Title: Method of making a needle and a needle
Abstract: A method is provided for forming a feature on a needle. In particular, a hollow, metal cannula has a first end, a second end and a substantially constant outer diameter extending over at least a portion of its length. An annular metal sleeve is provided that has a proximal shoulder and a distal shoulder. The length of the annular sleeve is less than the length of the constant diameter portion of the cannula. The sleeve has an inner diameter approximately equal to or less than the outer diameter of the constant diameter portion of the cannula. Two edges extend axially along the length of the sleeve, from the proximal shoulder to the distal shoulder, thereby defining a slit. The sleeve is positioned on the cannula at the constant outer diameter portion in an interference fit. An additional mechanical junction may be provided to secure the sleeve to the cannula. For example, the sleeve may be welded to the cannula using a laser welder at at least one edge of the sleeve near one of either the proximal face or the distal face. Alternatively and additionally, the sleeve may be crimped or glued to the cannula. In accord with another aspect of this invention, a needle is provided made in accord with this method.
Patent Number: 7,002,098 Issued on 02/21/2006 to Adams
| Inventors:
|
Adams; Chad Michael (West Jordan, UT)
|
| Assignee:
|
Becton, Dickinson and Company (Franklin Lakes, NJ)
|
| Appl. No.:
|
732025 |
| Filed:
|
December 10, 2003 |
| Current U.S. Class: |
219/121.6; 219/121.64 |
| Current Intern'l Class: |
B23K 26/00 (20060101) |
| Field of Search: |
219/1216,121.63,121.64,121.85
|
References Cited [Referenced By]
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| 4280496 | Jul., 1981 | Van Baelen.
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| 4846811 | Jul., 1989 | Vanderhoof.
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| 4883468 | Nov., 1989 | Kousai et al.
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| 5215528 | Jun., 1993 | Purdy.
| |
| RE34416 | Oct., 1993 | Lemieux.
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| 5364373 | Nov., 1994 | Waskonig et al.
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| 5372582 | Dec., 1994 | Skrabal et al.
| |
| 5419766 | May., 1995 | Chang et al.
| |
| 5540667 | Jul., 1996 | Tanner, II.
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| 5556410 | Sep., 1996 | Mittermeir et al.
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| 5558651 | Sep., 1996 | Crawford et al.
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| 5601536 | Feb., 1997 | Crawford et al.
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| 5647849 | Jul., 1997 | Kalin.
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| 5683365 | Nov., 1997 | Brown et al.
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| 5702367 | Dec., 1997 | Cover et al.
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| 5704926 | Jan., 1998 | Sutton.
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| 5897508 | Apr., 1999 | Konrad.
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| 5954670 | Sep., 1999 | Baker.
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| 6012213 | Jan., 2000 | Chang et al.
| |
| 6117108 | Sep., 2000 | Woehr et al.
| |
| 6183440 | Feb., 2001 | Bell.
| |
| 6322537 | Nov., 2001 | Chang.
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| 6379333 | Apr., 2002 | Brimhall et al.
| |
| 2002/0026154 | Feb., 2002 | Chang.
| |
| 2002/0103463 | Aug., 2002 | Luther et al.
| |
| Foreign Patent Documents |
| 28 25 346 | Dec., 1979 | DE.
| |
| 212 423 | Aug., 1984 | DE.
| |
| 1 250 943 | Oct., 2002 | EP.
| |
| WO 99/0874/2 | Feb., 1999 | WO.
| |
| WO 01/6817/4 | Sep., 2001 | WO.
| |
Other References
PCT International Search Report.
|
Primary Examiner: Elve; M. Alexandra
Attorney, Agent or Firm: Ghose; Mony R.
Parent Case Text
This application is a continuation of application Ser. No. 10/137,464 filed
May 1, 2002.
Claims
We claim:
1. A method of making a cannula having a feature comprising:
providing a cannula having a first end, a second end, a length and an outer surface
with en outer diameter;
forming a notch in the outer surface of the cannula at a predetermined position
along the length of the cannula;
providing a sleeve with a cylindrical shape and an inner cavity defining an inner
diameter that is less than the outer diameter of the outer surface of the cannula,
wherein the sleeve has a slit, wherein the slit extends over 20 degrees of arc
or less when positioned on the cannula;
positioning the sleeve over the cannula such that the notch is disposed, at least
in part, within the inner cavity; and
crimping the sleeve such that at least a portion of the sleeve is deformed radially
inward, causing the sleeve to engage the notch.
