AU2018202586B1

AU2018202586B1 - Stylet construction

Info

Publication number: AU2018202586B1
Application number: AU2018202586A
Authority: AU
Inventors: Peter Hebbard; Andrew Kellock; Kean Leong Tai
Original assignee: P & M Hebbard Pty Ltd
Current assignee: P & M Hebbard Pty Ltd
Priority date: 2017-07-07
Filing date: 2018-04-13
Publication date: 2018-06-14
Anticipated expiration: 2038-04-13
Also published as: WO2019006490A1

Abstract

A stylet 1 for a catheter including a connector 3 and an elongate member 15. The connector is connectable to a rear end of the catheter and has an inner passage. The elongate member projects from the inner passage to run along the interior of 5 the catheter and includes an anchor portion 17 fixed within the inner passage. A rear of the connector has a port 7 for fluid communication with an interior of the catheter via the inner passage and past the anchor portion.

Description

STYLET CONSTRUCTION

FIELD OF THE INVENTION

Various aspects of the invention relate to catheter systems, to stylets therefor and to methods of forming such stylets.

BACKGROUND TO THE INVENTION

The initial applicant has previously developed a catheter system that entails a stylet including a connector and an elongate portion. The connector connects to an ex vivo end of the catheter whilst the elongate portion runs along the interior of the catheter to project beyond the in vivo end of the catheter. According to preferred variants of the system, the stylets reduce the risk of occlusion of the catheter due to kinking and/or due to the in vivo end of the catheter pressing against body tissue. Such systems are described in the initial applicant's earlier international patent application published as WO2014/190373 A1. The contents of that publication are incorporated herein by reference.

It is desirable to produce such stylets cost efficiently and in a manner more likely to be accepted by regulatory authorities and medical practitioners.

With the foregoing in mind, the present invention aims to provide improvements in and for stylets and catheter systems including such stylets, or at least to provide an alternative for those concerned with catheter systems.

SUMMARY

One aspect of the invention provides a method of forming a stylet from a connecter connectable to a rear end of the catheter and having an inner passage; and an elongate member including an anchor portion; the inner passage including an anchor-receiving portion and a portion forward of, and narrower than, the anchor-receiving portion; the method including pressing the anchor portion into the inner passage from a rear of the connector to fix the anchor portion within the anchor-receiving portion of the inner passage such that elongate member projects from the inner passage to run along an interior of the catheter; a rear of the connector having a port for fluid communication with the interior of the catheter via the inner passage and past the anchor portion.

The method may include connecting an anchor body to an elongate body to form the elongate member such that the anchor body at least predominantly defines the anchor portion, e.g. the method may include deforming the anchor body to engage the elongate body, e.g. the anchor body may be approximately V-shaped and have ends; and the deforming may be deforming the ends to embrace respective portions of the elongate body. The method may include separating the anchor body from a carrier strip.

Another aspect of the invention provides a stylet formed in accordance with the method.

Another aspect of the invention provides the stylet and a further connector having a tubular projection wherein the port is configured to receive the tubular projection and the anchor portion is forward of a maximum engagement of the tubular projection.

The further connector may be a luer connector.

Also disclosed is a catheter, including a connecter connectable to a rear end of the catheter and having an inner passage; and an elongate member projecting from the inner passage to run along the interior of the catheter and including an anchor portion fixed within the inner passage; a rear of the connector having a port for fluid communication with an interior of the catheter via the inner passage and past the anchor portion.

Preferably the anchor portion is mechanically engaged with the inner passage to so fix the anchor portion. The anchor portion may be pressed into the inner passage e.g. pressed into the inner passage from a rear of the connector.

The anchor portion is preferably fixed within a forwardly-narrowing portion of the inner passage. The inner passage may include a portion forward of the anchor portion and narrower than a or the portion of the inner passage in which the anchor portion is fixed.

Preferably the elongate member includes an anchor body at least predominantly defining the anchor portion; and an elongate body connected to the anchor body to so project from the connector.

The anchor body may be deformed to engage the elongate body. Preferably it is metallic. The elongate body may be polymeric. The elongate body may be a monofilament.

Preferably at least a portion of the elongate member projecting from the inner passage has a cross-sectional area of not more than 0.13mm2.

The anchor portion may at least partly circumscribe a cross section of the inner passage. Preferably the inner passage has a narrow point having a cross-sectional area smaller than a cross-sectional area available for flow past the anchor portion.

The connector may be a luer connector. It preferably includes an internally threaded collar co-operable with the catheter.

Also disclosed is a catheter set including the stylet and the catheter.

Preferably the stylet is configured to project beyond a forward end of the catheter.

The set may further include a needle co-operable with the catheter for catheter over needle insertion of the catheter.

