Patent Description:
Enteral nutrition generally refers to a method of feeding that uses the gastrointestinal (GI) tract to deliver part or all of a person's daily caloric requirements. While enteral nutrition can include a normal oral diet and oral administration of liquid supplements and medications, it typically refers to delivery of some or all of a patient's daily caloric requirements by use of a tube (i.e. tube feeding). Enteral nutritional products are typically in the form of a relatively thick, flowable liquid or fluid, and many types are available for a variety of replacement and supplemental feeding requirements. In contrast, parenteral nutrition and total parenteral nutrition (TPN) refer to the intravenous delivery of some or all of the daily caloric requirements. Many hospitalized patients are given dextrose or amino acids by this method.

Enteral tube feeding is the preferred method of feeding when patients are unable to consume enough calories on their own, yet have a functional GI tract. Enteral access devices include many different types of feeding tubes placed directly into the GI tract, including orogastric and nasogastric tubes which are inserted through the mouth or nose, as well as percutaneous endoscopic gastrostomy (PEG, G-tubes) and jejunostomy tubes (J-tubes) which are inserted through the skin via a small incision through the abdominal wall. For example, stroke patients suffering from dysphagia may require enteral tube feeding both early in their recovery via a nasogastric tube, and permanently if necessary via a PEG tube.

Motor-driven peristaltic infusion pumps are commonplace for both enteral and parenteral applications, and provide controlled delivery of liquid nutrition, fluids and medications for various purposes. In a common arrangement, an infusion pump includes a motorized pumping mechanism which is connected to various components and/or accessories for transferring the fluid or liquid nutritional product from a container (e.g., a bottle or a collapsible bag) into the patient. The container is typically provided in combination with compressible tubing, as well as other connections and fitments for accessing the patient's GI tract. Enteral tubing delivers fluids having a much thicker consistency than intravenous fluids, and so typically has a larger internal diameter compared to parenteral tubing. All of these components (e.g., container, tubing and connectors) are often collectively referred to as a feeding set. The feeding set is typically single-use and disposable, while the infusion pump itself is typically reused many times.

Both rotary and linear peristaltic infusion pumps are well-known and commonly used for enteral feeding. The pumping mechanism for a rotary peristaltic pump as known in the art typically includes a motor-driven rotor fitted with a set of circumferentially spaced rollers, cams or fingers which during operation compress a segment of the feeding set tubing. The feeding set tubing is typically wrapped or otherwise stretched or tensioned around the rotor, and as the rotor turns the rollers are sequentially brought into contact with the tubing to cause the fluid to peristaltically flow through the tubing and into the patient's GI tract at a desired volumetric rate. In contrast to rotary pumping mechanisms, the pumping mechanism for a linear peristaltic pump uses a plurality of mechanical fingers or cams which extend and retract in a wave format to compress the pump tubing. A rotor typically is used to operate the movement of the fingers, which translate the rotational motion of the rotor into a linear peristalsis. When placed alongside an elastic conduit or feeding tube segment, the fingers can reversibly compress and occlude the tubing in this wave format so as to cause the fluid to peristaltically flow through the tube at a desired volumetric rate.

Whether the pumping mechanism for a peristaltic infusion pump is rotary or linear in design, as each roller revolves around the rotor (in a rotary pump), or as each finger moves to its extended position (in a linear pump), the pumping mechanism makes contact with a portion of the tubing, compressing it to form an occlusion. Free flow of fluid is therefore restricted by the pressure of the pump rollers/fingers synchronously closing off the tubing. Each occlusion is advanced along the tubing and then released, so that a specific volume of fluid is advanced between successive occlusions through the tubing by the pumping mechanism. The infusion pump can therefore deliver a predetermined amount of fluid to the patient over a period of time.

Despite improvements over the years, manufacturers and users of both rotary and linear peristaltic infusion pumps have continued to experience a number of difficulties and challenges. For example, with many of the commercially available peristaltic pumps it is problematic that the feeding set may be improperly mounted to the infusion pump. Indeed, many prior art infusion pump designs make it possible for unintended disconnection of the pump tubing from the rollers. For example, the patient's movements in their bed may inadvertently pull the feeding set tubing from the pump, which can release the restriction of flow provided by compression the tubing by the pumping mechanism, leaving only the force of gravity to control the flow of the enteral fluid into the patient. This situation is commonly referred to as "free flow", and occurs when the pumping mechanism's rollers, cams and/or fingers are not able to properly compress the tubing to restrict flow into the patient. Such uncontrolled flow can result in a large volume of feeding fluid being delivered into a patient over a very short period of time, which can lead to serious medical problems including aspiration (food entering the lungs), pneumonia, high blood sugar, nausea, vomiting, and sometimes death in more frail patients due to sudden cardiac arrest.

Numerous devices have been developed in an attempt to prevent such free flow conditions. These devices are typically manually operated clamps or cassettes, with some form of automatic flow control mechanism. However, such devices are typically complex in design and can add significantly to the overall cost of the infusion set, while providing only marginal protection against free flow. Furthermore, proper use of these devices can be complicated, making it difficult for medical personnel to properly operate them. Indeed, inadvertent free flow errors have occurred in diverse clinical settings, causing serious patient injuries and deaths. Despite advances in many areas of infusion pump design, disconnections leading to free flow continue to create dangerous medical situations.