2. The method of claim 1 further comprising welding the sleeve to the cannula
after crimping.
3. A cannula formed by the method of claim 1.
4. A method of forming a needle comprising:
providing a hollow, metal cannula having a first end, a second end, a beveled
tip at the second end, an axis, a cannula length extending from the first end to
the second end, and an outer diameter;
providing a distinct annular metal sleeve positioned on the cannula at a predetermined
position with respect to the tip, the sleeve having a proximal shoulder and a distal
shoulder, and a sleeve length extending from the proximal shoulder to the distal
shoulder, wherein a slit is disposed in the sleeve, wherein the slit extends over
20 degrees of arc or less when positioned on the cannula; and
forming a mechanical bond integrally with the sleeve or the cannula, thereby
fixedly attaching the sleeve to the cannula at a predetermined location.
5. The method of claim 4 wherein the mechanical bond includes a crimp formed
in the sleeve engaging a notch in the cannula.
6. The needle of claim 4 wherein the mechanical bond is a weld.
7. A needle formed by the method of claim 4.
8. A method of forming a feature on a cannula comprising:
providing a hollow, metal cannula having a first end, a second end, an axis,
a length extending from the first end to the second end, and an outer surface extending
over at least a first portion of the length;
providing an annular sleeve with an exterior surface, wherein the sleeve has
a slit extending over 20 degrees of arc or less when positioned on the cannula;
positioning the sleeve on the cannula at the first portion of the cannula; and
joining the sleeve to the cannula by welding through the sleeve to the cannula.
9. The method of claim 8 further comprising delivering a laser beam to an exterior
surface of the sleeve and welding through the sleeve to the cannula.
10. The method of claim 8 wherein a contact point between the sleeve and the
cannula exists before joining occurs.
11. The method of claim 8 wherein a rib is mounted to the sleeve, extending,
at least in part, radially outward from the exterior surface of the sleeve.
12. The method of claim 8 further comprising providing a flat metal sheet and
rolling the sheet into an annular shape to form the sleeve.
13. The method of claim 8 further comprising positioning an adhesive material
between the sleeve and the cannula, securing the sleeve to the cannula.
14. A method of forming a feature on a cannula comprising:
providing a cannula having a first end, a second end, an axis, a length extending
from the first end to the second end, and an outer diameter extending over at least
a first portion of the length;
providing a sleeve with a proximal shoulder, a distal shoulder, an inner diameter,
a sleeve length extending from the proximal shoulder to the distal shoulder, and
a slit extending over 20 degrees of arc or less when positioned on the cannula;
positioning the sleeve on the cannula at the first portion of the cannula in
an interference fit such that the sleeve accommodates the cannula; and
welding the sleeve to the cannula.
15. The method of claim 14 further comprising crimping the sleeve to the cannula.
16. The method of claim 14 wherein welding comprises providing a seam weld formed
by a laser welder extending substantially the full length of the sleeve.
17. The method of claim 14 wherein the sleeve is glued to the cannula by an adhesive
material before welding.
18. A cannula formed by the method set forth in claim 13.
Description
FIELD OF THE INVENTION
The subject invention relates to the field of infusion therapy. In particular,
the invention is related to an introducer needle having a shoulder disposed at
a predetermined distance from the tip of the needle and to a method for making
such a needle.
BACKGROUND OF THE INVENTION
Catheters, particularly intravenous (IV) catheters, are used for infusing
fluid, such as normal saline solution, various medicaments and total parenteral
nutrition, into a patient or withdrawing blood from a patient. Peripheral IV catheters
tend to be relatively short, and are on the order of about one and one-half inches
in length. The most common type of IV catheter is an over-the-needle peripheral
IV catheter. As its name implies, an over-the-needle catheter is mounted over an
introducer needle having a sharp distal tip. The catheter and the introducer needle
are assembled so that the distal tip of the introducer needle extends beyond the
distal tip of the catheter with the bevel of the needle facing up away from the
patient's skin.
