The present invention relates to an infusion device for subcutaneous administering a medication or a therapeutic fluid to a patient, comprising a base element, which comprises fluid receiving means for receiving said fluid and fluid communication means for transferring said fluid into a cannula, said base element being provided with at least one recess accommodating a septum being pierceable by a needle.
Infusion devices are generally known in the art for delivering a medication or a therapeutic fluid, including insulin to a subcutaneous site in a patient. Such infusion devices commonly comprise a tubular cannula extending into the subcutaneous site of the patient from a housing adapted to receive the desired medication. Said cannula may either be rigid or soft, a rigid usually being a steel cannula although other possibilities exist, and a soft being e.g. a TeflonĀ® cannula, but it is however possible to utilise several other polymer material cannulas.
In order to inject a soft tubular cannula into a patient, an infusion device may be provided with a septum being pierceable by a discardable insertion needle, allowing for a single injection of the insertion needle surrounded by the soft cannula for placement of the soft cannula inside a patient. A soft cannula allows for increased user comfort when moving around wearing such an infusion device.
In order to improve user mobility, the housing of the infusion device may be disconnectably connected to further components of the infusion system, e.g. to a comparatively large insulin pump. The user is accordingly enabled to perform activities which do not allow the presence of such a pump or the like.
In order to provide such disconnectable means and still maintain a fluid tight sealing towards the interior of the housing and the tubular cannula in order to prevent contamination of the injection site, such devices are commonly provided with a self-sealing penetrable septum on either the housing or the disconnectable component and a hollow needle on the other part adapted to penetrate the septum. Upon withdrawal of the needle from the septum, possibly multiple times, this provides a fluid-tight sealing between the housing and the connector means when medication or therapeutic fluid, particularly insulin is delivered to the patient from the external parts of the infusion system.
The manufacture of such an infusion device including one or more septums is rather cumbersome for several reasons. Firstly, the device is relatively small in order to attach to the skin comfortably and consequently the constituting parts of the device are relatively small, which complicates assembly of the device. Secondly, the securing of a septum inside the device involves both fixation to the device and fluid-sealing against the contributing parts of the device abutting the septum. Fixation is important, as an improperly fixed septum, due to the elasticity of the septum material, elastically bends and provides resistance, when a needle is inserted into the septum, and fixation and fluid sealing is important in order to provide a leak tight device. For these reasons the assembly of the device often involves the use of many small parts, which adds to the complicated manufacture.
Different approaches to secure a septum to an infusion device are known. A known and widely used approach is mounting a septum with a generally circular cross section in a fluid-tight and compressed manner between two annular discs or jaws with a smaller cross section than said septum, compressing the septum to a lesser thickness than in its unstressed condition. A drawback is the thus secured compressed septum being subject to fatigue induced fracturing.
U.S. Pat. No. 5,968,011 discloses a septum containing subcutaneous injection set, which set comprises a base element with a hub and a top element rotatably attached to said base element by the use of a flange. In one embodiment a septum is secured inside a cavity in the base element, said septum being fixed by resting against cannula securing means. The injection set is fluid-sealed by ultrasonic welding the septum sides to the abutting sides of the hub. A drawback is the relatively large number of small parts being used to assemble the injection set.
Another known infusion device in U.S. Pat. No. 5,257,980 comprises a base element, provided with a large fluid-sealant upper part being secured to a lower part and to the base part. The septum is placed between said base element and said upper part, and the septum is fixed by the introduction of rib parts on the septum as a fixing arrangement against the under side of the upper part. The securing of the septum is thus achieved by the use of relatively large and bulky upper and lower parts, and by the use of especially to each other adapted upper and lower pails, base element and septum, and these provisions add to the cost of manufacturing the infusion device.
For these reasons there is a need for improvement in the infusion devices of the type mentioned above, in particular with respect to simplifying the manufacture of said infusion device comprising at least one septum.
This object is achieved by an infusion device for subcutaneous administering a medication or a therapeutic fluid to a patient, comprising a base element, comprising fluid receiving means for receiving said fluid, fluid communication means for transferring said fluid into a cannula, and at least one recess for accommodating a septum pierceable by a needle; and a septum housing accommodating the septum; wherein the septum is secured to the base element by the septum housing in such a way that a fluid transfer volume is formed in said at least one recess between an internal surface of the septum and an inner section of the recess in the base element, said fluid transfer volume communicating with the fluid communication means, characterized in that the septum is radially compressed in the septum housing so that a fluid-tight seal is provided between the septum and the septum housing, as well as between the septum housing and the base element.
