Catheters

Abstract

A catheter for removing urine from the bladder comprising a polymeric tube having a drainage lumen, the tube being dimensioned so that the lumen, in use, extends from the bladder only part way along the urethra, thereby leaving a substantial remaining part of the urethra at least substantially free for the normal passage of urine.

Description

This invention relates to catheters.

In particular the invention relates to self-retaining catheters, especially male urethral balloon catheters, for use in prostatic conditions.

At present, the traditional balloon catheter is widely used in cases of prostatic urethral stricture and one well known type comprises a flexible tube which extends from outside the body along the urethra and into the bladder, the tube comprising a main lumen for the passage of urine and a much smaller lumen leading to an annular expansible sac or bulb which is adjacent the inner end of the catheter and can be expanded within the bladder by pumping a fluid along the smaller lumen to prevent accidental retraction of the catheter. Most notable of this type of catheter is the Foley catheter.

The known type of balloon catheter, while serving its purpose, suffers from a number of disadvantages. The urethra and the washing action of urine passing therethrough functions to prevent the passage of infection up the urethra and the known balloon catheters tend to interfere with this function. On occasions, the catheter has an irritant effect on the walls of the urethra and may cause abscesses and fibrosis, particularly at the outer end and at bends in the urethra. Moreover, the presence of the catheter interferes with the natural control of urination and the means at the outer end of the catheter necessary for control and disposal of urine are inconvenient.

The invention seeks to overcome these disadvantages.

According to the present invention there is provided a catheter for removing urine from the bladder comprising a polymeric tube having a drainage lumen, the tube being dimensioned so that the lumen in use, extends, from the bladder only part way along the urethra, thereby leaving a substantial remaining part of the urethra at least substantially free for the normal passage of urine.

When used as a urethral catheter the length of the tube is about three inches such that it can extend from the bladder along the urethra at least part way through the prostate gland, but walls of the tube bounding the urine passage through the catheter, i.e., the drainage lumen stop short of the sphincter urethrae muscles. When such a short catheter is used, the patient can still make use of the sphincter urethrae muscles for urine control and there is no urine-conveying tube extending along the majority of the urethra. In the case of certain patients, however, the tube may pass the sphincter urethrae muscles and well into the urethra, although a considerable length of the urethra remains unimpeded by the tube.

In most instances the catheter will require means to ensure its retention in position and the retention means may take various forms. In a first form, the catheter is intended to remain in position for extended periods and consists of a short length of tube which is preferably relatively stiff and may be made of polymeric material. The tube has a window adjacent the orifice of the prastatic otricle and may have other windows, the tube being retained in position by the protrusion of tissue through the window or windows. In a second form, which is more suitable for shorter periods, the retention means is similar to that of the known balloon catheter and includes an expansible sac, preferably annular although other shapes are possible, adjacent the inner end of the catheter in communication with a passage long enough to extend the full length of the urethra so that the sac may be expanded within the bladder by pumping from the exterior. A part of the pumping passage which is coextensive with the urine passage may be formed integrally with it but the remainder may be formed from a fine bore tube which has external dimensions substantially smaller than the traditional balloon catheter. Thus, although in the preferred embodiment a fine bore tube still passes along the entire length of the urethra to the outside, it is very much smaller than that of the known catheter and does not carry urine. This fine bore tube may also be used for withdrawal of the catheter, the outer end of the tube forming the urine passage preferably being tapered or inclined to facilitate passage along the urethra during withdrawal.

For insertion, there may be provided a probe such as a flexible rod or tube which is formed at one end for a releasable connection with the outer end of the catheter. This connection may be in the form of a spigot and socket joint. The rod or tube may be shaped to receive the pumping tube (where this is provided) and may have a longitudinal groove in the outer surface for this purpose.

A preferred example of the invention is now described with with reference to the accompanying drawing, in which:

FIG. 1 is a schematic elevation, partly in section,

FIG. 2 is a section on the line II--II of FIG. 1,

FIG. 3 is a section on the line III--III of FIG. 1,

FIG. 4 is a section on the line IV--IV of FIG. 1, and

FIG. 5 is a section on the line V--V of FIG. 1.

Referring to the drawings, a catheter includes a tube 1 of polymeric material, for example rubber latex or a vinyl polymer, which has a conventional domed closed end 2 and a pair of diametrically opposed openings 3 for admitting urine to a drainage lumen 1a of the tube. Just behind the openings 3 the tube is surrounded by a thin-walled sac 4 which can be expanded to form a traditional balloon-like, collar by pumping liquid such as water through a fine-bore lumen or passage 5 in the tube wall. As so far described, the catheter is similar to a Foley catheter. However, the tube 1 terminates in an inclined end face 6 and is of a length (about three inches) such that when the collar formed by the sac 4 is within the bladder, the end face 6 will be situated adjacent to but slightly on the bladder side of the sphincter urethrae muscles. The tube thus passes through at least the greater part of the prostate gland. Beyond the end face 6, the pumping passage or lumen 5 communicates with the passage or lumen of a fine flexible tube 7 which is of a length to extend along the full length of the urethra and a convenient distance beyond.

