Catheter stylets

[57] ABSTRACT

The present invention relates to a new adjunct to the insertion of a urethral catheter. It is a catheter stiffener and former made of a plastic rod which has the properties of being a flexible, resilient member capable of properly stiffening a urethral catheter or the like while also being sufficiently compliant to preshaping into various and multiple curvatures to facilitate insertion into a body cavity.

Claims, 6 Drawing Figures

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PATENTED FEB 2 51975

3,867, 945

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3.867.945

CATHETER STYLETS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to surgical devices for aiding in catheter insertion into a body cavity and, more particularly, but not by way of limitation, it relates to an improved urethral catheter stiffener and former, i.e., as variously termed a stylet, mandrin or catheter guide, and the invention is particularly adapted for use with the Foley urethral catheter.

2. Description of the Prior Art

The prior art includes various types of catheter stylets, not only for use in Foley-type urethral catheters but other catheters as designed for insertion in particular body cavities, i.e. endotrachea catheters, trocar catheters, etc. Generally, the prior forms of stylets have been formed from wire or other rigid metallic materials. The prior art devices, especially as employed for insertion of urethral catheters, had inherent shortcomings due to the very fact of their necessary rigidity. The use of the conventional wire stylets required manipulation and insertion by a trained urologist in performance of the routine as well as the more difficult catheterizations, as the wire guide could very easily force the catheter to pierce the delicate wall of the urethra when not properly avoiding obstructions.

SUMMARY OF THE INVENTION

The present invention contemplates a readily expendable catheter stiffener formed of desirably resilient material and it is particularly adapted for use with the Foley urethral catheter. The stiffener and former consists of an elongated portion having the proximal end formed with a pre-selected curvature and a distal portion with an enlarged diameter formed for co-action with the distal end of the Foley catheter. The proximal end of the stylet is formed with a curvature of optimum radius for encounter with the particular obstructions and curvatures present along the urethral tract.

Therefore, it is an object of the present invention to provide a catheter stylet that is semi-rigid and sufficiently stiff to guide the catheter during insertion and to prevent collapsing of the catheter tube.

It is still another object of the invention to provide a stiffener and former which may be pre-formed into a variety of curves as selected to implement insertion of the catheter device.

It is yet another object of the present invention to provide a catheter stylet having greater resiliency and which is unlikely to damage the fragile lumen of the urethra when the catheter is inserted.

It is also an object of the present invention to provide a stiffener of simple design having no moving parts which is inexpensive to manufacture and may be disposable after a single usage.

It is therefore an object to provide a stiffener and former compatible with the design of the Foley urethral catheter which may be factory inserted for sale with the Foley catheter as a unit, thereby reducing extra handling and contamination prior to its usage.

Finally, it is an object of the present invention to provide a stiffener and former for use with the Foley catheter which will enable the more routine catheterization to be carried out by nurses or physicians assistants without danger of damage to the urethral tract of the patient.

Other objects and advantages of the invention will be evident from the following detailed description when 5 read in conjunction with the accompanying drawing which illustrates the invention.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a top plan view of the stiffener and former 10 as constructed in accordance with the present invention;

FIG. 2 is a side elevation of the stiffener of FIG. 1;

FIG. 3 is a side elevation of an alternative form of stiffener;

FIG. 4 is a vertical section of a Foley urethal catheter as is well-known in the prior art;

FIG. 5 is a vertical section of the Foley catheter with stiffener inserted; and

FIG. 6 is a section taken along lines 6—6 of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings in greater detail, FIGS. 1 and 2 show a catheter stiffener and former 10 25 as constructed in accordance with the present invention. The stiffener and former 10 is comprised of a rod 12 as securely joined or affixed to what may be termed a handle 14. A proximal end portion 16 is then preformed with a curvature 18 of selected radius, gener³θ ally not too severe but of sufficient curvature to allow optimum probing manipulation during catheter insertion. A proximal tip 20 of rod 12 is rounded off to prevent damage to the proximal end portions of the catheter and/or the urethral wall.

Rod 12 is preferably formed from selected plastic materials having the requisite properties as to resiliency, and prototype stiffener and formers 10 have been successfully formed from nylon rod stock of approximately one-sixteenth inches in diameter. The han⁴θ die 14 may also be formed of the similar plastic material, and it should be of cylindrical formation having a diameter of approximately three-eights inches such that it fits snuggiy in the distal end of a Foley catheter, as will be further described below. Thus, a bore 22 may ⁴⁵ be formed in handle 14 to receive the end of rod 12 therein to be secured through interference fit. While the rod 12 and handle 14 are shown as being formed in two separate pieces, it should be understood that the stiffener and former 10 can be formed unitarily in one ⁵⁰ piece through conventional plastic molding practices.

While the stiffener and former 10 is shown in FIG. 2 as having a curvature 18, that which is known as the single curved or coude’ tip, some practitioners prefer, and the exigencies of certain therapeutic applications may demand, a double curved tip 24 such as is shown in FIG. 3. The curve 24 also subtends a relatively gentle curvature through formation of two distinct angular bends 26 and 28.

