WO1998057689A1

WO1998057689A1 - Shield for catheter introducer needles

Info

Publication number: WO1998057689A1
Application number: PCT/US1998/012416
Authority: WO
Inventors: Richard J. Caizza
Original assignee: Becton Dickinson And Company
Priority date: 1997-06-16
Filing date: 1998-06-15
Publication date: 1998-12-23
Also published as: AU8144198A

Abstract

A shield mechanism is provided for an IV catheter assembly that includes an introducer needle (14) for inserting the IV catheter (22) into a vein of a patient. The shield mechanism includes a guard (40) that is slidably movable along the needle (14) from a proximal position where the sharp distal tip (18) of the needle (14) is exposed to a distal position where the sharp distal tip (18) of the needle (14) is safety shielded. A hinged arm (54) connects the guard (40) to a hub (20) of the needle (14). The hinged arm (54) can be collapsed upon itself, such that the guard (40) is adjacent the hub (30) of the needle (14). Alternatively, the hinged arm (54) can be extended to cause the guard (40) to move distally along the needle (14) and into a position for shielding the sharp distal tip (18) of the needle (14). A spring (68, 90, 95) may be provided to assist movement of the guard (40) toward the distal shielded position. A mechanism is provided to temporarily connect the guard (40) to the catheter hub (30) to automatically shield the needle (14') when it is withdrawn from the catheter.

Description

SHIELD FOR CATHETER INTRODUCER NEEDLES

BACKGROUND OF THE INVENTION

The subject invention relates to single-handedly actuatable shields for catheter introducer needles to prevent accidental needle sticks.

Catheters, particularly intravenous (IV) catheters, are used for directing fluid into or withdrawing fluid from a patient. The most common type of IV catheter is an over-the-needle IV catheter. As its name implies, an over-the- needle IV catheter is mounted over an introducer needle having a sharp distal tip. With the distal tip of the introducer needle extending beyond the distal tip of the IV catheter, the assembly is inserted through the patient's skin into a vein. Once placement of the assembly in the vein is verified by flashback of blood in the needle, the needle is withdrawn leaving the IV catheter in place. The proximal end of the IV catheter typically has a hub that is designed to be connectable to an IV fluid supply line after insertion of the IV catheter in a patient.

In recent years, there has been great concern over the contamination of clinicians and other health care workers with a patient's blood and the immediate disposal of needles after use. This concern has arisen because of the advent of currently incurable and fatal diseases, such as Acquired Immunodeficiency Syndrome ("AIDS"), which is believed to be transmitted by the exchange of body fluids, typically blood, from an infected person to another person. Such transmission of blood borne pathogens between an infected person to another person may also be the vehicle for transmitting other diseases such as Human Immunodeficiency Virus ("HIV") and hepatitis B and C. Thus, contact with the body fluid of an infected person must be avoided. If a needle has been used to place a catheter in the vein of an infected person, the needle is a vehicle for the transmission of blood borne pathogens between people. And a needlestick provides an immediate transmission of such blood borne pathogens into the bloodstream of the non-infected person. Thus it is extremely important to avoid a needlestick with a contaminated needle. However, in certain medical environments, such as emergency situations or as a result of inattention or negligence on the part of the clinician, needlesticks with a contaminated needle still occur. In view of the need to prevent accidental needlesticks, much work has been done to develop a shield mechanism that will cover the sharp distal tip of a catheter introducer needle after it has been used to place a catheter into a patient. Unfortunately, such devices have not been totally satisfactory. For example, some needle shields are bulky, which makes the device difficult to use and which can interfere with the clinician's technique during venipuncture. Other needle shields allow the needle to be exposed after the needle is withdrawn from the catheter and before the needle is shielded. This could still allow for accidental needlesticks since the contaminated needle can be exposed to the environment before it is shielded.

Thus, there still remains a need to provide an IV catheter assembly that includes a needle shield assembly which is simple to use, compact, and shields the needle immediately upon withdrawal of the needle from the catheter after venipuncture.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide a needle shield assembly that is simple to use.

It is another object of this invention to provide a needle shield assembly that is compact.

