This invention relates generally to implantable medication delivery devices, sometimes referred to as infusion pumps, having one or more inlet ports configured to exchange fluid with a hypodermic needle.
Typical implantable medication delivery devices include two needle receiving ports; i.e., (1) a reservoir fill port and (2) a catheter access port. The reservoir fill port includes an entrance opening configured to allow a hypodermic needle to penetrate a self healing septum for discharging medication to fill an internal reservoir. The catheter access port includes an entrance opening configured to allow a hypodermic needle to penetrate a self healing septum for introducing fluid into or extracting fluid from a catheter. It is often desirable to use differently sized needles for different functions. For example, a larger needle (e.g., 22 gauge) is generally desired for rapid reservoir filling and a smaller needle (e.g., 25 gauge) is generally desired for catheter access.
In order to prevent the inadvertent use of a larger needle in the catheter access port, U.S. Pat. No. 5,328,465 teaches using a screen member above the catheter access port septum for limiting access to hypodermic needles smaller than a predetermined size; e.g., 25 gauge.
U.S. Pat. No. 6,293,922 cites the aforementioned U.S. Pat. No. 5,328,465 and observes that “a few shortcomings of such screens are that they tend to damage hypodermic needles when a needle is inserted not aligned with a hole in the screen”. U.S. Pat. No. 6,293,922 then describes an alternative device intended to eliminate or reduce the possibility of “inadvertent injections of drug directly into the catheter access port without damaging hypodermic needles”. More particularly, U.S. Pat. No. 6,293,922 describes a device wherein a conical depression guides a hypodermic needle into a hole at the center of the depression. The diameter of the hole is chosen to prevent needles having a diameter greater than a certain size, e.g., 25 gauge, from passing therethrough to the septum.
The present invention is directed to a medication delivery device having a housing including at least one needle receiving port comprising a septum and a needle entrance opening. The entrance opening in accordance with the invention comprises an elongate slot having a length L and a width W where L is significantly greater than W and where W is dimensioned to pass only needles smaller than a certain size.
The use of an entrance opening slot, rather than a single hole as in U.S. Pat. No. 6,293,922, allows the needle to successively penetrate the underlying septum at randomly located points. This avoids repeated penetrations at the same location and thus enhances the long term reliability of the septum and thus, the device.
Moreover, the use of a slot, rather than a hole, reduces the likelihood of physical damage to the hypodermic needle, e.g., bending. That is, the needle is less constrained when inserted through a slot since only the slot side walls (i.e., slot walls spaced by the width) are likely to engage the needle. The slot end walls spaced by the slot length provide significant freedom of movement in the length direction and reduce the potential of needle damage.
In an exemplary embodiment of the invention, the entrance opening of a catheter access port comprises a slot dimensioned to admit 25 gauge needles (having an outer diameter of about 0.0205 inches), or smaller. In a preferred embodiment, the access port entrance opening slot has a length L, of about 0.1200 inches, and a much smaller slot width W of about 0.0210 inches to prevent needles larger than 25 gauge from passing therethrough.
The slot is preferably located at the bottom of an oval shaped depression whose sloping peripheral wall surface converges downwardly toward the slot. The peripheral wall surface is preferably smooth to enable it to readily guide the needle tip toward the slot. The peripheral wall flares upwardly and outwardly from the slot to provide a large target area for receiving and guiding the needle tip.
Slotted entrance openings in accordance with the invention are useful in a variety of differently configured implantable medication delivery devices. For example, in one application, multiple devices each having only one needle receiving port are configured with differently sized entrance slots so that each device will reject needles larger than a certain size. This facilitates the use of a plurality of such devices implanted in close proximity in a body since it reduces the risk of introducing a wrong needle into a port.
Additionally, the use of differently sized entrance slots facilitates the inclusion of multiple medication reservoirs within a single device. That is, it is convenient to provide an implantable device having two or more reservoirs with each reservoir having a separate fill port and with the multiple fill ports each having a differently sized slot. This feature reduces the risk of a particular needle being introduced into the wrong fill port.
Attention is initially directed to
The inlet port 14 includes a conventional needle receiving entrance opening 20 which is shown as being large enough to accept virtually any size hypodermic needle. The inlet port 16 includes a needle receiving entrance opening 28 comprising a slot having a width narrow enough to prevent the entry of needles larger than a certain size.
