Patent Application
20130103006
The present invention relates to implantable pumps, more particularly, an improved safety feature for preventing overdosage to a patient.
Implantable pumps have been well known and widely utilized for many years. Typically, pumps of this type are implanted into patients who require the delivery of medication or other fluids (hereinafter referred to as “active substances”) to specific areas of their body. For example, patients that are experiencing severe pain may require pain killers daily or multiple times per day. Absent the use of an implantable pump or the like, a patient of this type would be subjected to one or more painful injections of such active substances. In the case of pain associated with more remote areas of the body, such as spine, these injections may be extremely difficult to administer and particularly painful for the patient. Furthermore, attempting to treat conditions such as this through oral or intravascular administration of an active substance often requires higher doses and may cause severe side effects. Therefore, it is widely recognized that utilizing an implantable pump may be beneficial to both the patient and the treating physician.
Many implantable pump designs have been proposed. For example, U.S. Pat. No. 4,969,873 (“the '873 patent”), the disclosure of which is hereby incorporated by reference herein, teaches one such design. The '873 patent is an example of a constant flow pump, which typically includes a housing having two chambers, the first chamber for holding the active substance to be administered to the patient and the second chamber for holding a propellant. A flexible membrane separates the two chambers such that expansion of the propellant in the second chamber pushes the active substance out of the first chamber. This type of pump also typically includes an outlet opening connected to both the first chamber and a catheter or other delivery device for directing the active substance to the desired area of the body, a replenishment port for allowing refilling of the first chamber, and a bolus or catheter direct access port for allowing the direct introduction (i.e., a bolus dose) of an active substance through the catheter without having to pass through other portions of the pump. Bolus dosages can be important in treating moments of intolerable pain or other situations where a patient requires a quick does of an active substance. The replenishment and bolus ports are typically each covered by septa, which reseal after a filling device such as a needle, syringe, cannula or the like (hereinafter “an injection device”) is passed therethrough.
As pumps of this type are designed to provide a constant flow of active substance to a specific area of the body, they must be refilled periodically with the proper concentration of active substance suited for extended release. The overall volume of active substance to be contained in the first chamber is often significantly more than would be given to a patient in a single bolus dose. It has been a safety concern for some time that medication meant to refill the first chamber not be inadvertently administered as a bolus dose. In fact, the prior art is replete with different safety features for preventing such an inadvertent administration of an active substance.
For instance, U.S. Pat. No. 4,978,338 (“the '338 patent”), the disclosure of which is hereby incorporated by reference herein, teaches the use of multiple syringes each having an opening set forth at a different height. The openings in the syringes of the '338 patent are meant to be utilized in connection with a multiple septum pump design so that only a syringe having an opening at a certain height can be utilized to administer a bolus dose. U.S. Pat. Nos. 5,328,465 (“the '465 patent”) and 6,293,932 (“the '932 patent”), the disclosures of which are also hereby incorporated by reference herein, each teach pump structures overlying bolus ports that are sized to only allow injection devices of a certain diameter to be inserted therethrough. More particularly, the '465 patent teaches a screen member having a plurality of circular openings that will only allow injection devices of a size less than a predetermined diameter to pass therethrough, while the '932 patent teaches a conical depression having a single opening that is similarly sized to only allow injection devices having a certain diameter to pass therethrough. Although these prior art safety features may indeed fulfill their intended purposes, they all include their own drawbacks.
The '338 patent, for instance, is relatively complex and requires injection devices having openings situated at different heights. The '465 and '932 patents, on the other hand, both include structure that can lead to damage of an injection device tip if the injection device is not held properly during attempted insertion into the pump. Specifically, the '932 patent includes only a single opening, and although such reference describes the conical depression as having a smooth surface and an angle such that injection devices are guided into the single opening, such design often leads to inadvertent damage of an injection device tip during insertion. Moreover, the '465 patent teaches a screen member having a plurality of circular openings that are situated such that a plurality of “flats” (solid surfaces) extend therebetween. During insertion, if the injection device tip hits the relatively large solid surface between the circular openings, there is the potential of damage to the injection device tip.
Therefore, there exists a need for an improved safety feature for preventing inadvertent bolus dosages.
A first aspect of the present invention is an implantable pump. According to one embodiment, the pump includes a housing having a replenishment port and a bolus port, a cover disposed on the housing, the cover partially covering the bolus port and including an entry opening allowing for entry into the bolus port, and a screen member associated with the entry opening, the screen member including a plurality of square holes sized so as to prevent entry of an injection device having a larger size into the bolus port.