For example, <CIT> discloses an assembly configured to position a peristaltic tube with respect to a linear peristaltic pump drive of an infusion pump. The assembly can include a peristaltic tube, first and second tube couplers, a frame, first and second securement plates, a free-flow prevention arm, and a biasing mechanism. The frame can include a snap-fit tab configured to releasably secure the assembly to an assembly receptacle of the infusion pump. The free-flow prevention arm can be selectively movable between a free-flow preventing position and a free-flow allowing position. A latching mechanism can be ergonomically manipulable to latch the free-flow prevention arm in a free-flow allowing position, and to unlatch the free-flow prevention arm such that the biasing mechanism is able to bias the free-flow prevention arm to the free-flow preventing position. <CIT> discloses an infusion pump cassette that is insertable into an infusion pump for delivery of a fluid to a subject that has a housing with two ends for holding flexible tubing through which the fluid is directed. The housing has an open area exposing the tubing, which engages a pumping mechanism when inserted into an infusion pump. An anti-flow valve mechanism associated with the tubing or the cassette and present either in, on or near the housing is made up of a piston and spring, where the spring biases the piston against the tubing to prevent fluid flow. A fluid flow control clamp for in-line insertion on flexible fluid tubing is disclosed by <CIT>. A flow-directing member is positioned intermediate a source of sterilized water or other fluid and a medical humidifier. A blocking element is provided within the flow directing member and inlet and outlet ports are provided on either side of blocking member. Resilient tubing is attached to inlet, outlet ports of an appropriate length such that it kinks or crimps when relaxed and unactivated, preventing fluid flow through the clamp. The clamp is activated by insertion of fingers or other opening means within the loop of resilient tubing, unkinking the tubing, and permitting fluid flow through the clamp. Release of the resilient tubing causes it to resume its normal kinked position, thereby cutting off the fluid flow through the clamp. A secondary embodiment discloses a spike connector affixed to the flow-directing member for direct attachment of the clamp to the source of sterilized water. The spike connector may be sheathed with a plastic sleeve to protect it from touch contamination.

In light of the above, it is apparent that there is a need in the art for an improved means to safely deliver enteral nutritional fluids to a patient. It would thus be beneficial to provide a device and method for preventing inadvertent free flow of enteral fluids into a patient. It would likewise be advantageous to provide a cassette for an enteral infusion pump that can be utilized by medical professionals and other users having various skill levels. It would also be beneficial to replace complex infusion pump connection features with intuitively easy-to-use features which reduce user confusion, decrease manufacturing costs and improve safety.

Accordingly, the present invention provides improved means for connecting a feeding set to a peristaltic infusion pump. The inventive connectors and cassettes can be quickly and easily connected to the infusion pump while reliably ensuring that free flow of fluids will not occur, even upon inadvertent release of the feeding set tubing from the pump.

A first aspect of the invention provides a cassette for loading a nutritional feeding set onto a peristaltic infusion pump, the cassette comprising: (a) a pump tubing segment for engagement with a motor-driven pumping mechanism located within a receiving portion of a peristaltic infusion pump, the pump tubing segment including: (i) an anti-flow mechanism in the form of a pre-set kink for preventing free flow of fluid through the pump tubing segment, wherein the pre-set kink causes an obstruction to flow when the pump tubing segment is not engaged with the pumping mechanism, and wherein the obstruction is relieved when the pump tubing segment is engaged with the pumping mechanism; and (ii) a pair of free ends; and (b) a connector for connecting to the receiving portion of the infusion pump, the connector including: (i) a first mating member for reversibly connecting to a second mating member located in the receiving portion of the infusion pump, wherein connection of the first mating member with the second mating member aligns the pump tubing segment with the pumping mechanism and locks the cassette in place within the receiving portion; (ii) a first set of attachment structures for connecting inflow tubing and outflow tubing of a nutritional feeding set to the connector; and (ii) a second set of attachment structures for connecting the free ends of the pump tubing segment to the connector, wherein the attachment structures are hollow and fluidly connect the inflow tubing and the outflow tubing to the pump tubing segment.

A second aspect of the invention provides a method for loading a nutritional feeding set onto a peristaltic infusion pump, the method comprising: (a) providing a peristaltic infusion pump, the infusion pump comprising: (i) a housing, the housing including a receiving portion; and (ii) a motor-driven pumping mechanism within the receiving portion; (b) providing a cassette configured to load a nutritional feeding set onto the infusion pump, the cassette comprising: (i) a pump tubing segment for engagement with the pumping mechanism, the pump tubing segment including an anti-flow mechanism in the form of a pre-set kink for preventing free flow of fluid through the pump tubing segment, wherein the pre-set kink causes an obstruction to flow when the pump tubing segment is not engaged with the pumping mechanism, and wherein the obstruction is relieved when the pump tubing segment is engaged with the pumping mechanism; and (ii) a connector for connecting to the receiving portion of the infusion pump, the connector including a first mating member for reversibly connecting to a second mating member located in the receiving portion of the infusion pump, wherein connection of the first mating member with the second mating member aligns the pump tubing segment with the pumping mechanism and locks the cassette in place within the receiving portion; (c) inserting the cassette within the receiving portion of the pump housing; (d) connecting the first mating member with the second mating member; (e) engaging the pump tubing segment with the pumping mechanism to overcome the pre-set kink of the pump tubing.