It is a further object of this invention to provide an IV catheter assembly that includes a needle shield assembly that shields the needle immediately upon withdrawal of the needle from the catheter after venipuncture.

The subject invention includes a shield mechanism mounted adjacent to the proximal end of an introducer needle. As used herein, the term

"proximal" refers to locations closer to the clinician, and hence further from the tip of the needle. The term "distal" refers to locations further from the clinician, and hence closer to the tip of the needle. The shield mechanism includes a needle guard that can be moved from a first position adjacent to the proximal end of the needle, where the sharp distal tip of the introducer needle is exposed for use, to a second position at the distal end of the needle where the sharp distal tip of the needle is substantially enclosed.

The shield mechanism of the subject invention includes a hinged arm. The hinged arm may include a proximal segment and a distal segment articulated to one another. The distal segment of the hinged arm is articulated to the needle guard, while the proximal segment of the hinged arm is articulated to a location spaced proximally from the sharp distal tip of the needle. For example, the proximal segment of the hinged arm may be articulated to the needle hub or to an additional member which is attached to the needle hub. This proximal segment of the hinged arm may be unitary with the needle hub or the additional element. Similarly, the distal segment of the hinged arm may be unitary with the needle guard.

The proximal and distal segments of the hinged arm are dimensioned to fold toward one another when the needle guard is near its proximal position. The segments of the hinged arm also are dimensioned to preferably extend into a substantially linear orientation when the needle guard encloses the sharp distal tip of the needle. Thus, over extension of the shield mechanism is prevented by limits imposed by the dimensions of the hinged arm.

The needle guard preferably comprises a rigid cap having side walls and a distal end wall extending transversely across the side walls. The distal end wall may have an aperture for slidably receiving the needle. The cap and the hinged arm may be dimensioned to have the sharp distal tip of the needle safely engaged between the side walls and the distal end wall of the cap when the hinged arm is in its extended position. The needle guard may also include a clip, which is preferably metallic, engaged in the cap. A distal wall of the clip may be biased against the side of the needle for sliding movement therealong. As the hinged arm reaches its fully extended position, the distal wall of the metallic clip in the cap will pass the sharp distal tip of the needle, and will biasingly move into a position where the distal wall of the metallic clip protectively covers the sharp distal tip of the needle.

The distal end of the needle guard preferably includes a plurality of fingers extending distally from the needle guard. These fingers are radially spaced from one another to define a diameter between the fingers that is about equal to the diameter of the catheter hub. In this manner, the fingers grab onto the catheter hub in an interference fit and allow the needle guard to move distally with respect to the needle during needle retraction while the catheter is held in place in the patient. Once the needle is fully withdrawn and the needle guard is locked in place over the sharp distal tip of the needle, the fingers can be removed from the catheter hub by withdrawing the needle and needle guard assembly in the proximal direction with a slight increase in force to overcome the interference fit between the fingers and the catheter hub. The shield mechanism of the subject invention may include biasing means for urging the needle guard toward its distal position. The biasing means preferably is in a stable condition with little or no stored energy when the needle guard is in its proximal position. The clinician may have to overcome forces exerted by the biasing means to urge the needle guard from its proximal position. This initial actuation may urge the biasing means into an orientation where the biasing means effectively propels the hinged arm into an extended condition, such that the needle guard covers the sharp distal tip of the needle. The biasing means preferably extends unitarily between the proximal segment of the hinged arm and either the needle hub or an element attached to the needle hub, and may define a portion of the hinged joint therebetween. For example, the biasing means may define an over-center hinged spring where stored energy accumulated during early stages of rotation propels the hinged components during later stages of rotation.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages will be apparent upon consideration of the following drawings and detailed description. The preferred embodiments of the present invention are illustrated in the appended drawings in which like reference numerals refer to like elements and in which:

FIG. 1 is a perspective view of an IV catheter assembly having a needle shield in accordance with the subject invention;

FIG. 2 is a perspective view similar to FIG. 1 but with the catheter removed from the needle shield assembly;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 1 ; FIG. 4 is a cross-sectional view similar to FIG. 3, but showing the needle shield in its partially extended condition;

FIG. 5 is a cross-sectional view similar to FIG. 4 but showing the needle shield in its fully extended position shielding the sharp distal tip of the needle and with the catheter removed from the needle;

FIG. 6 is a cross-sectional view similar to FIG. 3, but showing an alternate spring; and FIG. 7 is a cross-sectional view similar to FIG. 3, showing an alternate spring.

