Cannula system with rigid cannula

Abstract

The present specification discloses a cannula system (1) comprising a rigid cannula (2), a cannula unit (3), and an insertion unit (4). The rigid cannula (2) is connected to the cannula unit (3). The cannula unit (2) includes a diaphragm (31) mounted on a mounting structure (32) of the cannula unit (3), a connection structure (33) for reversibly or irreversibly connecting the cannula unit (3) to a cannula unit holder (5), and a cavity (34) formed at least partially by the diaphragm (31). The rigid cannula (2) is in fluid communication with the cavity (34). Additionally, the insertion unit (4) includes a rigid needle (41) that penetrates at least partially the diaphragm (31) and an attachment structure (42) for reversibly attaching the insertion unit (4) to the cannula unit (3).

Description

Technology Field

[0001] The present invention relates to the field of injection technology. More specifically, the present invention relates to a cannula system comprising a rigid cannula and the use of such a cannula system in an injection system. Background Technology

[0002] Infusion pumps are used to provide liquid medications to patients parenterally over extended periods. Nowadays, very small infusion pumps that can be accommodated by the patient's body are available. These small, portable infusion pumps are particularly useful for metering small amounts of highly effective liquid medications, such as insulin for diabetes treatment or analgesics for pain relief, which are delivered to the patient's tissues through a cannula.

[0003] In one approach, there is an infusion pump housed somewhere in the body, for example, attached to a belt, which is fluidly connected to an infusion site interface, also known as an insertion head, attached to the patient's body via a flexible tube. The infusion site interface includes a cannula inserted into body tissue, a housing, and a cannula system having connector means for fluidly connecting the cannula to a flexible tube connected to an upstream infusion pump. The infusion site interface may be attached to the patient via an infusion pump cradle. The tube may be repeatedly connected and disconnected from the infusion site interface. The connector means may include, for example, a diaphragm that seals off the fluid system of the housing and the cannula. The diaphragm may be pierced by a hollow needle to reversibly implement the fluid connection. Since the cannula may be made of a flexible material, it may be a flexible cannula. Such a cannula is more comfortable for the user, particularly during body movement. Since the flexible cannula cannot be inserted directly into the tissue, an additional perforation device, for example, a device in the form of a rigid perforation needle made of metal, is positioned inside the flexible cannula. The pointed end of the perforation device protrudes from the proximal end of the cannula, and the cannula will open toward the interstitial fluid. After inserting the perforation device and the stabilized cannula into the body tissue, the rigid perforation device is removed from the flexible cannula. The cannula remains in the body tissue. Typically, the perforation needle is positioned to penetrate the diaphragm, and after the perforation needle is withdrawn, the distal end of the currently open cannula fluid path is sealed closed.

[0004] In another approach, the infusion pump unit is fluidically connected directly to the infusion site interface. The fluid connection between the pump and the cannula is implemented by the pump's hollow connector needle, which reversibly penetrates the diaphragm of the cannula unit, thereby sealing off the distal end of the cannula fluid path. Advantageously, the pump can be repeatedly connected and disconnected from the infusion site interface.

[0005] While the use of flexible or soft cannulas is generally preferred due to their comfortable fit for the user, they can also be problematic for certain patients suffering from intolerance to soft cannula materials, such as latex, silicone, or rubber, which can lead to skin irritation and / or infection. For these patients, metal cannulas, for example, steel cannulas, offer a favorable alternative. The overall setup of a rigid cannula is generally less complex because it typically does not require a puncture needle.

[0006] Accordingly, the overall general objective of the present invention is to advance the latest technology regarding a cannula system having a rigid cannula as used in connection with liquid drug infusion, preferably to completely or partially prevent the disadvantages of the prior art.

[0007] In an advantageous embodiment, a cannula system with increased compatibility for patients, particularly those with intolerance to silicone, rubber, etc., is provided.

[0008] In a further advantageous embodiment, a cannula system is provided in which the fixation of the rigid cannula is improved and / or the occurrence of leakage is reduced.