In all of the embodiments described herein an optical reader can be incorporated into the infusion pump to verify that its matching feeding set tubing has been properly loaded. The nature and advantages of the present invention will be more fully appreciated after reviewing the accompanying drawings, detailed description, and claims.

The accompanying drawings illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description given below, serve to explain the principles of the invention.

Below is disclosed a plurality of embodiments of infusion pump connectors and cassettes, as defined herein, for connecting an enteral nutritional fluid feeding set to a peristaltic infusion pump. The cassettes allow the feeding set to be quickly connected to the infusion pump while reliably ensuring that inadvertent free flow of fluids will not occur when the feeding set tubing is not engaged by the infusion pump's rollers.

As used herein, the terms "connector(s)", "connection(s)" and "connector device(s)" mean a device for reversibly connecting a peristaltic infusion pump to a feeding set. A connector is typically one element of a cassette, as defined herein, and can provide a simple "infusion pump-to-feeding set" integration or "keying" system for connecting a single use feeding set to a matching reusable infusion pump, ensuring proper operation of both.

The term "cassette" as used herein means a portion of a feeding set, specifically, a connector in combination with a pump tubing segment, as defined herein. In use, the connector portion of a cassette can be locked into a receiving portion of a peristaltic infusion pump housing, which aligns the pump tubing segment for engagement with the pumping mechanism.

The terms "engage", "engaged", "engaged with", "engaged by" "engagement", or "engagement with" as used herein refer to the relationship between the pump tubing segment and the pumping mechanism as defined herein, and specifically mean stretching engagement or external tensioning of the pump tubing segment by the pumping mechanism. For example, recitation in the claims of "a pump tubing segment for engagement with a pumping mechanism" means that the pump tubing segment is caused to be stretched or placed under external tension by the pumping mechanism; disengagement means removal of this tension or stretching.

The phrase "feeding set" as used herein is a collective term which includes a container (having a particular nutritional fluid), feeding set tubing (as defined below), and a cassette (as defined above). A feeding set may also be referred to in the art as a "fluid delivery set", "infusion set", "feed set" or "pump set".

The phrase "feeding set tubing" as used herein is a collective term which when used herein includes inflow tubing, outflow tubing, and a pump tubing segment (as each are defined herein). The feeding set tubing is typically a compressible, single-use and disposable type of tubing , but it may also be reusable.

The phrase "inflow tubing" as used herein means a segment of the feeding set tubing which connects the container to the proximal end of the pump tubing segment.

The phrase "motor-driven pumping mechanism" or "pumping mechanism" as used herein means the pumping machinery for a peristaltic infusion pump, which can be either rotary or linear in design. If pertaining to a rotary pump, the pumping mechanism can be an array of spaced apart and circumferentially mounted rollers, cams or fingers which are mounted to and rotate around a motor-driven rotor to sequentially make contact with, compress and occlude a segment of the feeding set tubing. If pertaining to a linear pump, the pumping mechanism can be an array of rollers, cams or fingers which are moved by a motor-driven rotor to an extended position in a wave format to sequentially make contact with, compress and occlude a segment of the feeding set tubing. Whether the pumping mechanism for a peristaltic infusion pump is rotary or linear in design, in operation the free flow of fluid is restricted by the pressure of the pump rollers/fingers synchronously closing off the tubing.

The phrase "outflow tubing" as used herein means a segment of the feeding set tubing which connects the distal end of the pump tubing segment to the patient.

The phrases "pump tubing" and "pump tubing segment" as used herein refer to a piece or segment of the feeding set tubing that is coupled with a connector to form a cassette. The pump tubing segment engages, i.e. is stretched or externally tensioned by the motor-driven pumping mechanism of a peristaltic infusion pump. The pump tubing segment includes a proximal end which typically connects to the inflow tubing, and a distal end which typically connects to the outflow tubing of the feeding set.

As known in the art, a "peristaltic infusion pump" or "infusion pump" typically includes a mechanical pump having a housing for receiving tubing of a feeding set, and a motor-driven pumping mechanism (as defined herein) mounted in the housing for driving nutritional fluid through the feeding set.

A preferred embodiment of a cassette for a nutritional fluid delivery system <NUM> according to the present invention is shown in <FIG>. Looking at <FIG>, a "pre-kinked" cassette <NUM> is intended to assist in loading a feeding set <NUM> onto an infusion pump <NUM>, for controlled delivery of nutritional fluid to a patient. The feeding set <NUM> includes inflow tubing <NUM> and outflow tubing <NUM>, together with a segment of pump tubing <NUM>, and the three tubing segments <NUM>, <NUM>, <NUM> complete a fluidic pathway between a container or bag <NUM> of nutritional fluid and the patient. A receiving portion <NUM> within the front housing <NUM> of a peristaltic infusion pump <NUM> can provide access to a pumping mechanism, here in the form of a motor-driven rotor <NUM> mounted on a rotatable shaft.

According to the present invention, a user typically mounts the cassette <NUM> to a corresponding infusion pump <NUM> and primes the feeding set <NUM> with the prescribed nutritional fluid stored inside the container <NUM>. Thereafter the loaded feeding set can be connected to the patient and the infusion pump can be actuated by a medical professional or other user to effect safe and controlled delivery of the proper nutritional fluid to the patient.