DETAILED DESCRIPTION OF THE INVENTION A shieldable needle assembly in accordance with the subject invention is identified generally by the numeral 12 in FIGS. 1 -7. Needle assembly 12 is engaged with an IV catheter 22 as shown in FIGS. 1 , 2 and 3. The IV catheter 22 includes a cannula 24 having opposed proximal and distal ends 26 and 28 respectively and a hub 30 connected to proximal end 26 of cannula 24. The proximal end of hub 30 includes a luer collar 38 including external threads which may be engaged by the male luer tip of a hypodermic syringe (not shown), an IV fluid supply line (not shown) or a valve connector (not shown).

Needle assembly 12 includes a needle 14 having a proximal end 16, a sharp distal tip 18 and a lumen 19 extending therebetween. Distal tip 18 in this embodiment includes a bevel aligned at an acute angle to the longitudinal axis of needle 14. Shieldable needle assembly 12 further includes a needle hub 20 which is securely and permanently engaged with proximal end 16 of needle 14. Needle assembly 12, enables unimpeded use of needle 14 to introduce IV catheter 22 into a patient's vein during venipuncture, and ensures effective shielding of tip 18 of needle 14 immediately after withdrawal of needle 14 from cannula 24, as explained herein.

The preferred needle assembly 12 includes a guard 40 which comprises a cap portion 42 and a clip 44. As depicted most clearly in FIGS. 1-4, cap 42 is preferably molded from a thermoplastic material to include a cylindrically generated side wall 46, preferably extending circumferentially through more than 180°, and having opposed proximal and distal ends 47 and 48. Side wall 46 preferably is longer than the bevel at tip 18 of needle 14. Cap 42 further includes an end wall 50 extending across distal end 48 of side wall 46. End wall 50 includes an aperture 51 which is slidable along needle 14. Extending distally from end wall 50 are a plurality of fingers 55 radially spaced apart to define a diameter between fingers 55 that is substantially the same as or slightly smaller than the diameter of the proximal end of hub 30 or, in this case, luer collar 38. This provides an interference fit between fingers 55 and luer collar 38 so that when they are engaged, guard 40 stays with hub 30 during proximal movement of needle assembly 12 until a sufficient proximally directed force is applied to needle assembly 12 to overcome the interference fit between fingers 55 and luer collar 38. To ensure that fingers 55 stay coupled with luer collar 38 during proximal movement of guard 40, each finger may include a radially inwardly directed appendage 55a that overlaps a small portion of the distal face of luer collar 38. Such an arrangement requires that a larger proximally directed force be applied to guard 40 for the interference fit between fingers 55 and luer collar 38 to be overcome.

Clip 44 of guard 40 is retained between needle 14 and cap 42. Clip 44 includes a distal wall 52 that is configured to be biased against needle 14. However, sufficient distal movement of cap 42 with respect to needle 14 will cause distal wall 52 of clip 44 to pass beyond tip 18 of needle 14. Distal wall 52 of clip 44 will then be biased over tip 18 as illustrated in FIG. 5 and as described further herein. Clip 44 is preferably made of metal such as stainless steel or other material exhibiting good penetration resistance. Clip 44 provides more protection against penetration by tip 18 than could be provided by the plastic of cap 42. Additionally, a clip made of metal or other puncture resistant material enables the plastic of the shieldable needle assembly to be selected in view of its resiliency and other performance characteristics, and without concern for the ability of the plastic to resist needle punctures.

Needle assembly 12 further includes a hinged arm assembly 54 having a proximal segment 56 and a distal segment 58 which are articulated to one another at hinge pins 60. Proximal segment 56 of hinged arm assembly 54 is articulated to needle hub 20 at proximal hinge 62. Distal segment 58 of hinged arm assembly 54 is articulated to cap 42 at distal hinge 64, which is adjacent proximal end 47 of side wall 46. Needle hub 20, cap 42 and hinged arm 54 may be unitary with one another. However, in the preferred embodiment shown herein proximal and distal segments 56 and 58 are snapped into engagement with one another through hinge pins 60.

