The invention relates to improvements in catheters and similar surgical devices and more especially to catheters intended for urological use.
Objects and advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attained by means of the Instrumentalities and combinations pointed out in the appended claims.
The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.
The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention, Of the drawings: Fig. 1 is an elevation, with parts in section, showing a catheter embodying the invention; Fig. 2 is a transverse section on line 2-2 of Fig. 1; Fig. 3 is an enlarged fragmentary side elevation of a catheter of the general form shown in Figs. 1 and 2 but having a filament of twisted wire; g. 4 is a section on line 4-- of ig. 3; Fig. 5 is a view similar to Fig. 3, showing a filament of braided wire; Fig. 6 is a section on line 6-6 of Fig. 5; Fig. 7 Is a view similar to Fig. 3 showing a linked chain as the filament; Fig. 8 is a section on line "8 of Fig. 7; Fig. 9 is a view, similar to Fig. 1, showing an "olive tip" catheter; Fig. 10 is a horizontal plan view of the catheter shown in Fig. 9; Fig. 11 is a fragmentary elevation of a modified form of catheter having a helical filament; Fig. 12 is a section on line 12-12 of Mg. 11; and Fig. 13 is a section on line I--13 of Fig. 11.
As to its generic subject matter and also as to certain species, the present application comprises a division and continuation-In-part of subject matter disclosed but not claimed in my co-pending application Serial No. 235,934, filed October 20, 1938 for "Surgical device"; and as to other parts of the present application, it constitutes an improvement upon and species additional to tht subject matter disclosed in said parent application Serial No. 235,934.
The invention is primarily directed to providing improved surgical devices of the type hereinafter generally designated as catheters and comprising a general class of flexible surgical devices including catheters and bougles designed for insertion into and through natural bodily passages such as the human urethra and ureter, antrum and other such passages in which catheters are used for exploration, dilation, drainage, medication and the like. The invention provides an improved catheter construction whereby a highly flexible catheter, having the necessary minimum external diameter consonant with adequate strength and the longitudinal rigidity required for insertion and manipulation, is nevertheless- of greatly increased tensile strength and longitudinal cohesion.
One of the major problems in catheter construction and use is to provide a tube which is sufficiently flexible to conform easily to the long, narrow and tortuous bodily passages (for example, the human ureter from bladder to kidney), yet has sufficlent inherent longitudinal rigidity to permit proper manipulation and Insertion through such passages and also is possessed of a high degree of tensile strength without sacrifice of the required flexibility. The necessity for such high tensile strength is especially prominent in ureteral catheters where in passing the tube through the ureter to the kidney, it comes in contact with the sharp and jagged surfaces of stones.
The bending, twisting and abrasion of the catheter against the stones not infrequently causes a part of the catheter to become broken or severed, especially the portion near the tip. When the catheter is withdrawn, the broken off piece may thus be left in the kidney or other organ and its removal thereafter entails a major operation.
One important object of the invention is to provide catheters with auxiliary reinforcing means imparting properties of high tensile strength and longitudinal cohesion so that even when the catheter matrix material may become cracked or severed it will nevertheless remain connected to the general structure and can be withdrawn even when exertion of a relatively high withdrawal force is required.
In addition the construction of my catheter is such that the reinforcing means is so intimately connected to the catheter matrix that it remains 0 an integral part of the instrument even after said instrument has been bent or curved as required to fit the various oriflces or bodily canals in which it is inserted and manipulated. The union of the matrix with the reinforcing member remains constant and unimpaired over, long periods of time and there is substantially no tendency for the reinforcing member to back away from the matrix portion upon normal continued re-use and changing of shape.
With these objects in view, the invention provides a catheter provided with a flexible reinforcing member of high tensile strength running from one end of the catheter to the other and embedded preferably wholly within the plastic composition or other flexible material of which the catheter matrix is formed. Preferably said member is a filament in form, said filament possessing a very high degree of tensile strength, preferably many times greater than that of the plastic material forming the catheter body.
Preferably also said filament is exceedingly flexible and pliable, having little or no longitudinal and transverse rigidity so that in these respects it is less rigid than the catheter matrix itself.
