RELATED APPLICATIONS  
       [0001]     This application is a divisional application of U.S. Ser. No. 09/720,309, filed Apr. 9, 2001, which is a 371 of PCT/EP99/04421, filed Jun. 25, 1999 which claims priority of PCT/EP98/03892, filed Jun. 25, 1998. 
     
    
     TECHNICAL FIELD  
       [0002]     A pre-filled Foley catheter can be regarded as one example of a medical device with a proximal end and a distal end, an elastomeric bulb at the proximal end for storing fluid under pressure and a fluid acceptor at the distal end and a lumen connecting the bulb and the acceptor for flow of fluid from the bulb to the acceptor when the device is used, and including a control device at the proximal end of the lumen to prevent said fluid flow until said flow is desired. It is in this class of medical devices that the present invention is to be found.  
       BACKGROUND  
       [0003]     The Foley catheter is a catheter device usually made out of elastomeric material, which is for urine drainage and which is installed with its distal end in the bladder of the patient. When the distal end of the catheter has been advanced into the bladder, sterile water is caused to flow along a lumen from the proximal to the distal end of the catheter, there to fill a balloon at the distal end of the catheter. This balloon retains the distal end of the catheter in the bladder and allows a second lumen in the catheter shaft, open to the bladder at the distal end of the shaft, to drain urine from the bladder to the proximal end of the catheter.  
         [0004]     In a pre-filled Foley catheter, the device includes a reservoir of sterile water in the proximal end of the device, and a clip over the shaft of the catheter at its proximal end, which clip prevents the sterile water from flowing from the distended reservoir bulb along the lumen to the distal end of the catheter. The person placing the catheter is required to hold the catheter in the desired disposition relative to the body of the patient, and then remove the clip and squeeze the reservoir bulb, in order to inflate the balloon. It would be desirable to provide an improved device for preventing fluid flow from the reservoir to the balloon until it is desired to do so. U.S. Pat. Nos. 3,275,001 and 3,675,658 disclose the use of internal plugs instead of clips.  
         [0005]     Achievement of a satisfactory shelf-life for pre-filled Foley catheters has proved to be a challenge. Common elastomeric material, such as latex, is not entirely impermeable to the passage of water. Accordingly, the water in the distended bulb reservoir of elastomeric material can escape through the wall, given enough time. In order to achieve a satisfactory shelf-life (18 to 24 months) it has been proposed to cover the outside of the reservoir bulb with a coating of material more resistant to passage of water than latex. Nevertheless, residual problems remain, some of which are discussed in U.S. Pat. No. 3,602,226.  
         [0006]     One such problem is that the coating tends to crack. This reduces the resistance to escape of water and can adversely affect appearance. Another problem is to achieve satisfactory continuity of the coating around the clip at the distal end of the bulb, and the customary filler valve at the proximal end of the bulb. Even then, there is potential for water to escape from the bulb by flowing lengthways along the elastomeric material of the wall of the bulb, until it has passed the distal and proximal ends of the waterproof coating material.  
         [0007]     The thickness of latex catheters made by a conventional dipping process is always liable to vary, and this variation can prejudice the goal of reliable sealing with an external moulded clip. With a conventional U-shaped one-piece clip, and latex walls of uncertain thickness, there is some potential for the clip to damage the latex lumen wall.  
       SUMMARY OF THE INVENTION  
       [0008]     The invention may be incorporated in embodiments that may include one or more of the following objects, features and characteristics.  
         [0009]     An object of the present invention is to achieve greater certainty, during the manufacture of pre-filled Foley catheters, that the catheter will deliver a satisfactory shelf life.  
         [0010]     A further object of the present invention is to provide a pre-filled catheter which lends itself to easy actuation, with a single manipulation (like removal of the conventional clip) being sufficient to achieve the result that all fluid in the reservoir flows to the distal end balloon cavity.  
         [0011]     Another object of the invention is to improve the design of the catheter so that its manufacture is streamlined, its packaging and storage made more compact and reliable, and its appearance made more attractive.  
