US 20090171299 A1
An adaptor comprises a plate having upper and lower surfaces, and oppositely disposed side edges therebetween. A luer mating structure is associated with the plate upper surface. A blunt cannula is associated with the lower surface. The blunt cannula has a proximal portion extending from the plate lower surface and a distal portion extending from the proximal portion to a tip end. A pair of generally flat guide walls extends from the plate side edges to either side of the blunt cannula.
1. An adaptor comprising:
a plate having upper and lower surfaces, and oppositely disposed side edges therebetween;
luer mating structure associated with the plate upper surface;
a blunt cannula associated with the lower surface, the blunt cannula having a proximal portion extending from the plate lower surface and a distal portion extending from the proximal portion to a tip end; and
a pair of generally flat guide walls extending from the plate side edges to either side of the blunt cannula.
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This application is a divisional of co-pending U.S. application Ser. No. 11/687,533 filed Mar. 16, 2007, the disclosure of which is incorporated herein by reference in its entirety.
The present invention relates to blunt cannulas used to adaptors having blunt cannulas.
Sample sites and injections sites typically comprise a plastic housing with one or more ports for fluid ingress or egress relative to the interior cavity of the housing. The housing also typically has a cylindrical portion defining a large aperture adjacent the cavity but which is closed off by a solid septum. A sharp needle may be inserted through the material of the septum to bring the distal opening of the needle at the sharp tip into communication with fluid within the housing to facilitate fluid flow through the lumen of the needle. To reduce needle-stick risks, the needle is contained within a shroud that is generally sized and shaped to prevent fingers from touching the needle tip. The shroud fits over the cylindrical portion of the housing as the needle extends into and through the septum into the cavity. In some arrangements, the shroud may also include slots positioned and sized to fit over the port(s) of the housing, and further may be shaped, such as to define a J-shape, so as to be rotatable relative to the port(s) to lock the shroud to the site.
In an effort to reduce or eliminate needles, the solid septum is replaced with a slit septum through which a blunt cannula is to be inserted. Typically, the blunt cannula may form part of an adaptor having luer mating structure to connect with the luer structure of a standard medical device, such as a syringe by way of example, in order to fluidly couple into the site cavity via the central lumen of the blunt cannula. The blunt cannula typically has an upper or proximal circular cross-section cylindrical portion, and a lower or distal portion that tapers to a tip, with the tip defining or including a distal opening for fluid flow relative to the central lumen of the blunt cannula. It has been proposed to control the taper of the distal portion so that it is gradual and uniform between the proximal portion and the tip, which uniform taper is said to reduce insertion forces necessary to insert the cannula through the slit. Also, the proximal portion is intended to be a cylinder without any significant taper, other than perhaps a nominal taper due to draft in the molding process, to reduce the tendency for kick back of the cannula (i.e., the septum material and cannula surface interacting in a manner which would urge the cannula back out of the slit) when the cannula is inserted far enough into the slit to reach the proximal portion of the cannula as is typically desired.
There are various drawbacks with these blunt cannulas. By way of example, the slit may not seal against the proximal portion of the cannula extending therein, thus creating an area for possible fluid leakage. Further, some of the tip ends of the blunt cannula have been found to be quite sharp. While that “sharp” end allows the cannula to make initial entry into the slit, a shroud is still necessary therewith to prevent finger-touching of the tip as was done with the sharp needles these blunt cannula were intended to replace. Alternatively, the tip end or surface of the cannula may be flat and so is desirably blunt rather than sharp. But the flat end can impede initial entry of the cannula into the slit.
The present invention provides an improved blunt cannula design with a uniquely shaped distal portion so as not to require a tip end that is either essentially sharp or flat while advantageously reducing insertion resistance. In accordance with the principles of the present invention, the distal portion of the blunt cannula presents a rounded tip end or surface, which may be solid, and a plurality of tapered segments having different tapers extending between the proximal portion and the tip end. The differently-tapered segments present a non-uniformly tapering distal portion which is believed to provide the advantage of reduced insertion forces, but without the disadvantage of a tip end that is so sharp as to have need for a protective shroud nor so flat as to impede entry into the septum slit.
The distal portion advantageously includes at least a conically tapered segment and a generally arcuately tapered segment. Further advantageously, there are four differently-tapered segments (by type and/or size). The four segments may alternate between conical and arcuate tapers. A first tapered segment adjacent the proximal portion may extend with a conical taper, followed by a second tapered segment having a generally arcuate taper with a radius of curvature. A third tapered segment may extend with a conical taper, which may advantageously be greater than the conical taper of the first tapered segment, and a fourth tapered segment may lead into the solid, rounded tip and may have a generally arcuate taper with a radius of curvature less than that of the second segment.
