Patent Description:
The present invention relates to medical devices, and more particularly, to medical devices with molded hollow cannulas, and to methods for making such medical devices and cannulas.

One mode of insulin infusion treatment includes infusion pump therapy via a catheter, needle, or other type of cannula. Infusion pumps offer the advantages of continuous infusion of insulin, precision dosing, and programmable delivery schedules. Together, these advantages result in more accurate blood glucose control. In this mode of insulin infusion treatment, the infusion pump remains attached to the user and required doses of insulin are delivered to the user via the pump.

One type of cannula is a catheter, which generally is a tube that can be inserted into the body to permit the administration of fluids. In infusion pump therapy, the types and sizes of the catheter may vary, but generally, the catheter is a thin, flexible tube. In some uses, however, it may be larger and/or rigid. A rigid, hollow, metal needle may also be used in place of a soft plastic catheter.

One type of conventional infusion set is sold as the Quick-Set ® infusion set by Medtronic. In such devices, the infusion pump includes a catheter assembly connected to a pump via a tubing set, and a separate insertion device inserts and/or attaches the catheter assembly into/to a user via an introducer needle provided as part of the infusion set. The infusion set and insertion device can also be combined, as in the Mio® infusion set sold by Medtronic, which is an "all-in-one" design that combines the infusion set and insertion device into one unit.

Another type of insulin infusion device, known as a "patch pump," has recently become available. Unlike a conventional infusion pump, a patch pump is an integrated device that combines most or all of the fluid components in a single housing that is adhesively attached to an infusion site, and does not require the use of a separate infusion (tubing) set. A patch pump adheres to the skin, contains insulin (or other medication), and delivers the drug over a period of time, either transdermally, or via an integrated subcutaneous mini-catheter. Some patch pumps communicate with a separate controller device wirelessly (such as one sold under the brand name OmniPod®), while others are completely self-contained.

A conventional infusion device can include a fluid connector, which may be releasably attached to a base that can be secured to a user's skin. An infusion pump supplies fluid to a catheter via the fluid connector/base engagement.

As previously noted, medical devices that are intended to deliver medicament or monitor patient conditions over an extended period of time, are designed to be worn by the patient, and have a cannula that is inserted through the patient's skin for delivering the medicament. One way to manufacture such devices is extrude a cannula via dies and pins, and secure the cannula in the device using a metal or plastic wedge. But such extrusion processes can be slow and unpredictable, and can be a bottleneck for production.

A method of manufacture of a cannula by injection molding is disclosed in <CIT>.

Accordingly, it is an aspect of the present invention to provide a method of molding a cannula.

The foregoing and/or other aspects of the present invention are achieved by providing a method, including the operations of designing a mold for molding a cannula for a medical device so that an intentional flash is formed at parting lines of the mold during molding of a cannula, molding a cannula using the mold, maintaining the flash on the molded cannula after the molding, and installing the molded cannula with the flash in a medical device.

Additional and/or other aspects and advantages of the present invention will be set forth in the description that follows, or will be apparent from the description, or may be learned by practice of the invention.

The above and/or other aspects and advantages of embodiments of the invention will be more readily appreciated from the following detailed description, taken in conjunction with the accompanying drawings, in which:.

Reference will now be made in detail to embodiments of the present invention, which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments described herein exemplify, but do not limit, the present invention by referring to the drawings.

The embodiments are not intended to be mutually exclusive; features of one embodiment can be combined with other embodiments as long as they do not contradict each other.

It will be understood by one skilled in the art that this disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The embodiments herein are capable of other embodiments, and capable of being practiced or carried out in various ways. Phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Unless limited otherwise, the terms "connected," "coupled," and "mounted," and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. In addition, the terms "connected" and "coupled"" and variations thereof are not restricted to physical or mechanical connections or couplings. Further, terms such as "up," "down," "bottom," "top," "front," "rear," "upper," "lower," "upwardly," "downwardly," and other orientational descriptors are intended to facilitate the description of the exemplary embodiments of the present invention, and are not intended to limit the structure of the exemplary embodiments of the present invention to any particular position or orientation. Terms of degree, such as "substantially" or "approximately" are understood by those skilled in the art to refer to reasonable ranges around and including the given value and ranges outside the given value, for example, general tolerances associated with manufacturing, assembly, and use of the embodiments. The term "substantially" when referring to a structure or characteristic includes the characteristic that is mostly or entirely.