         [0012]     Thus, in accordance with a first aspect of the present invention, there is provided a medical device of the type identified above, and which is characterised in that said control device comprises a plug which blocks the lumen at its proximal end and includes a parting line, which enables the plug to be parted into two separate parts, by manual manipulation from outside the lumen, such parting having the effect of opening up fluid communication along the lumen from the elastomeric bulb to the balloon to fill the balloon.  
         [0013]     Advantageously, once the plug is parted, there is no need for the person installing the catheter to manipulate any longer the plug or lumen.  
         [0014]     Additionally the stress distribution in the wall of the bulb at the neck at its distal end is much more uniform with a plug than with the customary clip. An enhanced ability to predict patterns of stress and strain at the balloon neck should in turn allow better waterproofing in the distal neck region.  
         [0015]     Moreover, provision of a parting line avoids the need to disturb the interface between plug and lumen. This is especially advantageous with latex lumens, or other lumens created by dipping, in which the wall thickness varies, because actuation of the control device need not involve any surface in contact with the lumen wall. Where the lumen wall thickness varies, so will the elastic performance, and when the elastic performance varies, there will be unpredictability in the manipulation of any surfaces constrained elastically by the lumen wall surface.  
         [0016]     Conventionally, a Foley catheter of latex is molded with a narrow lumen (of the order of 0.8 mm diameter) and a proximal bulb inner diameter much larger. Thus, in another aspect of the invention, the distal neck of the bulb cavity can be molded to correspond in shape with the distal end of the plug. These complementary surfaces prevent excessive advance of the plug distally beyond the bulb neck.  
         [0017]     Stabilisation of the interface between the lumen wall and the surfaces of the control device makes it easier to render the bulb fluid-tight in this interface zone. The medical device is much easier to pack and to handle in the terminal stages of manufacture because it lacks the bulk of an external clip.  
         [0018]     Conventional external clips become separated from the conventional pre-filled Foley catheter, once the catheter has been installed, and one then has the task of disposing of the loose clip. With the device of the invention, the component parts of the control device are retained within the bulb.  
         [0019]     One-handed operation of the valve requires less manual dexterity than with an external clip which has to be removed. Snapping of the plug into two pieces provides a tactile signal that the fluid passage has been opened up. With opaque lumen material, such as latex, the plug cannot be seen, so such a tactile signal is especially valuable with opaque materials.  
         [0020]     In another aspect of the invention, the use of the plug facilitates avoidance of potential difficulties in coating the interior of the reservoir, as may be desired to waterproof the reservoir to minimize liquid loss during storage. By placement of a plug in the distal neck of the bulb, before the coating process the coating material will be precluded from blocking the lumen. A coating of proofing material on the external surface of the plug ought not to have any adverse effect on the operation of the plug device.  
         [0021]     In another embodiment, it is envisaged that the plug device might carry with it a skirt or cylinder of waterproof material, to serve as the fluid-resistant wall of the bulb, or an inner waterproof surface coating of the wall of the bulb, the skirt or cylinder being gathered at the proximal end of the bulb, and fitted around the customary bulb filler valve. Cakes are decorated using an icing sugar mixture which is extruded through an icing nozzle, itself set in the neck of an icing bag. The other end of the bag is held closed by the hand of the user. The contemplated arrangement of plug and skirt might resemble an arrangement of icing nozzle and icing bag, with the filler valve closing the end of the skirt remote from the plug.  
         [0022]     The control of flow of fluid in a lumen, using a device in the lumen which is separable into two parts in order to allow fluid flow, is not in itself new. Such an arrangement is disclosed in, for example, GB-A-1573482 and U.S. Pat. No. 4,007,738 published Feb. 15, 1977. It is to be noted, however, that the proposal of the present invention allows the control device to be placed such that it extends proximally into the interior of the bulb.  
         [0023]     This provides more room for displacement of one part of the control device relative to the other, and for eliminating elastic stresses in a lumen wall which might otherwise act to bring the two displaced parts of the control device back into their original sealing disposition relative to each other. Depending on the materials used and the dimensions of the plug and lumen walls, locating the control device partly within the bulb may assist in delivering many of the attractive technical effects of the present invention.  