[0009] According to one aspect of the present invention, the overall objective is achieved by a cannula system comprising a rigid cannula, a cannula unit to which the rigid cannula is connected, preferably directly connected, and an insertion unit. The cannula unit comprises a diaphragm mounted in a mounting structure of the cannula unit. The mounting structure may be, for example, a recess or groove formed by the inner wall of the cannula unit. For example, the diaphragm may be crimped or clamped to the mounting structure to achieve a tight seal between the inner wall of the cannula unit and the diaphragm. The cannula unit further comprises a connection structure for reversibly or irreversibly connecting the cannula unit to a cannula unit holder. The cannula unit holder may generally be an infusion pump cradle for attaching the cannula unit to the patient's body. Additionally, the cannula unit includes a cavity for receiving liquid medication when the cannula unit is connected to an infusion pump by penetrating the diaphragm with an infusion pump cannula. The cavity is formed at least partially by the diaphragm. A rigid cannula is in fluid communication with the cavity. To achieve a releaseable but stable connection between the cannula unit and the insertion unit, the insertion unit includes a rigid needle that penetrates at least partially the diaphragm of the cannula unit. Thus, the rigid needle prevents any lateral movement of the insertion unit relative to the cannula unit, except for any movement made possible by the elastic properties of the diaphragm. The rigid needle preferably extends into the cavity. The rigid needle preferably does not extend into the rigid cannula, and preferably, the distal end of the rigid needle does not extend into the lumen of the rigid cannula. Due to the rigidity, the rigid cannula can penetrate and be inserted into the skin without the aid of a wrapped or enclosed rigid insertion needle. This contrasts with flexible cannulas, which require a rigid insertion needle wrapped by or around the flexible cannula to stabilize the flexible cannula, at least during insertion into the skin.This difference relates to the advantage of simplifying the design of the cannula system and the rigid cannula insertion process compared to a system using a rigid insertion needle and a flexible cannula. For example, in the case of a combination of a flexible cannula and a rigid insertion needle of the prior art, the rigid insertion needle must be inserted and withdrawn while keeping the inserted flexible cannula in place. Such a device is complex because the insertion needle and the flexible cannula are in direct mechanical contact with each other while being inserted into the skin; however, in the case of the present invention, since the rigid insertion needle is not in direct mechanical contact with the rigid cannula, this complex insertion needle withdrawal process is not required. The insertion unit further includes an attachment structure configured to reversibly attach the insertion unit to the cannula unit.

[0010] As used herein, the term “diaphragm” is readily understood by those skilled in the art and is generally a hermetic seal, such as a membrane or plug, capable of being punctured by a cannula or needle, for sealing and separating a first side and a second side in a fluid, e.g., gas and / or liquid. Generally, the diaphragm does not include a hole or opening through which a needle or cannula passes from the first side to the second side before the needle or cannula is punctured through the diaphragm. Accordingly, the diaphragm cannot be easily punctured by a stump needle without applying a high force. Apart from the first surface, which is shaped as further described above and below, the first and second surfaces may preferably be coplanar.

[0011] The rigid cannula may be manufactured from any suitable metal, preferably steel, particularly stainless steel. Additionally, at least the cannula unit may be injection molded, preferably directly injection molded onto the rigid cannula. It is understood that the rigid needle is typically a solid body, that is, the rigid needle may not include a through hole or orifice and thus may not be a cannula.

[0012] In some embodiments, when the insertion unit is attached to the cannula unit, the rigid needle penetrates the diaphragm at a central position of the diaphragm. Thus, the diaphragm having two coplanar surfaces is penetrated along a central axis perpendicular to both coplanar surfaces. This arrangement facilitates the connection setup between the cannula unit and the insertion unit.

[0013] In an additional embodiment, the cavity is formed by the diaphragm and the inner wall of the cannula unit.

[0014] In some embodiments, the rigid cannula includes a fixing structure for fixing the cannula to the cannula unit.

[0015] In certain embodiments, the fixing structure provides a positive fixation and / or adhesive bond between the rigid cannula and the cannula unit. For example, the cannula can be fixed to the cannula unit using an adhesive, such as glue.