In other words, in the preferred form of my invention, the filament is provided solely for the purpose of imparting additional longitudinal tensile strength to the catheter matrix in which it is embedded and the inherent longitudinal rigidity of the matrix itself is sufficient to provide the necessary stiffness for insertion and manipulation. Thus the tensile-strengthening filament does not offer any opposition to bending and manipulation of the catheter but in these characteristics is entirely subservient to the catheter matrix itself.
Other characteristics of the invention comprise provision of a tensile-strengthening member or filament which is of a material well adapted to blend and adhere intimately with the matrix material of the catheter. In the preferred form of the invention this member comprises a textile filament or thread, preferably of "Nylon" or synthetic textile material of equivalent high tensile strength, high flexibility and other known characteristics. Nylon thread not only possesses these advantages but it also is adapted to adhere to or cohere with the plastic or gummy material of which the matrix may be formed so that intimate and strong connection is provided between the filament and matrix throughout their length.
It will be understood that the foregoing general description and the following detailed description as well are exemplary and explanatory but are not restrictive of the invention.
Referring now in detail to the present preferred embodiment of the invention illustrated by way of example in the accompanying drawings, there is shown in Figs. 1 and 2 a catheter of the socalled "whistle tip" type having a tubular body portion or matrix I preferably formed of a plastic cellulosic material such as etherized cellulose, as Smore fully disclosed in my copending application Serial No. 235,934, filed October 20, 1938. That is, the body portion or matrix of the catheter is preferably formed of an extruded thermo-plastic material which is insoluble in water and bodily fluids and in the medicaments normally used in catheter treatments. The plastic material used is preferably also highly flexible so that the catheter can conform to and be inserted through long, narrow and tortuous bodily passages, yet is possessed of sufficient inherent longitudinal rigidity to permit manipulation and insertion through such passages. These characteristics are inherent in the plastic materials disclosed and claimed in my prior filed pending applications, Serial No. 232,406, Serial No. 232,407, Serial No. 232,408, Serial No. 232,409, Serial No. 232,410, all filed September 29, 1938, and Serial No. 236,190, filed October 21, 1938, although it will be understood that the present invention is not limited to catheters formed of those plastic materials Salone but may also be utilized with other catheter matrix materials which are capable of similar use.
In form, the catheter shown is a relatively long, externally smooth, circular tube of small outside diameter primarily intended for ureteral exploration and treatment but not limited to such uses. The standard length for such catheters is normally about thirty inches and the external diameter may be as small as fifty thousandths of an inch. The catheter is provided with a smooth interior circular bore or lumen 2 which extends from the open rear end to near the tip 4, stopping short thereof to form a closed tip.
The bore 2 may be concentric with the exterior circumference of the catheter but preferably, in accordance with the invention, its location is somewhat eccentric to the exterior circumference thereby providing at one side a relatively thicker matrix wall I . The whistle-tip catheter is also provided with the usual side wall openings or eyes 5 which are preferably formed in the thinner part of the matrix wall and always in such positions as to avoid exposing the filament.
In accordance with the invention a tensilestrengthening or reinforcing member comprising a filament 3 of high flexibility and high tensile 30-strength is embedded within the catheter wall and extends rectilineally the length of the catheter. When the catheter wall construction is eccentric as shown, the tensile strengthening filament 3 is preferably embedded in the thicker part of said wall, said additional thickness thereby providing for adequate coverage of the filament with the plastic matrix material in all directions. In the preferred form of the invention, the filament 3 is of "Nylon" thread or other similar textile material, preferably artificial, and thereby possessing a high degree of flexibility, elasticity, suppleness and tensile strength substantially in excess of that possessed by the plastic material forming the catheter body. Other fibrous materials such as linen, natural silk, wool, cotton or hair may be used, but my experiments have shown that "Nylon" is to be preferred.
While I have referred to the reinforcing member 3 as a filament, it will be understood that this term is broadly to be understood as comprising any slender threadlike flexible member of one or more strands. In practice (Fig. 2) a plurality of strands are twisted together and embedded at the same locus in the matrix, but if desired several such filaments may be embedded at different loci circumferentially thereof within the matrix wall. Also, a single untwisted strand filament of adequate strength may be used instead of a twisted plurality of strands or fibres.