The housing <NUM> of the infusion pump <NUM> typically includes a user interface <NUM> with a display screen <NUM> capable of displaying information about the status and operation of the pump. The user interface <NUM> can further include buttons <NUM> for use with the display screen <NUM> to facilitate exchanging information between the pump <NUM> and the user. Various user interfaces may be implemented as known in the art for displaying and receiving information.

The cassette <NUM> serves as a "keyed" interface device for connecting the feeding set <NUM> to the infusion pump <NUM>, and includes a connector <NUM> and a segment of kinked pump tubing <NUM>. The connector <NUM> is designed to hold a predetermined length or segment of pump tubing <NUM>, which is seated within the connector <NUM> and includes an anti-flow mechanism in the form of a "pre-set kink" <NUM>. This pre-set kink <NUM> is manufactured into the pump tubing and, when not stretched or placed under external tension around the rotor <NUM>, presents an obstruction to free flow of fluid through the pump tubing segment <NUM>.

As can be appreciated from viewing <FIG>, <FIG> and <FIG>, the pre-set kink or anti-flow mechanism <NUM> manufactured into the pump tubing prevents free flow of fluid when it is not stretched or placed under external tension around the pumping mechanism <NUM>. As can be appreciated from viewing <FIG>, the obstruction <NUM> is reversible and can be relieved when the pump tubing segment <NUM> is stretched or tensioned about the rotor <NUM>. Unlike long, hanging segments of tubing which are typically caused to kink by prior art pinch valves, the pre-set kink <NUM> is located in a tubing segment <NUM> which does not hang freely for access by a user; rather, the kinked pump tubing segment <NUM> is protected within the connector and is intended to be reversibly engaged (i.e. tensioned about) and disengaged with the pumping mechanism <NUM>.

As noted above, the housing <NUM> of the infusion pump <NUM> includes a receiving portion <NUM> in the form of a window or door. The recessed shape of the receiving portion <NUM> preferably matches the physical shape of the cassette <NUM>, so that only a cartridge identical to the connector <NUM> of the pre-kinked cassette <NUM> can be locked into the receiving portion <NUM> of the pump <NUM>. This advantageously decreases the chances of an inadvertent connection between incompatible products, and can ensure that only a particular brand of feeding set can be connected to a particular brand of infusion pump. For example, both the cassette's connector <NUM> and the pump's receiving portion <NUM> can include a mating member <NUM>, <NUM>, respectively (see <FIG>, <FIG> and <FIG>), such that a specific cassette can be configured to reversibly connect to only a specific infusion pump, to ensure that the correct infusion pump is being used with the correct corresponding feeding set. As discussed below, an optical reader can also be incorporated into the infusion pump to read an imprinted item on the feeding set tubing (typically on the pump tubing segment). The optical reader can thus verify that a specific infusion pump has been properly loaded with a matching feeding set, so that the prescribed nutritional fluid can be properly and safely delivered.

In use, a medical professional can load the cassette <NUM> into the receiving portion <NUM> of the infusion pump by first aligning the cassette with the pumping mechanism <NUM> and then sliding, snapping, locking, mating, or otherwise reversibly connecting the mating member <NUM> of the connector <NUM> with the mating member <NUM> of the receiving portion. In the embodiment shown in <FIG>, proper alignment and insertion of the connector <NUM> within the receiving portion <NUM> allows the pump tubing <NUM> within the cassette <NUM> to be automatically tensioned or stretched around the rotor <NUM> of the infusion pump. In other embodiments, e.g. <FIG>, the pump tubing segment <NUM> must initially be tensioned manually about the pumping mechanism <NUM>, such as by the user stretching the pump tubing around or over the pump rotor.

<FIG> illustrates the connector's mating member <NUM> extending from a recess <NUM>. Mating member <NUM> can reversibly connect to the pump housing's mating member <NUM>, which is seated in and extends from a recess <NUM> in the pump's receiving portion <NUM>. The mating members <NUM>, <NUM> can function in a manner that is known in the art. For example, the mating members <NUM>, <NUM> can be configured to reversibly extend from spring-loaded recesses <NUM>, <NUM> as illustrated in <FIG>, such that proper insertion of the cassette by the user causes the mating members to push one another into their respective spring-loaded recesses. In one embodiment, the mating members can function much like a pen that a user clicks to extend and/or retract the writing element, initially "over centering" within their recesses and then locking back into place. To release the cassette, the user can then simply push down on the loaded cassette, causing the mating members to be expelled from their recesses. Removal of the cassette <NUM> from the pumping mechanism <NUM> will remove the tension in the pump tubing segment <NUM> and cause the pre-set kink <NUM> to form once again, once again causing an obstruction to the free flow of fluid. A similar type of retention means can include a snap-in feature as is known in the art, in which a push button (not shown) on the pump display can be pressed to release the cassette from the pump.