Also disclosed is a method of forming a stylet for a catheter; the stylet including a connecter connectable to a rear end of the catheter and having an inner passage; an elongate member including an anchor portion; a rear of the connector having a port for fluid communication with an interior of the catheter via the inner passage and past the anchor portion. the method including fixing the anchor portion within the inner passage such that elongate member projects from the inner passage to run along the interior of the catheter.

The method may include connecting an anchor body to an elongate body to form the elongate member such that the anchor body at least predominantly defines the anchor portion.

The method preferably includes deforming the anchor body to engage the elongate body. The anchor body may be separated from a carrier strip.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a perspective view of an anchor member;

Figure 2 is a perspective view of another anchor member;

Figure 3 is a perspective view of a portion of an elongate member;

Figure 4 is a perspective view of another anchor member;

Figure 5 is a cross-section view of a portion of a stylet;

Figure 6 is a perspective cutaway view of a portion of an elongate member; Figure 7 is an exploded view of a portion of a stylet;

Figure 8 is a cutaway perspective view of a portion of the stylet of Figure 7; Figure 9 is an end view of the stylet of Figure 7;

Figure 10 is a flow chart of a stylet production process;

Figure 11 is a perspective view of a folding operation;

Figure 12 is an end view of a placement operation;

Figure 13 is a perspective view of the placement operation;

Figure 14 is an end view of a first phase of a crimping operation;

Figure 15 is a perspective view of the first phase of the crimping operation; Figure 16 is an end view of a second phase of the crimping operation;

Figure 17 is a perspective view of the second phase of the crimping operation; Figure 18 is an end view of a shearing operation;

Figure 19 is a perspective view of the shearing operation;

Figure 20 is a cross-section view of a pressing operation.

DETAILED DESCRIPTION

Figure 5 illustrates a portion of a stylet 1 including a connector 3 and an elongate member 5.

In this example the connector 3 is a luer connector. By using a connector, such as a luer connector, familiar to medical practitioners, the stylet is more likely to be accepted by regulatory authorities and by medical practitioners. The connector includes a forwardly projecting male luer portion 7b and a port in the form of a rearwardly open female luer portion 7a. An internally threaded collar 9 surrounds the male luer portion 7b. The male luer portion 7b and the collar 9 cooperate with a catheter (not shown) to connect the connector 3 to the rear (ex vivo) end of the catheter. The connector 3 is preferably formed of polymeric material.

An inner passageway 11 including the female luer portion 7a and the interior of the male luer portion 7b runs through the connector 3 to communicate the interior of the catheter with the outside world. Figure 5 shows a male luer fitting 13 cooperating with the female luer portion 7a to fluidly connect the connector 3, and in turn the catheter, to the outside world e.g. to a fluid source (such as a saline drip), to a fluid destination (such as an evacuated vial for receiving a blood sample) or a sensor such as a blood pressure transducer.

The elongate member 5 may be a single integrally formed member. In other embodiments, the elongate member is formed of at least two parts. For the avoidance of doubt 'integrally formed' and similar terms are used in their conventional sense in this context to refer to a component formed of a single continuous phase of material. Two components may be integrated through processes such as welding but not through typical mechanical fastening techniques.

The elongate member 5 includes elongate body 15 and an anchor body 17.

The elongate body 15 is, in this example, a polymeric monofilament known to medical professionals as Radene™. Of course other filaments are possible. The filament 15 has a diameter of about 0.3mm. A diameter of about this value (corresponding to a cross-sectional area of not more than 0.1mm2) has been found to be advantageous for the various applications described in the initial applicant's earlier international patent application.

The filament 15 is connected to the anchor body 17 with the aid of a knot 19, formed in the filament 15, and/or adhesive such as epoxy adhesive or cyanoacrylate. The anchor body 17 takes the form of a square-profiled ring. Between an interior and an exterior of the ring, a stepped bore 21 passes through the material of the ring. The forward end of the bore 21 is dimensioned to enable the filament 15 but not the knot 19 to pass therethrough. In this case the forward portion of a bore 21 has a diameter of 0.35mm. The rearward end of the bore 21 is dimensioned to receive the knot 19. In this case it has a diameter of 0.55mm. This provides a positive engagement between the knot 19 and the forward portion of the bore 21 so that the filament 15 cannot be left behind when the connector 3 is removed from a catheter. The adhesive sits within the rearward end of the bore 21 and bonds to the anchor and to the filament to prevent the filament reversing out of the anchor.

In another variant (not shown), the anchor body 17 has two bores 21. The filament 15 goes through one of the bores then back through the other bore whereat it is secured with a knot.

