US 3204634 A
Description (OCR text may contain errors)
Sept. 7, 1965 w. R. KOEHN SURGICAL CATHETER 2 Sheets-Sheet 1 Original Filed Jan. 15, 1961 FIG. 3
Sept. 7, 1965 w. R. KOEHN SURGICAL CATHETER 2 sheets sheet 2 Original Filed Jan. 13, 1961 /2 FIG. /0
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United States Patent 3,264,634 SURGIQAL CATHETER Wilbur R. Koehn, Sherwood Drive, Sands Point, N.Y. Original application Jan. 13, 1961, Ser. No. 82,534. Di-
vided and this application Feb. '5, 1964, Ser. No.
Claims. (Cl. 128214) This application is a continuation-in-part of prior ap lication Serial No. 690,709, filed October 17, 1957, now Patent No. 3,030,953, issued April 24, 1962, and a division of prior application Serial No. 82,534, filed January 13, 1961, now abandoned.
The present invention relates to surgical catheters and more particularly to a method of fabricating a catheter directly on a needle and the resulting combined needle and catheter which facilitates the insertion of the catheter into a body cavity of a patient.
It is the usual practice in blood transfusions intravenous feedings, or when fluids are to be withdrawn from the human body to attach a hollow needle to an end of a tube and insert the needle into a vein or other body cavity. The fluid then flows from a source through the tube and hollow needle into the body when fluids are to be delivered thereto, or from the body through the needle and tube when fluids are to be withdrawn. Repeated punctures of veins with metal needles tend to cause Venus thromboses and subcutaneous hematomas. To avoid this result the metal needle is sometimes left in the body. However, the metal needle is apt to cause an infection and the part of the body where the needle is inserted must be immobilized with considerable discomfort to the patient. This is especially true when the needle is inserted into a vein as, for example, in the arm where relative movement might cause a puncturing of the vein and produce additonal trauma. To prevent such relative movement the arm is usually strapped in a fixed position.
Obviously, it is desirable to insert the end of a relatively soft, flexible catheter into the body cavity, in place of a metal needle, to eliminate the necessity of immobilizing the arm or other portion of the body of the patient and the resulting discomfort.
One of the objects of the present invention is to provide an improved method of fabricating a catheter directly on the needle used to insert the end of the catheter in a body cavity.
Another object is provide an improved needle and catheter in a self-contained sterile unit which facilitates the insertion of the end of the catheter into a body cavity and the removal of the needle therefrom.
Still another object is to provide an improved catheter and needle unit which is of relatively simple and compact construction, adapted for economical manufacture as a disposable unit and one which is reliable in operation for inserting the end of a plastic catheter into a body cavity.
These and other objects will become more apparent from the following description and drawings in which like reference characters denote like parts throughout several views. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not a definition of the limits of the invention, reference being had for this purpose to the appended claims.
In the drawings:
FIGURE 1 is a side elevational view of a combined catheter and needle unit made in accordance with the method of the present invention;
FIGURE la is an enlarged View of the beveled end of the needle and catheter to show the rounded contour of the end of the catheter;
FIGURE 2 is a view illustrating one method of dipping a needle in a liquid containing a plastic at an angle to the surface of the liquid to coat the needle with plastic from adjacent its pointed end;
FIGURE 3 is a view similar to FIGURE 2 showing an alternate method of moving the needle in a bath of the liquid to produce a plastic coating thereon with an end conforming generally with the beveled end of the needle.
FIGURE 4 shows the coated needle hung vertically from its pointed end to cause the liquid plastic to fiow by gravity and produce a coating having a thin rounded edge adjacent the pointed end of the needle and of progressively increasing thickness from its pointed end;
FIGURE 5 is a view similar to FIGURE 4 showing the coating of plastic cut around the periphery of the handle or hub of the needle to form the catheter and a cap applied over the needle and catheter;
FIGURE 6 is a side elevational view similar to FIG- URE 5 showing the cap removed and the cut end of the plastic coating stripped from the handle to prepare it for use;
FIGURE 7 illustrates the manner of inserting the end of the needle and catheter assembly into a body cavity;
FIGURE 8 is a view similar to FIGURE 7 showing the manner in which the needle is withdrawn from the catheter;
FIGURE 9 shows the tapered fitting at the end of the catheter adapted for connection to a fitting on a tube for supplying or removing fluids to or from the body;
FIGURE 10 is a view similar to FIGURE 9 illustrating a removable plug which may be inserted in the catheter to stop the flow of fluid therethrough; and
FIGURE 11 is an enlarged fragmentary elevational view of the forward end of the surgical catheter with certain parts broken away, removed and sectioned.
