Safety Catheter Placement Assembly

Abstract

Safe placement of a flexible catheter is enabled by (a) novel positive connection of the separable parts and (b) by unique indicating means. A syringe has a functionally integral needle and provides a convenient handle to which the catheter sheathing the needle is releaseably attached by a smoothly operating twist lock against inadvertent separation during venipuncture and catheter placement manipulation. After venipuncture catheter placement free from danger of damaging a blood vessel lumen wall is effected by advancement of the catheter tip into sheathed relation to the leading end of the needle serving as a stiffener to facilitate advance of the catheter within the lumen. Cooperating means respective associated with the catheter and with the needle and remaining exposed after the catheter and sheathed needle have entered the lumen provide indication of the relative longitudinal position of the catheter end and needle tip, and may also helpfully indicate whether the catheter and needle are safely interconnected against unintentional longitudinal displacement as well as a condition of relative freedom for separation when it is desired to withdraw the needle from the catheter.

Description

This invention relates to catheter placement assemblies, and is more particularly concerned with a new and improved assembly enabling safe handling and placement with assurance against separation of the parts and safe utilization of the needle as a stiffener for the catheter while advancing it in a blood vessel lumen.

A major problem in catheter placement has been the ever-present liability of separation of the parts during the placement maneuver, especially under difficult conditions of tissue density, involuntary or spasmodic movements, resistive reaction by the patient, and the like. At the least, unintentional separation may result in blood spillage. All too often such unintentional separation results in injury or damage to the patient or the attending technician or physician, or both as a result of recovery or retrieval reaction on his part. It is well known, for example, that such personnel frequently contract hepatitis by exposure to an infected patient's blood thus spilled.

Another serious problem that has prevailed in catheter placement involves further puncturing of the vascular lumen as the needle is advanced therein after venipuncture in assisting advance of the catheter, especially under conditions where venous collapse or constriction renders it difficult or virtually impossible to advance the flexible catheter unassisted by the relatively stiffer needle. As heretofore constructed, catheter placement units of the type disclosed herein have required either that the needle point remain in lead relation to the lead end of the catheter or that the needle be removed from the catheter before or during advancement of the catheter in the lumen.

It is to the alleviation and elimination of the foregoing and other disadvantages, defects, inefficiencies, shortcomings and problems in prior structures and methods that the present invention is directed.

An important object of the invention is to provide a new and improved means for catheter placement.

Another object of the invention is to provide a new and improved catheter placement assembly in which a catheter and needle are positively but separably connected, eliminating reliance on prior axial press fits while nevertheless enabling easy separation of the needle and catheter as desired.

A further object of the invention is to provide a new and improved catheter placement device enabling quick and easy advance of the catheter in a blood vessel lumen, taking full advantage of the needle stiffness in maneuvering the catheter but with complete safety and freedom from danger of punctures from the fully sheathed needle point.

Still another object of the invention is to provide a new and improved catheter placement assembly having an advantageous relationship of the needle to the catheter enabling accurate advancement of the catheter over the needle point in a manner to gain full reinforcing or stiffening value of the needle during catheter advance in a vascular lumen.

A yet further important object of the present invention is to provide new and improved indicating means to facilitate safe catheter placement.

It is also an object of the invention to provide a new and improved syringe equipped catheter placement unit in which the syringe serves as an efficient handle for catheter placement.

Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts embodied in the disclosure, and in which:

FIG. 1 is a fragmental longitudinal sectional view through a syringe-equipped catheter placement unit embodying features of the invention;

FIG. 2 is a similar fragmental longitudinal view showing the catheter partially advanced over the needle;

FIG. 3 is a similar fragmental longitudinal view showing the catheter disconnected for withdrawal of the needle;

FIG. 4 is an enlarged end elevational view of the catheter hub; and

FIG. 5 is a fragmentary longitudinal sectional detail view through a modified arrangement.

On reference to FIGS. 1-3, a safety catheter placement assembly embodying features of the invention includes a flexible catheter 10 having a leading end 11 which is desirably of tapered form for ease in entering a venipuncture produced by a needle 12 removably sheathed within the catheter and having a sharp, tapered point penetrating tip 13 projecting in advance of the leading end 11 to facilitate venipuncture.

