WO2004045696A1

WO2004045696A1 - Urinary drainage catheter

Info

Publication number: WO2004045696A1
Application number: PCT/GB2003/005022
Authority: WO
Inventors: Robert Graham Urie
Original assignee: Mediplus Ltd
Current assignee: Mediplus Ltd
Priority date: 2002-11-21
Filing date: 2003-11-19
Publication date: 2004-06-03
Anticipated expiration: 2005-05-21
Also published as: GB2395436A; AU2003302011A1; GB0227162D0

Abstract

A urinary drainage catheter provides fluid communication between a distal end and a proximal end of the catheter and includes a retention mechanism for retaining the distal end of the catheter within a patient's bladder. The catheter has an outer sleeve comprising a distal portion and a proximal portion with a deformable zone therebetween, the deformable zone having a plurality of elongate slits extending at least partially in an axial direction along the outer sleeve between the distal portion and the proximal portion of the outer sleeve; and a compression mechanism for causing relative displacement of the distal portion and the proximal portion so as to open the slits by deformation in the deformable zone.

Description

URINARY DRAINAGE CATHETER

The present invention relates to urinary drainage catheters, and in particular to retention mechanisms for ensuring that such catheters remain in position within the body for correct operation.

A conventional urinary drainage catheter generally comprises a tube having a distal end which is inserted into the patient's body, a proximal end which remains outside the patient's body, and at least one lumen extending through the tube for the passage of urine out of the body. The distal end is introduced into the bladder via the urethra, and extends a short distance into the bladder where it is maintained in position by a suitable retention mechanism.

A number of retention mechanisms are available in conventional catheter designs.

One of these conventional designs provides an inflatable balloon at the distal end of the catheter. When the distal end is introduced into the bladder via the urethra, the balloon is then inflated, usually by way of an inflation tube within the catheter. The inflated balloon engages with the neck of the bladder, preventing the catheter from inadvertently being withdrawn from or dislodged out of the bladder.

An acknowledged disadvantage of some balloon-type retention mechanisms is that the open end of the lumen at the distal end of the catheter must be distal of the balloon to ensure that the inflated balloon does not block the open end of the lumen. A consequence of this is that the balloon itself tends to cause a stagnant pool of urine to form around the neck of the bladder below the level of the open end of the lumen, which is necessarily higher than the top of the balloon. The formation of such stagnant pools that do not properly drain can undesirably lead to infections and other complications during long term use of the catheter.

Another retention mechanism makes use of a flexible, resilient wing structure at the distal end of the catheter, in which the wings can be compressed (closed) umbrella-like to be aligned with the catheter for introduction through the urethra. Once the wing structure reaches the bladder, it is allowed to spring back into an appropriate expanded or 'open' form to prevent egress of the catheter from the bladder. Typically, the wing structures have a natural resilience to return to the open configuration and are released using a control wire, such as a wire stylet, which also passes through the catheter.

An acknowledged disadvantage of some wing structure retention mechanisms is that patient mobility can sometimes cause unintentional collapse of the wing structure to the compressed profile. This then allows the catheter to escape from the bladder.

It is an object of the present invention to provide an alternative retention mechanism that overcomes some or all of the problems of existing catheters.

It is a further object of the present invention to provide a low cost urinary drainage catheter that is easy and simple to fabricate.

It is a further object of the present invention to provide a urinary drainage catheter that is easy to install and remove.

At least some or all of the objects of the invention are achieved by various embodiments of the invention described herein. According to one aspect, the present invention provides a catheter for providing fluid communication between a distal end and a proximal end of the catheter, comprising: an outer sleeve comprising a distal portion and a proximal portion with a deformable zone therebetween, the deformable zone having a plurality of elongate slits extending at least partially in an axial direction along the outer sleeve between the distal portion and the proximal portion of the outer sleeve; and a compression mechanism for causing relative displacement of the distal portion and the proximal portion so as to open the slits by deformation in the deformable zone.