In accordance with the method of the present invention, a catheter tube 2 of a plastic resin is fabricated directly on the needle 3 with which it is used whereby the needle constitutes a mandrel to form the inside of the catheter to the desired shape. Surprisingly, such a plastic catheter 2 formed directly on the needle 3 can be easily and quickly removed, after the pointed end of the needle and adjacent end of the catheter have been inserted into the body cavity, by merely withdrawing the needle with one hand while the catheter is held by the other hand.
In accordance with the present invention, a hollow needle 3 is provided having a beveled cutting edge at one end 4 and a handle or hub 5 at the opposite end. Needle 3 must have a smooth peripheral surface which may 'be of the same diameter throughout its length, or tapered outwardly from the pointed end 3, but must not taper inwardly or have any recessed areas rearwardly of the pointed end. The hollow needle 3 may be formed in a conventional way by drawing a seamless tube of, for example, stainless steel through a forming die and the end 4 pointed by grinding it on a bias to provide a sharp cutting edge extending rearwardly around the entire periphery of the end of the needle. The handle 5 is also hollow and surrounds the shank of the needle adjacent its rearward end. Thus, when the pointed end 3 of the needle is inserted into a vein, blood will flow through the needle and hollow handle. The handle 5 may be made of any suitable chemically inert material which will withstand the temperature required to cure the plastic catheter. For example, the handle may be composed of Teflon or nylon or any other chemically inert plastic or may be composed of metal. As shown in the drawings, the exterior of the handle 5 has a conical tapered portion 6 adjacent the needle 3 and a cylindrical portion 7 projecting rearwardly from the conical portion 6. The interior of the outer end of handle 5 has a conical tapered portion 8 of a shape corresponding to the shape of the portion 6.
The tapered portions 6 and S constitute standard Luer fittings and the fitting 8 adapts the handle 7 to be mounted on a conventional syringe for holding the needle and catheter.
The catheter 2 may be made from any suitable chemically inert and non-toxic plastic resin which is stiff enough to follow the pointed end 4 of the needle 3 through human tissue and flexible enough to conform to the contour of body cavities into which it is inserted. For example, the catheter 2 may be made from plastisols or organisols of vinyl resin or polyethylene resin in solution or suspension. As used herein the term plastisols comprise particulate suspensions of the plastic resin in a liquid plasticizer; and the term organisols comprise plastisols containing a thinner. For example, if the catheter 2 is to be made of vinyl resin, the resin in a fine, granular form is dispersed in a suitable plasticizer, such as di-octyl phthalate, which may be further diluted to a desired consistency by the addition of a suitable thinner, such as naptha or other volatile liquid solvent for the plasticizer which will not produce solvation of the vinyl particles. When the catheter is to be made of polyethylene, the resin may be dissolved in any suitable hot solvent, such as, for example, one of a group including xylene, toluene or amyl acetate at a temperature above 140 F. Instead of a hot solution, the granular polyethylene resin may be dispersed in a cold suspension of, for example, Xylene and the needle 3 heated above the temperature of 140 F. The heated needle then dissolves the resin granules and produces a thin uniform coating on the needle and simultaneously evaporates the solvent to leave a continuous film of the pure plastic. While'two examples of vinyl and polyethylene resins have been given, it will be understood that dispersions, suspensions or solutions of any other suitable plastic resin of a consistency for dipping may be used.
The plastisol, organisol, suspension or solution of the plastic material is placed in a tank 10, as shown in FIG- URES 2 and 3, and maintained at the proper temperature and/ or consistency to produce a liquid coating of the desired thickness when the needle 3 is dipped therein. When dipping, the entire needle 3 is immersed in the solution to a depth so that all except the pointed end 4 is coated. When the needle 3 is coated in the manner illustrated in FIGURE 2, the needle is held at an angle so that the plane of the flat beveled end 4 is parallel to the surface of the plastic solution in the tank 10. This may be accomplished by mounting the needle or needles 3 to be coated on a Wire or wires having an angular end extending into the hollow ends of the needles to support them at the proper angle. The needle or needles 3 are immersed to a depth at which the level of the liquid containing the plastic material is closely adjacent and parallel to the flat pointed end 4, as shown in FIGURE 2. After dipping, the needles 3 are withdrawn from the tank with a coating of the plastic thereon.
In accordance with a modified method of coating the needle 3 as shown in FIGURE 3, the needle is immersed vertically so that only the pointed end 4 projects above the surface of the solution in the tank 10 and the needle moved bodily in a direction at right angles to the point of the needle. The horizontal movement of the needle through the viscous material causes it to pile up in front of the needle in a wave to coat the needle in a plane roughly parallel .to its beveled end 4.