The catheter and introducer needle assembly is inserted at a shallow angle through
the patient's skin into a peripheral blood vessel, i.e., a smaller blood vessel
that is not connected directly to the heart but is one of the branches of the central
blood vessels that is directly connected to the heart. In order to verify proper
placement of the assembly in the blood vessel, the clinician confirms that there
is flashback of blood in the needle and in a flashback chamber located at the proximal
end of the needle, which is typically formed as part of the needle hub. Once proper
placement is confirmed, the clinician applies pressure to the blood vessel by pressing
down on the patient's skin over the distal tip of the introducer needle and the
catheter. This finger pressure occludes further blood flow through the introducer
needle. The clinician withdraws the introducer needle, leaving the catheter in
place, and attaches a fluid-handling device to the catheter hub. Once the introducer
needle is withdrawn from the catheter, it is a "blood contaminated sharp" and must
be properly handled.
In recent years, there has been great concern over the contamination of clinicians
with a patient's blood and a recognition that "blood contaminated sharps" must
be immediately disposed. This concern has arisen because of the advent of currently
incurable and fatal diseases, such as Acquired Immunosuppressive Deficiency Syndrome
("AIDS"), which can be transmitted by the exchange of body fluids from an infected
person to another person. Thus, contact with the body fluid of an HIV-infected
person should be avoided. As noted above, if an introducer needle has been used
to place a catheter in the vein of an HIV-infected person, the introducer needle
may be a vehicle for the transmission of the disease. Although clinicians are aware
of the need to properly handle "blood contaminated sharps," in certain medical
environments, such as emergency situations or as a result of inattention or neglect,
needle sticks from contaminated introducer needles may occur.
As a result of the problem of accidental needle sticks by "blood contaminated
sharps," various needle shields have been developed. Examples of such shields are
disclosed in U.S. Pat. No. 6,004,294 and U.S. patent application Ser. No. 09/717,148
(filed Nov. 21, 2000), both incorporated herein by reference. These shields operate
by engaging a feature, such as an enlarged diameter portion, formed on the needle.
The engaging means may take many forms, such as a spring gate biased to contact
the enlarged diameter portion of the needle when the tip of the needle is within
the shield. Due to the small size of the needle and its delicate structure, it
has been difficult to provide a feature that can withstand adequate force without
affecting the operation of the needle itself. Further, such features have traditionally
included a ramp, a radius or angled surface extending from the surface of the needle
that may create difficulty in capturing the tip within the shield or may result
in exertion of force on the needle in a non-axial direction.
SUMMARY OF THE INVENTION
It is therefore an advantage of one aspect of the instant invention to provide
a needle and method of making a needle that may be employed with various safety-engineered
shielding devices.
It is an advantage of another aspect of the invention to provide a needle and
a method for making a needle having a feature with a right-angled shoulder.
It is an advantage of another aspect of the instant invention to provide a needle
having a sleeve secured to a cannula at a predetermined location and a method for
securing the sleeve to the cannula at the predetermined location.
It is an advantage of yet another aspect of the instant invention to provide a
technique for securing a feature on a needle having a sharp, right angled shoulder
that can be readily captured by an engaging means in a needle shield and, once
captured, can direct the forces from the engaging means to the needle in a substantially
axial direction.
In accord with one aspect of the invention, a method is provided for forming a
feature on a needle. In particular, a hollow, metal cannula has a first end, a
second end and a substantially constant outer diameter extending over at least
a portion of its length. An annular metal sleeve is provided that has a proximal
shoulder and a distal shoulder. The length of the annular sleeve is less than the
length of the constant diameter portion of the cannula. The sleeve has an inner
diameter approximately equal to or less than the outer diameter of the constant
diameter portion of the cannula. Two edges extend axially along the length of the
sleeve, from the proximal shoulder to the distal shoulder, thereby defining a slit.
The sleeve is positioned on the cannula at the constant outer diameter portion
in an interference fit. An additional mechanical junction may be provided to secure
the sleeve to the cannula. For example, the sleeve may be welded to the cannula
using a laser welder at at least one edge of the sleeve near one of either the
proximal face or the distal face. Alternatively and additionally, the sleeve may
be crimped or glued to the cannula. In accord with another aspect of this invention,
a needle is provided that has been made in accord with this method.