         [0024]     In a further aspect the present invention provides a medical device which is a drainage catheter having first and second lumens, with the first lumen serving as a drainage lumen and having a fluid inflow port at its distal end and a fluid drain coupling at its proximal end. The second lumen serves to convey inflating fluid from a fluid supply element at the proximal end of the device to a fluid acceptor balloon at the distal end. The fluid supply element and fluid drain coupling are arranged side by side at the proximal end of the coupling, and the device is characterised by a sleeve which extends around both the fluid drain coupling and the fluid supply element.  
         [0025]     Normally, the fluid supply element will be an elastomeric bulb which is destined to be inflated with the inflating fluid. In that case, the sleeve would be of a material which is more impervious to the inflating fluid than is the elastomeric material of the bulb, so that the presence of the sleeve has the effect of slowing the rate of loss of fluid radially outwardly from the bulb through the wall thickness of the bulb.  
         [0026]     Although this is the normal situation, it is envisaged that the provision of a sleeve around both the fluid drain coupling and the fluid supply element could have other advantages independent of reducing fluid loss during storage of a pre-filled device. For example, in the case where the device is made of material which does not readily accept printed text, or in a case where it is desired that there should be no printed text on the device as such, the sleeve material could be selected as suitable for use as a printing substrate, and could receive printed matter which serves to inform those handling the device, until such time as the device is put into use, at which point the sleeve would be removed.  
         [0027]     It is particularly envisaged that the technical feature of a sleeve, which characterises the second aspect of the invention, is used in combination with the technical feature of a lumen plug which parts into two pieces, characteristic of the first aspect of the invention. In particular, a urinary drainage catheter, such as a Foley catheter, which incorporates a reservoir pre-filled with liquid to inflate the distal bulb of the catheter, and which is made, as conventionally, with latex rubber material, benefits from an enhanced shelf life both by the provision of a sleeve around the reservoir bulb at the proximal end of the catheter, and the provision of a plug instead of a conventional external lumen clip, because the sleeve over the bulb works more effectively when there is no clip on the external surface of the catheter adjacent the reservoir bulb. This is because it is easier to arrange the sleeve for full effectiveness when the surface it covers is without discontinuities, and when the sleeve is not subject to localised stresses caused by the external clip.  
         [0028]     In this way, the sleeve and plug work together to enhance the shelf life of the device.  
         [0029]     In this connection, inclusion of the fluid drain coupling alongside the fluid supply element inside the sleeve will not appreciably reduce the effectiveness of the sleeve in slowing down the rate of loss of fluid through the wall of the reservoir bulb. This is because both elements can be made with surface topographies made up of gentle curves and out of relatively soft materials which therefore deform relatively easily to conform to the embrace of a sleeve applied using shrink wrapping techniques. However, placing the sleeve around both the fluid drain coupling and the fluid supply element can deliver the technical effect that the device is packed in a more compact and orderly way, which facilitates further manufacturing processing and packaging of the device, and improves the visual attractiveness of the device to those who purchase and use it. It also provides a packaging over the fluid drain coupling (which in present devices is not sleeved) and a vehicle for carrying printed matter.  
         [0030]     Both aspects of the invention are particularly applicable to medical devices made of latex rubber, especially urine drainage catheters made of latex rubber. However, both aspects of the invention will also be useful with devices made of other materials. One of these may be silicone rubber, an alternative material for urine drainage catheters.  
         [0031]     Normally, the fluid received at the distal end of the catheter will be water, that is, sterile water, but the invention is not restricted to fluids which are liquids. Fluids which are gases may also be of interest.  
         [0032]     The plug control device is conveniently formed as an annulus of material with a proximal end face and a distal end face and a bore extending between the two end faces. Coaxial with the annulus is a stem, blocking the bore in the annulus, until the plug is parted into two separate parts, these two separate parts being the annulus and the stem. Conveniently, the plug is formed of synthetic polymeric material, injection moulded as a single component, with a circle of weakness, constituting the parting line, between the annulus and the stem, at one end of the bore through the annulus. However, it can also be envisaged that the plug is formed of two components, the annulus and the stem, put together as the plug is installed in the lumen, and parted into the respective annulus and stem components, along the parting line where the two components abut one another, when the stem is manipulated from outside the device. In such a case, the stem might be friction fitted within the bore of the annulus.  