<FIG> is a perspective view of a related art two-piece fluid connector <NUM> and associated base <NUM>, such as those found in <CIT>. <FIG> is a bottom view of the fluid connector <NUM>, and <FIG> is a cross-sectional view of the fluid connector <NUM> connected with the base <NUM>. The fluid connector <NUM> includes two components: a fluid path portion <NUM>, and a latching portion <NUM>. Together, the fluid path portion <NUM> and the latching portion <NUM> form a housing <NUM>. The latching portion <NUM> includes activation levers <NUM>, fluid connector latches <NUM>, and a rigid stop <NUM>.

The fluid path portion <NUM> includes a tubing connector portion <NUM> for connecting the fluid connector <NUM> with tubing. The fluid path portion <NUM> can be secured to the latching portion <NUM> via snap-fit engagement.

As shown in <FIG>, <FIG>, the fluid path portion <NUM> has a blunt carmula <NUM> extending distally from a proximal interior surface of the housing <NUM>. When connected to a corresponding base <NUM> with a patient cannula <NUM> that has been inserted into the user's skin, the blunt cannula <NUM> pierces a septum <NUM> in a mushroom-shaped head <NUM> of the base <NUM> to fluidly connect a pump with the patient cannula <NUM> on the distal side of the base <NUM>. The patient cannula <NUM> is flexible, and is held in the base <NUM> by a metal wedge. "Typically, the patient cannula <NUM> is inserted into a patient's skin using a known insertion device.

Injection molding is a known process that uses molds that wear down over time. Once worn, the injected material (e.g., plastic) seeps out of the mold cavity at joint lines or parting lines, and forms what is known as "flash" at edges of the molded part. In current practices, such flash is undesirable, and is removed after removing the molded object from the mold, for example, as described in <CIT> Brown discloses a catheter with flash, generally shown in <FIG>, comprising a catheter <NUM> that is molded from a material, such as plastic. Flash <NUM> is produced on each side of the catheter <NUM> at the mold's parting line. The flash <NUM> is trimmed from the catheter <NUM> using a die to punch the flash <NUM> from the catheter <NUM>. Flash can also be trimmed using a cutting tool or a laser.

In embodiments of the present invention, the molds are designed specifically to create a purposeful flash edge profile on the injection molded catheter. For example, this can be done by controlling the tolerances of the mold (e.g., the tightness of the interface between the two mold halves) to promote the formation of the flash edges. More specifically, for a typical mold, there is a gap of about <NUM> inches (about <NUM>) between mated mold halves. This small space permits air to escape the mold as the plastic or other material is, for example, injected into the mold, but is too small for the plastic to escape from the mold. A molder can, for example, widen this gap using, for example, an end mill or an electrode, along a subsection of the mold that forms a longitudinal portion of the cannula. If the gap along corresponding portions of each mold half is widened to about <NUM> inches (about <NUM>) along a subsection of the longitudinal portion of the cannula, the resulting gap in the mated mold would be about <NUM> inches (<NUM>), which would be sufficient to allow some plastic to escape and form the flash.

As shown in <FIG>, the cannula with flash assembly, generally shown at <NUM>, comprises a hollow cannula <NUM> that is molded using a material, such as plastic. Flash <NUM> is produced on opposing sides of the cannula <NUM> at the parting line of the mold. In embodiments of the present invention, the flash <NUM> remains on the cannula <NUM> as the final product, and the flash <NUM> acts as a cutting edge for improved insertion of the cannula into a patient. The molding can be, for example, injection molding. According to one embodiment, the entire flash is maintained on the cannula. According to another embodiment, the flash <NUM> can be modified subsequent to removal from the mold.

As a result of the manufacturing process previously described, the flash <NUM> tapers down as it extends radially form the cannula <NUM>, and thus, the flash <NUM> edge profile is designed to be bladelike, and may decrease the amount of force required to insert the cannula. According to one embodiment, as shown in <FIG>, the flash edge is serrated.