Certain implementations of this aspect of the invention provide that the
proximal shoulder is perpendicular to the axis of the cannula or the distal shoulder
is perpendicular to the axis of the cannula. The sleeve may be welded to the cannula
proximate to both the proximal face and the distal face, or a seam weld may be
applied along the length of the sleeve. Alternatively or additionally, the sleeve
may be crimped or glued to the cannula. The sleeve may be formed by rolling a flat
metal sheet into an annular shape, such as a cylinder, and then slipped onto the
cannula. A window may be formed in the sleeve at a predetermined position with
respect to the slit and the sleeve may be welded to the cannula at the window.
Such a window may be disposed in the sleeve at a position 180 degrees from the slit.
In accord with another aspect of the invention, a distinct mechanical junction
is formed between the sleeve and the cannula to secure the feature in place. For
example, a notch is formed in the outer surface of the cannula at a predetermined
position along the length of the cannula. A cylindrical sleeve has an inner cavity
with an inner diameter that is less than the outer diameter of the outer surface
of the cannula. The sleeve is positioned over the cannula such that the notch is
disposed within the inner cavity. The sleeve is crimped such that at least a portion
of the sleeve is deformed radially inward, causing the sleeve to engage the notch.
Certain implementations of this aspect of the invention provide that the sleeve
is welded to the cannula after crimping or that an adhesive is employed to join
the sleeve to the cannula. The use of an adhesive may be particularly advantageous
to hold the sleeve in place before the crimp or weld is formed.
In accord with yet another aspect of the invention, a needle includes a hollow,
metal cannula having a first end, a second end, a beveled tip at the second end,
an axis, a cannula length extending from the first end to the second end, and an
outer diameter. A distinct annular metal sleeve is fixedly attached to the cannula
at a predetermined position with respect to the tip. The sleeve has a proximal
shoulder and a distal shoulder, and a sleeve length extending from the proximal
shoulder to the distal shoulder. At least one of the proximal shoulder or the distal
shoulder is perpendicular to the axis of the cannula. Certain implementations of
this aspect of the invention provide that the sleeve has two edges extending axially
along the sleeve length from the proximal shoulder to the distal shoulder, thereby
defining a slit and a weld is disposed along the slit. A flash opening may be positioned
in the cannula, proximal to the sleeve, that would provide the caregiver with a
visual indication when the beveled tip of the needle has accessed the patient's
vein. Radially extending tabs may be positioned on the sleeve to orient the needle
during manufacture and use.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an exploded perspective view of a cannula and sleeve in accord with
one aspect of the invention.
FIG. 2 is a perspective view of a cannula and sleeve in accord with an aspect
of the invention with a seam weld.
FIG. 3 is an exploded perspective view of a cannula and an over-the-needle catheter
in accord with an aspect of the invention.
FIG. 4 is a cut-away side view of the cannula and catheter of FIG. 3.
FIG. 5 is a perspective view of a cannula and a sleeve in accord with another
aspect of the invention.
FIG. 6 is a side elevation view of the cannula and sleeve of FIG. 5.
FIG. 7 is a top elevation view of a cannula and sleeve in accord with another
aspect of the invention.
FIG. 8 is a bottom elevation view of the cannula and sleeve of FIG. 7.
FIG. 9 is a perspective view of a sleeve in isolation.
FIG. 10 is a front elevation view of the sleeve of FIG. 9.
FIG. 11 is a side elevation view of the sleeve of FIG. 9.
FIG. 12 is a top elevation view of a sheet used to form the sleeve of FIG. 9.
FIG. 13 is a top elevation view of a cannula and sleeve in accord with an aspect
of the invention.
FIG. 14 is a side elevation view of the cannula and sleeve of FIG. 13.
FIG. 15 is a cut-away side view of the cannula and sleeve of FIG. 13.
FIG. 16 is a perspective view of a sleeve for use in accord with aspects of
the invention.