The manufacture of said infusion device, particularly the securing, i.e. the fixation and fluid-sealing of the septum to the base element, has been simplified by utilising a base element provided with a recess and a septum premounted in a septum housing, which is inserted in, fixed to and fluid-sealed to the base element in the inner section of said recess. Due to the elastic nature of the septum and the dimensions of the septum and septum housing, the fluid-seal there between is provided by the septum being radially compressed inside the septum housing, which further assist in the fixing and fluid-sealing of the septum housing inside the recess. Accordingly, due to the need for a relatively small part of the septum housing abutting the inner section of said recess in said base element in order to fix and fluid-seal said septum housing to said base element, the size of said parts needed for securing said septum to said infusion device can be kept to a minimum. A further advantage by providing a relatively small fixation and fluid-sealing area is decreasing the need for specially formed upper parts or lids adapted to fit a corresponding base element and/or lower part, nor for a specially formed septum provided with grooves etc.
In one embodiment, said fluid transfer volume is accommodating cannula securing means. In combination with the septum securing means a fluid-tight sealing and a passage to the fluid communication means is provided.
In another embodiment the septum housing is a tubular element accommodating said septum, at least one end of which tubular element forming a substantially partial enclosure over one surface of said septum. This allows advantageously for a small septum housing having a non-complex form, further simplifying the manufacture of said septum housing. Further, the only externally exposed part of the septum is the open part of the enclosure, which part may be made optionally small, allowing for lesser possibility for contamination of this exposed part of the septum.
In a further embodiment the septum housing includes an integrally formed cannula bushing. The advantage is further reducing the number of device parts being used to secure said septum and thus to assemble the infusion device. In another embodiment one of the surfaces of said septum is substantially exposed.
In further embodiments the septum housing is fixed to said base element by welding, in particular ultrasonic welding, or by a snap-lock. Welding is both fixing and fluid-sealing the septum housing to the base element in one operation. A snap-lock reduces the need for a welding treatment after insertion of the septum housing into the recess in order to fix said septum housing to the base element.
In a still further embodiment the septum housing is fluid-sealed by ultrasonic welding to the base element or by a gasket arranged between said septum housing and the inner section of said recess. Providing a gasket is advantageous in cases in which the insertion is eased by a clearance being provided between the inner section of the recess and the septum housing, said clearance leaving space for a gasket.
In further embodiments the septum is fixed inside said septum housing by friction, or by welding, in particular ultrasonic welding. Friction advantageously utilises the septum material property against the inner sides of the septum housing and need no further operation. Welding is advantageous as it in one operation both fixes and fluid-seals the septum housing to the base element.
The infusion device according to the invention will now be described, by way of example, with reference to the diagrammatic drawings in which
Fixation and fluid-sealing of the septums 4A and 4B is accomplished by covering part of the externally facing surface of the septum 4A, 4B by a covering part 22A, 22B, respectively, of the base element 1, while the septum 4A, 4B, respectively, is resting against cannula securing means 60 provided under the septum 4A or a base element neck 15 being provided for this purpose, and thus by slightly compressing the septum 4.
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Cannula securing means may be provided inside the infusion device according to the invention inside the fluid transfer volume 5, similar to the arrangement of the prior art infusion device of
Fluid-sealing of the septum 4 is provided by ultrasonic welding of the septum 4 to the tubular element 31, this may be performed during pre-mounting of the septum 4 or after insertion of the tubular element 31 into the recess 20, and by ultrasonically welding the septum 4 to the base element 1 by the provision of a septum resting flange 23 in the inner section of the recess 20 in the base element 1.
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The septum material is preferably a pierceable flexible material, often rubber or other material, and the base element and septum housing material may be any kind of suitable material, preferably plastic.
The size and shape of the septum, septum housing, and recess are adapted to each other, and may be any of these, preferably comprising a substantially cylindrical septum. Optionally, a previously slit septum may be utilised in order to facilitate the passage of a blunt needle, e.g. as is described in U.S. Pat. No. 6,017,328 to Unomedical.
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Number | Date | Country | Kind |
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04075489.7 | Feb 2004 | EP | regional |
Number | Date | Country | |
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60545134 | Feb 2004 | US |
Number | Date | Country | |
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Parent | 10589946 | Jun 2007 | US |
Child | 13310183 | US |