According to other embodiments of the first aspect, the implantable pump may include additional and/or modified components. For instance, the replenishment and bolus ports may be covered by septa. The bolus port may extend around the perimeter of the housing, and the housing may be circular with the entry opening being an arcuate portion. Still further, the entry opening may include sloped walls and bounding walls disposed at its ends. The bounding walls may converge towards the replenishment opening. The square holes of the screen member may include sloped walls. The screen member may be constructed of a metallic material, may be a wire mesh, may be disposed between the housing and the cover, may be press fit within the entry opening, and may include a flange. Additionally, the cover may further include a replenishment opening allowing for entry into the replenishment port, and the injection device may be a needle or syringe.
A second aspect of the present invention is a screen member for use in an implantable pump. According to one embodiment, the screen member includes a body having a plurality of square holes formed therethrough and a flange, wherein the square holes include sloped walls defining a minimum size so as to prevent entry of an injection device having a larger size therein. The body may be constructed of a metallic material, may be a wire mesh, may include a flange, and may be of an arcuate shape.
A third aspect of the present invention is another implantable pump. The pump includes a housing having a replenishment port and a bolus port and a plurality of pins partially covering the bolus port, the plurality of pins defining a plurality of holes sized so as to prevent entry of an injection device having a larger size into the bolus port. The pump may further include a cover covering the housing, and the cover may define an entry opening allowing access to the bolus port. The housing may be circular and the entry opening may be an arcuate portion. The entry opening may include sloped walls and bounding walls disposed at its ends. The plurality of pins may be disposed within hole formed in the sloped walls and bounding walls. The plurality of holes may be defined by the plurality of pins are square shaped. The pins may be constructed of a metallic material. The injection device may be a needle or syringe.
A more complete appreciation of the subject matter of the present invention and the various advantages thereof, can be realized by reference to the following detailed description in which reference is made to the accompanying drawings in which:
In describing the preferred embodiments of the subject matter illustrated and to be described with respect to the drawings, specific terminology will be used for the sake of clarity. However, the invention is not intended to be limited to any specific terms used herein, and it is to be understood that each specific term used herein includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
Referring to the drawings wherein like reference numerals refer to like elements, there is shown in
As is shown in
As shown in
Screen member 30 may be constructed of many different types of materials, including metallic materials and polymeric materials. However, the member is preferably designed so as to be hard enough to prevent an injection device from penetrating through any of its solid portions. Although shown as disc-shaped (i.e., circular and flat), screen member 30 can employ many different shapes, including, but not limited to, flat structures that employ a square, rectangle, elongate curved, or oval shape, as well as non-flat structures of similar shapes. Moreover, it is to be understood that the particular opening 32 layout of the screen member shown in
As is shown in
During the administration of a bolus dose, a doctor or other medical professional would select a properly sized injection device and insert such through the patient's skin over the area of opening 236. As is noted above, the structure of that opening, including walls 240a and 240b, is such that it preferably can be felt from outside of the patient's skin, thereby providing a landmark for the initial insertion of the syringe. Walls 238a and 238b again are sloped so as to preferably guide the syringe towards screen 230. Once in contact with screen 230, the tip of the injection device is preferably then guided into one of openings 232, which also include sloped walls to aid in the smooth insertion of the syringe. If the injection device is properly sized, it is allowed to pass through openings 232 and ultimately through the ring septum (not shown) and into the bolus opening (also not shown). However, if the injection device includes too large a diameter, like that meant for a replenishment process, the diameter of openings 232 act as a block to the insertion of the syringe. Moreover, the configuration of openings 232 acts to soften the force that occurs when an injection device is “rejected” from insertion. In certain cases, the tip of the injection device may enter opening 232, but not pass therethrough. This prevents inadvertent damage to the tip of an injection device that may thereafter still be utilized in, for instance, a replenishment process. Although this method has been discussed in connection with the embodiment depicted in
Another embodiment pump 310 is depicted in
Opening 336 again only extends along a portion of the perimeter of pump 310, but it is to be understood that such could extend as much as entirely therearound. Opening 336 preferably also includes side walls which are rounded so as to aid in guiding an injection device towards openings 332. The rounded nature of pins 350a-f also aids in the introduction of an injection device through openings 332, while also providing a minimum opening size at the base of such openings. That minimum opening size is preferably such that only injection devices having a certain diameter or smaller can be inserted therethrough and into the septum. Thus, like in the above-discussed screen member, injection devices having a larger diameter are generally designated for a replenishment procedure, while injection devices of a smaller size are utilized for administering a bolus dose as described above.
In the embodiment shown in
During construction of pump 310 in accordance with this second embodiment, pins 350a-f are inserted within the holes formed in cover 312. It is to be understood that certain of those holes may be blind holes, i.e., only extending partially through the wall in which they are formed. In such a case, a corresponding hole would preferably extend entirely through the opposite wall, and the pin insertion would begin at the wall with the complete hole. This results in a situation where the pin could not be inserted too far, i.e., entirely through a hole. As is noted above, pins 350a-f can be affixed within the holes of cover 312 by virtue of a tight fit therewith or other means may be employed. Additionally, in the embodiment shown in
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