Although the needle 12 might, if preferred, be a solid stylet, it is desirably a hollow hypodermic needle permanently attached at its end opposite to the tip 13 to a hub 14 integral with a base wall 15 of a hypodermic syringe barrel 17 at the opposite end of which is a lateral finger flange structure 18 and within which is reciprocably operable a piston 19 on the inner end of a plunger 20 having an outer end manipulating head flange 21. Within the syringe barrel 17 may be contained any preferred infusion material or medication to be injected subcutaneously or intravenously. In addition or alternatively, the syringe may be used to withdraw a blood sample. Further, the syringe serves as a convenient handle for catheter placement.

For operative association with the needle 12, the catheter 10 is provided with a permanent hub 22 on its end opposite to the leading end 11 and equipped for releasable but positively held connection with the hub structure of the needle to afford full assurance against unintentional relative displacement of the catheter and needle. To this end, the hub 22 has a tubular concentric attachment flange extension 23 which has a twist-lock connection with a complementary tubular concentric hub flange 24. In this instance both of the hub flanges 23 and 24 are cylindrical and telescopically interengageable wherein the flange 23 is received in assembly within the flange 24. A twist-lock connection between the flanges 23 and 24 is provided by internal substantially spaced spiral threads 25 on the flange 24 interengageable by a pair of diametrically opposite follower lugs 27 (FIG. 4) on and projecting radially from the free end portion of the flange 23 and of complementary pitch to the threads 25 to engage in threaded, twist-lock relation. Such a twist-lock connection is sometimes referred to as a Luer-Lok. As a result, by relative rotation of the needle hub structure and the catheter hub structure an interlocked or released relationship is easily and smoothly and quickly attainable without any axial pull or thrust or pressure required from the person manipulating the device. This entirely eliminates the disadvantages of prior arrangements wherein a simple axial frictional press fit has been relied upon in connecting the members so that unless extreme care is exercised during a separating maneuver, jerking reaction may result in damaging injury or at least discomfort to the patient.

Both the catheter 10 and the functionally integral needle 12 and syringe may be of the low cost disposable type. To this end the catheter 10 and its hub 22 are desirably constructed as a one-piece molding of suitable plastic material. While the needle 12 is of a suitable metal, its hub 14 and the associated syringe base and barrel parts are constructed as a one-piece plastic molding. Through this arrangement, the catheter remains permanently affixed to its hub and the needle 12 remains permanently affixed to its hub and thus to the syringe. Therefore the placement unit comprises, in effect, just two separable parts, namely the catheter and its unitary hub structure and the needle and its unitary hub structure, and since the hub structures are interlocked against axial pull-apart separation catheter placement manipulation of the assembly can be effected with fail-safe assurance against unintentional separation even under the most adverse conditions.

As the initial step in catheter placement, the catheter 10 and the needle 12 are related in the assembly with the needle point 13 projected in advance of the leading end 11 of the catheter and with the hub flange 23 bearing endwise against the syringe base wall 15 so that by manipulation utilizing the syringe, and more particularly the syringe barrel 17, as a handle the needle point 13 can be confidently driven in a venipuncture thrust until the tip and the leading end 11 have entered the desired blood vessel as shown more or less schematically in FIG. 1. Entry into the vein may be visibly signalled by blood passing through the hollow needle into the syringe barrel. Thereupon the catheter and needle are relatively longitudinally displaced by holding the syringe barrel 17 stationary and turning the catheter hub 22 to work the threads 25 and the lugs 27 to effect advance of the catheter hub and thus advance of the catheter relative to the needle until the tip 13 is fully encased within the leading end 11 of the catheter substantially as shown in FIG. 2. In this relationship, the needle tip 13 provides stiffening for the leading end portion of the catheter as does the remainder of the needle for the remainder of the catheter to enable further advance of the leading end 11 within the blood vessel lumen free from danger of damaging the lumen wall by the now sheathed tip 13. This greatly facilitates advancing of the needle-stiffened catheter within the blood vessel even though there may be collapse, stricture, blockage, branching, turning, or the like. Where medication is to be infused by way of the syringe or other device, it is often desirable to have the discharge end of the catheter as far as practicable away from the venipuncture. Where the catheter is to be left in position for any length of time for repeated testing or infusion or transfusion purposes it is desirable to have it thoroughly received with a substantial length in the blood vessel to avoid inadvertent displacement and to relieve the venipuncture from possible back pressure during infusion or transfusion.

