Tabbed Eccentric Locking Device

Abstract

A locking guard device regulating the penetrating depth of a rigid or semi-rigid hollow member such as a hypodermic needle, catheter, or hollow members used for draining body cavities, is formed by mounting on the shaft of the member a guard comprising a male and female element with holes bored therethrough, the holes being concentric with respect to each other but eccentric with respect to the true centers of the elements. Both the male and the female elements of the guard are provided with projecting tab members, so that pinching the tab members together locks the guard upon the shaft upon which they are mounted.

Description

This invention relates to an improved device especially adapted for removing fluid from a body cavity by surgical puncture or drainage. More specifically, it relates to an improved locking guard device, mounted on the shaft of a hollow member such as a needle or semi-rigid catheter, intended to regulate the depth of penetration of the needle or catheter into a body cavity in a paracentesis or catheterization procedure, especially thoracentesis.

In a thoracentesis procedure, a sharp-pointed cannula, hypodermic needle, or the like is thrust into the pleural cavity in order to remove fluid. Various well-known valve arrangements are employed to allow the aspiration of fluid without allowing air to enter the pleural cavity, with the consequent danger of lung collapse.

In inserting the aspirating needle into the cavity, it is most important that the depth of penetration be closely controlled, so that the pleural cavity will be tapped but without the danger of excessive penetration which could cause the sharp needle point to puncture or tear the lung itself. The desired degree of penetration may vary with the physical condition of the patient.

Various expedients have been resorted to in the past to serve as a guard or stop mechanism, controlling the depth of penetration of the needle. One well-known method is to clamp a hemostat on the needle shaft. Others include the clamping of a coiled spring on the shaft, as in U.S. Pat. No. 3,477,437, and various set-screw arrangements as in U.S. Pat. Nos. 2,001,638 and 2,338,800, as well as by guard devices such as disclosed in U.S. Ser. No. 208,657, filed Dec. 16, 1971 of common assignee.

In Ser. No. 208,657 there is described a guard device comprising a male and female elememt, each being provided with an aperture, said apertures being concentric with each other but eccentric with respect to the true centers of the elements. Rotation of one element with respect to the other element locks both elements onto the shaft of the needle or catheter upon which they are mounted.

Such a device, however, requires a two-handed manipulation for the locking operation, since one element must be held in a defined position on the shaft while the other element is rotated by the other hand. In many procedures it is desirable that the guard device be capable of being locked onto or unlocked from the shaft of a needle or semi-rigid catheter or the like with one hand, leaving the other hand free for other manipulations.

In addition, such devices depend on a frictional fit between the outer surface of the male element and the inner surface of the female element, in order that the two elements be held together so that they cooperate in locking the device on the shaft of the cannula. Frictional fits of this nature are unreliable and subject to slippage, whereby the two-element guard device is no longer held in the desired locked position on the cannula.

It is therefore a primary object of the invention to provide a guard device which can be slidably adjusted to any desired position on the shaft of a cannula, and can be locked onto said shaft by a simple one-hand operation.

It is an additional object of the invention to provide a guard device comprising two rotatable elements which are locked in unitary combination when the guard device is adjusted to be slidably fitted to the desired position on the shaft of a cannula.

Other objects of the invention will be better understood from the following description and drawings, in which

FIG. 1 is a perspective view of an embodiment of the invention.

FIG. 2 is a perspective view, partly cut away, of the male element of FIG. 1.

FIG. 3 is a perspective view of both elements of FIG. 1, in dismantled relationship.

FIG. 4 is an idealized view of a pair of superimposed elements, each containing an aperture eccentrically disposed with respect to the true centers of the elements.

FIG. 5 is an idealized view of the constricting effect on these apertures caused by rotation of the elements effected by approximation of the projecting tab portions.

FIG. 6 is an end view of the assembled elements of the invention, in concentricity, with an adhesive mass applied to the bottom face of the female element 50.

FIG. 7 is a perspective view of the invention in use, locked on a cannula, and held in position on a patient.

The basic device of the invention comprises a pair of interengaging elements, male and female, each provided with a projecting tab, and each apertured, the apertures being capable of being manipulated into concentricity with each other, but both apertures being eccentric with respect to the true centers of the elements.

Referring to FIG. 1, a male element 40 and a female element 50 are shown in interengaged position. In the partially cutaway view of the male element in FIG. 2, the male element is shown as comprising a cylindrical collar portion 42 provided on one side with a tab-like projection 44, one end of the cylindrical portion being open and the other end being closed except for the eccentric circular hole 46, of a predetermined size so as to slide easily on the shaft of a cannula.