         [0033]     Normally the stem is cylindrical and has a diameter not more than about half that of the plug at its widest point. Advantageously, the stem is not more than one third the plug diameter. In one example, the stem is 2.25 mm diameter and the plug at its widest is 7.5 mm in diameter. This leaves plenty of room around the stem to engage the stem with an injector rod to position the plug in the lumen.  
         [0034]     Normally, the plug is advanced into the lumen from the proximal end of the lumen with its stem directed rearwardly. Normally, the open proximal end of the lumen is closed by a filler valve, and the plug is spaced some way from the filler valve, distally along the lumen. The lumen length between the filler valve and the plug contains the cavity for storing fluid under pressure, that is to say, the fluid supply element and elastomeric bulb of preferred embodiments of the present invention. Fluid is introduced through the filler valve into the lumen cavity between the filler valve and the plug, to inflate the elastomeric bulb between the valve and the plug. The valve is a check valve (not unlike one on a bicycle tyre) which resists reverse flow of the fluid in the bulb. In these respects, the reader will be informed by conventional practice in the technical field of urine drainage catheters, particularly Foley catheters. Variations of construction of the filler valve are not in themselves an aspect of the subject matter of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0035]     For a better understanding of the present invention, and to show more clearly how the same made be carried into effect, reference will now be made, to the accompanying drawings, in which;  
         [0036]      FIG. 1  is a longitudinal diametral section through a Foley catheter which is within the state of the art;  
         [0037]      FIG. 2  is a longitudinal diametral section through a Foley catheter in accordance with the present invention; and  
         [0038]      FIG. 3  is a longitudinal diametral section through the proximal end of the  FIG. 2  catheter, showing the plug parted into two parts;  
         [0039]      FIG. 4  is a longitudinal diametral section of a catheter in accordance with  FIG. 2 , showing a sleeve extending around both the fluid drain coupling and the fluid supply element;  
         [0040]      FIG. 5  is a longitudinal section, similar to that of  FIG. 4 , but showing a sleeve which extends only around the fluid supply element, and not around the fluid drain coupling;  
         [0041]      FIG. 6  is a longitudinal section through apparatus for placing the plug inside the lumen of the Foley catheter; and  
         [0042]      FIG. 7  is a section like  FIG. 6 , but showing the plug after placement in the lumen. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0043]      FIG. 1  shows a known pre-filled Foley catheter. The catheter  10  comprises a shaft  11  of latex rubber which defines a balloon inflation lumen  12  and a drainage lumen  13 . The drainage lumen  13  extends from a distal drainage port  14  to a drainage bag coupling element  15  at the proximal end of the catheter. The inflation lumen  12  connects a chamber  20  at the distal end of the catheter, but proximal of the drainage port  14 , with a reservoir bulb  21  at the proximal end of the device. In  FIG. 1 , both of the balloon  20  and bulb  21  are shown inflated, for the sake of clarity, but those skilled in the art will appreciate that the sterile water within the bulb  21  is not sufficient simultaneously to fill both the bulb and the balloon. The reality is that, when the bulb  21  is full, the balloon  20  is not yet inflated and, when the balloon  20  is fully inflated, the bulb  21  is deflated.  
         [0044]     The bulb  21  has a proximal end  22  and a distal end  23 . At the proximal end  22  is a conventional one-way filler valve  24  with which those skilled in the art will already be familiar. At the distal neck  23  of the bulb  21 , there is a conventional external clip E to clamp together the walls of the lumen  12 .  
         [0045]     Turning to  FIG. 2 , the catheter shown in this drawing figure is identical to that of the  FIG. 1  catheter, except that the external clip E has been replaced, in accordance with the invention, by a plug  25  which is a friction fit inside the lumen  12 , the plug  25  being introduced distally into the lumen  12  through the interior of the-bulb  21  and, in so doing, elastically deforming the material of the shaft  11  of the catheter  10 .  FIG. 3  shows in more detail the construction of this control device.  
