US3506007A - Catheter-needle - Google Patents

Description

April 4, 1970 M. L. HENKlN 3,506,007

CATHETER-NEEDLE Filed July 24. 196'? 2 Sheets-Sheet 1 MEL vy/v L. HA/M/M,

(5y M5 firropmgys JMvEA/r'aa April 14, 1970 M. L. HENKIN 3,506,007

CATHETER-NEEDLE Filed July 24. 1967 2 Sheets-Sheet 2 United States Patent 3,506,007 CATHETER-NEEDLE Melvyn L. Henkin, 3326 Sawtelle Blvd., Los Angeles, Calif. 90066 Filed July 24, 1967. Ser. No. 655,513 Int. Cl. A61m 5/00 US. Cl. 128-221 Claims ABSTRACT OF THE DISCLOSURE An improved catheter-needle for injecting and withdrawing fluids from cavities and channels of a subject is disclosed consisting of a hollow needle; a catheter disposed exteriorly of the needle and slidable thereon; and, a releasably interlocking hub assembly interconnecting the needle and the catheter. The interlocking hub assembly is constructed to selectively maintain the needle in a predetermined withdrawn position within the catheter. Alternative catheter constructions are disclosed whereby the catheter may be selectively maintained in a predetermined inserted position.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to an instrument for the administration of fluids into the cavities and channels of a human body and more particularly to an improved epidural catheter-needle for the introduction and placement of a catheter and the administration of epidural anesthesia.

' Description of the prior art The use of hollow needles and flexible catheters ,in the administration off epidural anesthesia is not new. However, the heretofore utilized cooperation of catheter and needle is found to have severe disadvantages in the light of the present invention.

In known epidural administrations, a hollow needle is introduced into the spinal structure through the interspinous ligaments and the bordering ligamenturn flavurn directly into the epidural space. As the epidural space is only approximately two to four millimeters in depth, the cutting edge of the needle is thereby laced in critical proximity to the dura, the outer membrane of the cerebrospinal fluid canal. Accidental penetration of the dura in administration of the anesthetic agent into the canal could cause severe damage to the patient. In this position, the needle itself is used for administration of test or initial dosages of the anesthetic agent and as an external guide for the threading therewithin of a long, extremely fine catheter utilized for repeated and/or continuous administration of the anesthetic agent. After placement of the fine catheter, the hollow needle must be carefully withdrawn from the subject avoiding dislodgment of the fine catheter. g

A major disadvantage of previously known epidural administration techniques is the difficult manufacture of a needle suitable to both minimizing the possibility of dura penetration and guiding the fine catheter in the desired direction within the epidural space. To date there does not exist a needle which satisfactorily achieves these objectives or that can be manufactured at a cost compatible with disposable use. A few blunt-needle configurations have been found to substantially preclude dura penetration. However, introduction of the large bore blunt needle through the interspinous ligaments and ligamentum fiavum is extremely laborious, requiring great force. Furthermore, a blunt needle must have its opening at or near a right angle to its axis. Therefore, the internally threaded catheter must negotiate a sharp turn in order to emerge into the epidural space. Great diificulty in catheter threading therewithin has been experienced; such ditficulty sometimes resulting in complete failure of the technique.

Another disadvantage of the known administration techniques is that the catheter used must be extremely fine, as it must be threaded through the needle, thus rendering aspiration relatively unreliable. The small size and mode of placement of the catheter increases the likelihood of its undetected erosion into either a blood vessel or the subarachnoid space. Further, injection of the anesthetic agent through the extremely fine catheter, often requires undesirably great pressures because of the high resistance to fluid flow imposed by the relatively small bore of the catheter over its entire length. Such inherent difiiculty of fluid flow is further compounded by the known tendency of the fine catheter to twist and kink within the epidural space thereby further restricting fluid flow. A larger bore catheter, as provided by the present invention, substantially eliminates such undesirable restrictions to fluid flow.

