US3388703A - Intravenous cannula assembly unit - Google Patents

Description

June 18, 1968 D. R. Bowes INTRAVENOUS CANNULA ASSEMBLY UNIT Filed March 22, 1966 /Vw///n//V /Yv NN E INVENTOR. aA/Az en/Es ATTORNE I United States Patent O 3,388,703 INTRAVENGUS CANNULA ASSEMBLY UNIT Donald R. Bowes, Fanwood, NJ., assignor to Johnson It Johnson, a corporation of New Jersey Filed Mar. 22, 1966, Ser. No. 536,376 7 Claims. (Cl. 12S-214.4)

ABSTRACT F THE DISCLOSURE An intravenous cannula assembly unit comprising a rigid hypodermic needle and a ilexible cannula fitted over the needle and shrunk into intimate contact with the shank of the needle and in particular, with a reduced diameter portion of the needle located between the head and the shank of the needle. As a result, the combined needlecannula diameter just rearwardly of the needle point is no greater than the normal diameter of the needle Shank, thereby reducing the likelihood of trauma in inserting the unit.

The present invention relates to intravenous devices of the type which are inserted in a vein or body cavity to allow fluids to be infused into or removed from the patient.

Devies of this type are described in United States Letters Patent 3,030,953 and 3,094,122 and generally are in the form of an insertion unit comprising a rigid hypodermic needle and a flexible cannula fitted over the needle. The unit normaly is fitted on the end of a hypodermic syringe for insertion into the vein and then the syringe and needle are removed from the cannula after the cannula has been properly positioned lfor use. The cannula then is attached through suitable 4fittings to tubing through which the desired uid may be administered or removed.

In using this type of unit, it is sometimes diiiicult to control the pain of insertion due to the large diameter of the needle-cannula combination. Efforts have been made to recess the leading end of the cannula behind an enlarged shoulder adjacent the point of the needle. However, this does not solve the problem created by the increased diameter of the unit, and creates an additional problem in withdrawing the needle through the cannula.

The present invention contemplates an intravenous device of the above general type wherein the combined needle-cannula diameter of the portion inserted prior to removal of the needle is no greater than normal needle diameter and wherein, in fact, the front portion of the cannula does not protrude at all beyond the needle head. For this purpose, the needle comprises a needle head of normal needle diameter adjoining the pointed front end of the needle, a shank of normal needle diameter adjoining the rear end of the needle, and an elongated section of reduced diameter between the head and the shank of the needle. A flexible hollow plastic cannula then is placed over the needle and shrunk into intimate contact with the outer surfaces of the reduced section and shank thereof. This provides a reduced diameter -portion at the tip of the cannula just rearwardly ofthe needle head and assures that the tip of the cannula grips the needle securely so that there will be no undesired relative movement between the cannula and the needle at any time. The reduced section of the needle is connected to the head of the needle and the shank, respectively, by smoothly tapered front and rear annular fairing surfaces which provide a gradual transition between the normal needle diameter of the head and the shank and the reduced diameter section between them. The difference between the outer diameters of the needle head and the reduced section just rearwardly of the head is substantially equal to the thickness of the hollow cannula wall, with the result that the outer diameter "ice of the reduced diameter tip portion of the cannula which is shrunk over the reduced section of the needle is substantially equal to the outer diameter of the needle head.

Preferably, the front end of the cannula wall, at the tip of the cannula, fits over the front fairing surface of the needle and is tapered to conform generally to the taper of the front fairing surface. This imparts maximum flexibility to the front end of the cannula wall and thereby facilitates fleXure of the cannula over the needle head when the needle is withdrawn through the cannula. The tapering of the cannula wall in this manner also allows the cannula to extend out to the surface of the head of the needle without protruding radially beyond the needle head. The front end of the cannula wall may be tapered for this purpose either before or after it is shrunk in position over the needle. Preferably, however, it first is shrunk in the desired position and then ground or cut down at the tip to reduce the outer diameter of the tip of the cannula to that of the needle head and thereby provide the aforesaid tapered section at the tip of the cannula.