[0016] In some embodiments, the fixation structure comprises at least one projection, preferably a collar preferably arranged at the most distal end of the rigid cannula. The distal portion of the cannula is understood to mean the end region of the cannula facing away from the patient during surgery. Alternatively or additionally, the fixation structure may comprise at least one hole, preferably a through bore or a blind hole. In particular, such a fixation structure is preferred when the cannula unit is injection molded. During manufacturing, material may enter the hole or surround the projection, thereby providing a strong positive fixation connection after cooling.

[0017] In a further embodiment, the insertion unit includes connecting means for connecting the insertion unit to the inserter. The connecting means may include any suitable connecting mechanism such as a bayonet, a snap fit, a latch, a hook, etc. Generally, the connecting means is configured to provide a releaseable connection between the insertion unit and the inserter.

[0018] In some embodiments, the insertion unit includes a slit extending toward a rigid needle. The slit may contain an adhesive such as glue. The slit may be arranged, for example, across the rigid needle. The slit enables a secure connection of the needle within the insertion unit and further simplifies the manufacturing process of the insertion unit.

[0019] In an additional embodiment, the rigid needle is immovably connected to the rest of the insertion unit.

[0020] In some embodiments, the attachment structure includes a releaseable adhesive or a releaseable positive fixing structure. The releaseable adhesive may be, for example, an adhesive layer, and the connection force can be easily overcome by the user. The positive fixing structure may include any suitable form of fixing mechanism, such as a bayonet, snap fit, latch, hook, etc.

[0021] In an additional embodiment, the force required to release the cannula unit from the insertion unit is less than the force applied by the connection structure to reversibly or irreversibly connect the cannula unit to the cannula unit holder and / or less than the force required to separate the rigid cannula from the cannula unit. Thus, when a pulling force is applied on the insertion unit in a direction away from the cannula unit, the attachment structure is released and the insertion unit is separated from the cannula unit, while the rigid cannula remains connected to the cannula unit and the cannula unit remains connected to the cannula unit holder.

[0022] According to a further aspect of the present invention, the overall objective is achieved by an injection system comprising a cannula system according to any embodiment described herein.

[0023] According to a further aspect of the present invention, the overall objective is achieved by a method of using a cannula system according to any of the embodiments described herein in an injection system. Brief explanation of the drawing

[0024] FIG. 1 illustrates a schematic cross-sectional view of a cannula system according to an embodiment of the present invention. Specific details for implementing the invention

[0025] FIG. 1 illustrates a cannula system (1) having a rigid steel cannula (2), a cannula unit (3), and an insertion unit (4). The rigid cannula (3) is connected to the cannula unit (2) through a fixing structure (21), the fixing structure (21) includes an enlarged cross section of the distal region of the cannula (2), e.g., the collar, in the specific embodiment illustrated above. The cannula unit (3) includes a diaphragm (31) mounted in a mounting structure (32) of the cannula unit (3). As can be seen, the mounting structure (32) is formed by an inner wall (35) of the cannula unit (3) that presses the diaphragm into the cannula unit (3). The cannula unit (3) further comprises a cavity (34) formed partially by the diaphragm (31) and partially by the inner wall (35) of the cannula unit (3). As can be seen in FIG. 1, the rigid cannula (2) is fluidly in communication with the cavity (34), and liquid medication can be delivered into the cavity (34) and injected into the patient through the cannula (2) in an operating state, i.e., when the inserter (4) is removed and the infusion pump is fluidly in communication with the cavity (34) through the diaphragm (31). The cannula unit (3) further comprises a connection structure (33) for connecting the cannula unit (3) to an infusion pump cradle. As illustrated, the connection structure (33) includes a protrusion and a recess that may be part of a snap-fit ​​connection.

