Unidirectional Blunting Apparatus for Hypodermic Needles

The present invention relates generally to medical devices, and more particularly to a blunting apparatus useable to prevent hypodermic needles from causing inadvertent penetration trauma.

In view of the potential for inadvertent infection of healthcare workers with blood born pathogens such as human immunodeficiency virus (HIV) and hepatitis B. There exists an ongoing motivation to provide safety devices and apparatus for preventing healthcare workers from incurring inadvertent needle trauma when handling used hypodermic needles.

Examples of devices and apparatus which have heretofore been known for preventing inadvertent trauma by hypodermic needles (e.g., intravenous needles) and the like, include those described in U.S. Pat. Nos. 5,112,312; 5,120,317 and 5,273,540.

Although many of the heretofore proposed needle safety devices and apparatus do effectively prevent or deter inadvertent needle trauma, none of these prior devices or apparatus are universally usable in connection with all types of hypodermic needles, in all applicable clinical situations. Accordingly, there remains a need for the development of additional safety devices and/or apparatus for preventing or deterring inadvertent needle sticks, especially when handling used hypodermic needles.

The present invention provides a blunting apparatus which is usable in conjunction with any type of hollow needle having a sharpened distal tip. The blunting apparatus preferably comprises an elongate blunting member having a blunt distal tip, and an outer diameter which is only slightly smaller than the inner diameter of the needle lumen. The blunting member is axially disposed within the needle lumen and is moveable from first "non-blunting" position wherein the blunt distal tip of the blunting member resides within the lumen of the needle, to a second "blunting" position wherein the blunt distal tip of the blunting member protrudes out of the sharpened distal tip of the needle. A positioning member may be formed on the proximal end of the blunting member, such positioning member being engageable with the proximal end of the needle to alternately hold the blunting member in its "nonblunting" or its "blunting" position.

In accordance with the invention, one type of positioning member which may be mounted on the proximal end of the blunting member is a generally cylindrical member having a series of annular engagement fins formed thereabout. Such annular engagement fins are preferably formed of elastomeric or pliable material, and are sized to be advanceable into the bore of a proximal hub formed on the hollow needle. In this regard, as the engagement fins are advanced into the bore, they will be proximally deflected by and frictionally engaged by the inner surface of the needle hub bore. In this manner, such proximal deflection and frictional engagement of the annular fins with the inner surface of the needle hub bore will substantially hold the blunting member in either its "nonblunting" or its "blunting" position, and will substantially deter inadvertent proximal retraction of the blunting member.

Various additional objects and advantages of the present invention will become apparent to those skilled in the art upon reading and understanding of the following detailed description of a preferred embodiment.

FIG. 1 is a perspective view of an over-the-needle intravenous cannula assembly of the present invention having a needle safety sheath mounted thereon.

FIG. 2 is a perspective view of the intravenous cannula assembly of FIG. 1 following removal of the needle safety sheath therefrom and following slight proximal retraction of the needle blunting apparatus which is incorporated therein.

FIG. 3 is an exploded view of the intravenous cannula assembly shown in FIG. 2.

FIG. 4 is a partial longitudinal section view of an intravenous cannula assembly of the present invention wherein the needle blunting apparatus is in its proximally retracted "non-blunting" position.

FIG. 5 is a partial longitudinal view of an intravenous cannula assembly of the present invention wherein the needle blunting apparatus is in its distally advanced "blunting" position.

FIGS. 6a, 6b and 6c are a step-wise illustration of a preferred method of using the intravenous cannula assembly of the present invention.

The following detailed description and the accompanying drawings are provided for the purpose of describing and illustrating presently preferred embodiments of the invention only, and are not intended to limit the scope of the invention in any way.

With reference to the drawings, there is shown an over-the-needle intravenous cannula assembly 10 comprising a pliable intravenous cannula 12, a needle 14 and a needle blunting apparatus 16.

The intravenous cannula 12 of the assembly 10 comprises an elongate pliable tubular sheath 18 having a distal taper 20 and a hollow lumen 22 extending longitudinally therethrough. A Luer hub 24 is formed on the proximal end of the elongate pliable sheath 18, as shown.

The needle 14 of the assembly 10 comprises a rigid, elongate needle member 26 having a beveled or otherwise sharpened distal tip 28 and a hollow needle lumen 30 extending longitudinally therethrough. A transparent or partially transparent flash chamber 32 is mounted on the proximal end of the needle member 26. A hollow flash chamber bore 34 extends longitudinally through the flash chamber 32 and leads directly into the hollow lumen 30 of the needle member 26. A cylindrical distal sleeve portion 38, a tapered distal seating member 36 and an annular shoulder 39 are formed on the distal aspect of the flash chamber 32, as shown.

The needle blunting apparatus 16 of the present invention comprises an elongate rigid blunting member 40 formed of material such as stainless steel hypotubing. This rigid blunting member 40 has an outer diameter which is slightly smaller than the inner diameter of the needle member 26. This elongate rigid blunting member 40 has an opening formed in its blunt distal tip 42 and a hollow lumen which extends longitudinally therethrough from the opening in the blunt distal tip to a plurality of proximal outlet apertures 48 formed in the sidewall of the blunting member 40, near its proximal end.