The reduced section of the needle should be at least twice as long as the needle head and, at any rate, of sufticient length to assure that the reduced portion of the cannula can be properly positioned in the appropriate vessel or body cavity prior to removal of the needle through the cannula. `In other words, one of the main advantages of this invention is that the needle-cannula combination may be inserted easily until the reduced portion of the cannula, which is shrunk into contact with the reduced section of the needle, has been inserted into the vessel, and then the needle may be removed -by withdrawing it through the cannula. Thereafter, the cannula may be inserted further into the vessel with minimum trauma because the rigid needle has been removed therefrom and the cannula itself is flexible both radially and laterally.

Preferably, the needle is hollow and the reduced section thereof is formed by applying pressure to the needle as it is being rotated in contact with a suitable tool thereby simultaneously reducing its inner and outer diameter. The tool used may be appropriately shaped to assure that the front and rear fairing surfaces are formed in the desired shape. This technique is very simple and quick. However, during this step, the lumen of the needle normally should not be reduced to a diameter of less than about 0.01 inch.

Other and further advantages of this invention will occur to one skilled in the art from the following description and claims taken together with the drawings wherein:

FIG. 1 is a plan view of an intravenous device according to a preferred embodiment of this invention, mounted on the front end of a hypodermic syringe.

FIG. 2 is an exploded view of the cannula, needle and syringe of the embodiment of FIG. 1 in unassembled relation to one another.

FIG. 3 is a greatly enlarged view partly in section and partly in elevation of the front end of the device of FIG. 1, showing the cannula before its wall has been tapered at the tip of the cannula.

FIG. 4 is a view partly in section and partly in elevation and similar to FIG. 3 showing the tip of the cannula after it has beenl tapered.

FIG. 5 is a very greatly enlarged view showing how the tip of the cannula fits against the adjacent portions of the needle.

FIG. 6 is an enlarged sectional view taken along the line 6--6 of FIG. 4.

FIG. 7 is a view partly in section and partly in elevation at the same enlargement as FIGS. 3 and 4, and showing the intravenous device of the preceding figures after it has been inserted through the skin into a vein in such a way that the reduced diameter portion of the device is positioned in the vein and the needle is ready for removal from the device by withdrawing it through the cannula as indicated in phantom.

FIG. 8 is a partial section at the same enlargement as FIG. 7 showing the tip of the cannula in position in the vein after the needle has been removed therefrom. Referring to the drawings, there is shown an intravenous device, or unit, according to a preferred embodiment of this invention which comprises a rigid hollow pointed hypodermic needle 11 and a fiexible hollow plastic cannula 12 fitted tightly over the needle. The needle 11 and cannula 12 are aihxed at their rear ends to first and second hubs, 13 and 14 respectively, by which they are assembled over one another and positioned on the front end of a hypodermic syringe 15 for insertion of the unit into a patients vein 16 or body cavity.

The rear end of the needle 11 is permanently secured to the rst hub 13 by conventional means, and this hub presents a rearwardly facing tapered socket, not shown, and a frontwardly extending tapered extension 16a which cncloses the needle.'The tapered socket is adapted to fit tightly over a tapered fitting 17a at the front end of the syringe for positioning the needle on the syringe, and the frontwardly extending tapered extension 16a is adapted to fit inside a corresponding tapered socket presented by the rear end f the second hub 14 which, in turn, is affixed to the cannula 12. The cannula may be secured to the front end of the second hub 14 by conventional means such as are described in United States Letters Patent 3,094,122.