Embodiments of the present invention will now be described by way of example and with reference to the accompanying drawings in which:

Figure 1 shows a side view of an outer sleeve of a catheter according to the present invention;

Figure 2 shows a side view of an inner sleeve of the catheter of figure l; Figure 3 shows a cross-sectional side view of one end of the catheter of figures 1 and 2 in assembled and closed configuration; and

Figure 4 shows a cross-sectional side view of one end of the catheter of figures 1 and 2 in assembled and open configuration;

Figure 5 shows a cross-sectional side view of the other end of the catheter of figures 3 and 4 illustrating an opening and closing mechanism for the catheter; and

Figure 6 shows a perspective end view of the opening and closing mechanism of figure 5. With reference to figure 1, an outer sleeve 10 for a catheter comprises a flexible tube of suitable material such as polymer compounds including PVC or polyurethane, latex, or rubber having an outer diameter suitable for introduction of the catheter into the urethra of a patient's body. The length of the outer sleeve may be any suitable length sufficient to reach from the bladder of a patient to a position external of the body.

The outer sleeve 10 has a proximal end 11 that normally remains outside the patient's body, and a distal end 12 that reaches into the bladder. A plurality of slits 13 are cut through the walls of the outer sleeve to define a deformable zone 14. The deformable zone 14 effectively separates a distal portion 15 and a proximal portion 16 of the outer sleeve 10. The outer sleeve defines a lumen therethrough extending from the proximal end 11 to the distal end 12.

The outer sleeve 10 generally defines a longitudinal axis, but it will be understood that the flexible tube of the outer sleeve allows the outer sleeve to deflect sideways along this axis to assume any necessary curves for entry into and passage through the urethra of the patient. References to the 'axis' of the sleeve herein will generally refer to the centre line of the sleeve regardless of any curvature thereof.

However, the slits 13 in the deformable zone 14 of the outer sleeve 10 allow a further degree of freedom in that the flexible tube is generally axially compressible within the deformable zone. The distal portion 15 and proximal portion 16 may be relatively axially displaced towards one another to effect longitudinal or axial compression such that the tube walls 17 between the slits 13 will splay or bulge outwards to 'open' the slits, as will be described in more detail in connection with figure 4. It will be recognised that to achieve this longitudinal compression, the slits 13 need not be aligned with longitudinal axis, but merely have a component in that direction. For example, the slits 13 may have diagonal or spiral alignment, in which case longitudinal compression will still cause the tube walls between the slits to buckle or bulge outwards.

In order to facilitate the desired longitudinal compression of the outer sleeve 10, relative displacement along the longitudinal axis of the distal portion 15 and the proximal portion 16 is required. A compression mechanism is provided to effect this.

The compression mechanism may be provided in a number of forms, for example by way of a simple control wire extending through the outer sleeve and coupled to the distal end 12 thereof. The control wire can be operative to effect relative displacement of the distal portion 15 and the proximal portion 16 of the outer sleeve towards one another so as to cause the walls of the outer sleeve to bulge outwards.

However, with reference to figure 2, in the preferred embodiment, the compression mechanism is formed as an inner sleeve 20 which extends through the outer sleeve 10. The inner sleeve 20 has a proximal end 21 and a distal end 22 and at least one aperture 23 positioned close to the distal end. More than one aperture 23 may be provided, for example, arranged circumferentially around the inner sleeve 20.

The outside diameter of the inner sleeve 20 is less than the inner diameter of the outer sleeve. The inner sleeve 20 is also formed from a suitable flexible material as indicated above to allow flexing and curving along its longitudinal axis. However, it is preferably sufficiently rigid that compression of the inner sleeve along its longitudinal axis is not possible during normal use.

With reference to figure 3, a portion of the assembled catheter 30 is shown in an installation ('closed') configuration, ie. ready for insertion into a patient. The inner sleeve 20 is contained within the outer sleeve 10 and generally in sliding engagement therewith. However, at the distal ends 22, 12, the inner and outer sleeves 20, 10 are coupled together,- using some suitable attachment means. In the example shown in figure 3, the attachment means comprises a suitable adhesive or other bonding compound 32. Alternatively, any mechanical fixing mechanism could be used to lock the distal ends of inner and outer sleeves together. For example, where the inner and outer sleeves are formed as simple tubes with open ends, a closure device such as a plastic cap may be used to engage both the inner and outer sleeve together while forming a closure of both.

The walls 33 of the outer sleeve 20 between the slits 13 form the deformable part of the catheter 30 and thereby a retention mechanism to be described in detail later.