A unidirectional positioning member 44 is mounted on the proximal end of the elongate rigid tube 40. Such unidirectional positioning member 44 is a generally cylindrical body having a series of annular, elastomeric engagement fins 46 formed thereon. These engagement fins 46 are spaced apart and formed in a longitudinal array, as shown. A proximal end surface 50 is formed on the proximal end of the positioning member 44.

FIGS. 4 and 5 show the manner in which the blunting apparatus 16 is inserted through the needle 14 of the assembly 10 to prevent the occurrence of inadvertent skin puncture or other trauma by the beveled or sharpened distal tip 28 of the needle 14. With specific reference to FIG. 4, the blunting apparatus 16 is initially positioned in a first "non-blunting" position wherein only the distal-most ones of the engagement fins 46 are advanced into the proximal portion of the flash chamber bore 34, such that those distal-most ones of the engagement fins 46 are in abutment with, and are proximally deflected by, the surrounding inner wall 45 of the flash chamber bore 34, as shown. When so positioned in its first non-blunting position, blunt distal tip 42 of the blunting member 40 resides within the lumen 30 of the needle 26, at a spaced distance X.sub.1 proximal to the sharpened distal needle tip 28.

With reference to FIG. 5, when it is desired to advance the blunting apparatus 16 to its second "blunting" position, distally directed finger pressure may be applied against the proximal surface 50 of the proximal positioning member 44, thereby pushing the blunting apparatus 16 further through the lumen 30 of the needle, to a second position wherein the blunt distal tip 42 of the blunting member 40 extends out of and slightly beyond the sharped distal needle tip 28, thereby preventing the sharpened distal needle tip 28 from causing penetration trauma. When so advanced to its second "blunting" position, the proximal positioning member 44 is further advanced into the flash chamber bore 34, causing additional ones of the engagement fins 46 to be advanced into the bore 34 and to come into abutment with, and to be proximally deflected by, the surrounding inner wall 45 of the bore 34. Such frictional engagement and proximal deflection of the engagement fins 46 by the inner wall 45 of the bore 34 substantially deters or prevents the blunting apparatus 16 from moving or being retracted in the proximal direction. Such deterrence against subsequent proximal retraction of the blunting member 16 ensures that the blunting member 16 will remain in its second "blunting" position, after the needle member 14 has been removed and discarded.

FIGS. 6a-6c show, in step wise fashion, a preferred method of utilizing the intravenous cannula assembly 10 shown in FIGS. 1-5.

As shown, the protective sheath 11 is initially removed from the intravenous cannula assembly 10, and the blunting apparatus 16 is deployed in its initial or "first" position as shown in FIG. 4. With the blunting apparatus 16 in such first position, the blunt distal tip 42 of the elongate blunting member 40 of the blunting apparatus 16 is retracted within the lumen 30 of the needle member 26 a spaced distance X.sub.1 from the sharpened distal tip 28 of the needle member 26. This allows the sharpened distal tip 28 of the needle 26 to be introduced percutaneously into a blood vessel BV. The introduction of the needle member 26 into the blood vessel BV is verified by the backflow of blood through the lumen 30 of the needle member 26 and the lumen of the blunting member 40 into the flash chamber 32 via the outlet apertures 48 within the blunting member 40. After the distal tip of the needle member 26 has been inserted into the blood vessel BV, the needle 14 and the accompanying blunting apparatus 16 (positioned in its "blunting" position) are retracted in the proximal direction, and thumb pressure is applied to the proximal surface 50 of the positioning member 44 of the blunting apparatus 16, thereby forcing the blunting apparatus 16 to move from its first position (FIG. 4) to its second position (FIG. 5) simultaneously with proximal retraction and withdrawal of the needle 14, as shown in FIG. 6b. When in its second position, the distal tip 42 of the blunting member 40 is spaced a distance X.sub.2 distally beyond the distal tip 28 of the needle member 26.

Thus, upon its withdrawal, the sharp distal tip 28 of the rigid needle member 26 is effectively blunted or shielded by the blunt distal tip 42 of the elongate blunting member 40 so as to prevent or deter health care workers, trash carriers or others from suffering inadvertent trauma by the sharpened distal tip 28 of the rigid needle member 26.

After the needle 14 and blunting apparatus 16 have been discarded, a solution administration tube SAT having a Luer connector LC thereon is attached to the Luer hub 24 of the intravenous cannula 12 to accomplish fluid infusion through the pliable tubular cannula 18 of the intravenous cannula apparatus 12.

It will be appreciated by those skilled in the art that the invention has been described hereabove with reference to certain presently preferred embodiments only and no effort has been made to exhaustively describe all possible embodiments in which the invention may be practiced. Indeed, those skilled in the art will recognize that various addition, deletions and modifications may be made to the above-described embodiments without departing from the intended spirit and scope of the invention. Accordingly, it is intended that all such additions, deletions and modifications be included within the scope of the following claims.