         [0046]     In  FIG. 3  the control device can be seen to be made up of a tapered plug portion  26  and a solid stem portion  27  which occludes the proximal end  28  of a bore  29  which extends completely through the plug portion  26 , as far as its distal end  30 . The solid stem  27  is integral with the plug portion  26 , but joined to it by a narrow and weak circle  31  of material around the proximal end  28  of the bore  29 . The circle  31  constitutes a parting line.  
         [0047]     The tapered portion  26  is itself made up of adjacent more or less frusto-conical portions. The larger frusto-conical portion  26   a  has a relatively gentle taper along the plug axis, and the smaller frusto-conical portion  26   b  has a relatively faster steeper taper, together giving the plug a rounded bullet nose to be advanced along the lumen to the desire location. There is a step  26   c  between the tapered portion of the plug and its cylindrical portion  26   d  of largest diameter.  
         [0048]     The length of the large diameter cylindrical portion  26   d  is preferably smaller than its radius, thereby enhancing lumen sealing around this portion of the plug. The length of the plug annulus is preferably greater than its maximum diameter, which helps to keep the plug pointing in the axial direction as it is pushed from behind to advance along the lumen.  
         [0049]     The control device is formed from synthetic polymeric material which is selected so that manual manipulation of the solid stem  27  relative to the plug portion  26  is quite sufficient to tear the polymer material at a point on the circumference of the weak circle  31 , thereby allowing the stem  27  to rotate relative to the plug portion  26 , with further tearing of the material around the circle  31  putting in fluid communication the bulb  21  surrounding the stem  27  with the bore  29  through the length of the plug portion  26 .  
         [0050]     Because of the softness of the bulb, and the open space between the wall surfaces of the bulb  21  surrounding the stem  27 , there is great scope for manual manipulation of the bulb, from outside it, to achieve a large angle of rotation of the stem  27  relative to the plug portion  26 , with consequent great certainty of putting the bulb  21  in communication with the bore  29 . Nevertheless, the stem  27  may lie in the lumen  12  spaced from the bulb, if the lumen is susceptible enough to external manipulation and bending to permit the stem  27  to be snapped away from the annulus  26 .  
         [0051]     Those skilled in the art will be familiar with the conventional dimensions of a pre-filled Foley catheter. Of course, many of these are determined by the dimensions of the associated parts of the human body. The researches of the present applicant, as to what are the preferred dimensions of the plug control device, have resulted in a proposal that the control device should be constructed in accordance with the following scheme of dimensions (all in mm): the stem portion  27  has a length of 10 and a diameter of 2.25; the plug portion has a length of 9 and a bore diameter of 2; the frusto-conical outer diameter range is from 5.5. to 4.3; there is a transition zone from the proximal end of the 2 mm axial bore of the plug portion, to the 2.25 mm diameter circle on the proximal end face of the plug portion, which extends distally from the proximal end face over a distance of 0.625 mm.  
         [0052]     The bulb can be water-proofed (as is known) for example by dipping in Saran® a polyvinylidene chloride coating composition. Otherwise it could be water-proofed by, e.g. dipping or spraying it with silicone, neoprene rubber, butyl rubber or hydrophobic polyurethane. Those skilled in the art will be aware of such procedures and practices.  
         [0053]     One suitable polymer material for the plug device is polyvinylchloride. However, there is currently prejudice against the use of PVC. High impact polystyrene is another possibility. A polyester material such as polybutyleneterephthalate may be worthy of consideration. Styreneacrylonitrile is another polymer of particular interest. The selection of polymers for medical applications is a field in which there is considerable experience. Some special factors apply, for example, gamma ray sterilisation is usual, and the polymer must obviously be able to withstand all production process steps, including sterilisation, as well as being stable enough to survive the required shelf life period in the environment in which it finds itself. Resistance to solvents, possibly acetone, may be another significant factor. Putting the bulb interior in communication with the tube should not result in any loose fragments of the control device, especially not any transport of such fragments to the fluid acceptor. Accordingly, the preferred failure mode between stem portion  27  and plug portion  26  is tearing.  