The needle 3 coated with a film of the liquid plastic is then hung from its pointed end 4. In the case of organisols the coating may be heated at a low temperature to drive off the thinning solvent. During the hanging operation the coating tends to run down the sides of the needle and handle 5 by gravity and produces a layer of gradually increasing thickness from adjacent the pointed end of the needle 3 to the lower end of the handle 5. Following the hanging and dripping operations the entire assembly, as illustrated in FIGURE 4, is subjected to a temperatpre which will cure the liquid plastic coating and form a stable plastic layer. For example, when the needle is coated with a plastisol or organisol of a vinyl resin, it is heated to 350 F. for a period of approximately four minutes. In addition to curing the plastic, the 350 F. temperature sterilizes the needle and plastic coating thereon. When the needle 3 and handle 5 are preheated and dipped in a cold suspension of polyethylene, for example, the heated needle causes the particles of plastic adjacent the needle to go into a solution which gel at the surface of the needle. The further heating of the gelled solution on the needle then produces a complete solvation of the polyethylene resin particles which are fused in a solid body of the clear plastic. Furthermore, the heat drives out the solvent in the coating.
After the needle 3 has been dipped to form the coating and then heated to cure the plastic, the enclosing coating is cut on a circular line around the periphery of the handle 5, to form the catheter 2. A cap 9 is then applied over the needle 3 and catheter 2 thereon with the end extending beyond the circular cut and engaging the plastic sleeve 11 beyond the cut to provide a sealed joint. Thus, cap 9 provides a hermetically sealed sterile unit.
Preferably, the needle 3 is twice dipped in liquids containing plastics and at diflierent consistencies to form a catheter 2 having a relatively thin and flexible tube and a thicker and stifler conical end 12. For purposes of description, let it be assumed that the catheter 2 is to be made of a vinyl resin. The entire needle 3, except the pointed end, is first dipped into an organisol of the vinyl resin comprising about 50% plasticizer and suflicient thinner to produce a coating, when cured, having a thickness of from .005 inch to .008 inch at its end adjacent the pointed end of the needle and a thickness of from .010 inch to .013 inch at the conical section 6. The vinyl coating is then cured at a temperature of 350 F. for approximately four minutes. The handle end 5 of the needle 3, only, is then redipped in a plastisol of the vinyl resin comprising 35% plasticizer, but only to where the needle and handle join each other. The more viscous plastisol then deposits a thicker layer of the plastic on the tapered portion 6 of the handle 5. The second coating of vinyl resin permeates the underlying coating and the product is again cured at a temperature of 350 F. for another period of approximately four minutes. The resulting catheter has a relatively soft, flexible tube extending from adjacent the pointed end of the needle to one handle 5 and a harder and thicker conical end portion 12. When other plastic resins are used, the liquids containing the plastics are so formed as to produce a thin coating on the needle shank and a thicker and stiffer coating of the conical portion 6 of the handle 5.
The pointed end of the combined catheter 2 and needle 3 then is inserted through the tissue of the human body into a cavity, such as a vein, as illustrated diagrammatically by the reference character V. Due to the close fit of the forward end of the catheter 2 with the periphery of the needle 3 on which it was formed and the thinness of the end of the catheter 2, due to flow of the plastisol along the needle, the end of the catheter follows the pointed end of the needle into the body cavity. When the ends of the needle and catheter have entered a body cavity, such as a vein V blood will flow through the hollow needle 3 and handle 5 to indicate that the end of the catheter is properly position, as illustrated in FIG- URE 7. The rearward end of the catheter 2 is then held between the forefinger and thumb of one hand while the handle 5 of the needle 3 is held between the forefinger and thumb of the other hand and withdrawn relative to the catheter 2, as illustrated in FIGURE 8. Due to the method of making and the tapered thickness of the wall of the catheter 2, the catheter 2 will retain its original shape without buckling while the needle 3 is being with drawn. As a result, the end of the catheter 2 remains in the body cavity as the end of the needle 3 is withdrawn.
When the needle 3 is withdrawn, the catheter 2 is sufiiciently flexible to follow the contour of the part in which it has been inserted without cutting or otherwise damaging the surrounding tissue.
As stated above, the needle 3 and handle 5 constitute a mandrel for forming the shape of the inside of the catheter 2. Thus, the internal taper 9 at the outer end of handle 5 provides a Luer-type fitting for attaching the needle 3 to a standard syringe for inserting the catheter 2, and the thicker wall portion 12 of the catheter surrounding the conically tapered portion 6 of the handle 5 produces a similar tapered fitting into which a tapered plug 13 may be inserted after the needle 3 has been withdrawn, see FIGURE 9, to connect the catheter to an extension tube 14. Fluids then may be supplied to or withdrawn through the catheter 2. When it is desired to intermittently use the catheter 2 as, for example, to give intravenous feeding through the catheter 2 at intervals of time over a long period, the plug 13 with attached extension tube 14 is used alternately with a rod type plug or stopper 15 for preventing a reverse flow between periods of use.