To assemble the stylet 1, the filament is inserted into the female luer portion 7a so that it passes through the passageway 11 to forwardly project from the connector 3. The following anchor body 17 is pressed into the female luer portion 7a and is dimensioned to form an interference fit between the cylindrical exterior of the anchor body 17 and the forwardly-converging conical interior of the female luer portion 7a. This interference fit fixes the anchor body 17 to the connector 3. The connector is preferably built to IS0594/1. The anchor body 17 is configured so that when pressed into position it sits within a portion of the female luer portion 7a forward of the maximum engagement of the male luer portion 13 (as dictated by the ISO standard) so as not to interfere with that male luer portion. Similar positioning is possible with components that do not necessarily comply with the ISO standard.

The anchor body 17 is rearward of a narrow point 23 of the passage 11. The inner diameter of the anchor body 17 is no smaller than the inner diameter of the narrow point 23 such that the anchor body 17 presents negligible impedance to flow through the connector 3.

The anchor body 17 may be formed of polymeric material such as polycarbonate although other materials are possible.

Figure 2 shows an alternate anchor body 17'. Instead of having a simple cylindrical interior, the anchor 17' includes an inward projection in which the bore 21' is located. This may enable the inner diameter of the anchor 17' to be enlarged.

Figure 3 illustrates an alternate anchor 17" for which the knot 19 is not required. Instead of the knot 19, the filament is bent through 180° over a wraparound portion 24 of the anchor 17" so that a forwardly projecting end portion 15a of the filament 15' is located within a gripping portion 25 of the anchor member 17". The gripping portion 25 includes a groove in which the portion 15a of the filament 15' is seated and a click-in arrangement 27 including a cooperable pair of hooks. The portion 25 is deformable to click into place so that the hooks of the portion 27 engage to retain the portion 25 in a position in which it grips the end 15a. Other click-in arrangements are possible.

Figure 4 shows an alternate anchor 17"' without any click-in mechanism. Instead, the gripping portion 25 is arranged to deform to grip the filament 15 when the anchor portion 17"' is pressed into the connector 3.

Figure 6 illustrates an alternate click-in arrangement 27' including a finger 29 including a forwardly facing groove 31 and being inwardly moveable to click over, and bring the groove 31 into engagement with, a rearwardly projecting ridge 33.

Figures 7 to 9 illustrate another stylet T incorporating a connector 3 and an elongate member 5'. The member 5' includes a filament 15 akin to that previously described and an anchor member 17a. The anchor member 17a is crimped to the end of the filament 15.

Referring to Figure 10, to produce the stylet 1', at step 100 a suitable length of filament is drawn from roll stock and cut to length. At step 102 an end 15a of the filament 15 is bent to 180°.

As best shown in Figure 11, the anchor portion 17a is formed from a crimp blanks 17a' which is carried with other similar blanks on an elongate carrier strip 35. The carrier strip 35, and blanks carried thereby, preferably together take the form of roll stock.

At 102, the forward most blank 17a' is positioned within a lower crimping dye 37.

As best shown in Figures 12 and 13, the blank 17a' is approximately V-shaped. At step 104 the filament 15 and the turned back return portion 15a thereof are positioned within the arms of the V-shaped blank 17a'. At steps 106a and 106b the upper crimping dye 39 is lowered towards the lower crimping dye 37 to deform the arms of the blank 17a' so that the ends of those arms inwardly deform to embrace and grip both portions of the filament 15. This double-gripping provides an extra degree of assurity that the filament 15 will not be left behind when the connector 3 is withdrawn from the catheter.

At step 108 the crimping dyes 37, 39 are separated to facilitate removal of the member 15, 17a. A waste portion 35a of the carrier strip 35 is sheared away. The carrier strip 35 can then be advanced and operations 102 to 108 repeated to produce further members 15, 17a.

Each member 15, 17a is then trimmed at step 110. The anchor 17a can be used as a reference point to locate the member whereby the finished length of the projecting portion of the filament 15 may be more accurately controlled. At step 112, a protective sheath 41 for protecting the filament 15 is fitted to the connector 3. In this example the sheath 41 is a silicone protective sheath engaged with the exterior of the male luer portion 7b. At step 114 the filament 15 is inserted into the rear of the connector 3 to pass through the connector 3 and slide into the sheath 41. The anchor 17a is pressed into its final position by a rearward tool portion 43 having a suitable tubular end portion to bear against the anchor 17a' without damaging the loop of filament 15.

The connector sits against a connector engaging anvil towards which the tool portion 43 presses. Of course it matters not which of the tool portion 43 and the connector-engaging portion is moved. The tool portion 43 could be the anvil which serves to press the anchor 17a into the connector 3 when the connector-engaging portion is driven towards the tool portion 43.

This pressing operation creates an interference fit between the anchor 17a and the inner passage 11 of the connector 3 by which the anchor 17a is fixed within that inner passage.

The stylet is then subject to a Quality Assurance check and bagged at step 116. The bagged stylet is then sterilised (at step 118) to produce a transportable product that remains sterile and ready for use.