Each mating member <NUM>, <NUM> can be shaped to easily slide onto and make contact with the other during initial insertion. In addition, each mating member may have a particular profile, e.g. a rectangular button, slot or pin having a hemispherical or concave shape, which can correspond to the other. In other embodiments (see, e.g., cassette <NUM> of <FIG>), the cassette can be retained in the pump's receiving portion by a friction fit between the mating members. The mating members can have any shape and can be made of any suitable material, so long as they can function to reversibly load and secure the cassette to the infusion pump.

In addition to ensuring proper alignment and locking of the cassette <NUM> in place within the receiving portion <NUM>, the mating member <NUM> of the pump housing <NUM> can also be associated with, or serve as, a micro-switch which must first be triggered or activated before the pumping mechanism <NUM> can be set in motion. Proper insertion of the cassette into the receiving portion of the pump housing can cause connection of the mating members <NUM>, <NUM>, which locks the cassette in place and also triggers the micro-switch <NUM>, which then allows the pumping mechanism or rotor to be acuated.

As can be appreciated from viewing <FIG>, loading the cassette <NUM> into the pump <NUM> stretches and relieves the obstruction to fluid flow in the kinked pump tubing <NUM>, so that fluid can now be caused to flow through the pump tubing <NUM>. The restriction of flow is now under the control of the pumping mechanism, i.e. rotor <NUM> and its circumferentially mounted rollers <NUM>, such that controlled flow can be instituted when the motor-driven pump is actuated. More specifically, when the cassette <NUM>, including the connector <NUM> and its associated kinked pump tubing segment <NUM> is locked into the receiving portion <NUM>, the pre-set kink <NUM> engages and is tensioned around the rotor <NUM>, stretching the kink <NUM> to overcome its anti-flow capabilities. The now un-kinked pump tubing <NUM> is engaged with the pump rotor <NUM> and its rollers <NUM>, and the nutritional fluid in the container <NUM> can be delivered through the feeding set <NUM> in a controlled manner by activation of the infusion pump. Should the pump tubing <NUM> for some reason become disengaged from the pumping mechanism during use, either inadvertently or intentionally, the roller's tension on the pump tubing <NUM> would be released which will allow the pre-set kink <NUM> to return to a kinked position, once again preventing any free flow of fluid through the feeding set.

It is notable that cassette <NUM> of <FIG> provides and also protects the connection between the feeding set <NUM> and the pumping mechanism <NUM>. Specifically, while most infusion pumps have a separate door or cover for protecting the interface between the feeding set tubing and the pump, the inventive connector <NUM> serves as an insertable door/cover that also provides such an interface. Further, due to the kink <NUM> in the pump tubing <NUM>, when the connector is not inserted into the pump receiving portion <NUM>, the free flow of fluids through the feeding set <NUM> is prevented by the kink <NUM>. In use, the connector can be quickly inserted into the pump <NUM> via the receiving portion <NUM>, putting tension on the kink <NUM> and thus allowing mechanical fluid flow, and the pumping mechanism <NUM> can then be actuated to deliver nutritional fluid to the patient.

The pre-kinked cassette <NUM> embodiment of the invention is shown in more detail in <FIG>. The pump tubing <NUM> is seated within an inner curve <NUM> of the connector <NUM>, the shape of which substantially matches the physical curvature of the rotor <NUM>, such that insertion of the connector <NUM> tensions the pump tubing <NUM> around the rotor. External attachment structures <NUM> and <NUM>, located outside the opposing ends of the inner curve <NUM>, can be included to provide facile and secure attachment of the inflow tubing <NUM> and outflow tubing <NUM>, respectively. Internal attachment structures <NUM> and <NUM> located inside the opposing ends of the inner curve <NUM> can provide means to easily and securely connect the free ends of the pump tubing segment <NUM> to the connector <NUM>. The attachment structures <NUM>-<NUM> are typically hollow, having substantially the same size and diameter as the tubing <NUM>, <NUM>, <NUM> they connect to. Further, attachment structures <NUM> and <NUM> are fluidly connected to one another by a pathway through the body of the connector, as are attachment structures <NUM> and <NUM>. That is, their hollow structures pass through the opposing ends of the inner curve <NUM> of the connector <NUM>, ensuring that inflow tubing <NUM> and outflow tubing <NUM> are fluidly connectable to one another via the pump tubing <NUM> of the cassette.

Depending on the desired feeding regime, the container <NUM> and tubing <NUM>, <NUM>, <NUM> of the feeding set <NUM> can be varied for different types of nutritional fluid. For example, the attachment structures <NUM>-<NUM> may connect only to a particularly sized tubing, e.g. tubing having a specific diameter and which is associated with a specific type or formula of nutritional fluid product. The flow rate may depend on the tubing resistance of a particular feeding set, and/or the consistency or viscosity of the fluid being delivered through the feeding set. The inventive cassette can therefore both advantageously reduce the likelihood of an inadvertent connection between incompatible products, and increase the likelihood of delivering nutritional fluid according to the intended delivery protocol.