DETAILED DESCRIPTION
As used herein, the term "proximal" refers to a location on the needle
1
that, during normal use, is closest to the clinician using the device and farthest
from the patient in connection with whom the device is used (the right side of
FIG.
4). Conversely, the term "distal" refers to a location on the needle
that, during normal use, is farthest from the clinician using the device and closest
to the patient in connection with whom the device is used (the left side in FIG.
4).
In various stages of the manufacture of needle assemblies and during the use
of
needles, it would be advantageous to have a distinct feature on the needle
1
that is secured at a fixed location and orientation with respect to the rest of
the needle
1, particularly the tip
14. For example, such a feature
may be employed to orient the needle
1 with respect to a needle hub or holder.
Consequently, the needle tip
14 would also be at a fixed orientation with
respect to the holder. A caregiver would thus know immediately to orientation of
the needle tip
14 by simply grasping the holder. Further, such a feature
may be more readily graspable by machines designed to automatically manufacture
needles and over-the-needle catheter assemblies. The feature may be used to engage
a ledge
101 in a catheter
100 (see FIG.
4), thereby positioning
the needle at a particular location within the catheter and ensuring that the tip
14 of the needle extends out of the catheter a satisfactory distance. Additionally,
such a feature may be more readily grasped by a safety device designed to capture
the needle tip
14 after use.
In accord with an aspect of the invention, a needle
1 includes a cannula
10 having a ferrule or sleeve
40 attached at a fixed, predetermined
position along the length of the cannula. As will be discussed more fully below,
the sleeve
40 is preferably sized with an inner diameter that is smaller
than the outer diameter of the cannula. Consequently, there is an interference
fit between the sleeve
40 and the cannula which helps maintain the sleeve
in its predetermined position. Additional mechanical junctions or bonds
60
may be provided to better maintain the sleeve
40 in place. With the sleeve
40 in place, the needle
1 includes a feature (which may include the
proximal shoulder
44 and/or distal shoulder
45 of the sleeve, or
the sleeve itself, or some other structure attached to or formed integral with
the sleeve, such as a tab
80) that can be employed for various purposes
related to the manufacture and use of the needle
1. For example, once formed,
the needle
1 may be inserted into a catheter
100 for insertion into
the tissue of a patient. After use, the needle
1 may be withdrawn from the
catheter. The needle tip
14 may then be captured within a safety-engineered
shielding device that grips the feature such as disclosed in U.S. Pat. No. 6,004,294
and U.S. patent application Ser. No. 09/717,148, incorporated herein by reference.
The cannula
10 includes a proximal end
11 and a distal end
12
extending along an axis
13. Typically, the cannula has a cylindrical shape.
Preferably, at least a portion
21 of the cannula has a constant outer diameter.
A beveled tip
14 is positioned at the distal end of the cannula. The beveled
tip may be formed of two beveled surfaces, a proximal bevel
15 and a distal
bevel
16 (see FIG.
2), that are disposed at different angles from
the axis of the cannula to ease entry into a patient's vein. The cannula includes
an outer surface
20 and an inner surface
19. The inner surface
19
defines a central cavity
17 that extends from the proximal end of the cannula
to the distal end, forming a tip opening
23 at the distal end.
A flash opening
18 is located in the wall of the cannula
10, creating
a fluid flow path from the central cavity
17 to the exterior of the cannula
within the catheter
100. Preferably, the flash opening is proximal to the
sleeve
40. The catheter is operably engaged to a flash chamber
90.
The flash chamber may simply be the annular space about the needle within the catheter
(see FIG. 4) or a separate chamber located in a needle hub. During use, this flow
path provides the caregiver with a visual indication that the vein has been successfully
entered because a small amount of blood will flow through the tip opening, through
the flash opening and into the flash chamber where it is visible to the caregiver.
As shown in FIG. 4, the catheter is translucent so that blood in the annular space
90 is visible to the caregiver.