CO In the manufacture of the catheter as above described, the plastic material and the "Nylon" thread 3 are preferably extruded together through a suitably formed extrusion die which feeds the plastic material from a thermoplastic mass and with it the filament 3 into the proper final relationship as shown. By this method the filament is thoroughly and permanently embedded in the thicker part of the catheter wall where it becomes a substantially integral part of the catheter construction. The thermoplastic mass is thus brought in contact with the filament under heat and great pressure so that the plastic matrix is firmly bound to the filament. The cellulosic matrix tends to adhere to the textile filament so that separation of the two becomes very difficult. Moreover there is no tendency for the matrix or the filament to become distorted or loosened in use and under changes in temperature because the coefficient of expansion of the cellulosic plastic and of the textile filament are virtually the same.
The catheter may be of the "whistle tip" construction shown in ig. 1 in which case the end 4 is separately remoulded to the desired form, it being noted that the filament 3 terminates at or slightly short of the end of the catheter and is entirely covered by matrix. The formation of one or more side eyes or openings 5 is also preferably done by a remoulding process wherein the matrix is forced out of the opening and packed against the opposite wall of the catheter by the moulding die. When a thermoplastic matrix of the nature previously referred to is used, said matrix is sufficiently compressible to allow for this operation without loss of any of the material.
In Figs. 9 and 10 a catheter of the "olive tip" type is shown in which the end portion 14 is slightly bulbous in form and a constricted neck is formed between the olive end 14 and the main body of the catheter. In this construction also the formation of the olive tip, and of the opening or openings 5, is effected by a remoulding operation and here again the filament is entirely embedded within the solid olive tip of plastic matrix. Preferably the moulding operation is such that the strengthening member is embedded substantially centrally within the constricted portion 15 thereby guarding against exposure in breakage. It is at and in the constricted or narrow portion of the catheter that breaks heretofore have been most prone to occur, with consequent retention of tip portion in the orifice of the body.
Referring now to the species of my invention shown in Figs. 3 to 8 hereof it will be understood that same were originally disclosed in my parent application Serial No. 235,934. Each of the forms shown in these figures possesses to some degree the generic features heretofore referred to as constituting my invention, namely a catheter having a tensile strengthening filament of high flexibility and high tensile strength with relatively little or no longitudinal rigidity. In the form shown in Figs. 3 and 4 the reinforcing and tensile strengthening filament comprises a cable 6 of twisted strands of fine wire embedded in the matrix of the catheter. In Figs. 5 and 6 a plurality of strands of fine flexible wire are braided together to form the tensile strengthening filament or member. In Figs. 7 and 8 a chain form is shown in which the strengthening member is made up of a plurality of fine mesh links. In these several forms a considerable movement or "play" is allowable in bending the catheter to the desired curve or angle without breaking the "weld" between the strengthening member and the matrix. Particularly in using the link chain form of Fig. 7 it will be obvious that much "play" or flexibility subservient to, the bending of the catheter matrix itself is available.
It will further be clear that in the various forms of metal strengthening members shown, the surfaces thereof are sufficiently irregular through the twisting, braiding or chain link constructions to facilitate the embedment and adhesion of the filament member to the matrix. In the case of the chain and braided members, it will be found that a certain amount of the matrix will be squeezed entirely through openings therein thus affording a strong welding of the matrix to the strengthening member. Moreover, other materials than metal may be used in these forms. In Figs. 3 to 6 in particular, two or more textile strands of "Nylon" or the like may be twisted or braided to provide the composite form of filament. Other fibrous inorganic materials besides metal may be used, such as threads formed of asbestos fibres, for example.
