The patent's inventors are Meek,
This patent was filed on
From the background information supplied by the inventors, news correspondents obtained the following quote: "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.
"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.
"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.
"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.
"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."
Supplementing the background information on this patent, VerticalNews reporters also obtained the inventors' summary information for this patent: "The invention may be incorporated in embodiments that may include one or more of the following objects, features and characteristics.
"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.
"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.
"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.
"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.
"Advantageously, once the plug is parted, there is no need for the person installing the catheter to manipulate any longer the plug or lumen.
"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.
"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.
"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.
"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.
"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.
"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.
"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.
"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.
"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
"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.
"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.
"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.
"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.
"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.
"In this way, the sleeve and plug work together to enhance the shelf life of the device.
"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 divide 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.
"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.
"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.
"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.
"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.
"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 tire) 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."
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