US2472485A - Catheter-type instrument - Google Patents

Description

June 7, 1949. KRIPPENDORF 2,472;485

CATHETER-TYPE INSTRUMENT Original Filed May 5, 1944 I a Zia 325%, j

INVENTOR. 10w; H. far/ emover Patented June 7, 1949 UNITED STATES PATENT OFFICE CATHETEB-TYPE INSTRUMENT Louis H. Krippendorf, White Plains, N. Y., as-

signor to American Catheter Corporation, Port Chester, N. Y., a corporation of New York 2 Claims.

This application is a division of my co-pending application, Serial No. 534,207, filed May 5, 1944, now Patent No. 2,437,542.

The invention relates generally to surgical instruments and has particular reference to catheter-type instruments.

By the term catheter-type instrument, as used herein and in the appended claims, I intend to refer to the well-known kind of device which is inserted endwise into and through constricted body channels for diagnostic, therapeutic and allied purposes. Illustrative of such instruments are ureteral and urethral catheters, bougies, filiforms and the like.

A conventional instrument of this type is of elongated character and has a uniform over-all flexibility coupled with suflicient rigidity to permit its endwise advancement. This paradoxical requirement for both flexibility and rigidity has heretofore presented a peculiar problem to the manufacturer. For example, in the case of a ureteral catheter, it must be of sufficient flexibility to permit the tip of the instrument to advance harmlessly through the constricted ureteral canal and readily to follow the curvatures encountered, yet as the flexibility is increased by the manufacturer to meet this requirement, the body portion loses some of the rigidity necessary to enable the operator to effect the desired advancement by endwise pressure exerted upon the rear end of the instrument. Similarly, in the case of bougies or the like, it may under certain circumstances be desirable to increase the rigidity of the tip portion, yet the instrument as a whole may thereby become too inflexible to follow an irregularly curved path with adequate ease.

The principal object of my present invention is directed toward a solution of this problem, and my invention is predicated upon the discovery that a catheter-type instrument may be caused to embody different flexibilities along its longitudinal axis without materially altering its basic structural nature or impairing the other inherent qualities which it necessarily must possess. This desirable and advantageous result is achieved in an entirely practical and commercially-feasible manner.

In accordance with one conventional manufacturing procedure, the construction of a catheter-type instrument involves the formation of an initially limp fabric base of interwined threads, this base being usually first impregnated with a flexible stiffening medium and then coated with a flexible varnish. In the practice of my present invention, this general procedure is ad- 2 hered to, yet the body portion of the resultant instrument may be caused to embody a flexibility in the forward or other section thereof which is to a predetermined extent appreciably greater or less than the flexibility in an adjacent section.

This new result and its corresponding advantages may be accomplished in the manner illustratively exemplified in the accompanying drawings, in which:

Figure l is a perspective view of a typical catheter-type instrument.

Figure 2 is an enlarged fragmentary view of a portion of the instrument with the outer coating broken away to reveal the fabric base in the region of the line AA of Figure l; and

Figure 3 is a diagrammatic view illustrating the comparative characteristics, as far as flexibility is concerned, of a conventional cathetertype instrument and one which has been constructed in accordance with the present invention.

The features of the invention may best be described by brief preliminary reference to conventional practice.

A fabric base is first created. Usually, this base assumes the form of an elongated hollow tube, but under certain circumstances it need not have a longitudinal passageway extending through it. This base is formed of interwined threads of silk, cotton, or synthetic fibre, and usually the threads are braided into the desired relationship. Any weaving or other procedure may be restorted to, however, if desired, although braiding machines have proven to be admirably suited to produce a tubular or elongated fabric base of the character required. This base is initially limp in character, and is customarily impregnated with a flexible stiffening medium of suitable composition. Where the base is a tube, the impregnation is carried out While the tube is mounted upon a suitable rod or mandrel. After wiping off any excess, the mandrel (if one has been used) is removed and the impregnating medium is caused to harden or cure, either by air drying, or by subjection to a baking procedure or the like. The reinforced and strengthened fabric base is then subjected to a series of operations during which a flexible tough varnish coating is applied to it, layer by layer, the successive coatings being cured by baking or analogous procedures. After the desired coating has been formed, it is burnished and the instrument is subjected to such other finishing processes as may be deemed desirable.

The forward tip of the instrument may be formed either prior to or after the initial impregnation of the fabric base, depending upon the nature of the instrument, and the kind and shape of tip which it is intended to have. In the case of catheters, the several openings or eyes which characterize these instruments may be formed at or near the forward tip either during the braiding of the base or during a subsequent stage of treatment.

Depending upon the nature and size of the threads originally employed in forming the fabric base. upon the dimensions of this base and upon the impregnating and coating media which are employed, the resultant instrument will have a size and flexibility of predetermined character. Heretofore, in an instrument in which the body portion is of substantially uniform diameter, the bendability and over-all semi-rigidity has been uniform throughout, being usually determined by a suitable compromise between the flexibility required for any given purpose and the stiffness called for by the well-known method in which the-instrument is to be employed.