<FIG> illustrate another cassette embodiment <NUM> according to the present invention, which is referred to as a pre-kinked "loop" cassette. The pre-kinked loop cassette <NUM> includes a connector <NUM> which is similar and/or identical to the connector <NUM> of <FIG>, in combination with a segment of pump tubing <NUM> which includes a loop <NUM>. The loop <NUM> includes an anti-flow mechanism in the form of a pre-set kink <NUM>, similar and/or identical to kink <NUM> of <FIG>, for preventing free flow of fluid when the cassette <NUM> is not in the receiving portion of the pump. While not shown in <FIG>, the connector <NUM> of this cassette <NUM>, like connector <NUM> of <FIG>, can include a recess with an extending mating member for reversibly connecting to a corresponding pump mating member extending from a recess in the pump housing. As described above for the pre-kinked cassette <NUM>, a mating connection between the two mating members ensures proper alignment of the pump tubing <NUM> with the pumping mechanism <NUM> and reversibly locks the loop cassette <NUM> in place. When desired, the mating members can be disconnected from one another to allow the cassette to be easily removed from the receiving portion of the pump housing.

Prior to actuating the infusion pump <NUM>, the loop <NUM> of the pump tubing segment <NUM> is engaged by being manually placed over and tensioned around the rotor <NUM> by a user. The loop diameter of the pump tubing <NUM> can be such that the rotor maintains a radial stretch of the looped pump tubing <NUM>, which maintains tension on the kink <NUM> and thereby permits fluid flow through the cassette <NUM> upon actuation of the pump. This manual loading of the pump tubing segment <NUM> of the loop cassette <NUM> is in contrast to the automatic tensioning/loading of the pump tubing <NUM> onto the pumping mechanism <NUM> when using the pre-kinked cassette <NUM> (see <FIG>).

<FIG> illustrate a "simple V-kink" cassette embodiment <NUM> according to the present invention, which includes an H-shaped connector <NUM> and pump tubing segment <NUM>. The pump tubing segment <NUM> includes a pre-set kink <NUM>, and a pair of free ends which easily and securely attach to a pair of attachment structures <NUM>, <NUM> at one end of the connector <NUM>. Another pair of attachment structures <NUM>, <NUM>, provide facile and secure attachment of the inflow tubing <NUM> and outflow tubing <NUM>, respectively. The attachment structures <NUM>-<NUM> are hollow, and have substantially the same size and diameter as the tubing they connect to. Further, attachment structures <NUM> and <NUM> are fluidly connected to one another, as are attachment structures <NUM> and <NUM>, and attachment structures <NUM>, <NUM> are fluidly connectable to structures <NUM>, <NUM> via the pump tubing segment <NUM> of the cassette.

The connector <NUM> is maintained in position by the reversible connection (as discussed above) of its mating member <NUM> with the pump housing mating member <NUM> projecting from the pump housing (not shown). The pump housing mating member <NUM> can be a pair of brackets, as shown, or it can be in the form of a pair of pins, or a slot. Once the connector <NUM> is loaded into the pump housing and the pump tubing segment <NUM> is engaged by being tensioned about the rotor, the distance between the connector's mating member <NUM> and the rotor <NUM> maintains tension on the pump tubing segment <NUM> and thus relieves the obstruction caused by the anti-flow mechanism <NUM>. As can be appreciated from viewing <FIG>, the distance between the connector's mating member <NUM> and the rotor <NUM> can be such that it maintains tension on the pump tubing <NUM>. More specifically, the length of the pump tubing segment <NUM> can be such that a radial stretch is placed on the tubing <NUM> when tensioned around the rotor <NUM>, which stretches the kink <NUM> and removes the obstruction to fluid flow in the pump tubing. Fluid flow is then permitted through the stretched tubing of the V-kink cassette <NUM> upon actuation of the pump.

As illustrated, the kinked pump tubing segment <NUM> prevents free flow of fluid when not engaged with (i.e. stretched by or tensioned about) the pumping mechanism. Like the pre-set kinks <NUM>, <NUM> of cassettes <NUM> and <NUM>, the pre-set kink <NUM> of cassette <NUM> is located in a tubing segment that, when in use, is not normally straight and/or hanging freely. Unlike prior art hanging segments of tubing that are typically kinked by pinch valves, the kinked pump tubing segment <NUM> is intended to be stretched upon placement onto the pumping mechanism <NUM>. Such engagement between the pump tubing segment and the pumping mechanism relieves the obstruction caused by the anti-flow mechanism or pre-set kink <NUM> and allows fluid flow. Like the pre-kinked loop cassette <NUM>, the pump tubing segment <NUM> of the simple V-kink cassette <NUM> is manually placed over and tensioned around the rotor <NUM> by a user prior to actuating the pump.

With cassette <NUM>, loading is quickly and easily performed by the user by first securing the mating member <NUM> of the connector <NUM> onto the mating member <NUM> of the pump housing, and then manually tensioning the pump tubing <NUM> around the rotor <NUM>. As shown, the mating member <NUM> may be made of an elastic material capable of being radially stretched to secure the connector to the brackets <NUM>. The pump tubing may be positioned around the rotor first, but typically the user aligns the segment of pump tubing with the rotor while aligning and connecting the mating members. As noted above, once the cassette is loaded, the distance between the housing's mating member <NUM> and the rotor <NUM> ensures that the kink <NUM> is kept in tension and creates no obstruction to flow. Fluid flow is then permitted through the cassette <NUM>, and the motor-driven rotor <NUM> can be actuated to deliver fluid to the patient.