In accordance with a further aspect of the present invention, the central lumen of the blunt cannula extends distally through the proximal portion and only partially into the distal portion. Advantageously, the central lumen does not extend into the distal portion so far as to reach the solid, rounded tip end and further advantageously not so far as to reach even the lowermost tapered segment. To that end, some aspect of the tapered segment adjacent the tip (or that entire segment and possibly some aspect of the next, proximally adjacent segment) is solid. The fluid opening(s) of the distal portion coupling to the central lumen pass through one or more of the tapered segments, excluding the solid aspect(s) of the tapered segment. As a result, the fluid path to and from the central lumen via the fluid opening(s) advantageously will not extend into or through the tip so as not to interfere with the solid, rounded tip. A groove(s) may extend distally from the fluid opening(s) along some or all of the solid aspect(s) of the tapered segments toward, but not necessarily all the way, to the tip end. The fluid opening(s) may also extend through aspects of the proximal portion of the blunt cannula, particularly the aspect thereof closely adjacent to the distal portion of the blunt cannula.
The present invention may also or alternatively provide an improved blunt cannula design with a uniquely shaped proximal portion by which to enhance the seal between the septum slit and the blunt cannula during use. To that end, and in accordance with the principles of the present invention, the proximal portion of the blunt cannula may have a non-circular cross-section instead of a circular cross-section. Advantageously, the proximal portion is not a cylinder. In that regard, the cross-section of the proximal portion, at least along a substantial length thereof, is generally oval and tapers distally such that the major diameter of the oval cross-section decreases therealong to merge into the first tapered portion of the distal portion. It is believed that the shape created upon opening of the slit is not circular. The shaping of the proximal portion to have a generally oval cross-section is thus believed to afford a more complete seal between the surfaces of the slit and the blunt cannula during use. Yet, while the tapering of the major diameter of the proximal portion, along with the non-uniform taper of the distal portion, results in a blunt cannula that has a significant taper along substantially its entire length, it is believed that kickback is not problematic.
The blunt cannula of the present invention may form part of an adaptor to be used with a medical site, for example. In that regard, the medical site may be a sample site with oppositely disposed fluid ports extending from a central housing containing the septum to define a T-shape to the medical site. With such a T-shaped construction, fluid flows between the ports and across the septum. The central housing may be cylindrical, and support the septum at the top thereof adjacent the flow path. The adaptor has a plate with luer mating structure, such as a male luer lock, associated with one surface thereof and the blunt cannula extending from the opposite surface thereof with the central lumen of the cannula in fluid communication with the luer mating structure. Depending from opposite edges of the plate to either side of the blunt cannula is a pair of oppositely disposed, generally flat guide walls. The guide walls may have lateral edges extending into the area below the intermediate edges of the plate. Advantageously, the cannula may be spaced equidistant from the two guide walls. Further advantageously, the guide walls are spaced apart a distance approximating the diameter of the central housing such that the guide walls and housing cooperate to align the tip of the cannula with the slit of the septum for proper insertion therewith. One or more of the outboard or lateral edges of the guide walls may be provided with a rib aimed toward the blunt cannula and which further cooperates to align the blunt cannula to the slit.
The flat guide walls may be spaced apart enough to provide a distal mouth that is large enough not to preclude finger touching. The lateral edges of the flat guide walls may extend into the area below the intermediate edges of the plate sufficient to define a gap that conforms to the width of the port(s) so as to reduce the likelihood of rotation of the adaptor relative to the housing with the cannula inserted into the septum. While the guide walls could be shaped and positioned differently to provide a shroud and/or the ability to lock same to the site, it is not believed necessary to do so with the blunt cannula of the present invention and/or the adaptor containing same.
The outboard walls of the housing between the ports of the medical site could be generally flat rather than arcuate, such as by thickening the plastic thereat. The generally flat sides of the housing would cooperate with the generally flat guide walls to further enhance alignment and/or resist rotation. Advantageously, one or more of the lateral edges of the flat side walls of the housing define a groove edge to receive the rib(s) of the guide walls therealong to still further enhance alignment and/or resist rotation.
Where the proximal portion of the blunt cannula has a generally oval-cross-section, the cannula is advantageously inserted into the slit with the major diameter of the generally oval cross-section proximal portion aligned with the slit. To that end, the septum is generally affixed to the site housing aperture with the slit in a fixed orientation relative to the flow path between the ports. The blunt cannula and guide walls of the adaptor are fixed in relationship such that the major diameter of the proximal portion of the blunt cannula extends at an orientation thereto corresponding to the orientation of the slit of the septum relative to the fluid ports. Advantageously for the present invention, the slit orientation may be transverse to that flow path, in which case the blunt cannula is oriented in the adaptor with the major diameter transverse to the guide walls (i.e., with the minor diameter thereof parallel to the guide walls). The gap(s) between the lateral edges of the guide walls and/or the interaction of the rib(s) of the adaptor and the groove edge(s) of the site housing resist rotation of the blunt cannula aligned into the slit.
