Intravascular Catheters

Abstract

Intravascular catheters of improved vascular insertability are made with a plastic catheter snugly encircling a trocar. The catheter is tapered at the distal end which is blended with the exterior wall of the trocar, e.g., by being shrunk into a groove in the trocar wall. This structure permits smooth intravasculary entry of the catheter and reduces occurrence of phlebitis in the use of intravascular catheters.

Description

BACKGROUND OF THE INVENTION

Intravascular catheters are required in the variety of medical and clinical procedures for the administration of fluids of various types into the vascular system of a patient or for the removal of body fluids from the vascular system. The intravascular catheter is placed in the vascular channel by puncturing a hole through the skin and vascular channel wall and installing the intravascular catheter. Assemblies for accomplishing this comprising a trocar and an encircling catheter have been developed (see U.S. Pat. No. 3,313,299).

Numerous procedures performed on a patient using intravascular catheters require the catheters to remain positioned within the vascular channel for extended periods of time. Use of available intravascular catheters has resulted in frequent occurrence of phlebitis and there is a need for improvements in these medical devices which will serve to migitate or entirely eliminate phlebitis resulting from the use of intravascular catheters.

Another difficulty connected with use of intravascular catheters is irritation or damaging of the vascular wall upon insertion of the catheter. This can occur from the action of the tip of the catheter as it is forced through the vascular wall if it surrounds the stylet or trocar used to puncture the wall for the insertion.

OBJECTS

A principal object of this invention is the provision of new improvements in the construction of intravascular catheters. Further objects include the provision of:

1. Intravascular catheter assemblies of improved form which reduce occurrence of phlebitis in the use of intravascular catheters.

2. A new combination of trocar adapted to install an intravascular catheter within a vascular channel and an encircling catheter involving complementary structural features which aid in obtaining correct, noninjurious placement of the intravascular catheter and mitigation or elimination of inflammation of the vascular wall and phlebitis which may occur from intravascular placement of the catheter.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description, while indicating preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. It should also be understood the foregoing abstract of the disclosure is for the purpose of providing a nonlegal brief statement to serve as a searching-scanning tool for scientists, engineers and researchers and is not intended to limit the scope of the invention as disclosed herein nor is it intended it should be used in interpreting or in any way limiting the scope or fair meaning of the appended claims.

SUMMARY OF THE INVENTION

These objects are accomplished according to the present invention by forming an intravascular catheter assembly to include a trocar and a plastic catheter snugly encircling the trocar, with the catheter being tapered at the distal end, the tapered end in turn, being blended to the exterior wall of the trocar. The catheter tip which is formed in this manner presents a smooth-rounded orifice free of sharp edges or the like which can inflame the vascular channel wall when the catheter is installed within the vascular channel. Furthermore, the geometry of the new catheter assemblies ensures a minimum of irritation or injury to the vascular wall during installation of the catheter and subsequent withdrawal of the trocar. Several constructions are used to obtain the necessary blending of the catheter to the trocar exterior wall.

In a preferred embodiment, the new intravascular catheter assemblies comprise:

a. a tubular trocar adapted to pierce a vascular wall to create an opening therethrough,

b. said trocar having a sharp-angled tip and a longitudinal tubular body of substantially uniform diameter extending rearwardly of said tip,

c. a concave groove in said tubular body adjacent said tip,

d. a plastic catheter substantially uniform lumen throughout its length approximately equal to the OD of said tubular body, the catheter being fitted over the trocar snugly encircling it,

e. a distal end portion on the catheter which is tapered toward the catheter tip, and

f. a convex constriction extending radially inwardly on said catheter tip, the convexity of the constriction being complementary to the concavity of said groove,

g. said constriction being fitted into said groove in said assembly.

In another preferred embodiment, the new intravascular catheter assemblies, instead of having a convex constriction on the catheter tip to complement the trocar groove, has the catheter tip shrunk into a groove or undercut in the exterior wall of the trocar.