Referring to FIG. 3, the female element 50 preferably comprises the flange-like guard disk 52, on which is mounted the hollow cylindrical sleeve 54, provided with a tab projection 56, said guard disk being substantially normal to said cylindrical sleeve.

The cylindrical sleeve 54, unlike the sleeve 42 of the male element, is cut longitudinally as at 57 to allow the tab 44 of the male element to slide over the tab 56 of the female element until the lower surface of the male element rests on the upper surface 53 of the female element. The sleeve 54 is also cut away laterally, as shown at 62 in FIG. 3, so that the stem portion 45 of the tab 44 of the male element can be rotated around the axis of the assembly when the elements are interengaged as shown in FIG. 1. That is, the height of the lateral cut A in the cylinder of the female element should accommodate the width B of the stem 45.

The two elements are assembled by bringing the lower surface 43 of the male element into contact with the upper surface 53 of the female element, with the lower surface of male tab 44 sliding over the upper surface of female tab 56. It is preferred that when the tabs are thus in contact, the registration of the openings 46 (FIG. 2) and 58 (FIG. 3) shall not be concentric -- that is, the device shall be in locking position. Concentricity is achieved by rotating tab 44 away from tab 56 by a suitable angle, say 120.degree. as shown in FIG. 1. At this point, a needle shaft will readily pass through the aligned openings.

Also, in this position as shown in FIG. 1, the two elements are inseparable without bringing tab 44 back down into contact with tab 56, since the stem portion 45 of the male element (FIG. 3) is prevented from moving longitudinally by its contact with the lower surface of the laterally-slotted portion of the sleeve 54 of the female element. Thus two elements are combined into an interengaged unit when the guard device is in a posture so as to be adjusted to the desired position on a cannula.

In the use of this device in a surgical procedure, the desired penetration depth may first be determined. The male and female elements are preferably preassembled in interengaged position as shown in FIG. 1, with the holes 46 and 58 concentric as shown in FIG. 4. The guard device is then slipped onto the shaft of the cannula to the desired position, after which the tabs 44 and 56 are brought into closer approximation as by squeezing them between thumb and forefinger, whereby the male and female elements are rotated with respect to each other. In this manner, the holes 46 and 58 become eccentric, as shown in FIG. 5, and the guard element is locked onto the cannula.

Penetration of the needle beyond the predetermined depth is prevented by the flange-like lower surface of the female element 50 coming into contact with the body surface. If desired, in some instances the guard may be temporarily positioned on the shaft remote from the tip, either in locked or unlocked position, and then moved and locked into the desired position.

Preferably, the tab on one element of the device is either longer or wider, or both, than the tab on the other element. That is, referring to FIG. 1, the height C of the male tab 44 may be greater than the height D of the female tab 56, or the length E of the male tab may be less than the length F of the female tab. Arrangements of this sort facilitate the insertion of a fingernail in wedging fashion between the two tabs, when the device is in locking position, in order to separate the tabs and restore concentricity of the openings 46 and 58.

In referring to a portion of the female element of the guard of this invention as "disk-shaped, " or to the elements as being "cylindrical, " it should be appreciated that these terms are exemplary and not restrictive. It will be obvious that the elements may take other shapes on their exterior surfaces provided that the proper concentricity-eccentricity of the apertures drilled therethrough is maintained. For convenience in handling, the outside surfaces of one or both elements may be knurled or provided with bosses or the like.

For economy, lightweight, and sterlizability it is preferred that the product of this invention be moulded from a slightly deformable plastic material such as DELRIN (a du Pont trademark for an acetal resin), polystyrene, polystyrene-acrylonitrile, or the like.

actual size, the disk-shaped element serving as the actual guard shield may be one inch or less in diameter, and the total heighth of the interlocked elements may be 0.75 inches or less, with other dimensions in proportion. In many routine thoracentesis procedures, a size 16 needle is used, 0.063 inches in outside diamter. Using a pair of moulded plastic elements, it has been found that the holes 46 and 58 need be no larger in diameter, and may even be as small as 0.060 inches in diameter and still provide an adjustable sliding fit on the No. 16 needle shaft, due to the slight deformability of plastic materials.

The guard may also be provided with means for stable securement and maintenance of the needle or cannula in place against dislodgement from the body cavity. As shown in FIG. 6, the bottom flange-like surface of the female element 50 may be provided with an adhesive mass 59, which may be pressed into adhering contact with the skin of the patient. The surface of the adhesive may be provided with a releasable facing sheet for protection of the adhesive mass prior to application, as in the case of the facings conventionally employed in adhesive finger bandages. Other means for securing the guard may be provided: for example, body straps 60 may be attached to the female element disk portion, as shown in FIG. 7.