The catheter may be inserted into the urethra with the assistance of an inserter which consists of a length of thick-walled flexible tube 8 which has an outer diameter equal to that of the tube 1 (about a quarter of an inch) and has one end inclined and constructed to form a releasable connection with the outer end of the tube 1. For this purpose, the wall of the tube 8 is effectively reduced in diameter for a short length adjacent the outer end to form a hollow spigot 9 which is a push fit in the outer end of the drainage lumen of the tube 1. The spigot may be a separate length of tube provided in the end of the tube 8. The wall of the tube 8 terminates in a sloping shoulder which abuts the end face 6 at the end of the tube 1. Preferably, and as shown, one side of the outside surface of the tube 8 is formed with a longitudinal groove 10 which is dimensioned to receive within it the fine tube 7.

The catheter shown in the drawing is used as follows. It will normally be supplied with the inserter tube 8 attached to the tube 1 and with the fine tube 7 lying in the groove 10 if such a groove is in fact provided, and in this condition the catheter may be inserted in the same way as a Foley catheter. When the sac 4 has reached the bladder it is expanded by pumping a liquid along the fine tube 7 and the passage 5 as by attaching a syringe to the free end of the tube 7. The expansion of the sac 4 secures the tube 1 in position. The inserter tube 8 is then given a gentle tug to disengage the spigot 9 from the end of the tube 1 and the inserter tube 8 is completely withdrawn. This leaves the tube 1 in the way of the prostate gland with the end face 6 above the sphincter urethrae muscles which may be used by the patient in the usual way. The fine tube 7 remains along the urethra but it is of very small cross-sectional dimension and is thus unlikely to lead to the drawbacks caused by prior art catheters. When the catheter is to be removed, the sac 4 is drained of liquid through the tube 7 and is then pulled out by means of the tube 7.

The above description has been concerned with a urethral catheter. It is envisaged, however, that the invention could be incorporated in other types of catheter. Hence, in its broadest sense, the invention provides a catheter for assisting in the passage of a fluid past an unnatural blockage or constriction in a body passage, said catheter comprising a polymeric tube dimensioned so that, in use, it is located only in that part of the passage that is blocked or constricted, thereby leaving a substantial remaining part of the passage free to allow said fluid to pass along the passage.

Claims

1. A urethral catheter assembly comprising a polymeric tube having a drainage lumen and proximal and distal ends, and a flexible elongated member connected to said tube as an extension thereof for inserting the tube into the urethra, said member having means on the end thereof connected to said tube formed for releasing the member from the proximal end of the tube after the tube has been positioned, expansion means on said distal end for retaining the tube in position, and means other than said member for removing the tube from the urethra so that the drainage lumen, in use, extends from the bladder only part way along the urethra, thereby leaving a substantial remaining part of the urethra at least

2. The urethral catheter assembly of claim 1 in which the tube is so dimensioned that the proximal end thereof is in use situated adjacent but

3. The urethral catheter assembly of claim 1 in which the tube is approximately 3 inches long and about one quarter of an inch in external

4. The urethral catheter assembly of claim 1 in which said expansion means for retaining a tube in position includes an inflatable sac surrounding the tube, the interior of the sac being in communication with an inflation lumen along which fluid can be passed for inflating the sac, and in which a fine bore tube extends from said inflation lumen and, in use, extends along the remaining part of the urethra to a convenient distance beyond

5. The urethral catheter assembly of claim 4 in which said member for inserting the tube into the urethra has a longitudinal groove formed in

6. The urethral catheter assembly of claim 1 in which said formed end of the flexible member is in the form of a spigot adapted to slip it into the

7. The urethral catheter assembly of claim 1 in which an end face of the proximal end of the tube is inclined at an acute angle to the longitudinal

8. The urethral catheter assembly of claim 1 in which said member for

9. A surgical assembly comprising a two piece urethral catheter including a tube and tube inserting means separate from said tube; said tube having a drainage lumen, inlet opening means in said tube at one end thereof in communication with said drainage lumen, said tube also having a proximal end remote from said one end, retaining means carried by said tube adjacent said inlet opening means on said proximal end side thereof for normally retaining said tube against withdrawal, means connected to said tube and extending beyond said proximal end for rendering said retaining means inoperative and for withdrawing said tube from said urethra; and said tube inserting means being in the form of an elongated flexible member having connecting means at one end thereof for releaseable positive inkterlocking engagement with said tube at said proximal end during the insertion of said tube and for automatic separation of said flexible member from said tube when said flexible member is withdrawn, and said tube being of a length to terminate within an urethra in an unaccessible

10. The catheter of claim 9 wherein said flexible member is hollow and in communication with said drainge lumen to provide an initial visual indication when said tube is in place.