The problems attendant on the internally threaded catheter have been alleviated to some extent in general intravenous and intravascular applications. That art discloses the use of a larger bore catheter externally slidable on a hollow needle. In that application, the needle and catheter are longitudinally introduced into the vein or vessel. The needle is then Withdrawn into the catheter a small amount and the combination further advanced. When the catheter is firmly lodged within the channel, the needle is withdrawn from within the catheter leaving the large bore catheter in the vein or vessel. Such an application, however, is neither completely satisfactory nor does it fully meet the major problem attendant on epidural introductions. A major disadvantage of such placements of exteriorly disposed catheters is the awkwardness and relative lack of precision of hand holding the combination with the needle tip sheathed within the catheter. There exists the ever-present danger of the needle tip becoming unsheathed during advancement of the combination thereby damaging the vessel and necessitating withdrawal and reinsertion in another vessel. Further, with respect to epidural applications, the nature of the spinal structure precludes a longitudinal needle entry into the epidural space; the needle entry path being more transverse to the epidural space. Consequently, considering the narrowness of the epidural space, a transverse insertion of an exteriorly disposed catheter-needle as presently known does not allow selective threading of the catheter in a predetermined direction within the epidural space.

To provide an injection instrument admitting of safe, easy insertion and placement of a relatively large bore catheter, and to overcome the shortcomings of the prior art, a novel exteriorly disposed catheter-needle has been invented.

SUMMARY OF THE INVENTION The present invention is best summarized as an improved instrument for administering fluids into the channels and cavities of a subject including a hollow needle, through which fluids may be introduced or withdrawn, the needle further including a needle hub assembly thereon; a catheter member disposed exteriorly of the needle and slidable thereon; and a catheter hub aifixed to the proximal end of the catheter member, the catheter hub being constructed to releasably interlock with the needle hub assembly to selectively fix the needle in a predetermined position with the catheter member.

The novel features which are considered characteristic of the present invention, both as to its organization 3 and operation, will be better understood from the following description considered in connection with the accompanying drawings of an embodiment of the invention. It is expressly understood, however that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention. When viewed in the light of the preceding prior art discussion, the description and the drawings lend clear support to the advantages of the present invention as stated immediately thereafter.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: FIGURE 1 is an overall perspective view; FIGURE 2 is a partial section taken along the lines FIGURE 3 is a sectional view taken along the lines 33;

FIGURE 4 is a partial section taken along the lines 2-2;

FIGURE 5 is a sectional view taken along the lines 5-5;

FIGURE 6 is an alternative embodiment to FIGURE 2. in partial section;

FIGURE 7 is a partial section expanded over FIG- URE 6;

FIGURE E is a side elevation in partial section;

FIGURE 8a is an enlarged section taken at 8a;

FIGURE 9 is a side elevation in partial section;

FIGURE 9a is an enlarged section taken at 9a;

FIGURE 10 is a side elevation in section;

FIGURE 11 is a side elevation in partial section;

FIGURlE 12 is a side elevation in partial section;

FIGURE 13 is a side elevation in partial section; and,

FIGURE 14 is a side elevation in partial section.

DETAILED DESCRIPTION OF AN EMBODIMENT In thedrawings, a given reference numeral is used to refer to the same part in all views.

Referring to FIGURES 2 and 4, there is shown a disposable hollow needle 10 which defines a longitudinal bore 12 throughout its length. Any of the standard materials now utilized in the manufacture of disposable intravenous needles are suitable for the present invention. While the length and gauge of the needle 10 is not critical to the present invention, a needle length of three to three and one-half inches has been found to be satisfactory.

The needle 10 is ground, at one end thereof, to form the point and generally elliptical cutting edge 16. A point angle 17 of 45 has been found to provide an ease of introduction as well as the relatively short cutting edge axial length desirable in epidural applications.

The catheter member, or catheter 18, is an elongated, flexible plastic member designed to fit snugly about the needle 10 yet remain slidable thereon. At a terminal end 20 of the catheter 18, its outside diameter gradually decreases to form the tapered, wedge-like introducing surface 22. The inside diameter of the catheter may be uniform throughout its length as in the embodiment shown.

The catheter 18 may be fabricated of any flexible material common to the art. For epidural administrations a catheter made of the product Teflon is preferably employed to decrease frictional drag through the body tissue and ligaments thus facilitating introduction. Referring to FIGURE 14, the catheter may also be constructed to include the substrate section 19, made of such polymeric materials as polyvinyl, polyethylene and polypropylene; and the coating section 21 made of such polymeric materials as exhibit self-lubricating surface characteristics like the product Teflon and the organopolysiloxanes. The organopolysiloxanes used may generally be depicted as having the generic structure where R may be CH CH =CH or other alkyl groups.

As will be shown more clearly hereinafter, the length of the catheter 18 is critical to the present invention and primarily dependent on needle length.