According to another embodiment, the flash <NUM> edge is smooth, or not serrated. This can be accomplished by laterally mismatching the mold halves. In other words, the two mold halves meet along a plane. By laterally sliding one of the mold halves along the plane by a small amount (e.g., around <NUM>/<NUM> to <NUM>/<NUM> of a diameter of the cannula) or laterally offsetting one of the mold halves by the small about prior to mating the halves, a smooth flash following the shape of the molded item (cannula) can be produced. The smooth flash on one side of the cannula would be produced by one of the mold halves, and the smooth flash on the opposite side of the cannula would be produced by the other one of the mold halves.

As shown in <FIG>, the cannula <NUM> can be molded with one or more side ports <NUM>.

In such embodiments, by material choice, the cannula <NUM> can be made sufficiently stiff that a metal wedge is not needed to hold the cannula <NUM> in a medical device, such as the base <NUM>. In such an embodiment, rather than in a metal wedge, a septum <NUM>, can be installed directly in the one-piece injection molded cannula <NUM> to seal a fluid path. Such an embodiment would reduce the number of parts needed for a device, and would speed production.

<FIG> is a perspective view of a medical device <NUM> in accordance with embodiment of the present invention, and <FIG> is a cross-sectional view of the device. More specifically, the medical device <NUM> is a base of infusion device similar to the previously described base <NUM>. The base <NUM>, however, incorporates the hollow cannula member <NUM>. As shown in <FIG> and <FIG>, the cannula member <NUM> extends distally from the distal side of the base <NUM>. In addition, for the one-piece cannula member <NUM>, no metal wedge is needed to hold the cannula member <NUM> in the base <NUM>. The size of the flash <NUM> in <FIG>, <FIG>, and <FIG> is slightly exaggerated for clarity and illustration. According to one embodiment, an average radial dimension of the flash <NUM> is about <NUM>/<NUM> to <NUM>/<NUM> of the diameter of the portion of the cannula <NUM> that extends from the base <NUM>.

The flash <NUM> on the cannula member <NUM> may sufficiently reduce the force required for insertion into a patient's skin that an insertion device might not be needed. Alternatively, the base <NUM> may be inserted using a known inserter and introducer needle, but the flash <NUM> may ease insertion and reduce patient pain.

<FIG> is a flow chart illustrating a method <NUM> in accordance with an embodiment of the present invention. Operation <NUM> is molding a cannula to create flash at parting lines of a mold. Operation <NUM> is retaining the flash on the cannula, and operation <NUM> is installing the cannula with flash in a medical device, such as base <NUM>. According to one embodiment, the cannula is installed in the medical device without modifying the flash. The method <NUM> can include other operations, such as packaging the medical device having the cannula with the flash. According to one embodiment, the medical device is packaged without having modified the flash. The method can also include removing the medical device from the packaging, and inserting the cannula with the flash into a patient.

<FIG> is a flow chart illustrating a method <NUM> in accordance with another embodiment of the present invention. Operation <NUM> is designing a mold for molding a cannula to form intentional flash on the cannula at parting lines of the mold. Operation <NUM> is molding the cannula with flash using the mold. Operation <NUM> is maintaining the flash on the cannula, and operation <NUM> is installing the cannula with flash in a medical device, such as base <NUM>. According to one embodiment, the flash is maintained on the cannula without modifying the flash. According to one embodiment, the cannula is installed in the medical device without modifying the flash. According to one embodiment, designing the mold includes designing the mold so that the intentional flash is bladelike. According to one embodiment, the flash is serrated, and according to another embodiment, the intentional flash is smooth.

Claim 1:
A method, comprising:
designing a mold for molding a cannula for a medical device so that an intentional flash (<NUM>) is formed at parting lines of the mold during molding of a cannula;
molding a cannula (<NUM>) using the mold;
maintaining the flash on the molded cannula after the molding; and
installing the molded cannula with the flash in a medical device (<NUM>):
wherein designing the mold comprises designing the mold so that the intentional flash is bladelike.