By virtue of the foregoing, there is thus provided an improved blunt cannula design with a uniquely shaped distal portion so as not to require a tip that is either essentially sharp or flat while advantageously reducing insertion resistance. There is thus also provided an improved blunt cannula design with a uniquely shaped proximal portion by which to enhance the seal between the septum slit and the blunt cannula during use. There is further also provided an adaptor with the improved blunt cannula design(s) for use in accessing the slit septum of medical sites. There is still further provided a medical site configured to advantageously mate with the adaptor. These and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the general description of the invention given above and the detailed description of the embodiments given below, serve to explain the principles of the present invention.
With reference to
Advantageously, the tapered segments 22, 24, 26, 28 alternate between conical and arcuate tapers. To that end, first and third tapered segments 22, 26 have conical tapers and second and fourth tapered segments 24, 28 have arcuate tapers. The taper of the third tapered segment 26 is advantageously larger than that of the first tapered segment 22. By way of example, the taper of the first tapered segment 22 may be about 1° while that of the third tapered segment may be about 5°. The arcuate tapers of the second and fourth tapered segments 24 and 28 may also differ, with the radius of curvature of the latter smaller than that of the former. To that end, the radius of curvature of the second tapered segment 24 may be about ¼ inch while that of the fourth tapered segment may be slightly greater than 1/16 inch. The tip segment 16 may have a radius of about 1/36 inch to define rounded end 18.
In accordance with a further aspect of the present invention, the proximal portion 12 advantageously has a non-circular cross-section such as an oval cross section as seen particularly in
A fluid lumen 36 extends centrally from the upper end opening 31 of cannula 10 through proximal portion 12 and partially into distal portion 14, but terminates as at 38 spaced away from tip end 18. Advantageously, lumen 36 extends through the first and second tapered segments 22, 24 but only partially into third tapered segment 26, such that the rest 40 of tapered segment 26, and all of fourth tapered segment 28 and tip segment 16 are solid. Fluid communication is established with central lumen 36 via one or more fluid openings 44 extending through an aspect of proximal portion 12 as at 45 and the portions of first, second and third tapered segments 22, 24, 26 coextensive with lumen 36, excluding the solid portion 40 of tapered segment 26 and all of solid tapered segment 28 and solid tip segment 16, such that the fluid path to and from the central lumen 36 via the fluid opening 44 does not extend into or through tip end 18. As shown in
With reference to
The tapering of proximal and distal portions 12 and 14 presents a significant taper along substantially the entire length of cannula 10, but it is believed that with the foregoing arrangement, kickback is not problematic.
In accordance with yet another aspect of the present invention, the blunt cannula with the non-circular cross-section proximal portion 12 and/or the non-uniform tapered distal portion 14 may form part of an adaptor 60 for accessing a medical site 62 (
Guide walls 76, 78 have lateral edges as at 85, one or more of which may be provided with a rib 86 along a radial of the centerline of cannula 10 so as to be aimed toward cannula 10. Further, lateral edges 85 may extend as at 87 into the area 90 below the intermediate edges 92, 94 of plate 64, but if they do so extend, may advantageously form a gap 96 therebetween.
The adaptor 60 may be used with a medical site such as a sample site 62 shown in
Housing 102 may be supported on struts 120 which extend and are coupled to outboard support walls 122, each having an elongated flat portion 124 and lateral arcuate edges 126, the latter being secured to bracket 128. The flat portions 124 each define an inner surface 130 confronting housing 102 and an outer surface 136 facing away from housing 102. One or more ridges 138 are disposed on the outer surface(s) 136 of flat portion(s) 124 to facilitate gripping site 62. Ridges 138 each extend in a line in the same direction as the elongated flat portion on to which they are disposed so as not to form radially inwardly or outwardly curvatures thereof relative to housing 102.
An alternative sample site 62′ is shown in
In use, ports 104 of site 62 typically are connected to tubing such as in a closed blood sampling system. The cavity 106 of site 62 may be accessed by blunt cannula 10 to withdraw fluid from cavity 106. To that end, a syringe (not shown) may be coupled to luer connector 68 and adaptor 60 is positioned with guide walls 76, 78 to either side of housing 102 and ports 104 aligned with gaps 96. The user (not shown) may grip site 62 by support walls 122 and push adaptor 60 down over housing 102 to insert cannula 10, tip end 18 first, into slit 52 with the major diameter (DMAJ) of proximal portion 12 aligned with slit 52. The adaptor 60 may be pushed into place until the guide walls 76, 78 hits against struts 120 whereat portion 12 extends into slit 52 and distal portion 14 is in the cavity 106 so as to communicate with fluid path 54 extending therein as seen in
While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is, therefore, not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the general inventive concept.
Having described the invention, what is claimed is: