in the shielded position, the capture mechanism may prevent unintended sticking and/or blood exposure. To better explain the capture mechanism, a more detailed description of the mechanism is given below, followed by a more detailed description of the mechanism&#39;s use. 
       FIG.  1    illustrates a representative embodiment of a catheter device  10  that includes a cannula capture mechanism  12 . As illustrated in  FIG.  1   , in some embodiments, the cannula capture mechanism  12  may include a cannula (e.g., needle  14 ), an engageable cannula feature (e.g., needle feature  16 ), an inner housing  18 , and an outer housing  20 . Additionally,  FIG.  1    illustrates that the capture mechanism  12  may be selectively be coupled with a catheter adapter  22 . To provide a better understanding of the capture mechanism  12 , each of the aforementioned components is described in below in further detail. 
       FIG.  1    illustrates the capture mechanism  12  may include a cannula (e.g., needle  14 ). As used herein, the terms “cannula” and “cannulae” may refer to virtually any rigid tube that is configured to be inserted into an animal&#39;s body to draw off or to introduce fluid, wherein the tube includes a sharpened tip that allows the tube to puncture the body and access an intended space. Some examples of such cannulae may include hypodermic needles and other cannulae that may expose their operator to the risk of unintended sticking or blood exposure. 
     The cannula may include any cannula that can be used with the described capture mechanism, including, but not limited to, a hypodermic needle. Where the cannula includes a hypodermic needle, the cannula may include any suitable type of hypodermic needle, including an introducer needle for use in an IV catheter assembly (e.g., an over-the-needle peripheral IV catheter assembly). 
     As illustrated in  FIG.  1   , the cannula may include an introducer needle  14 . When the needle  14  is exposed from the inner housing  18  in the unshielded position, the needle  14  may extend axially through the inner housing  18  and the outer housing  20  so that the distal tip  24  extends past the distal end  36  of the inner housing  18  and the distal end  38  of the outer housing  20 . Additionally, in the unshielded position, a distal portion of the needle  14  optionally extends into a catheter  25  and the outer housing  20  is optionally coupled to the catheter adapter  22 . 
     In some embodiments, the needle  14  may include any component or characteristic that prevents the distal tip  24  of the needle  14  from exiting the proximal end of the inner housing  18 . For instance, the needle  14  may include any suitable needle feature that has an OD that is greater than an OD of the needle  14  or has at least one surface that extends laterally past the OD of the needle  14 . In one example, the needle  14  includes an engageable needle feature  16 , such as a notched crimp feature, a welded ferrule feature, a notch feature, a crimp feature, or another cannula feature that has an outer diameter (“OD”) that extends laterally past an OD of the cannula. In this example, the needle feature  16  may include a proximal engagement that is adapted to contact a surface of the inner housing  18  to restrict proximal movement of the needle feature  16  in the inner housing  18 . In some embodiments, the needle feature  16  may include one or more one-way barbs or a notch. Regardless of the specific type of needle feature  16 , the needle feature  16  may have any suitable characteristic. For instance, the needle feature  16  may be any suitable shape or size. 
     In some embodiments, the needle  14  may have any characteristic that is suitable for use with an IV catheter assembly. By way of illustration,  FIG.  1    shows an embodiment in which the needle  14  includes a sharpened distal tip  24 , a lumen  26  (not directly illustrated), an elongated tubular portion  28  with a substantially constant OD  30 , and an engageable needle feature  16 . Additionally, each of the needle&#39;s aforementioned components may include any suitable characteristic. For example, the distal tip  24  of the needle  14  may include a standard bevel, a short bevel, a true short bevel, a bias grind point, a vet point, a lancet point, a deflected point (anti-coring), or another suitable needle point. In another example, the lumen  26  and elongated tubular portion  28  may be any suitable size. For instance, the needle  14  may be any length or gauge (e.g., from a 7 to a  33  on the Stubs scale) that allows it to be used as the needle  14  in an IV assembly. 