<FIG> illustrate a "dual rotor, kinked figure-<NUM>" cassette embodiment <NUM> according to the present invention, which is intended for use with infusion pumps with a dual rotary peristaltic pumping mechanism. As shown in <FIG>, the cassette <NUM> includes a connector <NUM> having three (<NUM>) holes <NUM> for receiving and weaving a single segment of pump tubing <NUM> therethrough. The pump tubing <NUM> is inserted into holes <NUM> of the connector to form two separate kinked loops <NUM>, <NUM>. The connector <NUM> thus holds the two loops <NUM>, <NUM> together to provide the shape of a figure-<NUM> on its side. A pair of pre-set kinks <NUM>, <NUM> in the respective loops <NUM>, <NUM> restrict flow through the pump tubing <NUM> when the cassette is not loaded onto the pump, so that the cassette <NUM> provides an occlusion mechanism to prevent free flow of fluid through the unloaded feeding set.

In use, loop <NUM> is manually placed over and tensioned around the rotor <NUM> by a user, while loop <NUM> is similarly tensioned around the rotating member <NUM> prior to actuating the pump. The distance between the rotor <NUM> and rotating member <NUM> is such that a radial stretch is created, which maintains tension on the looped pump tubing <NUM>, relieving the obstruction caused by the kinks <NUM>, <NUM>. When the cassette <NUM> is loaded into the dual rotor infusion pump, the two loops <NUM>, <NUM> are typically manually stretched around the rotor and the rotating member <NUM>, <NUM>, respectively. The rotor <NUM> includes rollers <NUM>, and functions to peristaltically drive the fluid through the feeding set tubing like a traditional rotary peristaltic pump, while the other rotating member <NUM> "freewheels" or spins freely, it's only purpose being to keep tension on the loop <NUM> in order to keep the pump tubing <NUM> open to flow.

When the kinks <NUM>, <NUM> are tensioned about their respective rotors <NUM>, <NUM>, fluid flow is permitted through the cassette <NUM> so that the pump can then be actuated to deliver nutritional fluid to the patient. Also, similar to other connector embodiments described herein, the connector <NUM> can include a mating member (e.g. <NUM>, see <FIG>, <FIG>) for connecting to a corresponding pump mating member (<NUM>) extending from the pump housing, such as a button, slot, pins or other feature, to center the connector. Connection of the mating members can ensure proper alignment of the pump tubing <NUM> within the pumping mechanism for manual loading around the rotors, and can also reversibly lock the cassette in place within the receiving portion of the pump housing. The loaded cassette can then be unlocked and removed from the pump housing by a user, as described above.

<FIG> and <FIG> illustrate a "<NUM>-chamber diaphragm" cassette embodiment <NUM> according to the present invention. Cassette <NUM> includes a connector <NUM> with three (<NUM>) hemispherical chambers <NUM>, <NUM>, <NUM> and a pump tubing segment <NUM>, and is received within the receiving portion of the infusion pump housing, in a manner similar to the cassettes described above. Also, similar to other connector embodiments described herein, the connector <NUM> can include a mating member for connecting to a corresponding pump mating member extending from the pump housing, such as a button, slot, pins or other feature. Connection of the mating members ensures proper alignment of the pump tubing <NUM> within the pumping mechanism, and locks the cassette <NUM> in place. When needed the cassette can be unlocked and removed from the pump housing, as described above.

Looking at <FIG> it is apparent that chambers <NUM>, <NUM>, <NUM> are separated by passages <NUM> which constitute a portion of the pump tubing segment <NUM>. To prevent free flow of fluid through the connector <NUM> when not loaded in the pump, a thin flexible membrane or elastic film <NUM> is typically sealed around the connector <NUM> to prevent bulging of the chambers <NUM>, <NUM>, <NUM> or their passages <NUM>. The diameter of the passages <NUM> are small in comparison to the chambers <NUM>, <NUM>, <NUM>, and the compressive coating of elastic film <NUM> can also serve to constrict the passages. Thus, there is no free flow of fluid through the connecting chambers, unless the cassette is loaded onto the pump and one or more of the chambers are compressed by the mechanical fingers of the pumping mechanism. Each of the passages <NUM> can also include a small check valve or tight opening (not shown) to prevent free flow of fluid therethrough.

In order for fluid to flow through the cassette <NUM> during operation, the linear pump's array of mechanical fingers must exert a peristaltic force by sequentially contacting, compressing or otherwise occluding the chambers <NUM>, <NUM>, <NUM> to cause peristaltic flow through the feeding set. More specifically, when the linear pump is actuated, a motor driven rotor causes the mechanical fingers to linearly extend and retract in a wave format to compress the pump tubing segment chambers <NUM>, <NUM>, <NUM> in a sequential manner, deforming them and creating a pressure wave capable of driving fluid through the passages <NUM> towards the patient. Release of the cassette from the pump housing removes any external pressure placed on the chambers <NUM>, <NUM>, <NUM> by the pump's mechanical fingers, and free flow of fluid through the passages <NUM> is prevented.