         [0054]     Although the presently preferred embodiment involves a circle of weakness, and parting of the polymer material around the weakness circle  31 , nevertheless it is contemplated that alternative embodiments may be desirable in which, for example, the stem portion  27  is not integral with the plug portion  26  but, rather, is a separate piece which is friction fitted with the proximal end  28  of the bore  29 . If this were the case, then it might be appropriate to provide stepped or tapered portions of the proximal end of the bore  29  or the distal end of the stem  27 .  
         [0055]     Although the present invention arose out of a consideration of how to improve a specific product, the pre-filled Foley catheter, nevertheless the concept of the invention might be applicable elsewhere. In particular, the interaction of a plug stopper and a distended elastomeric reservoir of sterile fluid could be useful whenever there is need for a supply of sterile fluid from a bulb. Thus, it could be arranged that, while the plug remains intact, the fluid is safe and sterile within the bulb, and resistant to damage or decay but, upon a simple manipulation of the stem of the plug, a supply of sterile fluid is available, from the bulb, in whatever quantities and rate of flow are selected by the user, by varying the squeezing and manipulation of the elastomeric bulb.  
         [0056]      FIGS. 4 and 5  illustrate alternatives, in accordance with the second aspect of the present invention, to coating the fluid supply element at the proximal end of the device. Instead of dipping the proximal end in a coating liquid, the proximal end is surrounded by a sleeve. This sleeve can be like the sleeve  40  of  FIG. 4 , embracing both the bulb  21  and the coupling element  15 , or like the sleeve  42  of  FIG. 5 , embracing only the bulb  21  and not the coupling  15 .  
         [0057]     One way of providing the sleeve is to use stretchy material, pre-formed as a sleeve. The lumen  11  could be advanced through the sleeve, and then the sleeve restrained while the distal parts of the catheter are pulled through the sleeve, until the sleeve is stretched by the structures at the proximal end of the catheter and ends up stretched over the bulb  21  and bag connector  15 , as shown in  FIG. 4 .  
         [0058]     However, it is presently preferred by Applicant to pre-form the sleeve from shrink wrap material, which is 50 μm thick oriented polystyrene material. Such material, somewhat thinner, say 40 μm thick, is also seen as likely to be suitable and useful. For the conventional Foley catheters which Applicant makes, it is appropriate to use a pre-formed tube which, when flat, has a width of 45 mm and which, for use in the present invention, is cut into lengths of 90 mm, this being long enough to extend over not only the bulb  21  but also the fluid control device  25  and the distal end of the filler valve  24 , as shown in  FIGS. 4 and 5 . Preferred is shrink wrap sleeving which includes a tear strip or tab incorporated along its length. In the particular embodiment favoured at present by applicant, this tear tab has a width of 10 mm.  
         [0059]     Shrink wrap sleeving, of the description immediately above, is available from Decorative Sleeves Ltd, Hardwick Industrial Estate, Kings Lynn, Norfolk, England.  
         [0060]     Although a tear tab is not essential, and although the precise location of the tear tab relative to the drain coupling  15  and fluid bulb  21  is not critically important, it is presently preferred to locate the tear strip to lie over the surface of the bulb  21 , diametrically opposite from the location of the drain coupling  15 .  
         [0061]     Those skilled in the art will be familiar with techniques for printing on polystyrene film. Should it be desired, printed matter can be placed on the polystyrene tubing pre-form, before the sleeve is placed over the bulb of the catheter.  
         [0062]     As can be seen in  FIGS. 4 and 5 , heat shrinkage of the shrink wrap sleeving, in a length which extends distally beyond the sealing annulus of the fluid control device  25 , and proximally beyond the sealing annulus of the filler valve  24 , is sufficient to place a more or less fluid-impervious coating over the bulb  21 , whether the bag coupling  15  is inside or outside the shrink wrap sleeve.  