[0026] The insertion unit (4) includes a rigid needle (41), which allows the insertion unit (4) and the cannula unit (3) to be maintained in an axially aligned state. The rigid needle (41) penetrates the diaphragm (31) at a central position and preferably extends to the cavity (34). The rigid needle (41) preferably does not extend into the rigid cannula (2), and in particular, the end of the rigid needle (41) does not extend into the lumen of the rigid cannula (2). Due to the rigidity, the rigid cannula (2) can be inserted into the skin without the aid of a rigid insertion needle that is wrapped or surrounded by the rigid cannula (2). This contrasts with previously known flexible cannulas, which require a rigid insertion needle wrapped around or enveloping the flexible cannula to stabilize the flexible cannula, at least while the flexible cannula is inserted into the skin. The insertion needle (41) can be fixedly connected to the insertion unit by an adhesive provided within the slit (44). As can be seen, the slit (44) extends laterally toward the needle (41) so that the adhesive can fixally connect the insertion needle (41) and the insertion unit (4). It should be noted that, in contrast to the rigid cannula (2), the needle (41) is intended to provide a fixed connection, and therefore the needle (41) is generally a solid body, i.e., not a hollow needle. The insertion unit (4) further includes an attachment structure (42) for releasingly connecting the insertion unit (4) and the cannula unit (3). Through connecting means (43a and 43b), the insertion unit (4) and the cannula system (1) can each be connected to an insertion device known in the prior art. When in use, the cannula system (1) is connected to an insertion device that is inserted into a patient, and the cannula unit (1) is preferably connected to an infusion pump cradle through a connecting structure (33), and then the insertion unit is released.Importantly, the attachment structure (42) is configured such that the force required to release the cannula unit (3) from the insertion unit (4) is less than the force applied by the connection structure (33) to reversibly or irreversibly connect the cannula unit (3) to the cannula unit holder (5) (the cannula holder is not shown) and / or is less than the force required to separate the rigid cannula (2) from the cannula unit (3).

Claims

Claim 1 A cannula system (1) comprising a rigid cannula (2), a cannula unit (3), and an insertion unit (4), wherein the rigid cannula (2) is connected to the cannula unit (3), and the cannula unit (3) comprises a diaphragm (31) mounted on a mounting structure (32) of the cannula unit (3), a connecting structure (33) for reversibly or irreversibly connecting the cannula unit (3) to a cannula unit holder (5), and a cavity (34) formed at least partially by the diaphragm (31), wherein the rigid cannula (2) is in fluid communication with the cavity (34), and the insertion unit (4) comprises a rigid needle (41) that penetrates at least partially the diaphragm (31) and an attachment structure (42) for reversibly attaching the insertion unit (4) to the cannula unit (3), and the rigid needle (41) is rigid A cannula system (1) characterized in that the rigid needle (41) is not hollow and has a solid body, and does not extend into the cannula (2). Claim 2 In claim 1, the rigid needle (41) penetrates the diaphragm (31) at the central position of the diaphragm when the insertion unit (4) is attached to the cannula unit (3), in a cannula system (1). Claim 3 In claim 1, the cavity (34) is formed by the diaphragm (31) and the inner wall (35) of the cannula unit (3), in a cannula system (1). Claim 4 In claim 1, the rigid cannula (2) comprises a fixing structure (21) for fixing the cannula (2) to the cannula unit (3), in a cannula system (1). Claim 5 In paragraph 4, the fixing structure (21) provides a positive fixing and / or adhesive bond between the rigid cannula (2) and the cannula unit (3), in a cannula system (1). Claim 6 In paragraph 5, the fixed structure (21) comprises at least one protrusion and / or at least one hole, the cannula system (1). Claim 7 In claim 1, the insertion unit (4) comprises a connecting means (43a, 43b) for connecting the insertion unit (4) to an inserter, the cannula system (1). Claim 8 In claim 1, the insertion unit (4) includes a slit (44) extending toward a rigid needle, and the slit (44) includes an adhesive, cannula system (1). Claim 9 In claim 1, the rigid needle (41) is immovably connected to the rest of the insertion unit (4), the cannula system (1). Claim 10 In paragraph 1, the attachment structure (42) comprises a detachable adhesive or a detachable fixing structure, in a cannula system (1). Claim 11 A cannula system (1) according to claim 1, wherein the force required to release the cannula unit (3) from the insertion unit (4) is less than the force applied by the connection structure (33) to reversibly or irreversibly connect the cannula unit (3) to the cannula unit holder (5) and / or less than the force required to separate the rigid cannula (2) from the cannula unit (3). Claim 12 delete Claim 13 An injection system for injecting liquid drugs into a cannula system (1) according to any one of claims 1 to 11. Claim 14 A cannula system (1) for use in an injection system in any one of claims 1 to 11.

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