In yet another preferred embodiment, no groove or undercut is made in the trocar exterior wall. Instead, the wall is roughened, e.g., by sandblasting, or scored, e.g., by circumferential cutting or milling, and the tapered tip of the catheter is shrunk into the roughened or scored trocar wall.

BRIEF DESCRIPTION OF THE DRAWING

A more complete understanding of the new intravascular catheters of this invention and their method of use may be had by reference to the accompanying drawing in which:

FIG. 1 is a plan view of an intravascular catheter assembly constructed in accordance with the invention.

FIG. 2 is an enlarged fragmentary view partly in section showing the distal end portion of the catheter assembly of FIG. 1.

FIG. 3 is an enlarged fragmentary view partly in section related to FIG. 2 but illustrating the trocar of the catheter assembly being withdrawn from the intravascular catheter.

FIG. 4 is a plan view of another embodiment of an intravascular catheter assembly in accordance with the invention.

FIG. 5 is a plan view of the trocar unit of the assembly shown in FIG. 4.

FIG. 6 is a plan view of the catheter of the assembly shown in FIG. 4 prior to association with the trocar shown in FIG. 5.

FIG. 7 is an enlarged fragmentary sectional side view of the distal end of the catheter of FIG. 6.

FIG. 8 is an enlarged fragmentary side view, partially in section, of the distal end portion of the catheter assembly shown in FIG. 4.

FIG. 9 is an enlarged fragmentary side view, partially in section, of another embodiment of the new catheter assemblies.

FIG. 10 is an enlarged fragmentary side view, partially in section, of another embodiment of the new catheter assemblies.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring in detail to the drawings, the intravascular catheter assembly 2 comprises a trocar 4 and a plastic catheter 6.

The trocar 4 has a sharp tip 8 which angles from the point 10 to the tip base 12 suitably ground or otherwise formed upon the end of the longitudinal tubular body 14. The opposite end of the trocar comprises end means 16 which can be used to receive a cap or plug to close the longitudinal bore 18 of the trocar against flow of fluid therethrough. The end means 16 may be a metal hub formed with a tapered female opening 19, a molded plastic unit or the like that is suitably attached such as by welding, press fit, cementing or the like to the rigid longitudinal tubular body 14 of the trocar. Advantageously, the trocar 14 is a standard type of stainless steel hypodermic needle with the conventional syringe fitting metal hub 16 into which a groove 20 has been formed.

The concave groove 20 is formed in the tubular body 14 adjacent the tip 8 of the trocar 4. Advantageously, the base of the groove 20 is represented by the arc of a circle permitting smooth manipulation of the plastic catheter portion of the assembly as described hereinafter. However, the groove 20 may assume other configurations. The distance of the groove 20 from the trocar point 10 may be varied, but most satisfactory results in vascular wall penetration and insertion are obtained if the distance from the trocar tip base 12 to the groove 20 is less than the distance from the base 12 to the trocar tip 10. Further, the trocar tips of the preferred angle a, i.e., less than 45.degree., the distance from the base 12 of the angled tip 8 to the groove 20 is greater than the outside diameter of the tubular body 14.

The plastic catheter 6 comprises a distal end portion 22 which tapers from the catheter tip 24 rearwardly to a base 26 at which the outside diameter of the catheter remains substantially constant along the central body portion 28 until the proximal end section 30 of the plastic catheter is reached. The proximal end portion 30 may comprise a tapered opening metal or plastic hub 32 and a sleeve 34 which are suitably fastened such as by heat fusion or cementing to the body portion 28 of the catheter. Alternatively, the proximal end portion 30 may constitute a funnel end connector formed integrally with the plastic catheter body portion 28 or the hub 32 may be molded plastic to which the body portion is cemented or welded by a butt or shiplap joint.

The extent of tapering of the catheter tip in terms of taper angle or distance may be varied. However, most satisfactory results in use of the catheter assemblies are obtained if, in conjunction with trocar tip dimension relationships as discussed above, the distance from the tip 24 of the catheter to the base 26 of the tip tapering is greater than the diameter of the catheter lumen 34.