The hollow needle 11 possesses a normal outer diameter, i.e., is not enlarged, and is uniform in diameter throughout its length except for an elongated reduced diameter section 17 just rearwardly of the needle point. More specifically, the needle comprises a needle head 18 of normal needle diameter adjoining the pointed front end of the needle and a shank 19 of normal needle diameter adjoining the rear end of the needle. The reduced diameter section 17 of the needle is located between the head 18 and the shank 19 and is somewhat elongated as compared with the diameter of the needle. The elongated reduced diameter section 17 is connected to the head 18 of the needle by a smoothly tapered front annular fairing surface 21 and is connected to the shank 19 of the needle by a similar smoothly tapered rear annular fairing surface 22. The front and rear airing surfaces 21 and 22 provide gradual transition between the normal needle diameter of the head 18 and the shank 19 and the reduced diameter of the elongated section 17 between them. This reduced diameter section 17 of the needle is formed by turning hte needle in contact with a fitting, not shown,

which presses the walls of the needle inwardly to reduce its outer diameter to the desired extent without reducing the inner diameter of the needle below about 0.01 inch. This technique requires no special machining and is quick and efrlcient.

The hollow plastic cannula 12 is placed over the needle 11 in 1such a way that its front end or tip 23 overlaps the front fairing surface 21 of the needle but not the outer surface of the needle head 18. The cannula 12 then is shrunk into intimate contact with the outer surfaces of the reduced section 17 and the shank 19 of the needle. This shrinking may be accomplished by heat or by swelling the plastic of the cannula 12 prior ot fitting the cannula over the needle 11 and then drying it to cause it to shrink tightly over the needle. The cannula may be formed from any suitable material such as polyvinyl chloride or polyethylene which may be shrunk in this manner and is otherwise non-toxic and suitable for this use.

The wall of the cannula 12 at its front end or tip 23 is tapered so that it conforms with the taper of the front fairing surface 21 of the needle and does not extend radially beyond the outer diameter of the head 18 of the needle as is clearly shown in FIGS. 4, and 7. This may be accompanied by tapering the front end of the cannula wall prior to shrinking it in place over the needle or by rst shrinking a cannula 12 having uniform wall thickness onto the needle, as shown in FIG. 3. In the latter case, the tip 23 of the cannula initially will protrude radially outwardly beyond the head 1S of the needle. The cannula then is tapered as shown in FIG. 4 by grinding or cutting down the front end ofthe cannula wall to the same outer diameter as the needle head 18.

The difference between the outer diameter of the needle head 18 and the reduced section 17 ofthe needle just rearwardly of the needle head is substantially equal to the thickness of the hollow cannula wall. As a result, the outer diameter of the reduced diameter tip portion 24 0f the cannula which is yshrunk over the Ireduced section 17 of the needle is substantially equally to the outer diameter of the needle head 18. The tapered front end 23 of the cannula wall allows the cannula 12 to extend out to the surface of the needle head 18 without protruding radially beyond the head. As a result, the intravenous device of this invention presents a substantially continuous cylindrical outer surface of uniform diameter from the point `of the needle 11 to the rear end of the reduced diameter section 17 of the device. This allows the unit to be inserted through the skin into the vein 16 as shown in FIG. 7 until the reduced diameter portion 24 of the device is in position in the vein, without creating an enlarged incision .or in any way increasing trauma due to insertion of the front of the cannula into the vein or body cavity. Then, the rigid needle 11 may be removed easily from the cannula 12, while leaving the cannula in position in the vein, as shown in FIGS. 7 and 8, merely by withdrawing the needle rearwardly through the cannula. During this rearward motion of the needle, the tapered front end 23 of the cannula flexes outwardly and slides easily over the tapered front fairing sur-face 21 of the needle 11 so that a -minimum of resistance is presented to the withdrawal of the needle, thereby minimizing any trauma which might occur at this point. After the rigid needle 11 has been withdrawn yfrom the cannula, the front end 23 of the cannula remains in position in the vein, as shown in FIG. 8. Since the material of the cannula is quite flexible, the cannula itself now has become flexible in both a radial and a lateral direction. Thus, the cannula may be inserted further into the vessel with minimum trauma, if further insertion is deemed necessary for any reason. When the cannula 12 has reached the desired position, its hub 14 may be affixed to the skin by tape .or other means and attached to a tube, not shown, so that the cannula may be used for removal of blood from the vein or infusion of the desired fluid into the body.