Hinge 62 between needle hub 20 and proximal segment 56 of hinged arm assembly 54 is an over-center spring hinge. More particularly, hinge 62 includes substantially nonbiasing hinge member 66 and spring element 68. Nonbiasing hinge member 66 defines the rotational path about which proximal segment 56 of hinged arm assembly 54 will rotate relative to needle hub 20. Spring element 68 in this preferred embodiment includes first and second segments 70 and 72 which are orthogonally aligned to one another in an unbiased condition, as shown in Fig. 4. However first and second segments 70 and 72 of spring element 68 can be resiliently deflected from the unbiased angle alignment into a more linear alignment. Rotation of proximal segment 56 of hinged arm assembly 54 from the

FIG. 4 alignment toward the FIG. 5 alignment will cause segments 70 and 72 of each spring element 68 to be deflected from the right angle condition shown in FIG. 4 toward a more linear orientation as shown in FIG. 5. The clinician must manually overcome the forces attributable to the resiliency of spring element 68 to move proximal segment 56 of hinged arm assembly 54 from the FIG. 4 orientation to the FIG. 5 orientation. The resiliency inherent in spring element 68 will urge the spring hinges back toward an undeflected right angle condition. This resiliency will effectively propel proximal segment 56 of hinged arm assembly 54 from the FIG. 4 orientation into the FIG. 5 orientation, with proximal segment 56 being adjacent needle 14.

Simultaneously, distal segment 58 will rotate into substantially parallel alignment with needle 14, and guard 40 will slide distally toward tip 18. It is important that the interference fit between fingers 55a and luer collar 38 can be overcome only by a force greater than the force attributable to the resiliency of spring element 68. This ensures that guard 40 stays with hub 30 until guard 40 safely covers sharp distal tip 18 of needle 14.

As explained further herein, the self-propelling feature enabled by the hinge 62 is desirable and facilitates one-hand actuation of needle shield 12. Equally important, however, is the fact that hinge 62 is in a stable condition in the FIG. 4 orientation with virtually no stored energy exerting pressure on the plastic components of needle assembly 12. As noted above, stored energy acting on plastic can affect the reliability and performance of the part. In this instance, however, the stored energy is accumulated only after proximal segment 56 of hinged arm 54 is moved from the stable FIG. 3 orientation into the FIG. 4 orientation. The accumulated energy then performs work for the user and moves hinged arm assembly 54 toward the FIG. 5 orientation. Hinge 62 will again be stable with virtually no stored energy in the FIG. 5 orientation where needle 14 is safely shielded.

Another feature of the present invention is that the spring element will resist accidental or inadvertent pressure which would tend to force guard 40 toward the FIG. 5 orientation where clip 44 covers sharp distal tip 18 of needle 14.

As shown in FIG. 1 , proximal segment 56 of hinged arm assembly 54 includes a pair of parallel spaced apart flanges 74 and 76 which terminate at collinear bearing slots 78 and 80 respectively. The bearing slots are dimensioned to receive hinge pins 60 which in this embodiment are unitarily molded as part of distal segment 58 of hinged arm assembly 54. Flanges 74 and 76 define a channel which receives distal segment 58 in the collapsed condition, and which receives a portion of needle 14 in the extended condition of hinged arm 54 as shown in FIG. 5. Distal segment 58 of hinged arm assembly 54 also includes first and second parallel spaced apart side flanges 84 and 86 defining a cannula-receiving channel therebetween.