The ferrule or sleeve
40 preferably has a substantially cylindrical shape
(see FIG. 9) formed by an exterior surface
42, an interior surface
43,
and a length
47 extending from a distal face
145 to a proximal face
144. The interior surface
43 defines an inner cavity
51. Importantly,
in accord with certain implementations of the invention, the sleeve
40 is
sized to tightly fit on the cannula in an interference fit. The length
47
of the sleeve
40 is preferably no longer than the length of the constant
diameter portion
21 of the cannula. As can be seen in FIG. 4, when the sleeve
40 is positioned on the cannula, the distal face forms a distal shoulder
45 and the proximal face forms a proximal shoulder
44. Preferably,
the distal shoulder and the proximal shoulder are perpendicular to the outer surface
20 of the cannula
10 and to the cannula axis
13.
A slit
50 is formed in the sleeve
40 and defined by two edges
41.
Preferably, the slit extends axially through the sleeve
40 from the proximal
face
144 to the distal face
145. The slit may also have other shapes
and still practice the invention. In particular, the slit may proceed around the
sleeve
40 in a spiral shape or other curved shapes. Before positioning the
sleeve
40 on the cannula, the edges are adjacent or nearly adjacent (see
FIG.
5). As the sleeve
40 is forced onto the cannula, the edges separate
to accommodate the larger outer diameter of the cannula within the inner cavity
51.
The sleeve
40 may be formed in any manner such as extruding, casting or
the like. If the sleeve
40 is initially formed as a complete cylinder, the
slit
50 can be formed in the sleeve, such as by cutting, burning and so
on. In one implementation of the invention, the sleeve
40 is formed of a
flat sheet
46 (see FIG.
12). The sheet is rolled into a nearly cylindrical
shape, bringing the edges together and thereby forming the slit. The sheet is sized
so that the slit extends over less than 180 degrees of arc along the diameter of
the sleeve when the sleeve is positioned on the cannula. Preferably, the slit extends
over 20 degrees of arc or less when the sleeve is positioned on the cannula. It
will be appreciated that the slit may be larger or smaller and still practice the
invention. Further, in certain implementations, the slit may be formed as a groove
disposed in the sleeve
40 that does not extend fully through the sleeve
40 radially (that is, the edges are connected by a thin webbing before mounting
the sleeve on the cannula).
Once the sleeve
40 is formed, it is slipped over the distal end
12
of the cannula
10 and positioned at a predetermined location on a constant
diameter portion
21 of the cannula. Preferably, the sleeve
40 is
located a distance from the tip
14 such that the tip and the sleeve may
be secured within a shield after use, as discussed in U.S. Pat. No. 6,004,294,
incorporated herein by reference, and U.S. application Ser. No. 09/717,148, incorporated
herein by reference. It will be appreciated that the sleeve
40 may be located
at other locations and still practice aspects of the invention. Further, the sleeve
40 may be formed in other manners and be positioned on the cannula in different
ways and still practice aspects of the invention. For example, the flat sheet
46
may be rolled directly onto the cannula and secured in place as disclosed herein.
As discussed above, the diameter of the inner cavity
51 of the sleeve
40
is preferably less than the diameter of the outer surface
20 of the cannula
10, creating a close interference fit between the sleeve and the cannula.
The edges
41 of the sleeve
40 are forced apart to accommodate the
outer diameter of the cannula. If webbing connects the edges, it is broken as the
cannula is forced into the inner cavity. In any event, there is preferably direct
contact between the interior surface
43 of the sleeve
40 and the
outer surface
20 of the cannula when the sleeve is positioned on the cannula.
The interference fit between the interior surface
43 of the sleeve
40
and the outer surface
20 of the cannula prevents movement of the sleeve
40 along the length of the cannula under certain loads. Indeed, the interference
fit alone may provide adequate resistance to the movement of the sleeve
40
for a particular application such that the interference fit may be deemed an adequate
mechanical junction. In certain circumstances, however, a greater resistive force
will be desired. In those circumstances, an additional mechanical junction
60
is provided, securing the sleeve
40 to the cannula. For example, the sleeve
40 may be welded to the cannula using a laser welder. As depicted in FIG.
2, a laser beam
301 from a laser welding device
300, such as an Nd:
Yag laser welder, model Luxstar LX50 may be directed at contact points on the sleeve
40. The sleeve and the cannula are in direct physical engagement at the
contact points. A seam weld
160 may then be created along the slit
60
by delivering a laser beam in a series of spots over the length of the sleeve.