In order to enable ready determination of the relative longitudinal position of the catheter end 11 and the needle tip 13 after they are concealed within a puncture, indicating means are provided cooperatively related to the catheter and the needle remote from the end and tip, and remaining exposed outside of the puncture. More particularly such indicating means are provided to facilitate advancement of the concealed end of the catheter into sheathing but supported position over the concealed needle point. To this end, the catheter hub flange 23 and the needle hub flange 24 are of ample length to enable partial relative separation to be effected to the extent of just covering the needle tip 13 by the leading end 11 of the catheter without releasing the twist-lock provided by the threads 25 and the lugs 27. When the separating movement has progressed to the extent of protectively sheathing the needle tip, indicating means on the hub extension flange 23 conveniently in the form of an indicator mark such as an annular groove 28 becomes exposed outside of the end of the needle hub flange 24 with the end of this flange serving as an indicating edge 29 (FIG. 2) cooperating with the indicating groove 28 to advise by sight or by feel that the desired sheathed but supporting, stiffening relationship of the needle tip to the catheter end has been attained. Until the indicator 28 is exposed at the edge 29, the technician or physician will know that the point of the tip 13 remains dangerously exposed beyond the leading end 11 of the catheter. When the indicator 28 is exposed, the assembly may be confidently manipulated using the syringe as a handle to continue placement of the catheter by advancing it in the lumen into which it has been projected.

For utmost gentleness in removal of the needle 12 from the catheter after placement of the catheter has been completed, additional indicating means are provided to satisfy the technician or physician that complete separation and release of the twist-lock has been effected before relative longitudinal separating force is applied to withdraw the needle from the catheter. Accordingly, a second indicating mark 30 conveniently comprising an annular groove in the outer perimeter of the hub flange 23 is located in spaced relation from the indicating groove 28 in the direction toward the free end of the flange and at a point which, when the catheter hub has been turned sufficiently to advance away from the needle hub until the mark 30 is exposed outside of the indicator edge 29, will assure that complete release of the lugs 27 from the threads 25 has been effected as shown in FIG. 3. Thereupon, withdrawal of the needle can proceed smoothly and without any jerkiness. Similarly, should it become desirable to reinsert the hypodermic needle into the catheter, the marks 29 and 30 will show when the needle tip has reached the area of the leading end of the catheter but will enable stopping the insertion short of projection of the point of the needle tip from the catheter end.

If preferred, the structure of FIG. 5 may be used, wherein the catheter hub flange 23' is enlarged at its free end portion to receive the needle hub flange 24' telescopically, with the enlargement of the catheter hub flange having internal spiral rib threads 25' with which thread lugs 27' on the outer perimeter of the hub flange 24' are cooperative in providing a twist-lock for the parts. Gauging or indicating of the indrawn sheathed position of the needle tip within the catheter end is effected by exposure of an indicating mark groove 28' in the outer perimeter of the flange 24' exposed at the indicating edge 29' in this instance on the end of the hub flange 23'. Indication that complete separation of the twist-lock elements 25' and 27' is provided by the indicating mark groove 30' in the outer perimeter of the hub flange 24' spaced from the groove 28' an appropriate distance toward the end of the flange 24'.

Although the indicating marks 28, 28' and 30, 30' have been shown as in the form of grooves, they may, if preferred, be in the form of ribs, discontinuous projections, discontinuous depressions, or any other suitable or desirable reference mark or indicator which will serve the purpose.

It will be understood that variations and modifications may be effected without departing from the spirit and scope of the novel concepts of this invention.

