Adjustable Needle Hub

Abstract

An intravenous needle and catheter (or cannula) combination wherein the needle passes through the catheter, when assembled for venipuncture, the needle hub being formed distally in a plurality of steps adapted to support Luer lugs on the catheter hub in different positions, permitting determination of the distance the needle bevel tip projects beyond the catheter tip.

Description

In an intravenous needle and catheter set of the type wherein the needle is within the catheter, as illustrated by Gauthier and Massa U.S. Pat. No. 3,094,122 and Braun U.S. Pat. No. 3,348,544, for example, it has been found that accurate control of the catheter length cannot practically be assured under normal manufacturing conditions, so that uniform projection of the needle bevel from the tapered distal end of the catheter is difficult to achieve. While some deviation from the optimum projection can be tolerated, a simple means to compensate for abnormalities is desirable and the present invention constitutes such a means. It also provides the user with a possibility of varying the needle tip projection as may be desired in special situations, not necessarily related to variations of catheter length. The adjustment is effected by providing the distal face of the needle hub with a plurality (shown as three) of pairs of diametrically opposite "steps" located at different distances axially from the needle tip. The catheter hub is normally provided with Luer locking lugs projecting from its proximal rim and the steps are located to stop the lugs, axially, in positions such that the needle tip will project varying distances from the catheter tip.

Hill U.S. Pat. No. 1,248,492 shows a pointed needle with a tubular cannula slidable thereon and means, in the form of a bayonet joint, for securing the cannula in retracted position to expose the needle point or in extended position to cover the needle point entirely. Henkin U.S. Pat. No. 3,506,007 shows a catheter-needle combination in which the catheter hub has a keyway to receive a key on the needle hub when the needle is advanced, the catheter hub surface stopping the needle in retracted position when the key is not in register with the keyway. Neither of these patented devices is intended or adapted to serve the purposes of the present invention.

A practical embodiment of the invention is shown in the accompanying drawing wherein:

FIGS. 1, 2 and 3 represent side elevations of the needle and catheter assembly, portions of the hubs being broken away and in section, showing three different adjusted positions of the parts;

FIG. 4 represents a distal face view of the needle hub;

FIG. 5 represents an axial section on the line V--V of FIG. 4

FIG. 6 represents an axial section on the line VI--VI of FIG. 4

FIG. 7 represents an axial section on the line VII--VII of FIG. 4 and

An intravenous set is shown as comprising the catheter (or cannula) 10, the shaft 11 of which has a tapered distal tip 12 and is cemented in, or molded integrally with an adapter hub 13. The proximal (open) end 14 of the hub is annular and is provided with diammetrically oppositely projecting Luer lugs 15 each extending arcuately no more than 60.degree. and preferably somewhat less.

The needle 16 is of customary form with beveled cutting point 17 and is fixed at 18 in the slightly tapered distal end portion 19 of a hub 20. At the base of the portion 19 the hub extends radially outward and is bounded by an annular rim 21, within which the distally facing surface is partially flat, 23, indicated at 22, and partially stepped as shown at 22, 23' and 24, 24'. Each of the steps 23, 23' and 24, 24' is arcuate, extending around the margin of the flat surface 22 through an arc of no more than 60.degree., the pairs of steps 23, 23' and 24, 24' being disposed diametrically opposite each other and a stop 25 extending inward from the rim 21 at a point between an end of a step 24' and the adjacent flat surface 22.

In the manufacture of I.V. sets of the character described it is customary to mount a group of needles in a jig with their proximal ends positioned against a stop, the bevels being ground on the distal ends in a highly accurate machine operation, and the needles being then mounted in hubs 20 with their ends seated in a recess and fixed, as indicated at 18, by cementing or the like, the distance from the hub to the beveled tip 17 being uniform within established tolerances. The catheters 10, however, being of flexible plastic material and tapered by various methods, including grinding, molding and/or drawing characteristically show greater variations in length. For purposes of illustration, the catheters 10 in FIGS. 1, 2 and 3 are shown as being identical, the one in FIG. 2 having its beveled tip located at the point which is generally preferred, close to but slightly proximal of the heel of the bevel 17. This catheter, having optimal length, has its hub seated on the middle step 23, 23'. When the same catheter has its hub on the lower step 22, its tip is spaced too far from the bevel, as shown in FIG. 1, and when it is on the upper step 24, 24' its tip covers the heel of the bevel (FIG. 3) which is also undesirable.

Assuming, however, that a number of catheters are made and found to vary slightly in length, it will be evident that those slightly longer than the one shown can have their hubs seated as in FIG. 1 so that their tips will be acceptably close to the needle bevel, while those slightly shorter than the one shown can have their hubs seated on the upper step 24, 24' also in an acceptable relation to the needle. The range of tolerances in this critical dimension (catheter length) can thus be greatly enlarged with consequent reduction in the percentage of "rejects."

In effecting venipuncture with a needle and catheter set of the type disclosed herein the forces acting on the device are largely axial, so that there is little likelihood of the catheter hub being displaced from its adjusted position by rotation with respect to the needle. The frictional engagement of the needle in the catheter thus suffices to hold the parts reliably in their desired relative orientation.

While a three-step arrangement is shown and described, it will be understood that two steps or more than three steps could be provided, if desired. The reference to lugs 15 as being "Luer" lugs is intended to indicate generally a type of radially projecting lug, without limitation to those which could actually constitute a Luer lock.

It will be understood that various changes may be made in the form, construction and arrangement of the several parts without departing from the spirit and scope of the invention and hence I do not intend to be limited to the details shown or described herein except as the same are included in the claims or may be required by disclosures of the prior art.

Claims

What I claim is:

1. An intravenous needle and catheter set wherein a needle element is located within a catheter element with its point projecting from the distal end of the catheter element, comprising a needle fixed in a needle hub and a catheter fixed to a catheter hub, said needle hub being provided with a plurality of axially-facing surfaces disposed at different distances from the distal end of the needle and the catheter hub being provided with at least one complimentary axially-facing surface disposed at a given distance from the distal end of the catheter and adapted to bear selectively against any one of said first-named surfaces, whereby the relative positions of said respective distal ends may be determined, the needle hub being provided with a distally-facing annular channel and said plurality of surfaces being disposed in said channel.

2. An intravenous needle and catheter set according to claim 1 wherein the catheter hub is provided with a pair of diametrically oppositely disposed lugs each having a proximally-facing surface extending through an arc no greater than each of said plurality of surfaces.