The aperture 23 of the inner sleeve 20 is generally longitudinally aligned with the slits 13, or possibly slightly displaced towards the distal end, eg. at least partially into the distal portion 15 of the outer sleeve 10. The reason for this becomes clear with reference to figure 4.

In figure 4, a portion of the assembled catheter 30 is shown in an installed ('open') configuration, ie. after insertion into a patient and with the retention mechanism deployed. In this configuration, the inner sleeve 20 has been displaced relative to the outer sleeve 10 in the proximal portion 16, in an axial direction - to the right as shown in the figure. Because the distal portion of the outer sleeve is relatively fixed to the distal end of the inner sleeve 20, the relative displacement of the inner and outer sleeves in the proximal portion 16 causes the walls 33 of the outer sleeve to buckle or deform so as to bulge or splay outwardly as shown.

The outward splaying of walls 33 results in the slits 13 opening up into apertures 40 (shown in dashed outline), which apertures are coincident with the underlying aperture or apertures 23 of the inner sleeve 20, as shown. It will be observed that this provides two functions.

Firstly, the splaying of the walls 33 provides a retention mechanism that ensures that the catheter remains in situ within the bladder, the trailing edge 41 of the splayed wall 33 engaging with the neck of the bladder to prevent egress of the distal end past the bladder neck.

Secondly, the splaying of the walls 33 opens up the apertures 40 in the outer sleeve 10 so that fluid communication between the outer surface of the catheter and the lumen 42 of the inner sleeve 20 is possible via the aρerture(s) 23. Thus, urine may then drain out of the bladder via the catheter lumen 42.

A particular advantage of this configuration is that the apertures 40, 23 are in very close proximity to the trailing edge 41 of the wall 33 that engages with the neck of the bladder, so that there is very little tendency for pooling of urine near the neck of the bladder.

Preferably, the respective diameters of the inner and outer sleeves 20, 10 are closely matched so that there is very little gap 43 between the sleeves, while still allowing sliding engagement of the walls of the inner and outer sleeves. Preferably, the gap 43 is sufficiently small that no urine or other liquid can travel the length of the catheter 30 between the walls of the inner and outer sleeves 20, 10.

More preferably, a lubricious coating is applied to the inner surface of the outer sleeve 10 and/or to the outer surface of the inner sleeve 20 to facilitate the relative axial displacement of the inner and outer sleeves. An example of a lubricious coating could be PTFE.

Alternatively, a lubricant may be generally inserted into the gap 43 for similar purposes.

Preferably, the catheter 30 also provides a mechanism for locking the inner and outer sleeves 20, 10 in a particular axial displacement corresponding to the open configuration shown in figure 4. This locking mechanism is preferred especially when the walls 33 of the outer sleeve 10 are resilient such that there is a tendency for them to try to close the apertures 40 that have been opened up in the open configuration. The necessity for this locking mechanism may also depend upon the fiϊctional resistance to relative axial movement of the inner and outer sleeves 20, 10.

With reference to figure 5, a preferred mechanism for locking the inner and outer sleeves is now described.

In this arrangement, the inner sleeve 20 extends right through the outer sleeve 10 and emerges from the proximal end 11 of the outer sleeve, into a locking portion 50. A circlip or spring clip 51 extends at least partially around the inner sleeve in a tight frictional engagement that resists any axial movement of the clip 51 along the inner sleeve 20. This is also shown in the perspective drawing of figure 6. The clip 51 bears against the end wall of the outer sleeve at the proximal end 11, preferably by way of an intervening olive 52, which has a tapered leading edge to engage with, and slightly under, the proximal end 11 of the outer sleeve. This provides additional security against leakage of urine out of the gap 43 between the inner and outer sleeves, if any has penetrated that far.

In the embodiment of figures 5 and 6, the inner sleeve 20 also extends beyond the locking portion 50 to the proximal end 21 at which is preferably positioned a connector 53 for a urine collection receptacle (not shown). Various types of connector may be used, such as push fit, screw fit or quarter-turn lock connectors.

To ensure that the clinician installing the catheter 30 achieves the correct degree of compression of the deformable zone 14, the inner sleeve 20 may be provided with an index mark 54 or other suitable indicator at an appropriate longitudinal position. This index mark 54 may provide a visual or tactile indication of the appropriate degree of relative axial displacement of the inner and outer sleeves commensurate with correct deformation of the deformable zone to open the slits 13. This can help to ensure that the deformable zone is not completely compressed in a manner that would tend to re-occlude the apertures 23.