At a proximal end 24 of the catheter 18, the catheter hub 26 is concentrically affixed to the catheter. The hub 26 is preferably constructed of a non-flexible material such as a suitable metal, alloy, or plastic. In the embodiment shown in FIGURE 2, the exterior configuration of the hub 26 is substantially frusto-conical. The defined exterior surfaces of the hub include the interlocking surface 28 and the male mating surface 30. The mating surface 30 has a configuration common to intravenous to venous connections known in the art.

The hub 26 is constructed to define therethrough the axial opening 32. The opening 32 must be of sufficient diameter to admit of the passage of the needle 10. The hub 26 further defines, in cooperation with the opening 32 the axial keyway 34 having an open end 36 and a bearing shoulder 38. The open end 36 and the shoulder 38 are spaced apart a predetermined axial distance. In a present embodiment of the invention, an axial separation of two to four millimeters is preferable.

The needle hub 40 is concentrically disposed at the end of the needle 10 opposite the point. The hub 40 is constructed to removably receive on one side thereof, in any standard manner known in the art, a disposable syringe 42. The hub 40 includes the axial key 44 disposed oppositely on the hub from the syringe. The key 44 is constructed to such dimensions as to be matable within the keyway 34; the key bearing surface 46 abutting the keyway shoulder 38 when the needle hub 40 and the catheter hub 26 are in full mating relationship.

It is to be recalled that the catheter 18 has a critical length primarily dependent upon needle length. The axial separation between the keyway end 36 and shoulder 38 is also critical. The catheter length is such that when the needle and catheter hub are in full mating engagement, substantially all of the needle is enclosed within the catheter except the sloped surface of the point and portions of the needle immediately adjacent therto. The axial length of the keyway 34 must be such that when the needle 10 is withdrawn from the catheter 18 an amount equal to that. axial length, the needle point is withdrawn into the catheter a distance sufficient tc completely cover he point and cutting edge, yet no further. Thus, necessary rigid support of the tip 22 of the catheter is maintained. As indicated above, in the embodiment shown this withdrawal distance is approximately two to four millimeters.

With reference to the foregoing and FIGURES 3, 4 and 5, it may be seen that when the needle 10 has been withdrawn the requisite distance, the bearing surface 46 of the key 44 will exit the keyway 34 leaving the needle free to rotate. A slight rotation of the needle in either direction will place the bearing surface 46 in abutment with the interlocking surface 28 of the hub 26. The needle is thereby locked against further advancement into the catheter.

It is to be understood that it is the withdrawal of the needle point into the catheter, and its fixed position therein, that is critical. While a simple interlocking key arrangement is shown in the embodiment presented, the same axial withdrawal distance and interlock effect may be achieved by other similar mechanical arrangements. Other possibilities include eamming surfaces; screw type assemblies; and block wedge relationships.

Referring to FIGURES 6 and 7 there is shown an alternative embodiment of the present invention. This embodiment is of substantially the same construction as that described above. However, the catheter hub 26' is depicted as defining the female fitting 48 for connection with exterior tubing having a male connector. In this embodiment, the key 44 is displaced from the needle hub proper by an amount equal to the depth of the female fitting surface. The key thus disposed is supported by the extension member 52.

Referring now to FIGURES l1 and 12, there are shown illustrative alternative embodiments of the catheter 18. As shown in FIGURE 12, the catheter 18 has been preformed to define a naturally curved portion at the terminal end 20 of the catheter. As indicated herein before, it is preferably constructed of a flexible plastic material. Thus, when the needle is introduced through the catheter 18, the curved portion is maintained in a substantially straight position. However, the plastic memory of the preformed curved portion will cause the catheter to again resume its curved posture upon withdrawal of the needle. Correlatively, the direction mark 80 provided on the catheter hub 26 indicates to a practitioner the direction in which the curved end of the catheter will tend upon removal of the needle.

Referring to FIGURE 11 there is shown an additional alternative catheter embodiment wherein a plurality of Winged stops 82 are circumferentially disposed about the catheter near its terminal end 20. Each of the stops 82 in an integrally performed cut-out portion of the catheter wall 84. The stops 82 are preformed to assume a normally expanded position with respect to the catheter wall 84. Upon introduction through a surface, the stops 82 are constructed to resiliently assume a position coincident with the catheter wall. Following complete insertion through the surface the stops are free to resiliently return to their normally expanded position thereby creating an impediment to catheter withdrawal through the surface of insertion. Again, however, the natural flexibility of the catheter material may be such as to safely admit of catheter withdrawal against the biasing effect of the winged stops 82.