In the use of many existing devices, it is typical to use a large hypodermic needle, e.g., 22 gauge, for rapidly filling the reservoir 36 through the inlet port 14. In contrast, however, for safety reasons, it is generally preferred to use a smaller needle, e.g., 25 gauge, to access the catheter via port 16. In order to reduce the likelihood of a clinician inadvertently using the larger needle in port 16, it has been suggested (e.g. U.S. Pat. No. 6,293,922) that the port 16 have a central needle entrance hole whose diameter is only large enough to accept the smaller needle.
Attention is now directed to
The slot 48 is preferably formed in the bottom of an oval depression 62 formed in a frame structure 64. More particularly, note that frame structure 64 defines an oval top frame 66 surrounding an oval region 68. The depression 62 is formed in the region 68 by a downwardly converging peripheral wall surface 70 leading to the slot 48.
The slot 48 overlays a self healing septum 76 which is mounted above chamber 78. Chamber 78 is surrounded by a filter ring 80. A passageway 82 outside of the filter ring 80 communicates with channel 84 which leads to the aforementioned catheter outlet port 18.
The following table shows the dimensions of standard hypodermic needles for various gauge sizes. The table demonstrates that in order to restrict access to slot 48 to needles 25 gauge and smaller, the slot should have a width W of about 0.0210 inches between side walls 50 and 52.
1. Tolerance ∵ 10%
1. Tolerances:
2. ⅜ inch and shorter, ± 1/32 inch
3. ½ inch to ¾ inch, ± 3/64 inch
4. ⅞ inch to 1½ inch, ± 1/16 inch
5. 1¾ inches to 2½ inches, ± 5/64 inch
The use of a slot 48 having a width W and a length L considerably greater than W, affords multiple advantages as contrasted with the prior art. Initially, because the length L is several times greater than the width W, the needle is likely to pierce the septum at different points during successive penetrations. By not restricting the needle piercing to a single location, the long term reliability and useful life of the septum and device is enhanced. Moreover, the potential of needle damage is reduced because the needle is physically constrained only by the width dimension between side walls 50 and 52 and not by the length dimension between end walls 56 and 58. Further, the use of an oval depression 62 and slotted entrance opening 48 provides a larger target area for a clinician to properly insert the needle through the patient's skin in alignment with the oval depression peripheral surface 70. Note that the peripheral surface 70 flairs upwardly and outwardly from the entrance opening slot 48 to define the large oval depression 62 and target area. The peripheral surface 70 converges downwardly from frame 66 toward slot 48 and is preferably quite smooth so as to be able to easily guide a needle tip toward the slot 48.
Attention is now directed to
In accordance with the invention, the entrance opening slot 104 has a width W and a length L at least four times greater than W. The slot 104, as has been previously described, is surrounded by a slopping peripheral wall surface 124 which converges downwardly toward the slot. The slot width W is selected to prevent penetration by a hypodermic needle larger than a certain size. It is contemplated in accordance with the invention that a patient can have multiple single port devices 100 implanted in his body in close proximity. The devices can be used to discharge needed flow rates of different medications or of the same medication to different sites. Regardless, in order to reduce the risk of penetrating a port 102 with a wrong needle, the multiple devices are selected so as to have different slot widths.
The implantable devices thus far described with reference to
In the device of
Although the figures mentioned thus far all depict an entrance opening in the form of a straight elongate slot, it is recognized that the entrance opening slots can be alternatively configured. Thus,
From the foregoing, it should be recognized that improved needle receiving port configurations have been disclosed for implantable medical delivery devices. Although only a limited number of inlet port configurations have been specifically disclosed, it should be understood that various alternative and equivalent configurations will occur to those skilled in the art which are consistent with the teachings of the present invention and within the intended scope of the appended claims.
This application is a continuation of international application PCT/US04/12464 filed on 22 Apr. 2004 which claims priority based on U.S. provisional application 60/465,604 filed on 24 Apr. 2003. This application claims priority based on said aforementioned applications.
Number | Date | Country | |
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60465604 | Apr 2003 | US |
Number | Date | Country | |
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Parent | PCT/US04/12464 | Apr 2004 | US |
Child | 11255686 | Oct 2005 | US |