     As previously mentioned, the capture mechanism  12  may also include the inner housing  18 . In some embodiments, the inner housing  18  may be split longitudinally to form multiple arms  32 . The inner housing  18  may include any number of arms, such as, for example, two, three (as illustrated in  FIG.  1   ), or four. In some embodiments, the arms  32  may extend distally from a proximal portion, such as a proximal end, of the inner housing  18 . In some embodiments, when the needle  14  is exposed from the distal end  36  of the inner housing  18 , the needle  14  may be configured to bias the arms  32  apart. For example, in some embodiments, when the needle  14  is exposed from the distal end  36  of the inner housing  18  in the unshielded position, the arms  32  of the inner housing  18  may be resiliently splayed radially outward by the needle  14 , as illustrated in  FIG.  1   . 
     The inner housing  18  may be constructed of any suitable material or materials, such as, for example, a metal, a metal alloy, a ceramic, a plastic, a polymer, etc. Advantageously, a rigid plastic may allow the distal tip  24  to embed in an inner surface of the inner housing  18  when in the shielded position. Surfaces of the inner housing  18  that contact the needle  14  may include a coating to lower friction between the surfaces and the needle  14  and/or improve a feel of the needle  14  sliding relative to the surfaces. The coating may include, for example, a lubricant and/or a conformal coating. In some embodiments, the inner housing  18  may be a single piece. In some embodiments, the inner housing  18  may include multiple pieces that may be coupled together in any number of ways, such as, for example, threading, fitting, snapping, connecting, attaching, fastening, clipping, hooking, or any other suitable means of coupling. 
     The capture mechanism may also include the outer housing  20 . In some embodiments, when the needle  14  is retracted proximally within the inner housing  18  to the shielded position, the outer housing  20  may be configured to move from a compressed state, illustrated in  FIGS.  1  and  2 A , to a decompressed state illustrated in  FIG.  2 B . In some embodiments, when the outer housing  20  is in the decompressed state, the outer housing  20  may bias the arms  32  of the inner housing  18  together, which may securely seal or close the distal end  36  of the inner housing  18  and prevent the needle  14  from exiting the distal end  36  of the inner housing  18 . 
     The outer housing  20  may axially slide or expand over at least a portion of the inner housing  18  when the outer housing  20  decompresses or moves from the compressed state, illustrated in  FIG.  2 A , to the decompressed state, illustrated in  FIG.  2 B . The portion of the inner housing  18  over which the outer housing  20  slides or expands may be any suitable size or have any suitable shape. For instance, the portion of the inner housing  18  may be substantially cylindrical, cuboidal, tubular, etc. A restoring force in the distal direction may cause the outer housing  20  to axially slide or expand when the outer housing  20  moves from the compressed state to the decompressed state. 
     In some embodiments, the outer housing  20  may include a compressible portion  34 , which may be disposed between and/or coupled with a distal end  38  of the outer housing  20  and a proximal end  48  of the outer housing  20 . In some embodiments, the compressible portion  34  of the outer housing  20  may be compressed when the outer housing  20  is in the compressed state and decompressed when the outer housing  20  is in the decompressed state. In some embodiments, the compressible portion  34  may be compressible along an axis aligned with the needle  14 . In some embodiments, the compressible portion  34  may include a spring, an elastomer, or another compressible member. In some embodiments, the compressible portion  34  may be cylindrical. In some embodiments, the spring may be cylindrical and/or coiled. In some embodiments, the compressible portion  34  may be baffled or accordion-shaped. In these and other embodiments, the compressible portion  34  may include a tube or sleeve, which may be constructed of an elastomer, silicone, a liquid silicone rubber material, or another suitable material. In some embodiments, the compressible portion  34  may enclose the inner housing  18 , which may act as a redundant mechanism to ensure any residual blood on the needle  14  stays within the cannula capture mechanism  12 . 
     In some embodiments, an inner surface of the outer housing  20  may include a coating to lower friction between the inner surface and the inner housing  18  and/or an outer surface of the outer housing  20  may include the coating. The coating may include, for example, a lubricant and/or a conformal coating. 
     In some embodiments, a proximal end  48  of the outer housing  20  may be directly coupled with the proximal end of the inner housing  18 , and the distal end  38  of the outer housing  20  may move distally away from the proximal end of the outer housing  20  and the proximal end of the inner housing  18  when the outer housing  20  moves to the decompressed state. In some embodiments, movement of the outer housing  20  to the decompressed state may cause the distal end  38  of the outer housing  20 , which may be radially rigid and/or coupled with the compressible portion  34 , to slide or move distally along the inner housing  18 . 
     As illustrated in  FIG.  2 A , in some embodiments, an inner surface of the catheter adapter  22  may be configured to secure the inner housing  18  within the catheter adapter  22  when the needle  14  is exposed from the inner housing  18 . In some embodiments, the inner surface of the catheter adapter  22  may be configured to separate from the inner housing  18  to release the inner housing  18  from the catheter adapter when the needle  14  is retracted proximally within the inner housing  18 , as illustrated in  FIG.  2 B . In further detail, an outer surface of the inner housing may include one or more interlock components  46  that may interact with one or more interlock surfaces  54  formed in the inner surface of the catheter adapter  22 . The interlock components  46  may be biased against a corresponding interlock surface  54  of the catheter adapter  22  when the needle  14  is exposed from the distal end  36  of the inner housing  18  in the unshielded position. Contraction of the inner housing  18  radially inward, in response to retraction of the needle  14  proximally within the inner housing  18 , may cause the one or more interlock components  46  to be separated from the one or more interlock surfaces  54 , which may allow removal of the cannula capture mechanism  12  from the catheter adapter  22 , the distal tip  24  of the needle  14  being shielded inside inner housing  18 . Accordingly, unintentional needle sticks may be prevented, and the cannula capture mechanism  12  may be safely disposed. 
     Where the cannula capture mechanism  12  is used in conjunction with the catheter adapter  22 , the two can be coupled in any suitable manner that allows the cannula capture mechanism  12  to be coupled to the adapter  22  when the needle  14  is in the unshielded position and to be uncoupled from the adapter  22  when the needle  14  is in the shielded position. Also, the capture mechanism  12  may be used with any suitable catheter adapter  22 . Further, where the inner housing  18  is selectively coupled within the catheter adapter  22  by a coupling mechanism, the coupling mechanism may be located in any suitable position. For example, the interlock components  46  and the interlock surfaces  54  may be disposed proximally or distally within a lumen  47  of the catheter adapter  22 . 
       FIGS.  3 A- 3 B  illustrate cross sectional views of the cannula capture mechanism  12 . As illustrated in  FIG.  3 B , in some embodiments, the distal end  38  may slide over and snugly fit around a distal portion  40  of the inner housing  18 , which may bias the arms  32  of the inner housing  18  together and securely close the distal end  36  of the inner housing  18 . The distal portion  40  of the inner housing  18  may include at least a portion of the arms  32  and may have a first outer diameter  42  when the needle  14  is exposed from the distal end  36  of the inner housing  18  and the outer housing  20  is in the compressed state, as illustrated in  FIG.  3 A . The distal portion  40  of the inner housing  18  may have a second outer diameter  44  when the needle  14  is retracted proximally within the inner housing  18  and the outer housing  20  is in the decompressed state, illustrated in  FIG.  3 B . In some embodiments, the second outer diameter  44  may be approximately equal to an inner diameter of the distal end  38  of the outer housing  20  and may be smaller than the first outer diameter  42 . 
     In some embodiments, the distal end  38  may be configured to stop at the distal portion  40  due to a length of the compressible portion  34  and/or a presence of the interlock components  46  of the inner housing  18 , which may be disposed at least proximate the distal end  36  of the inner housing  18  and may act as a stop. In some embodiments, an inner diameter  56  of the inner housing  18  at the interlock components  46  may be larger than the first outer diameter  42  and the second outer diameter  44 . 
     As illustrated in  FIGS.  3 A- 3 B , the proximal end  48  of the outer housing  20  may be directly coupled with the proximal end  50  of the inner housing  18 . The proximal end  48  may be directly coupled with the proximal end  50  in any number of ways, such as, for example, threading (e.g., threads  52 ), fitting, snapping, connecting, attaching, fastening, clipping, hooking, or any other suitable means of coupling. 
     In some embodiments, the inner housing  18  may include inner walls  58 , which may define an interior space  60  through which the needle  14  axially extends. As illustrated in FIG.  3 B, in some embodiments, when the needle  14  is retracted proximally within the inner housing  18  to the shielded position, the needle  14  may be prevented from exiting the distal end  36  of the inner housing  18 . For example, the distal tip  24  may contact a surface of the inner housing  18  to restrict distal movement of the needle  14 . In further detail, distal ends of the arms  32  may include transverse barriers  62  that extend inwardly and are configured to extend towards the longitudinal axis of the needle  14 . The transverse barriers  62  may contact the distal tip  24  to restrict distal movement of the needle  14  when the needle  14  is proximally retracted within the inner housing  18 . In some embodiments, the transverse barriers  62  may contact and/or overlap with each other when the needle  14  is proximally retracted within the inner housing  18  and may form a seal that may prevent blood and/or the distal tip  24  from exiting the distal end  36  of the inner housing  18 . The transverse barriers  62  may thereby provide a needle tip capture mechanism that encloses the distal tip  24  to protect people from unintentional sticking and/or to reduce the risk of blood exposure. Additionally or alternatively, the arms  32  of the inner housing may include another suitable type of needle shielding component. 
     As illustrated in  FIG.  3 B , in some embodiments, when the needle  14  is retracted proximally within the inner housing  18 , the needle  14  may also be prevented from exiting the proximal end  50  of the inner housing  18 . In some embodiments, the needle feature  16  may be retracted proximally until it contacts the proximal end  50  of the inner housing  18 , preventing the distal tip  24  from exiting the proximal end  50  of the inner housing  18 . For instance, the proximal end  50  of the inner housing  18  may include any suitable type of needle shielding component. By way of example, as illustrated in  FIGS.  3 A- 3 B , the proximal end  50  may include transverse barriers  64  that extend inwardly and are configured to extend towards the longitudinal axis of the needle  14 . The transverse barriers  64  may contact the needle feature  16  to restrict proximal movement of the needle  14  when the needle  14  is proximally retracted within the inner housing  18 . As another example, the proximal end  50  may include a washer, cylinder, wedge, or other suitable component that includes a hole that allows the needle  14  to pass but does not allow the needle feature  16  to pass. 
     As mentioned, in some embodiments, the distal end  38  of the outer housing  20  may be radially rigid. In some embodiments, the distal end  38  of the outer housing  20  may be substantially radially rigid such that the distal end  38  has a degree of flexibility. In these embodiments, an internally applied radial force may cause the distal end to flex. The distal end  38  may radially rigid due to any number of factors. For example, the distal end  38  may include an end portion of a spring, which may be constructed of a metallic or polymeric or other suitable material. As another example, in some embodiments, the distal end  38  may be coupled with a radially rigid component. In some embodiments, the radially rigid component may be sized and configured to fit around the distal end  38 . In some embodiments, in order to provide stability, the radially rigid component may be sized and configured to fit into the lumen  47  of the catheter adapter  22  and abut inner walls  63  of the catheter adapter  22  or to fit into a lumen or interior space of a septum activator and abut inner walls of the septum activator. In some embodiments, the radially rigid component may include a ring constructed of a metallic or polymeric or other suitable material. In some embodiments, the radially rigid component may be separate or integrally formed with the outer housing  20 . 
       FIG.  4 A  illustrates an exploded view of a representative embodiment of the outer housing  20  and the inner housing  18  in which a radially rigid component  66  is separate from the outer housing  20 . Alternatively, in some embodiments, the outer housing  20  may include the radially rigid component  66 . For example, the radially rigid component  66  may be coupled with the distal end  38  of the outer housing  20 . As another example, the radially rigid component  66  may include an end of the spring portion, which may be coiled. The radially rigid component  66  may increase the rigidity of the distal end  38 . 