Having thus seen the physical arrangement of the parts of the present invention, a description of their cooperation in an illustrative application follows. Referring to FIG- URES 8 and 9, a stylet of a type commonly known in the art, but not shown, is inserted into the needle 10 to prevent fouling of the needle bore 12. The needle, with its exteriorly disposed catheter 18 in full mating relationship with the needle, is then introduced through the subjects back tissue into the interspinous ligaments 56. The stylet is then removed and a liquid or air loaded syringe 42 is attached to the needle. Continuous fluid pressure is maintained as the needle is urged closer to the epidural space 58. The density of the interspinous ligaments provides a great resistance to the flow of liquid out of the needle. This resistance becomes even more marked as the needle enters the denser ligamentum flavum 57. A marked decrease in the resistance to flow indicates entry of the needle point through the ligamentum flavum into the epidural space 58. This decreased resistance would indicate needle entry into the epidural space but not necessarily catheter entry. The self-lubricating qualities of the catheter 18 has rendered insertion through the interspinous ligaments relatively easy. However, because of the aforementioned precedent relationship of the needle to the catheter introducing surface 22, as the smaller diameter needle penetrates the ligamentum flavum, the wedge-like introducing surface 22 encounters the denser ligamentum flavum thereby creating a greater penetration resistance. See FIGURE 8a. Such increased penetration resistance, together with the decreased fluid flow resistance, indicates to the practitioner that not only has the needle entered the epidural space but also that the needle point and cutting edge are nearing critical proximity to the dura. Consequently, further advancement of the needle is ceased and the needle is immediately withdrawn in the catheter to its locked position as shown in FIGURES 9 and 9a. As previously described, the needle is withdrawn no further than is necessary to cover the point; yet the needle provides a rigid support for continued introduction of the catheter through the pre-dilated ligamentum flavum. After needle withdrawal into the catheter, fluid pressure is again applied. It the catheter is not in the epidural space, it is now rigid enough to serve as a blunt introducer Which will repierce, or dilate the remaining small amount of ligamentum flavum. The blunt point of the catheter 18 will prevent puncture of the dura 62. After advancement of the locked catheter needle, a decreased resistance to fluid flow will now signify the entry of the catheter in the epidural space. The needle may now be completely withdrawn leaving the catheter fixed in the epidural space by the interspinous ligaments. A portion of the catheter and the catheter hub project exteriorly of the patients skin or introducing surface. Necessary connections may now be made through the catheter for administration of the anesthetic agent.

In some applications it has been found that, following placement of the catheter 18, the terminal end 20 is placed in such flush proximity to the dura 62 as to obstruct or preclude the flow of fluid through the catheter. See FIGURE 10. Referring to FIGURE 12, it may be seen that such an obstruction may be overcome by utilizing the curved-end catheter previously described. While the catheter remains substantially straight during the insertion procedure described above, upon removal of the needle the curved end of the catheter returns to its normally curved position within the epidural space. The direction in which the catheter is to be trained may be easily selected by the practitioner with reference to the correlative direction mark on the catheter hub 26. Alternatively, the additional catheter embodiment depicted in FIGURE 11 may be employed to further fix the catheter within the epidural space as well as provide an unobstructed fluid exit through the openings 86 in the catheter wall 84 created by the pre-formation of the expanded winged stops 82.

A further alternative to final catheter placement within the epidural space is shown at FIGURE 13. Therein, the fine, small bore catheter 88, with a pretrained tip, is threaded through the catheter 18 into the epidural space. Using the fine catheter 88 as a curved introducing guide, the practitioner may then further insert the catheter 18 into the epidural space thereby precluding the undesirable flush proximity of the catheter terminal end 20 and the dura 62.

While the construction and use of the present invention catheter needle has been above described in terms of an epidural administration, it may readily be seen by one of ordinary skill in the art, in light of the shortcomings of the known techniques, that the insertion and catheter placement advantages thereof may be utilized in intravascular and intracavity applications as well.

There has thus been described an improved catheterneedle insuring greater subject safety as well as case and reliability of use.

The novel withdrawable interlocking catheter-needle relationship greatly minimizes the possibility of harmful penetration of the dura and facilitates accurate placement of the catheter. Concurrently however, each of introduction is retained with the sharp needle point and the selflubricating characteristics of the Teflon or silicone catheter coating. In the present invention catheter-needle, the catheter is in place when the needle is positioned; no awkward catheter threading is required.