Other techniques for welding may also be employed. Referring to FIGS. 7 and
8, two of the contact points or weld points
61 are positioned along the
edges
41 at the slit
50, one near the proximal shoulder
44
and one near the distal shoulder
45. The laser beam is directed at the juncture
of the edge and the cannula at the slit. The laser melts the material of the sleeve
40 and the cannula, which, in turn, cools to form a weld, integral with
both the sleeve
40 and the cannula, securing them together. Two other contact
points or weld points
64 are disposed on the opposite side of the sleeve
40, 180 degrees from the slit. Again, these weld points are disposed near
the proximal shoulder
44 and the distal shoulder
45. The laser beam
is directed at the exterior surface
42 of the sleeve
40, melting
through the wall of the sleeve so that the beams melt at least some portion of
the outer surface
20 of the cannula
10. The melted portions of the
sleeve
40 and the cannula
10 cool to form a weld, integral with both
the sleeve and the cannula, securing them together.
These four welds may be created by splitting a single laser beam into four
beams, and applying them to the desired weld points for a controlled period of
time, depending on the dimension of and materials forming the sleeve
40
and the cannula
10, as well as the desired resistive force to be withstood
by the mechanical junction
60. It will be appreciated that other techniques
for welding, in particular other techniques for laser welding, may be employed
and still practice aspects of the invention. For example, the weld may be provided
at locations distinct from the slit. Currently, on one preferred application of
the invention, two seam welds
160 are formed disposed 180° from each
other, neither being located along the slit. The laser beam is delivered to the
surface of the sleeve and creates a weld, bonding the sleeve to the cannula along
both seams. Alternatively or additionally, a window
48 may be provided in
the sleeve. The mechanical junction
60 can be formed by a spot weld at the
edge of the window (see FIGS.
3 and
4).
The dimensions and materials of the sleeve
40 and cannula
10, as
well as the operation of the laser welder, will depend on the particular application
for the needle
1. It is preferred that the sleeve
40 and the cannula
be formed of a similar alloy to ensure that a satisfactory mechanical bond is formed
by the laser weld or other mechanical junction. In one application of the instant
invention, the cannula is made of fully hard
301 (or
302) stainless
steel and has an outer diameter of between 0.007 and 0.080 inch (including, around
0.055 inch). The sleeve
40 is formed from a sheet of fully hard
301
(or
302) stainless steel about 0.002 inch thick and about 0.050 inch long.
The weld points are preferably about 0.005 inch inward from the proximal and distal
shoulders. Most preferably, the sleeve
40 contacts the cannula where the
weld is applied. In any event, it is preferred that there be a gap of no more than
0.0010 inches at a desired weld point. The laser beam is applied to the weld points
for a period of 0.2 seconds at 100 Hz at a setting of 30-50 KW. The resulting weld
at the weld point is about 0.010 inch in diameter and can withstand an axial force
of about 30-50 lbs.
Referring to FIGS. 13-15, another form of mechanical junction may be employed
in connection with an aspect of the instant invention. Crimp notches
70
are formed in the cannula at a desired location, such as at the otherwise constant
diameter portion
21 of the cannula (constant, that is, excluding the crimp
notches). Preferably, the crimp notches do not penetrate the wall of the cannula.
However, the crimp notches
70 may be formed as cut outs in the cannula wall.
Further, the flash notch
18 may be employed as a crimp notch. The number,
location and shape of the crimp notches
70 may be selected based on the
particular application of the needle. For example, two crimp notches may be employed,
disposed on opposite sides of the cannula at a position distal to the flash notch
18 (see FIG.
15). The sleeve
40 is formed and slipped over
the cannula until it is disposed directly over the crimp notches, capturing the
crimp notches within the inner cavity
51. The sleeve
40 is then crimped
into the crimp notches
21, creating a mechanical engagement at junction
63 between the sleeve and the cannula. The sleeve
40 may also be
secured to the cannula using an adhesive material
62 or weld points
61.
The use of an adhesive material may be particularly advantageous to maintain the
sleeve in position on the cannula until crimping or welding is completed.