₆₀ FIG. 4 represents a standard form of Foley urethral catheter as is now well-known in the art. The Foley catheter is the particular subject matter of U.S. Pat. Nos. 2,428,407 and 3,152,592 and the teachings embodied therein have enjoyed wide application and success. Conventionally, insertion of the Foley catheter has required either the use of a wire-form stylet with its attendant piercing and injury problems, or the attending physician has had to apply excessive lubrication and

3,867,945 short stroke insertions of very time-consuming and uncertain nature.

Briefly, the Foley catheter 30 consists of a distal portion 32 and tube portion 34, the tube portion 34 being formed to include a drainage lumen 36 and an inflation or control lumen 38. The Foley catheter’s may be formed as bi-luminal or tri-luminal tubes, at least one of which, such as tube 38, is in communication with a balloon 40 which is sealingly connected about tube portion 30 proximate the proximal end 42 of catheter 30. Dash-lines 44 illustrate in section the balloon 40 after it has been inflated to the attitude wherein it prevents withdrawal of tube portion 34 from the bladder. The drainage conduit 36, of larger diameter, is in communication with the fluid drainage holes 46 as formed near the proximal tip 42 of catheter 30. At the distal end, catheter 30 is formed with a control tube 48 in communication with control lumen 38 and serving to provide inflation and de-inflation control. A closure element 50 within control tube 48 serves to maintain inflation pressure within the balloon 44 when in use. A drainage outlet 52 in communication with drainage lumen 36 provides drainage outlet for urine and collected fluids.

FIGS. 5 and 6 illustrate the catheter 30 with the stiffener and former 10 inserted therein in operational position. Thus, the rod 12 is inserted along the entire length of drainage lumen 36 such that its rounded tip end 20 is fully inserted up to proximal tip 42 of catheter 30. The handle 14 of stiffener and former 10 is inserted within drainage outlet 52 to provide a reasonably tight fit to maintain stiffener and former 10 securely positioned within catheter 30 during entry manipulation. The length of rod 12 has been established so as to extend through the length of the catheter shaft or drainage lumen 36 such that the handle 14 receives snug fit in the distal end thereof, i.e., drainage outlet 52. In practice, the catheter is actually stretched slightly to cause it to conform to the shape of the former and to thereby further decrease the diameter of the catheter 30 itself. This constraint also serves to prevent buckling or collapsing of the catheter during insertion and manipulation.

OPERATION

In practice, the relatively resilient stiffener and former 10 is inserted into the catheter 30 as shown in FIGS. 5 and 6. Thereafter, the attending physician, attendant or nurse can then easily manipulate the catheter 30 for probing entry into the urethra of the requiring patient so that the proximal end 42 and drainage holes 46 are entered sufficiently into the urinary bladder. Thereupon, inflation control is exercised to inflate balloon 40 thereby to retain proximal end 42 within the bladder confines. Then, the attendant needs only to loosen the handle 14 from drainage outlet 52 to easily withdraw the rod 12 of stiffener and former 10. The catheter 30 is then in operational placement and the stiffener and former 10 may be discarded.

In practice it is envisioned that such catheters could be supplied to the physician or hospital with the stiffener and former 10 already inserted therein. After one use only, the stiffener and former would then be discarded. Such capability has the obvious advantages of sterilization assurance, and the minimal cost of stiffener and formers 10 should be quite acceptable for the disposability concept.

Some properties which make a catheter and former combination most desirable are (1) a certain degree of stiffness for ease of insertion; (2) some angulation at the tip to allow the tip to “ride over” obstructions; (3) highest proportion of luminal to catheter diameter ratio; (4) flexibility and softness of the catheter once inserted so as to not to cause undue stress and pressure on the fragile surface of the urethra; (5) inertness of the catheters material; (6) reduced expense; and (7) the facility of use. Previously used wire guides did not have the optimum compromise of qualities and were quite difficult to use safely and handily since the wireguided catheter could not be relied upon to “ride over” obstructions but rather to constantly endanger piercing of the urethral wall.

With the present shortage of qualified doctors, more and more catheterizations are done by nurses and physicians assistants, and generally speaking they do not have sufficient training or qualifications to perform difficult catheterizations which require the use of a stylet or, more important, they do not recognize the complications which may result from the use of the conventional stylets. Thus, the present invention converts the usual Foley catheter into an instrument capable of performing many of the more difficult as well as the routine catheterizations safely.

In summary, the aims and design of the catheter stiffener and former permit the use of a soft pliable urethral catheter with a large drainage lumen as compared to the catheter diameter. The catheter walls can be made thinner to increase the ratio of lumen to catheter size, thus allowing more free drainage of urine from the bladder during operative usage. The stiffener and former will permit easy passage of the catheter through the normal urethral canal or when narrowed, angulated, or otherwise obstructed through disease, such passage being made safely without buckling or collapsing of the drainage channels. The catheter stiffener is designed to be cheap and amenable to mass production as it can be packaged already within the catheter and ready for the insertion procedure.

Changes may be made in the combination, arrangement and size as heretofore set forth in the specification and shown in the drawings; it being understood that changes may be made in the embodiments disclosed without departing from the spirit and scope of the invention as defined in the following claims.