Added safety is found in the exteriorly disposed large bore catheter. All drugs are introduced through the catheter. The large bore catheter allows easy injection and reliable aspiration. The large bore catheter is much less likely to erode into either a blood vessel or the subarachnoid space because of its location and novel mode of placement.

What is claimed is:

1. An instrument for administering an epidural anesthesia comprising:

(a) a hollow needle through which fluid may be introduced or withdrawn, said hollow needle including a needle hub assembly having interlock means;

(b) a catheter member made of a resilient material more flexible than said needle, having a smooth exterior surface and of predetermined length disposed exteriorally on said needle and having an internal diameter substantially the same as the diameter of said needle whereby it is slideable thereon, said catheter terminating at an end thereof in a catheter hub; and

(c) said catheter hub having interacting means for releasably interlocking with said interlock means of said needle hub assembly to selectively fix said needle in a predetermined position within said catheter member.

2. In the combination defined in claim 1, wherein:

(a) said catheter hub defines therewithin a recess of predetermined axial length terminating in an interlocking surface;

(b) said needle hub assembly defines thereon a projection slideable within said recess; and,

() wherein said projection is constructed to abut with said interlocking surface and maintain said needle in said predetermined position when said needle is withdrawn into said catheter a distance equal to said predetermined axial length of said recess.

3. In the combination defined in claim 1 wherein said catheter member is made of a resilient polymeric material having self-lubricating surface characteristics.

4. In the combination defined in claim 3 wherein said polymeric material is selected from the group consisting of polytetrafluoroethylene, fiuorinated ethylene-propylene and polyethyleneterephthalate.

5. In the combination defined in claim 3 wherein said catheter member is preformed to define a normally curved portion at an end thereof axially opposite said catheter hub, said curved portion being adapted to maintain a substantially straight position when said catheter and said needle are in full mating relationship.

'6. In the combination defined in claim 1 wherein said catheter comprises a substrate section and a coating section, said coating section being imposed on said substrate section and having self-lubricating surface characteristics; said substrate section comprising a polymeric material selected from the group consisting of polyvinyl, polyethylene and polypropylene, and said coating section comprising a polymeric material selected from the group consisting of polytetrafiuoroethylene, fluorinated ethylenepropylene, polyethyleneterephthalate and organopolysiloxanes.

7. In the combination defined in claim 1 wherein an end of said catheter member axially opposite said catheter hub includes a plurality of winged stops circumferentially spaced about the catheter wall, each of said stops having a fixed end coincident with said catheter wall and a bearing end outwardly pivotally expandable about said fixed end, each of said stops being adapted to be positioned in a normal first position outwardly expanded with respect to said catheter wall and a second position coincident with said catheter wall.

8. The method of administering an epidural anesthesia into the spinal structure of a subject including the steps of:

(a) introducing a hollow needle having a first catheter member exteriorly slidable thereon into the interspinous ligaments of said spinal structure into the epidural space of said spinal structure;

(b) withdrawing said needle into said first catheter a predetermined distance and locking said needle within said first catheter against further introductory motion with respect to said first catheter;

(c) introducing said first catheter into said epidural space;

((1) entirely withdrawing said needle from said first catheter; and,

(e) introducing an epidural anesthetic agent through said first catheter into said epidural space.

9. The method recited in claim 8 including the additional steps of:

(a) threading a second catheter having a trained tip and a diameter smaller than that of said first catheter through said first catheter into said epidural space;

(b) threading said first catheter into said epidural space on said second catheter; and,

(c) withdrawing said second catheter.

10. A combination as defined in claim 1 and further including:

((1) a syringe receiving and retaining said hollow needle.

References Cited UNITED STATES PATENTS 1,248,492 12/ 1917 Hill l28347 2,862,495 12/1958 Gewecke l2822l 2,922,420 1/1960 Cheng l2822l 3,094,122 6/ 1963 Gauthier et al. l2822l 3,277,893 10/1966 Clark l2822l XR 3,308,819 3/1967 Arp l2822l XR 3,312,220 4/ 1967 Eisenberg l2822l XR 3,419,010 12/ 1968 Williamson l28350 3,358,684 12/1967 Marshall 128--214.4 3,406,685 10/ 1968 May l2822l XR 3,406,687 10/1968 Moyer l2822l FOREIGN PATENTS 605,067 2/ 1926 France.

WILLIAM E. KAMM, Primary Examiner US. Cl. X.R. 1282l4.4

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