As discussed above, the feature on the needle
1, such as the sleeve
40
and/or its proximal and distal shoulders, are preferably symmetric about the axis
of the catheter. It will be appreciated that the sleeve
40 may have other
distinct shapes and still practice the invention. For example, tabs or ribs
80
(see FIG. 16) may be formed on the sleeve
40 that extend radially outward
or which extend axially from the distal shoulder or the proximal shoulder along
the surface of the cannula. Such tabs or ribs may be employed to orient the cannula
(and thus the needle tip
14) with the catheter
100 (and thus a hub
that is grasped by a caregiver). Further, such tabs or ribs may be used as a register
to observe and control the orientation of the cannula during the manufacturing
process. The tabs or ribs may also be designed to cooperate with various structures
in a needle shield to better capture the needle tip
14.
Further, as disclosed herein, the cannula has a substantially cylindrical
shape. It will be appreciated that the cannula may have other shapes and still
practice aspects of the invention. For example, the cannula may have an oval cross
section such that the sleeve
40 contacts the cannula only along the major
axis of the oval. Conversely, the sleeve may be formed with an inner cavity having
an oval cross section such that it contacts the outer surface
20 of the
cannula at the minor axis of the oval. The mechanical junction may then be formed
at those contact points, such as by welding, using an adhesive material
62
or crimping the sleeve
40 into a notch on the cannula.
It is preferred that the sleeve
40 actually contacts the cannula at the
weld point during welding. Such a contact is preferably achieved by the interference
fit between the sleeve
40 and the cannula. However, it will be appreciated
that the sleeve
40 may be sized such that there is no interference fit and
practice aspects of the invention. For example, a solder material may be disposed
about the cannula as the sleeve
40 is slipped into position before welding.
Advantageously, a solder that also functions as an adhesive material may be employed.
If the internal diameter of the sleeve
40 is larger than the outer diameter
of the cannula, there will be a space between the cannula and the sleeve that might
interfere with satisfactory laser welding. To overcome this difficulty in this
situation, the sleeve
40 may be biased in a direction against the outer
surface
20 of the cannula to achieve a contact point where welding can take
place. Further, other welding techniques may not require the close positioning
of the sleeve
40 and the cannula to achieve a satisfactory weld. In fact,
in certain circumstances, the sleeve
40 may be sufficiently thick that enough
material can be melted by the laser welder to effect an adequate weld without affecting
the integrity of the sleeve.
As discussed herein, four spot weld points or two seam welds are employed. Any
number of welds and weld points may be employed as is required to achieve a satisfactory
bond between the sleeve and the cannula for a given application. Further, the weld
points and seams may be located at other positions and still practice aspects of
the invention. For example, the sleeve
40 may be secured to the cannula
with a single weld formed in the sleeve at any position, such as a position remote
from the slit. The weld point may be at the juncture of the proximal shoulder and/or
the distal shoulder and the outer surface
20 of the cannula. The weld may
be a single contiguous line extending axially along the full length of the sleeve
40, or circumferentially about a diameter of the sleeve.
The sleeve
40 is preferably positioned along the cannula at a point distal
of the flash notch
18. It will be appreciated that the sleeve may be positioned
at other locations and still practice aspects of the invention. For example, the
flash notch
18 may be positioned between the sleeve
40 and the tip
of the cannula. Alternatively, the sleeve
40 may be positioned in engagement
with or partially covering the flash notch
18. Further, the slit may be
orientated at different locations with respect to the flash notch
18 and
practice aspects of the invention.
The proximal shoulder and the distal shoulder preferably form right-angled surfaces
with the outer surface
20 of the cannula. It will be appreciated that the
shoulders may have different shapes and still practice aspects of the invention.
For example, the shoulder may be provided with an undercut at the cannula surface,
creating a crevice that may engage certain types of grasping mechanisms contained
within shields Further, the proximal face
144 and distal face
145
may have curved or notched surfaces, depending on the particular application of
the invention.
Although the invention is described herein in connection with a needle
1
employed with a peripheral IV catheter and a safety shield, it is understood that
the invention is applicable to other needles, such as hypodermic needles, epidural
needles and so forth. In addition, while this invention is satisfied by embodiments
in many different forms, preferred embodiments of the invention are shown in the
drawings and described in detail herein. The scope of the invention is measured
by the appended claims.
*
