FIELD OF THE INVENTION

The present invention relates generally to delivery of enteral nutritional fluids to a patient, and in particular to safe and reliable loading of enteral nutrition feeding sets to matching peristaltic infusion pumps to prevent free flow of fluids into the patient.

BACKGROUND OF THE INVENTION

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.

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.

SUMMARY OF THE INVENTION

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 providing an interface between a feeding set and a peristaltic infusion pump for delivery of an enteral nutritional fluid to a patient, the cassette comprising: (a) a pump tubing segment for engaging a pumping mechanism located within a receiving portion of a peristaltic infusion pump, the pump tubing segment comprising an anti-flow mechanism for preventing free flow of enteral nutritional fluid through the pump tubing segment, wherein the anti-flow mechanism causes an obstruction to flow when the pump tubing segment is not engaged with the pumping mechanism; and (b) a connector for connecting to the infusion pump, wherein connection of the connector with the infusion pump aligns the pump tubing segment with the pumping mechanism and locks the cassette in place within the infusion pump, and wherein engagement of the pump tubing segment with the pumping mechanism overcomes the anti-flow mechanism of the pump tubing.

A second 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 for preventing free flow of fluid through the pump tubing segment, wherein the anti-flow mechanism causes an obstruction to flow when the pump tubing segment is not 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 third 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 for preventing free flow of fluid through the pump tubing segment when the pump tubing segment is not 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 anti-flow mechanism of the pump tubing; and (f) actuating the pumping mechanism to cause controlled flow of nutritional fluid through the feeding set.

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.