The rod type plug 15 may be composed of a suitable plastic and coated with an anti-coagulant substance, such as heperin, to prevent blood from clotting or from sticking to the plug. The plug 15 also may include a relatively large amount of a bactericide, such as organic compounds of tin and quaternary ammonium compounds, which are molded therein and have a bactericidal effect even when located at a distance from the organism.
In addition to providing a method of fabricating a catheter, the present invention provides a novel form of combined needle 3 and catheter 2. As shown in FIGURES 1 and 5 to 8, inclusive, the catheter 2 has a beveled end 16 at least roughly parallel to the flat beveled end 4 of the needle 3, and of an extremely smooth, thin and rounded contour 17 from the outer periphery of the needle shank 3 to the outer periphery of the catheter 2. In addition, the catheter 2 has a wall of gradually increasing thickness from the rounded end 17 to its opposite end. Furthermore, the catheter 2 has a standard Luer fitting 12 of conical shape formed as an integral part of the catheter and of greater wall thickness than the tube section. In addition, the catheter 2 has a close, perfect fit on the outer periphery of the needle 3 because of the method by which it is made.
It will now be observed that the present invention provides an improved method of making a catheter directly on the needle with which it is used to insert the catheter in a body cavity. It will also be observed that the present invention provides an improved needle and a catheter in a self-contained sterile unit which facilitates the insertion of the end of the catheter into a body cavity and the removal of the needle therefrom. It will still further be observed that the present invention provides an improved catheter and needle unit which is of relatively simple and compact construction, adapted for economical manufacture and one which is reliable in operation for inserting the end of a plastic catheter into a body cavity.
While alternate steps of a method and a single form of combined catheter and needle are herein described and illustrated, it will be understood, that the steps of the method and form of the resulting product may be changed and modified within the scope of the present invention.
Therefore, without limitation in this respect, the invention is defined by the following claims.
1. A surgical unit comprising a needle having a smooth continuous shank with one end beveled to provide a sharp cutting edge and a handle at the other end, a catherer concentrically engaging the outer surface of the shank of the needle at the rear of the pointed end, said catheter having a tubular wall and an end adjacent the pointed end of the needle the wall of said catheter closely fitting the shank of the needle at the rear of the pointed end and substantially the entire length of the catheter wall being of progressively increasing thickness from its end adjacent the pointed end of the needle toward the handle, and the end of the catheter adjacent the pointed end of the needle being thin and having rounded edges from the periphery of the needle to the periphery of the catheter whereby to adapt the end of the catheter to follow the sharp pointed end of the needle into a body cavity and permit the needle to be withdrawn by relatively sliding the needle and catheter.
2. A surgical unit in accordance with claim 1 in which the catheter concentrically engages the outer surface of the shank and handle of the needle and is formed of a substantially integral one piece unit of coated resinous material.
3. A surgical unit in accordance with claim 1 in which the end of the catheter is beveled at an angle roughly parallel to the beveled end of the needle.
4. A surgical unit in accordance with claim 1 in which the portion of the handle adjacent the needle is conical to provide a tapered fitting at the end of the catheter.
5. Surgical apparatus for delivering fluids to or withdrawing fluids from the human body comprising, a penetrating element with a bevel pointed end and a shank projecting rearwardly therefrom and a hub coupled with the rear of the shank, and an integral plastic catheter tube having a shank portion and hub portion integral therewith surrounding the shank and hub, respectively, of the penetrating element and having an end disposed in a plane at an angle to the axis of the penetrating element and positioned adjacent the pointed end, said catheter tube having a tapered penetrating end positioned adjacent the pointed end of the penetrating element, said penetrating element and tube being cooperable to cause the tube to follow said pointed end through skin and tissue to locate the tapered end of the tube at the desired position in the body, the tapered end of the catheter tube and the pointed end of the penetrating element being relatively displaceable to permit the penetrating element to be Withdrawn through the catheter tube.
References Cited by the Examiner UNITED STATES PATENTS 3,017,884 1/62 Doherty et a1.
3,055,361 9/62 Ballard.
3,064,651 11/62 Henderson 128221 3,082,769 3/63 Palmer 128-221 3,094,124 6/63 Birtwell 128-348 3,097,646 7/63 Scislowicz.
OTHER REFERENCES Massa et al.: A Plastic Needle, Proc. Staff Meeting, Mayo Clinic, 25: 413-15, July 5, 1950.
RICHARD A. GAUDET, Primary Examiner.