       FIG.  5 A  illustrates an exploded view of a representative embodiment of an outer housing  20  and an inner housing  18  of another cannula capture mechanism  12 . In some embodiments, the cannula capture mechanism  12  may correspond to the cannula capture mechanism  12  of  FIGS.  1 - 4   . In some embodiments, the radially rigid component  66  may be integrally formed with the distal end  38  of the outer housing  20 . Also, as illustrated in  FIGS.  5 A- 5 B , in some embodiments, as opposed to directly coupling the proximal end  48  of the outer housing  20  to the proximal end  50  of the inner housing  18  via threads  52  (illustrated, for example, in  FIGS.  3 A- 3 B and  4 A ), the proximal end  50  of the inner housing  18  may have a larger outer diameter than an inner diameter of the proximal end  48  of the outer housing  20  and may act as a stop, preventing the outer housing  20  from moving in a proximal direction. 
     The inner housing  18  can be configured to selectively and removably couple to any suitable catheter adapter  22  or another component of the catheter device  10 , in any suitable manner. For example, as illustrated in  FIGS.  6 A , an inner surface of a septum activator  68  may be configured to secure the inner housing  18  within the catheter adapter  22  when the needle  14  is exposed from the distal end  36  of the inner housing  18  and/or to separate from the inner housing  18  when the needle  14  is retracted proximally within the inner housing  18 . For example, the one or more interlock components  46  of the outer surface of the inner housing  18  may interact with one or more interlock surfaces  70  formed in the inner surface of the septum activator  68 . In some embodiments, the interlock surfaces  70  may correspond to the interlock surfaces  54  of  FIGS.  1 - 3   . In some embodiments, a shape of the interlock surfaces  70  may prevent the inner housing  18  of the cannula capture mechanism  12  from moving proximally or distally when the needle  14  is exposed from the distal end  36  of the inner housing  18 , as illustrated in  FIGS.  6 A- 6 B . Contraction of the inner housing  18  radially inward, in response to retraction of the needle  14  proximally within the inner housing  18 , may cause the one or more interlock components  46  to be separated from the one or more interlock surfaces  70  of the septum activator  68 , which may allow removal of the cannula capture mechanism  12  from the catheter adapter  22 , the distal tip of the needle  14  being shielded inside the inner housing  18 . 
     In some embodiments, where the cannula capture mechanism  12  is used in conjunction with the septum activator  68 , the two may be coupled in any suitable manner that allows the cannula capture mechanism  12  to be coupled to the septum activator  68  when the needle  14  is in the unshielded position and to be uncoupled from the septum activator  68  when the needle  14  is in the shielded position. Also, the capture mechanism  12  may be used with any suitable septum activator  68 . Further, where the inner housing  18  is selectively coupled within the septum activator  68  by a coupling mechanism, the coupling mechanism may be located in any suitable position. For example, the interlock components  46  and the interlock surfaces  70  may be disposed proximally or distally within a lumen  71  of the septum activator  68 . 
     In some instances, slow retraction of the needle  14  proximally into the inner housing  18  may cause the transverse barriers  62  of the arms  32  to get stuck on a bevel of the needle  14 , as illustrated in  FIG.  7 A . In these instances, the interlock components  46  may release or separate from the interlock surfaces  54  or the interlock surfaces  70  when the needle  14  is retracted proximally, but the arms  32  may not contract radially inward with enough force to cause the transverse barriers  62  to meet and shield the needle  14  within the inner housing  18 . 
     Thus, in some embodiments, the distal tip  24  may be disposed in a generally cylindrical and/or square-edged sleeve  72 , as illustrated in  FIG.  7 B . In some embodiments, the sleeve  72  may be tubular and/or include an open distal end. Thus, when the interlock components  46  are released or separated from the interlock surfaces  54  or the interlock surfaces  70 , the arms  32  may contract radially inward more suddenly, which may allow the transverse barriers  62  to meet and shield the needle  14  within the inner housing. 
     Additionally or alternatively, lengths of the arms  32  may be different such that an inner surface  74  of a particular transverse barrier  62  is separated from an inner surface  76  of another particular transverse barrier  62  by a first length  78 , as illustrated in  FIG.  7 C . The bevel may be a second length  80 . In some embodiments, the first length may be greater than the second length in order to ensure that when the interlock components  46  are released or separated from the interlock surfaces  54  or the interlock surfaces  70 , the transverse barriers  62  will prevent the needle  14  from exiting the distal end of the inner housing  18 . 