The catheter tip 24 includes an integral convex constriction 36 which extends radially inward on the catheter tip. The convexity of this constriction 36 is preferably complementary to the concavity of the groove 20 so that there is a mating of the constriction 36 with the groove 20 when the catheter assembly is arranged as shown in FIGS. 1 and 2 in preparation for intravascular positioning in a patient. This mating relationship between the trocar 4 and the catheter 6 permits smooth intravascular entry of the catheter upon piercing of the vascular wall by the trocar and catheter assembly. Accordingly, such construction serves to reduce phlebitis, subcutaneous hematomas or similar undesired occurrences which may produce discomfort or other undesired reactions to the patient.

Although the trocar 4 is advantageously made entirely of metal, or with at least the tubular body and tip being formed of metal, the trocar or stylet can be formed of suitable rigid plastic material. Also, although the plastic catheter 6, and especially the proximal end portion 22 and main body portion 28 are formed of plasticized polyvinyl chloride, other flexible or semirigid plastic materials may be used for this purpose. The proximal end portion of the catheter 6 which comprises the connector means for connecting the catheter to a fluid conveying tube if required in the use of the device, may be formed integrally as an enlarged funnel end from the same plastic material used to construct the tubular body portion 28 or of different plastic material as well as metal. The construction of the catheter tip portion with the tapered section 22 and the convex constriction 36 may be attained in several ways. For example, the catheter 6 may be entirely molded such as injection molding from suitable plastic material. Alternatively, the main body portion 28 may be cut from extruded tubing, the tapering 22 may be ground or cut onto the end of the tube and the rounded tip 24 and convex constriction 36 may be attained by heat and pressure molding, by controlled flame polishing or other suitable plastic fabrication techniques known to the art.

Instead of the arrangement of a complementary bead 36 on the catheter, alternative constructions may be used to obtain the required blending of the catheter tip to the trocar exterior wall. One of these is illustrated in FIGS. 4-8. In this embodiment, instead of a semicircular groove in the trocar 40, which may be a heavy wall hypodermic needle or a solid stylet, an undercut 42 is ground or milled into the exterior wall 44 adjacent the angled tip 46. The catheter 48, in turn, is formed of a plastic cannula 50 with an inside diameter or lumen 52 of proper size to make a snug slide fit on the wall 44 of the trocar 40. A hub 54 of molded plastic with a female Luer tapered proximal opening 56 is fixed to the cannula 50 such as by solvent or heat welding, cementing or mechanically locked in the forward collar 58 of the hub.

The distal end 60 of the cannula 50 is molded or ground to a rounded or tapered tip 62 before the catheter 48 is assembled on the trocar 40. Just before such assembly, the distal end portion 60 of the cannula 50 is soaked in a volatile organic liquid which dilates the plastic of which the cannula is formed and leaches out plasticizer. For example, the cannula may be formed of polyvinyl chloride plasticized with dioctyl phthalate and ethyl acetate may be used as the leaching liquid. While the cannula tip is still in the dilated condition, it is slid over the trocar into position as shown in FIGS. 4 and 8. The plastic shrinks as the organic liquid evaporates. The resulting configuration of cannula tip 62 and trocar undercut 42 after the plastic is shrunk is shown in FIG. 8. The portion of the plastic which has been soaked in the organic solvent acquires a harder Durometer in the process because of leaching of plasticizer. This increase in rigidity helps the cannula tip to hold better in the undercut 42. This, in turn, helps to prevent "push back" of the cannula as the assembly is inserted through the vascular wall of a patient. Also, the resulting geometry of the shrunk cannula tip and trocar end, permits the catheter insertion to be accomplished without venous thrombosis.