In all of the embodiments disclosed herein, the infusion pump can also incorporate an optical reader or sensor, as is known in the art. For example, the optical reader can be in the form of an optoelectronic sensor, essentially, a tiny low-resolution video camera. Such an optical reader can be incorporated into a particular brand of infusion pump and used to recognize that a matching brand of feeding set tubing is being connected to the pump. Specifically, the optical reader can be used to recognize an imprinted item such as a particular trademarked logo (thus matching the trademark/brand of the infusion pump with tubing of the same brand), product number, RFID signal, bar code, or magnetic signature imprinted on the pump set tubing. Thus, the optical eye or sensor on the infusion pump can scan for the presence of the imprinted item on the feeding set tubing (preferably the pump tubing segment, as defined herein), which can confirm that a matching feeding set intended only for use with that type of infusion pump is loaded. The imprinted item can also be used for other functions; for example, depending on the particular item imprinted onto the tubing, a different functionality of the pump could be activated. For instance, one feeding set's tubing can include a particular imprinted item which when read by the optical sensor causes the pump to enter into a calibration mode. In addition, a particular imprinted item can provide wireless connectivity such as electronic medical record (EMR) connectivity to the user, or an imprinted item can indicate a feed and flush mode.

The various embodiments of the invention as illustrated and described above are simpler, easier to use, and are more cost effective than known prior art devices and products. Along with simplicity and ease of use, the inventive cassettes described herein can be relied upon to prevent inadvertent free flow of fluids into the patient. For example, in a prior art pinch valve the tubing made to form a kink is normally straight tubing, and typically requires an elastic member or spring member to put tension on and create a kink in the tubing. Should the spring member become inadvertently dislodged from the tubing, free flow of fluids will result. In contrast, the pre-set kink of the present invention is unique in that the pump tubing does not need to be put under tension to create the kink. Rather, the inventive pump tubing segment is held statically by the cassette, and the tubing must thereafter be stretched, tensioned around, or otherwise caused to engage the rotor/pumping mechanism of the pump before the restriction to flow within the pump tubing is relieved. In addition, the tubing of a prior art pinch valve is not tensioned by the pumping mechanism; rather, prior art pinch valves do not engage, wrap around, contact or otherwise become stretched, tensioned or acted upon by the rotor or pumping mechanism of the infusion pump, nor are prior art pinch valves included as part of a cassette that slides into place within the pump housing.

The inventive cassettes disclosed herein can function as a means to hold a predetermined length of pump tubing for reliably and reversibly engaging the pumping mechanism. By locking the cassette into the pump, the feeding set/pump circuit can be completed. While specifically intended for delivery of enteral fluids, the embodiments of the present invention disclosed herein may be suitable for use in many applications that involve peristaltic pumping systems generally, and can be particularly beneficial for delivery of parenteral fluids. The embodiments disclosed herein thus may be modified to accommodate many types of feeding sets and the like that are suitable for use in healthcare facilities as well as in home care environments. Such feeding sets may be adapted with various types of tubing to accommodate a variety of enterally deliverable liquid nutritional products which may have various viscosities and consistencies.

Claim 1:
A cassette (<NUM>; <NUM>; <NUM>) for loading a nutritional feeding set (<NUM>) onto a peristaltic infusion pump (<NUM>), the cassette (<NUM>; <NUM>; <NUM>) comprising:
a) a pump tubing segment (<NUM>; <NUM>; <NUM>) for engagement with a motor-driven pumping mechanism (<NUM>; <NUM>) located within a receiving portion (<NUM>) of a peristaltic infusion pump (<NUM>), the pump tubing segment (<NUM>; <NUM>; <NUM>) including:
i) an anti-flow mechanism in the form of a pre-set kink (<NUM>) for preventing free flow of fluid through the pump tubing segment (<NUM>; <NUM>; <NUM>), wherein the pre-set kink (<NUM>) causes an obstruction to flow when the pump tubing segment (<NUM>; <NUM>; <NUM>) is not engaged with the pumping mechanism (<NUM>; <NUM>), and wherein the obstruction is relieved when the pump tubing segment (<NUM>; <NUM>; <NUM>) is engaged with the pumping mechanism (<NUM>; <NUM>); and
ii) a pair of free ends; and
b) a connector (<NUM>; <NUM>) for connecting to the receiving portion (<NUM>) of the infusion pump (<NUM>), the connector (<NUM>; <NUM>) including:
i) a first mating member (<NUM>, <NUM>) for reversibly connecting to a second mating member located in the receiving portion (<NUM>) of the infusion pump (<NUM>), wherein connection of the first mating member (<NUM>, <NUM>) with the second mating member aligns the pump tubing segment (<NUM>; <NUM>; <NUM>) with the pumping mechanism (<NUM>; <NUM>) and locks the cassette (<NUM>; <NUM>; <NUM>) in place within the receiving portion (<NUM>);
ii) a first set of attachment structures (<NUM>, <NUM>, <NUM>, <NUM>; <NUM>, <NUM>, <NUM>, <NUM>) for connecting inflow tubing (<NUM>) and outflow tubing (<NUM>) of a nutritional feeding set (<NUM>) to the connector (<NUM>; <NUM>); and
iii) a second set of attachment structures (<NUM>, <NUM>, <NUM>, <NUM>; <NUM>, <NUM>, <NUM>, <NUM>) for connecting the free ends of the pump tubing segment (<NUM>; <NUM>; <NUM>) to the connector (<NUM>; <NUM>), wherein the attachment structures are hollow and fluidly connect the inflow tubing (<NUM>) and the outflow tubing (<NUM>) to the pump tubing segment (<NUM>; <NUM>; <NUM>).