Having now described the invention in specific detail and exemplified the manner in which it may be carried into practice, it will be readily apparent to those skilled in the art that innumerable variations, applications, modifications, and extensions of the basic principles involved may be made without departing from its spirit or scope.

What is claimed is:

1. An intravenous device which comprises a rigid needle comprising a sharp pointed front end, a needle head of normal outer diameter adjoining the pointedy front end of the needle, a shank of normal outer diameter adjoining the rear end of the needle, and an elongated sectiony of reduced diameter between the head and the shank of the needle; and a flexible hollow plastic cannula surrounding said needle and shrunk into intimate contact with the outer surfaces of the reduced section and the shank of said needle and providing a reduced diameter portion of the cannula just rearwardly of the needle head, the thickness of the cannula wall being substantially equal to the difference between the normal outer diameter of the needle and the outer diameter of said reduced section with the result that the outer diameter of the reduced 4diameter cannula portion shrunk over the reduced section of the needle is substantially equal to the outer diameter of the needle head and the front end of said cannula does not protrude radially beyond said head, the rear end of the needle being attached to a needle fitting which allows the needle to be mountedfon a hypodermic syringe or otherwise manipulated for insertion of the device into a blood vessel or body cavity and the rear end Iof the cannula being attached to a cannula fitting which is adapted to be connected with tubing for infusing fluid into or removing it from the said vessel or cavity, and said cannula being adapted to ex and slide over the needle head when the needle is removed from the cannula by withdrawing it through the cannula after the reduced diameter portion o fthe device is properly positioned in the said vessel or cavity.

2. An intravenous device according to claim 1, wherein the outer surface of the reduced section of the needle is connected to the larger diameter outer surfaces of the head and the shank, respectively, by smoothly tapered front and rear annular fairing surfaces.

3. An intravenous device according to claim 2, wherein the front end of the cannula wall fits over the front fairing surface of the needle and is tapered to conform generally to the taper of the front fairing surface so that the yfront end of the cannula does not protrude radially outwardly beyond the adjacent needle head, thereby imparting maximum flexibility to the front end `of the cannula and facilitating liexure of the cannula over the head when the needle is Withdrawn through the cannula.

4. An intravenous device according to claim 3, wherein the wall of said cannula is uniform in thickness when fitted tonto said needle, and wherein the front end of the cannula is ground or cut down to reduce its outer diameter to that of the needle head and provide the aforesaid tapered section at the front end of the cannula.

5. An intravenous device according to claim 1, wherein the reduced section of the needle is at least twice as long as the needle head to assure that the reduced diameter portion of the cannula can be properly positioned in the said vessel or body cavity prior to removal of the needle through the cannula.

6. An intravenous device accor-ding to claim 1, Wherein the needle is hollow and the reduced section of the needle is formed by applying pressure to the needle as it is being rotated, thereby simultaneously reducing its inner and outer diameter.

7. An intravenous device according to claim 6, wherein the lumen of the needle in said reduced section has a diameter of no less than about 0.01 inch.

References Cited UNITED STATES PATENTS 2,770,236 11/1956` Utley et al. 12S-221 2,899,960 8/ 1959 Ginsburg 128-221 3,030,953 4/ 1962 Koehn 128-214.4 3,082,769 3/ 1963 Palmer 12S- 221 3,094,122 6/ 1963 Gauthier et al. 12S-214.4 3,352,306 11/1967 Hirsch 12S- 214.4

DALTON L. TRULUCK, Primary Examiner.

UNITED STATES PATENT oEEIcE CERTIFICATE OF CORRECTION Patent No. 3,388,703 June 18, 1968 Donald R. Bowes It is certified that error appears in the above identified patent and that said Letters Patent gre hereby corrected as shown below:

Column 1 line 27 "Deves" should read Devices Column 3, line 49, "hte" should read the Column 4,

equal line 64, "shrunk line 13, "equa11y should read into" should read havngits inner surfaces in Signed and sealed this 28th day of October 1969.

(SEAL) Attest:

, Edward M. Fletcher, Ir.

Commissioner of Patents Attesting Officer WILLIAM E. SCHUYLER, IR.

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