Another way of blending the catheter distal end tip to the trocar wall is illustrated in FIG. 9. In this embodiment, the exterior wall 64 of the trocar 66 has the distal end portion 68 roughened, such as by sandblasting, centerless grinding, chemical etching, electrolytic etching or the like. The distal end portion 70, with the tapered tip 72 of the cannula 74 is dilated with volatile organic liquid and then placed upon the trocar so the dilated portion 70 overlays the roughened trocar surface 68. When the dilating liquid evaporates, the cannula end portion 70 and tip 72 shrink around the trocar and create a firm blending of the cannula tip to the trocar. This creates good holding and prevents push back of the flexible cannula on the trocar which the skin and vascular wall of the patient are pierced upon insertion of the catheter assembly.

Yet another modification is shown in FIG. 10. Here, the wall 76 of the trocar 78 is scored with a plurality of shallow circumferential grooves 80 by milling, cutting, pressing or the like. The cannula distal end portion 82 and tapered tip 84 are dilated with volatile organic liquid before assembly of the parts. Upon evaporation of the liquid, a blending of the distal end with the trocar wall is obtained simultaneously with an increase in rigidity of the cannula in the end portion.

In any of the embodiments described, the distal tip or any other portions of the catheters may be provided with X-ray opaque features to permit the position of the catheter or parts thereof, should they break off in use, to be determined in the body of the patient by X-ray observation, e.g., with photographic plate of fluoroscope.

In accordance with practice which is now standard in the marketing of intravascular catheters, the new catheter assemblies as described and shown will preferably be placed in a functional container or package and suitably sterilized such as exposure to ethylene oxide vapors, gamma radiations or the like. In such a packaged unit, the catheter assembly will preferably include a small plastic plug (not shown) inserted into the proximal end opening of the trocar connector to maintain sterility within the trocar bore and seal the bore against egress of blood or other vascular fluids until the exact moment for opening of the trocar bore as desired by the physician, nurse or other party using the catheter assembly upon a patient.

The use of the new catheter assemblies as described above follows general practice which has been developed for use of related devices known heretofore. With reference to the embodiment of FIG. 1, the sharpened end 8 of the trocar 4 is used to pierce the vascular wall of a patient to create an opening therethrough. As the assembly penetrates the vascular wall, the plastic catheter 6 enters the vascular channel along with the trocar 4. At this point, if special procedures require it, the vascular fluid may be withdrawn through the trocar bore 18 out the connector end 16, or fluids may be introduced through the same channel. However, normal use of the catheter assembly involves withdrawing the trocar 4 from the assembly. This is attained by holding the plastic catheter 6 immobile relative to the patient by grasping the catheter connector end 32 and pulling the trocar out through the catheter 6 by pulling on the trocar connector end 16. At this point, an infusion tube (not shown) or other suitable device is connected to the catheter at the connector end 32 and any necessary infusion flow into the vascular channel into which the catheter 6 has been placed may begin. Adhesive tape, or similar arrangements known to the art may be used to ensure retention of the catheter 6 in the patient safeguarding against possible accidental dislodgment through normal movement of the patient.

Not only does the unique structural arrangement between the blended trocar and special ended catheter as described provide for smooth intravascular entry of the catheter, but the rounded tip and hardened arrangement on the end of the catheter serves to reduce irritation to the internal walls of the vascular channel. This in turn serves to substantially reduce occurrence of phlebitis in patients in which intravascular catheters have been positioned.

Claims

The embodiments of the invention in which an exclusive property or right is claimed are defined as follows:

1. An intravascular catheter assembly comprising:

a. a trocar adapted to pierce a vascular wall to create an opening therethrough,

b. said trocar having a sharp-angled tip and a longitudinal tubular body of substantially uniform diameter extending rearwardly of said tip,

c. an arcuate concave groove in the exterior wall of said trocar adjacent said angled tip,

d. a plastic catheter having a distal end tip and a substantially uniform lumen throughout its length approximately equal to the OD of said tubular body extending proximally of said tip, the catheter being fitted over the trocar snugly encircling it,

e. the exterior wall of the distal end portion of the catheter being tapered toward said catheter tip, said tip being smoothly rounded, and

f. said tip having a smoothly rounded convex constriction that extends radially inwardly, said constriction filling said concave groove in said trocar wall.