Although the foregoing description relates to the use of the locking device of this invention in a thoracentesis procedure, it will be obvious to those skilled in the art that it is equally useful in limiting the depth of penetration of other rigid or semi-rigid surgical drainage appliances, such as plastic suprapubic catheters.

Claims

Having thus described my invention, I claim:

1. A guard member adapted to be locked onto the shaft of medical tubing for penetrating a body cavity comprising

a pair of interengageable guard elements,

one of said guard elements having a male projecting portion and the other of said guard elements having a counterpart female cavity portion into which the male portion is positioned,

said elements with their respective male and female portions being rotatable with respect to each other, each of said elements having an opening therethrough,

the openings in both elements being concentric with each other when the elements are in one position of orientation providing a passageway therethrough,

the openings in both elements being eccentric with respect to the true centers of said male projection and said female cavity portions;

the female element of said guard member comprising a cylindrical portion with a channel therethrough,

said channel having an inside diameter at least as great as the outside diameter of said male projecting portion,

said cylindrical portion of said female element having a slot extending both longitudinally and laterally,

both the male and female elements of said guard members being provided with projecting tab portions,

the tab on said male element being provided with a stem portion supporting the tab away from the cylindrical portion of said male element,

the width of said stem portion being not greater than the width of the slot in the cylindrical portion of said female element,

said male element being received within said female element by movement of said tab on said male element along said slot,

whereby a rotating force applied to one of said guard elements causes the openings in said elements to become eccentric to each other,

and whereby frictional engagement between the outer wall of the male projecting portion and the inner wall of the female cavity portion of said elements secures said portions against displacement.

2. The guard member according to claim 1 in which the openings in said male element and said female element are concentric with each other when the stem portion of the projecting tab portion of said male element is interengaged with the laterally slotted portion of the cylindrical portion of said female element.

3. The guard member according to claim 1 in which the projecting tab portions of the male and female elements are unequal in height.

4. The guard member according to claim 1 in which the projecting tab portions of the male and female elements are unequal in length.

5. The guard member according to claim 1 in which the cylindrical portion of said female element terminates in a flange-like disk portion substantially normal thereto.

6. The guard member according to claim 5 in which the flange-like disk portion of said female element is coated with a pressure-sensitive adhesive on its lower surface.

7. The guard member according to claim 5 in which the flange-like disk portion of said female element has straps extending therefrom.

8. The guard member according to claim 1 wherein said guard member includes means for attaching said member to the body.

9. An apparauts for penetrating a body cavity comprising:

a surgical member with an elongated shaft and

a guard member mounted on said shaft and lockable thereon against displacement along the axis of the shaft, said member compriying a pair of interengageable guard element;

each of said guard elements having an opening therethrough providing, in one position of the elements with respect to each other, a passageway through the guard member into which said shaft is inserted for mounting said guard thereon;

one of said guard elements having a male projecting portion and the other of said guard elements having a counterpart female cavity portion into which the male portion is positioned,

said elements with their respective male and female portions being rotatable with respect to each other,

the openings in both elements being concentric with each other when the elements are in one position of orientation providing a passageway therethrough,

the openings in both elements being eccentric with respect to the true centers of said male projection and said female cavity portions;

the female element of said guard member comprising a cylindrical portion with a channel therethrough,

said channel having an inside diameter at least as great as the outside diameter of said male projecting portion,

said cylindrical portion of said female element having a slot with a longitudinal portion extending from one end of said female element and having at its opposite end a lateral slot portion;

both the male and female elements of said guard members being provided with projecting tab portions,

the tab on said male element being provided with a stem portion supporting the tab away from the cylindrical portion of said male element,

the width of said stem portion being not greater than the width of the laterally slotted portion of the cylindrical portion of said female element,

the thickness of the stem portion of said tab portion of said male element being not greater than the width of the longitudinal slot portion in the cylindrical portion of said female element,

the male element being positioned with the stem of its tab portion opposite the open end of the lateral slot portion of said cylindrical portion of said female element,

whereby a rotating force applied to one of said guard elements, causes the openings in said elements to develop a position of eccentricity with respect to each other and to cause frictional engagement between the shaft and said openings,

and whereby frictional engagement between the outer wall of the male projecting portion and the inner wall of the female cavity portion of said elements secures said portions against displacement.

10. An apparatus in accordance with claim 9 wherein said guard elements are displaceable with respect to each other in a plane transverse to the axis of the shaft.