While in its preferred form the invention utilizes a rectilinear filament parallel to the axis of the catheter, many of the beneficial features of the invention may be realized by embedding a filament in non-rectilinear form in the catheter walls. For example, in Figs. 11, 12 and 13, a flexible filament 21 is disposed in a helical configuration embedded within the circular walls 21 of the catheter matrix. As shown the helix formed by the filament 20 describes a plurality of turns about the axis of the catheter throughout its length, but the pitch or number of turns relative to the length is such as to give a fairly wide spacing between turns. Said spacing should be sufficiently wide to provide adequate room for locating the several orifices 22, 23 and 24 of the catheter all without severing or exposing any part of the filament in the moulding of the orifices. As shown, the helical filament 20 is preferably composed of a plurality of twisted textile strands as in Fig. 1, but it obviously may be formed instead of the various other forms and materials illustrated in Figs. 3 to 8. In every case, however, it will be understood, that the filament 20 possesses the characteristics of flexibility and high tensile strength characteristic of the invention. As will be obvious from the drawings, the helical form of filament is preferably used with a cylindrical matrix having a concentric bore 25, and it will be understood that this construction imparts even greater cohesive strength to the general catheter structure. It will also be clear that in manufacture the helical form of the filament can be incorporated within the matrix during the extrusion process by imparting a rotary motion to the thread-feeding portion of the die during the extruding action.
While the invention has been described as primarily applicable to tubular catheters, it will be understood that in general its principles are also applicable to similar non-tubular or solid surgical devices such as bougies for the dilation of bodily openings. Bougies may be formed of a flexible moulded matrix similar to that used in my catheter but having no internal bore and usually being constructed of somewhat stiffer material.
Such bougies are generally relatively long instruments of small external diameter and are usually slightly tapered to facilitate dilation of bodily orifices. Also the tips of the bougies may be of various standard types such as olive tip, bulbous tip, conical tip, etc. It will be understood that the present invention is applicable to such bougies constructions by providing one or more tensile strengthening filaments extending substantially the length of the bougies and being embedded in the matrix forming the same. Inasmuch as there is no internal bore in the bougie the strengthening filament may be conveniently formed as a central core for the bougie or a plurality of such filaments may be distributed within the matrix and circumferentially spaced.
The invention in its broader aspects is not limited to the specific mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claim? without departing from the principles of the invention and without sacrificing its chief advantages.
What I claim is: 1. A surgical device of the class described comprising a matrix forming a relatively long member of circular cross-section of small external diameter which is externally smooth and formed of material which is non-porous and of high flexibility but having sufficient inherent longitudinal rigidity to permit insertion into long, narrow, tortuous bodily passages, said matrix having embedded in the material beneath its outer surface means for preventing separation of said matrix in use, said means comprising a filament of flexibility and tensile strength greater than that of the matrix extending throughout the length of the member and imparting thereto a tensile strength greater than that possessed by the matrix alone.
2. A catheter comprising a matrix forming a relatively long, hollow tube of small external diameter which is externally smooth and formed of material which is non-porous and of high flexibility but having sufficient inherent longitudinal rigidity to permit insertion into long, narrow, tortuous bodily passages, said matrix having embedded in the wall of material between its internal bore and its outer surface a textile filament of relatively high tensile strength and substantially no longitudinal rigidity extending throughout the length of the catheter and imparting thereto a tensile strength greater than that possessed by the matrix alone.
3. A catheter comprising a matrix forming a relatively long, hollow tube of small external diameter which is externally smooth and formed of plastic material capable of extrusion, which material when extruded into said tube is nonporous and of high flexibility but having sufficient inherent longitudinal rigidity to permit insertion into long, narrow, tortuous bodily passages, said matrix having embedded in the wall of material between its internal bore and its outer surface a filament of relatively high tensile strength and substantially no longitudinal rigidity extending throughout the length of the catheter and imparting thereto a tensile strength greater than that possessed by the matrix alone, said filament having surface characteristics which cause it to adhere intimately to plastic material applied thereto by extrusion.
4. A catheter comprising a tubular matrix of flexible material having a circular exterior and a circular bore, said bore being eccentric to the exterior circumference to form a matrix wall thicker on one side of the bore, and a longitudinally disposed tensile-strengthening filar member embedded in the thicker part of said wall, said member having a flexibility and tensile strength greater than that of the matrix.
VINCENT J. FLYNN.