The lock mechanism described above easily provides for full reversibility of the retention mechanism deployment simply by removal of the clip and relative axial displacement of the inner and outer sleeves. This enables easy removal and reinsertion if required.

After a period of use of drainage catheters known in the art, there can be a tendency for encrustations to build up on the retention structures which lie at the base of the bladder, and these encrustations can eventually block the catheter inlet port rendering the catheter useless. The preferred embodiments described above facilitate an occasional repeated opening and closing action of the slits 13 which will tend to dislodge any encrustations that may have built up during use, thereby prolonging the useful life of the catheter.

The catheter of the preferred embodiments may be formed from any suitable materials known to the person skilled in the art, so as to achieve the desired properties of flexibility to allow bending and curving of the catheter along its longitudinal axis, while maintaining resistance to tube wall collapse or buckling under the axial displacement forces required except at the deformable zone 14.

In preferred examples, the outer and inner sleeves 10, 20 are formed from PVC. The outside diameter of the outer sleeve preferably lies in the range 2 mm to 8 mm with a preferred outside diameter of 5 mm. The wall thickness of the outer sleeve 10 preferably lies in the range 0.05 mm to 1 mm. The diameter of the inner sleeve 20 preferably lies in the range 1.5 mm to 7 mm with a preferred diameter of 4 mm. The wall thickness of the inner sleeve 20 preferably lies in the range 0.05 mm to 0.8 mm. The gap 43 between the sleeves is preferably of the order of less than 0.04 mm.

A preferred slit length lies in the range 5 mm to 25 mm, and the aperture 23 has a diameter between 50% and 90% of the internal diameter of the inner sleeve.

Other embodiments are intentionally within the scope of the appended claims.

Claims

1. A catheter for providing fluid communication between a distal end and a proximal end of the catheter, comprising: an outer sleeve comprising a distal portion and a proximal portion with a deformable zone therebetween, the deformable zone having a plurality of elongate slits extending at least partially in an axial direction - along the outer sleeve between the distal portion and the proximal portion of the outer sleeve; and a compression mechanism for causing relative displacement of the distal portion and the proximal portion so as to open the slits by deformation in the deformable zone.

2. The catheter of claim 1 in which the compression mechanism is adapted to effect relative displacement of the distal portion and the proximal portion axially towards one another so as to cause the walls of the outer sleeve between the slits to bulge outwards.

3. The catheter of claim 1 or claim 2 in which the compression mechanism comprises a compression member extending through the outer sleeve, coupled to the distal portion and axially displaceable relative to the proximal portion.

4. The catheter of claim 3 in which the compression mechanism comprises an inner sleeve extending from the distal portion to the proximal end of the catheter.

5. The catheter of claim 4 in which the inner sleeve includes at least one aperture in a side wall thereof, positioned so as to be in axial alignment with the deformable zone when the slits are opened, thereby allowing fluid communication between the outside of catheter and a lumen in the inner sleeve, via the slits and the at least one aperture.

6. The catheter of claim 5 in which the outside diameter of the inner sleeve and the inside diameter of the outer sleeve are sufficiently close to allow relative axial sliding movement of the inner and outer sleeves without allowing passage of liquid from the distal end to the proximal end of the catheter between the inner and outer sleeves.

7. The catheter of claim 6 further including a lubricious coating on the outer wall of the inner sleeve and/or the inner wall of the outer sleeve.

8. The catheter of claim 6 further including a lubricant between the outer wall of the inner sleeve and the inner wall of the outer sleeve.

9. The catheter of claim 1 in which the compression mechanism includes means for locking the deformable zone in its deformed configuration.

10. The catheter of claim 8 in which the compression mechanism includes an inner sleeve extending out of the proximal end of the outer sleeve of the catheter, the inner sleeve including a clip mechanism attached thereto to inhibit relative axial movement of the inner sleeve and the outer sleeve.

11. The catheter of claim 9 in which the clip mechanism comprises a spring clip or circlip for at least partially encircling the inner sleeve and for bearing against an end wall of the outer sleeve.