       FIG.  8    illustrates a partial cut-away plan view of a representative embodiment of a catheter device  10  that includes another cannula capture mechanism  12 . In some embodiments, the inner housing  18  may include three or more arms  32 , as illustrated in  FIG.  8   . 
     In addition to the previously described embodiments of the cannula capture mechanism  12 , the capture mechanism  12  may be modified in any suitable manner that allows it to fulfill its intended purpose. Further, the cannula capture mechanism  12  can be used in any suitable manner. By way of non-limiting illustration,  FIG.  1    illustrates that before the needle  14  is inserted into a patient&#39;s blood vessel (not shown), the needle  14  extends axially through the inner  18  and outer housing  20  and through a distal tip of the catheter adapter  22 . Additionally,  FIG.  1    illustrates that before the needle  14  is inserted into the blood vessel, the needle feature  16  may be is disposed distal to the distal end  36  of the inner housing  18 . Moreover,  FIG.  1    illustrates at least a portion of the inner housing  18  may be disposed within the outer housing  20 . 
     Referring now to  FIG.  9   , in some embodiments, a septum  82  may be configured to move distally over a fixed septum activator  84  to open one or more barriers  86  of the septum  82  and allow the needle  14  to pass through the septum  82 , as illustrated in  FIG.  9   . In some embodiments, and the outer surface of the inner housing  18  may interact with one or more interlock surfaces  88  formed in the inner surface of the septum  82  in a same or similar manner as the interlock surfaces  54  or the interlock surfaces  70  described previously. For example, contraction of the inner housing  18  radially inward, in response to retraction of the needle  14  proximally within the inner housing  18 , may cause the one or more interlock components  46  to be separated from the one or more interlock surfaces  88 , which may allow removal of the cannula capture mechanism  12  from the septum  82  and the catheter adapter  22 , the distal tip  24  of the needle  14  being shielded inside inner housing  18 . 
     The described cannula capture mechanism  12  and associated methods may offer several advantages over certain prior art needle shielding devices. For example, the cannula capture mechanism  12  may be compact and/or may be internal to the catheter device  10 . Also, the cannula capture mechanism  12  may provide needle point protection as well as needle point blood containment. Additionally, the cannula capture mechanism  12  may provide a positive, tactile feedback to a clinician, indicating the needle  14  is in the shielded position. Further, the cannula capture mechanism  12  also provides a versatile interlock interface for interfacing with one or more components of a catheter device  10 , including, for example, the catheter adapter  22 , blood control or port valves, the septum activator  68 , etc. 
     The cannula capture mechanism  12  may be compatible with a variety of catheter devices, including, for example, ported, straight, and integrated catheter devices, as well as ported and straight blood control catheter devices. Referring now to  FIGS.  10 A- 10 B , in some embodiments, when the catheter device  10  includes an integrated catheter, the interlock surfaces  54  may be disposed distal to a needle hub  90  and/or proximal to a septum  92  of the catheter adapter  22 . In these and other embodiments, at least a portion of the cannula capture mechanism  12  may be disposed between the septum  92  and the needle hub  90 . In some embodiments, the interlock surfaces  54  may be disposed on the septum  92 , a septum canister or housing (not illustrated), or on the catheter adapter  22 . In some embodiments, a proximal end of the needle  14  may be fixed within the needle hub  90  using any suitable means, including, for example, a feature disposed on the proximal end of the needle  14  and/or an adhesive disposed within the needle hub  90 . 
     The needle hub  90  may include any shape or size. In some embodiments, the needle hub  90  may have an outer diameter approximately equal to or larger than an outer diameter of the catheter adapter  22 , which may facilitate use of the needle hub  90  as an insertion grip when moving the needle  14  through the catheter hub  90 . In some embodiments, the needle hub  90  may extend distally to partially or fully cover the cannula capture mechanism  12  when the needle  14  is exposed from a distal end of the catheter  25 , as illustrated in  FIG.  10 A . 
     The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. In some embodiments, particular interlock surfaces, such as the interlock surface  54 , may be disposed on a surface of any suitable component of a catheter device, including, for example: a catheter adapter, a septum activator, a blood control septum, an integrated catheter septum, or a septum housing. The described embodiments and examples are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.