Figure 9 is an end view of the stylet T illustrating that the anchor 17a has an inner diameter 45 that is larger than the diameter of the narrow point 23. As such, the cross-sectional area available for flow passed the anchor 17a is about double the cross-sectional area of the narrow point 23 whereby the anchor 17a presents negligible resistance to flow.

In the examples described thus far, anchors having cylindrical exteriors have been pressed into the conical interiors of connectors to form interference fits. Other forms of engagement are possible. By way of example, an anchor having a suitable arrangement of barbs might cooperate with a cylindrical interior of a connector. Equally, the interior of the connector may be fitted with the barbs.

The anchor 17a is preferably metallic, although other suitably malleable materials may be used. The described process is particularly suited to high volume/low cost manufacture.

Preferred forms of the described stylet find a place in a catheter system including a) a peripheral vascular catheter cooperable with the stylet and b) a needle cooperable with the catheter for catheter-over-needle insertion.

Catheter-over-needle insertion is advantageous in that a better 'seal' between the exterior of the catheter and the flesh of the patient is created relative to the seal created when a catheter is inserted using a conventional catheter-through-needle insertion technique.

Catheters for catheter-over-needle insertion typically have relatively thin walls and are therefore at risk of kinking. The inventor has also recognised that the open end of such catheters can be occluded, e.g. when pressed against the interior of a blood vessel.

The stylet T is configured for insertion into the catheter after the needle has been removed. The filament 15 is dimensioned to project beyond the open in vivo end of the catheter when the connector 3 is engaged with the catheter.

The projecting free end of the stylet has been found to prevent the catheter tip being occluded by a blood vessel wall. Polymeric monofilaments (such as radene) having a diameter of not more than 0.4mm (corresponding to a cross-sectional area of not more than 0.13mm2) are preferred. In stark contrast to metallic guide wires that might be used in some other applications, such filaments have been found to be sufficiently soft so that the protruding end portion of the filament does not damage the blood vessel and to have a desirable degree of compliance. Such filaments are stiff enough to enable the stylet to be easily placed yet compliant to allow the catheter to bend as necessary. Whilst the catheter is allowed to bend as necessary, the stylet adds some stiffness and resistance to kinking. Furthermore, the inventor's earlier experiments have shown that the presence of such stylets prevent the catheter being fully occluded if and when kinking occurs.

Whilst polymeric monofilaments are preferred, other suitably soft and compliant materials could be used.

The invention is not limited to the described examples. Rather, the invention is defined by the claims.

Claims

1. A method of forming a stylet from a connecter connectable to a rear end of a catheter and having an inner passage; and an elongate member including an anchor portion; a rear of the connector having a port for receiving a tubular projection; the inner passage including an anchor-receiving portion and a portion forward of, and narrower than, the anchor-receiving portion; the method including pressing the anchor portion into the inner passage from a rear of the connector to fix the anchor portion, within the anchor-receiving portion of the inner passage to be forward of the tubular projection, such that elongate member projects from the inner passage to run along an interior of the catheter; the port being for fluid communication with the interior of the catheter via the inner passage and past the anchor portion.

2. The method of claim 1 wherein the anchor-receiving portion is forwardly-narrowing.

3. The method of claim 2 wherein including connecting an anchor body to an elongate body to form the elongate member such that the anchor body at least predominantly defines the anchor portion.

4. The method of claim 3 including deforming the anchor body to engage the elongate body.

5. The method of claim 4 wherein the anchor body is approximately V-shaped and has ends; and the deforming is deforming the ends to embrace respective portions of the elongate body.

6. The method of claim 4 or 5 including separating the anchor body from a carrier strip.

7. The method of any one of claims 3 to 6 wherein the anchor body is metallic.

8. The method of any one of claims 3 to 7 wherein the elongate body is polymeric.

9. The method of any one of claims 3 to 8 wherein the elongate body is a monofilament.

10. The method of any one of claims 1 to 9 wherein at least a portion of the elongate member projecting from the inner passage has a cross-sectional area of not more than about 0.13mm2.

11. The method of any one of claims 1 to 10 wherein the anchor portion at least partly circumscribes a cross section of the inner passage.

12. The method of any one of claims 1 to 11 wherein the inner passage has a narrow point having a cross-sectional area smaller than a cross-sectional area available for flow past the anchor portion.

13. The method of any one of claims 1 to 12 wherein the connector is a luer connector.

14. The method of any one of claims 1 to 13 wherein the connector includes an internally threaded collar co-operable with the catheter.

15. A stylet formed in accordance with any one of claims 1 to 14.

16. The stylet of claim 15 and a further connector having the tubular projection.

17. The stylet and further connector of claim 16 wherein the further connector is a luer connector.

18. A catheter set including the stylet of claim 15 and the catheter.