As shown in FIGS. 1 and 2, distal segment 58 can be articulated about hinge pins 60 into a collapsed condition nested in the channel between flanges 74 and 76 of proximal segment 56. The relatively small dimensions of each segment 56 and 58, and the nesting of those segments in a collapsed condition substantially eliminates visual or physical obstruction of cannula 14 by hinged arm assembly 54. To the contrary, hinged arm assembly 54 preferably is aligned to define a plane which passes symmetrically through the bevel defining tip 18 of needle 14. Thus, hinged arm assembly 54 can be used to achieve a desired alignment of the bevel prior to insertion of needle 14 and cannula 24 into a patient. If it is desirable to have the bevel of tip 18 facing upwardly, the clinician need merely have the collapsed hinged arm point upwardly. After properly positioning IV catheter 22 into the vasculature of a patient, proximal and distal segments 56 and 58 of hinged arm assembly 54 can be articulated toward an extended position, with guard 40 slidably telescoping along needle 14 and away from needle hub 20. This invention ensures that sharp distal tip 18 is safely shielded once needle 14 is withdrawn from cannula 24. Specifically, the clinician can use the standard technique of applying pressure to the venipuncture site with one hand to prevent blood from flowing out of hub 30 while withdrawing needle 14 from cannula 24. Since fingers 55a are initially coupled to luer collar 38, guard 40 travels along needle 14 while it is being withdrawn until sharp distal tip 18 is withdrawn into guard 40. At this point, the clinician can exert a slightly greater proximally directed force to needle hub 20 to overcome the interference fit between fingers 55a and luer collar 38 and thus separate needle assembly 12 from catheter 22.

Proximal and distal segments 56 and 58 of hinged arm assembly 54 are dimensioned to permit end wall 50 of cap 42 and end wall 52 of clip 44 to pass distally beyond tip 18 of needle 14, as shown in FIG. 5. However, the respective lengths of proximal and distal segments 56 and 58 of hinged arm assembly 54 prevent complete separation of guard 40 from needle 14. Additionally, the configuration of clip 44 causes tip 18 of needle 14 to be biasingly trapped by clip 44. Portions of needle 14 between needle hub 20 and cap 42 will be surrounded by flanges 74 and 76 of proximal hinge segment 56 and flanges 84 and 86 of distal hinge segment.

As an alternative to the over-center hinge spring 62 of Figs. 1-5, a separate coil spring may be provided. In particular, with reference to FIG. 6, a coil spring may extend from needle hub 20 to proximal segment 56. Coil spring 90 is stretched by moving hinged arm 54 from the FIG. 3 orientation to the FIG. 5 orientation. Coil spring 90 then resiliently contracts and urges the needle guard distally over tip 18 of needle 14, substantially as explained in the preceding embodiment.

FIG. 7 illustrates an alternative placement for the coil spring illustrated in the embodiment of FIG. 5. In particular, a coil spring 95 may be connected between proximal segment 56 and distal segment 58. Coil spring 95 is stretched by moving hinged arm 54 from the FIG. 3 orientation to the FIG. 5 orientation. In this embodiment the guard is extended to the position where the distal end of the guard is positioned beyond tip 18 of needle 14. Further motion of the hinged arm assembly causes segments 56 and 58, at hinge pin 60, to bend inwardly to contact needle 14 and lock into a position much as a weight lifter locks his elbows to hold a weight in an extended position. This embodiment is not a preferred embodiment because the spring does little to propel the.guard in a distal direction. However, this embodiment does provide a locked linkage which can eliminate the need for a metal clip in the guard or supplement the clip for additional resistance to backward motion of the guard with respect to the needle.

Thus it is seen that an IV catheter assembly is provided that includes a needle shield assembly which is simple to use, compact, and shields the needle immediately upon withdrawal of the needle from the catheter after venipuncture.

Claims

WHAT IS CLAIMED IS:

1. A shieldable needle assembly comprising: a needle having a proximal end and a distal tip; a guard having a proximal end, an opposed distal end and a side wall extending therebetween, said guard being slidably movable along said needle from a first position substantially adjacent said proximal end of said needle to a second position where said distal tip of said needle is intermediate said opposed proximal and distal ends of said guard, said guard including a plurality of distally directed fingers for engaging the proximal end of another medical device; a hinged arm having proximal and distal segments articulated to one another for movement between a first position where said segments are substantially collapsed onto one another and a second position where said segments are extended from one another, said proximal segment of said hinged arm being articulated to a portion of said needle assembly adjacent said proximal end of said needle, said distal segment of said hinged arm being articulated to said guard, said proximal and distal segments of said hinged arm having respective lengths for permitting said guard to move from said first position to said second position on said needle, and for preventing said guard from moving distally beyond said second position; and spring means connected to said hinged arm for urging said guard along said needle toward said second position.