         [0063]     As the presently favoured method of placing the shrink wrap sleeve over the catheter bulb  21 , Applicant uses a vertically arranged heat shrink tunnel. Thus, the shaft  11  of the catheter is advanced through the sleeve prior to shrinking, so that the 90 mm length of the shrink sleeve lies over the catheter bulb  21  in the axial position shown in  FIG. 4  or  FIG. 5 , and then the catheter, with the sleeve in place, is placed between two vertical conveyor belts of the heat shrink tunnel, with the proximal end of the catheter uppermost. The conveyor belts advance the catheter downwardly through the vertically arranged heat shrink tunnel and, as the proximal end of the catheter passes through the tunnel, the heat within the tunnel will cause the sleeving to shrink around the catheter bulb  21 .  
         [0064]     At the bottom end of the heat shrink tunnel, the catheter is taken from the conveyors, again to be subjected to a manual quality check before being placed into a transport box for further processing.  
         [0065]      FIG. 6  shows schematically the presently favoured method which applicant uses to insert the fluid control device  25  into the lumen of the catheter. A plurality of long flexible fingers  50 , themselves mounted at their proximal ends to a finger ring  52 , are introduced into the open end  22  of the catheter lumen which is to become the elastomeric bulb  21 . Radially outward movement of the fingers  50  allows the plug  25  to be advanced axially past the open end  22  of the lumen, and beyond the part of the lumen  21  which becomes the bulb, until the plug  25  reaches the part  23  of the lumen which will become the distal neck of the bulb  21 . Here, the lumen narrows down, over the length of a neck-in section R 4  to the diameter of the lumen in the shaft, which here is 0.8 mm.  
         [0066]     This advancement of the plug  25  along the lumen  12  is accomplished by an engagement of a female end  54  of an engagement rod  56  arranged on the axis of the plug insertion apparatus. The stem  27  of the plug  25  is received within the bore  58  of the female engagement portion  54  of the injector rod  56 .  
         [0067]     Conveniently, the injector rod  56  is pneumatically operated. In practice, it is convenient to provide the apparatus with a foot pedal actuator for the injector rod  56 , so that a human operative can arrange the lumen end  22 , fingers  50  and plug  25  as desired, with delicate use of the fingers, and then achieve plug insertion in the lumen  12  using a movement of the foot to actuate the foot pedal.  
         [0068]     The rod  56  advances the plug  25  to the position shown in  FIG. 7 , in which it is snugly and co-operatingly abutting the neck-in section R 4  of the lumen.  
         [0069]     Once the plug is inserted, and the injector rod  56  retracted, the fingers  50  retract to their initial disposition, enabling the open end  22  of the lumen  12  easily to be withdrawn from the fingers. The latex lumen wall is opaque, but because the prominent ring  26   d  of the large diameter cylindrical portion of the plug  25  distorts the latex lumen wall, as can be seen in  FIGS. 2, 3 ,  4  and  5 , the operative can check that the plug  25  is in the desired location. It will be noted that the stem  27  projects proximally into the void within the bulb  21 . After this check, the partially manufactured catheter can be placed in a transport box, for onward transport and further processing.  
         [0070]     It should be appreciated that the foregoing description of the invention is intended merely to be illustrative and that other embodiments, modifications and equivalents may be apparent to those skilled in the art which may be within the literal or equivalent scope of the claims as presented below or as they maybe broadened or narrowed by further amendment.
In a pre-filled Foley catheter for urine drainage, the conventional clip for releasing sterile water from a bulb ( 21) at the proximal end of the catheter, to fill the anchor bulb ( 20) at the distal end of the device, is replaced by a plug ( 25) which has an annular portion connected to a thin stem ( 27) by a circle of weakness. Snapping the stem ( 27) from the annulus provides a tactile signal through the opaque latex lumen that the catheter has been actuated. There is no separate clip to be disposed of. The interface between the latex and the plug remains undisturbed. Further improvement in the shelf- life and convenience of use of the catheter is delivered by the use of a sleeve, which can be of shrink-wrap material, around the bulb ( 21) and optionally also around the drain coupling ( 15) of the catheter. Apparatus for placing the plug and the sleeve is also described.