In accordance with my invention, the essential nature of the manufacturing process remains unchanged, yet varying degrees of flexibility may be imparted to the resultant instrument along its longitudinal axis. For illustrative purposes, I have chosen to describe and illustrate the manner in which a catheter may be caused to have an appreciably increased flexibility in its forward region adjacent to the tip, as compared with the flexibility and rigidity of the remaining main portion thereof.

Thus, in Figure 1, I have illustrated a catheter H] in which the region forwardly of the dot-anddash line A has been caused to embody a greater flexibility than the remaining main portion of thecatheter.

In the procedure followed in accordance with the present invention, the initially limp fabric base tube 22 is impregnated with a flexible stiffening medium, which may be, for example, of the general type in which a suitable carrier such as tung oil is associated with a resin or resins of J polymerizable type, together with a plasticizer or other customary ingredients. There are numerous resins which can be employed, and among them are, for example, resins of the phenolic type. The plasticizer used may 'be any of the usualones, such as castor oil, dibutyl phthallate, tri-cresyl-phosphate, and the like.

In practice, the tube may be mounted on a suitable rod or mandrel (not shown) either before or after the forward tip is formed, and may then be dipped into the impregnating medium. The excess is then wiped off, the rod or mandrel is withdrawn, and the impregnated tube may be placed in a suitable oven to bring about a curing of the impregnating medium.

Subsequently, the tube is handled to form on it the outer coating 23 of flexible varnish, which may be composed, for example, of a tung oil base, a phenolic or other suitable resin, and a plasticizer. By curing this coating to a greater extent in one section than in a longitudinally-adjacent section. the desired different fiexibilities can be imparted to the corresponding sections of the instrument. For example, in producing a catheter having the characteristics shown in Figure 1, the normal and conventional procedure may be followed throughout, and the rearward part of the instrument may then be subjected to an additional baking or curing whereby a greater rigidity is, imparted to it. In Practice, this ,maybe accomplished by dipping the forward region (up to the line A-A, for example) in a suitable 011 or other liquid while the entire instrument is subjected to a baking temperature.

The outer coating 23 is a tough and ,flexlble film having a smooth glossy surfacaand resistant to water, body fluids generally, and standard types of sterilization.

The basic difference between the instrument of Figure 1 and the ordinary type of instrument is indicated diagrammatically in Figure 3. If the ordinary catheter I8 is pressed endwise against an abutment wall i9, by pressure exerted in the direction indicated by the arrow 20, it will buckle throughout its length. On the other hand, if the instrument I0 of Figure 1 is similarly pressed against an abutment 19 by a similar pressure exerted along the direction of the arrow 2|, it will buckle in the formed region of greater flexibility, but not otherwise. Accordingly, when the instrument It! is inserted into and advanced through one of the ureters or through anyother' similar constricted body canal, it will feel its was: more easily past the curvatures encountered, .and this makes the operation safer and simpler.

llhile I have illustrated a catheter, it will be understood that the invention is equally-applicable to any catheter-type instrument, whether hollow or not; and while I have chosentoillus trate the manner in which the forward region of the instrument may be made more flexible: than the balance, it will be understood that other. relative fiexibilities may be produced, depending upon particular requirements.

In general it will be understood that thedetalls herein described and illustrated to explain the. general nature and objective of the invention. may readily be modified by those skilled in the. art without departing from the spirit and-,SQOI-lfi. of the invention as expressed in the appended. claims.

Having thus described my inventionand illus trated its use, what I claim as new and desire:

to secure by Letters Patent is:

1. In an elongated flexible catheter-type 1nstrument, an initially limp fabric base ,impreg. natecl with a flexible stiffening medium. and: coated with a flexible varnish, the varnishwhlch. coats one region of said base being of appreciably greater flexibility than that which coats a longie tudinally-adjacent region thereof, the fiexibilities. of the corresponding sections of the instrument. being correspondingly affected.

2. In an elongated flexible catheter-type .inestrument, an initially limp fabric base impregnated with a flexible stiffening medium and. coated with a flexible cured varnish, the varnish which coats one region of said base being cured, to a lesser extent than that which coats alongltudinally-adjacent region thereof, the lessercured coating being of appreciably greater fiexibility than the other and the flexibilitiesofithm corresponding sections of the instrument being. correspondingly affected.

LOUIS H. KRIPPENDQRE.

REFERENCES CITED The following references are of record ln-the file of this patent:

UNITED STATES PATENTS Number Name Date 757,877 Bosch .Apr..19, 191).. ,776,879 Baekeland Sept. .30, 193.0. 2,437,542 Krippendorf Mar- 9,1958.

Images