2. The shieldable needle assembly of Claim 1 , wherein said proximal end of said guard comprises a proximal wall having an aperture therethrough, and wherein said needle slidably extends through said aperture of said proximal wall of said guard.

3. The shieldable needle assembly of Claim 1 , wherein said side wall of said guard is generally annular and is disposed in surrounding relationship to said needle.

4. The shieldable needle assembly of Claim 1 , wherein said distal end of said guard comprises a distal end wall having an aperture slidably engaged around said needle when said guard is disposed at said first position, said distal end wall being distally beyond said tip of said needle when said guard is in said second position.

5. The shieldable needle assembly of Claim 1 , wherein said guard comprises a clip retained between said side wall and said needle, said clip being configured to cover said tip when said guard is in said second position on said needle.

6. The shieldable needle assembly of Claim 1 , further comprising a needle hub securely engaging said proximal end of said needle, said proximal segment of said hinged arm being articulated to said hub.

7. The shieldable needle assembly of Claim 6, wherein said hub and said proximal segment of said hinged arm are unitary with one another.

8. The shieldable needle assembly of Claim 1 , wherein said spring means is substantially unbiased when said guard is in said first position.

9. The shieldable needle assembly of Claim 1 , wherein said sp ng means is a coil spring.

10. The shieldable needle assembly of Claim 9, wherein said coil spring extends from a portion of said needle assembly adjacent said proximal end of said needle to a location on said proximal segment of said hinged arm.

11. The shieldable needle assembly of Claim 1 , wherein said spring means comprises an over-center hinge extending unitahly from said proximal segment of said hinged arm and said portion of said needle assembly adjacent said proximal end of said needle.

12. The shieldable needle assembly of Claim 1 , wherein the proximal and distal segments of the hinged arm each comprise channels dimensioned and disposed to substantially surround said needle when said guard is in said second position.

13. The shieldable needle assembly of Claim 12, wherein the channel of one of said proximal and distal segments is dimensioned to receive at least a portion of the other of said proximal and distal segments when said guard is in said first position.

14. The shieldable needle assembly of Claim 1 , wherein said tip of said needle is defined by a bevel having a plane of symmetry, said hinged arm being in said plane of symmetry for indicating orientation of said bevel.

15. The shieldable needle assembly of Claim 5 wherein said clip is made of metal.

16. A shieldable needle assembly comprising: a needle having a proximal end and a sharply pointed distal tip; a guard having a proximal end, an opposed distal end and a side wall extending therebetween, said guard being slidably movable along said needle from a first position substantially adjacent said proximal end of said needle to a second position where said distal tip of said needle is intermediate said opposed proximal and distal ends of said guard, said guard including a clip retained between said side wall and said needle, said clip being configured to cover said tip when said guard is in said second position on said needle, said guard including a plurality of distally directed fingers for engaging the proximal end of another medical device; and a hinged arm having proximal and distal segments articulated to one another for movement between a first position where said segments are substantially collapsed onto one another and a second position where said segments are extended from one another, said proximal segment of said hinged arm being articulated to a portion of said needle assembly adjacent said proximal end of said needle, said distal segment of said hinged arm being articulated to said guard, said proximal and distal segments of said hinged arm having respective lengths for permitting said guard to move from said first position to said second position on said needle, and for preventing said guard from moving distally beyond said second position.

17. The shieldable needle assembly of Claim 16, further comprising a needle hub securely engaging said proximal end of said needle, said proximal segment of said hinged arm being articulated to said hub.

18. The shieldable needle assembly of Claim 17, wherein said hub and said proximal segment of said hinged arm are unitary with one another.

19. The shieldable needle assembly of Claim 16, wherein the proximal and distal segments of the hinged arm each comprise channels dimensioned and disposed to substantially surround said needle when said guard is in said second position.

20. The shieldable needle assembly of Claim 19, wherein the channel of one of said proximal and distal segments is dimensioned to receive at least a portion of the other of said proximal and distal segments when said guard is in said first position.

21. The shieldable needle assembly of Claim 16 wherein said clip is made of metal.