Claims

We claim as our invention:

1. An assembly including a flexible catheter having a leading end and a relatively stiff needle therein retractably extendible with a sharp tip of the needle projectable in advance of said leading end to facilitate venipuncture, and comprising:

a hub on said catheter;

a hub on said needle;

spiral thread means fixed with respect to one of said hubs;

lug means fixed on the other of said hubs interengaging and cooperative with said thread means;

said thread and lug means effecting connection of said needle and catheter through said hubs and relative axial shifting of the catheter on the needle by turning of the catheter hub, whereby in one relative assembled relationship of the catheter and needle determined by said thread and lug means the needle tip projects in advance of the leading end of the catheter until venipuncture has been effected, said thread means and lug means then functioning by turning of the catheter hub relative to the needle hub to advance the catheter relative to the needle until the leading end of the catheter protectively covers the tip of the needle; said thread and lug means being of sufficient length to remain positively connected after turning of said catheter hub and the catheter to advance said leading end into covering relation to said needle tip, whereby safe advance of the catheter within a blood vessel lumen can be effected utilizing the needle and tip as a stiffener within the catheter; and

cooperative indicators spaced from said thread means and lug means and associated with said hubs to show that said thread and lug means remain positively engaged, and to provide readily observable assurance of said catheter end fully covering said needle tip although the tip and end are concealed within a puncture.

2. An assembly according to claim 1, said indicators comprising mark means on one of said hubs and an edge cooperative therewith on the other of said hubs.

3. An assembly according to claim 2, including additional mark means on said one hub cooperative with said edge to indicate full separation of said thread and lug means to then enable free removal of the needle from the catheter.

4. An assembly according to claim 3, wherein said marks comprise annular respective differentiating marks.

5. An assembly according to claim 1, wherein said hubs are relatively telescopically related, the inner of said hubs having a mark thereon providing one of said indicators and the other of said hubs having an edge thereon providing the indicator thereof cooperative with said mark.

6. An assembly according to claim 5, said mark on the inner of said hubs comprising an annular groove.

7. An assembly according to claim 5, wherein said inner of said hubs has an additional indicator mark spaced from said first-mentioned indicator mark and cooperative with said edge to indicate full separation of said lug means from said thread means to enable smooth uninterrupted withdrawal of the needle from the catheter.

8. An assembly according to claim 5, said inner hub being on the catheter.

9. An assembly according to claim 5, said inner hub being on the needle.

10. In an assembly including a flexible catheter having a leading end and a relatively stiff hypodermic syringe needle within the catheter retractably extendible in the catheter with a sharp tip on one end of the needle projectable in advance of said leading end to facilitate venipuncture:

a syringe barrel permanently attached to the opposite end of said needle and having a permanent hub;

a permanent hub on the end of said catheter opposite to said leading end;

said hubs being telescopically one within the other;

means on said hubs providing releasable twist-lock connection of said hubs in relative rotary and axially movable assembly and with the catheter sheathing said needle;

said connection enabling manipulation of said syringe barrel to advance said needle for venipuncture by said tip projecting in advance of said leading end;

said connection having means of sufficient length to remain positively connected after turning of said catheter hub and the catheter to advance said leading end into protective relation over said needle tip so that by continued manipulation of the syringe barrel, safe insertion of the catheter into the lumen of the punctured blood vessel utilizing the needle as a stiffener for the catheter can be effected with full assurance that none of the assembly will separate unintentionally during push or pull manipulation; and

observable guide indicators separate from said connection and cooperatively located on said hubs registering when said tip is fully sheathed within said catheter end and showing that said connection remains positively engaged.

11. An assembly according to claim 10, including additional cooperating indicators on said hubs separate from said connection and registering when said catheter is further advanced on the needle until the twist-lock connection is released, to enable smooth uninterrupted withdrawal of said needle from said catheter.

12. An assembly according to claim 10, the outer of the telescoped hubs having an edge serving as an indicator, and the inner of said hubs having an indicating mark concealed within the outer of said hubs when the needle tip is projected in advance of said leading end of the catheter, but which registers with said edge when the catheter end is advanced into sheathing, stiffened relation to the needle tip.

13. An assembly according to claim 12, including another indicating mark on said inner of said hubs spaced from said first-mentioned mark and cooperative with said edge to indicate fully hub releasing relation of said twist-lock connection for smooth uninterrupted withdrawal of said needle from said catheter.

14. An assembly according to claim 13, both of said marks comprising respective annular grooves in said inner of said hubs.