Peristaltic pump and removable cassette therefor

[0001] The present invention relates generally to a peristaltic pump and a removable cassette therefor.

[0002] Peristaltic pumps are often used to deliver fluid in a very controlled manner such as, for example, the intravenous delivery of medicine to a patient. The peristaltic pump may generally include a pump body having a cassette removably attached thereto, and a tube supported by the cassette. A fluid (e.g., medicine) flows through the tube, generally by increments, as the tube is occluded against a race formed in the cassette in response to rotational movement of a planetary system of rollers driven by a motorized drive shaft. In some instances, the cassette may further include an occlusion mechanism or occluder that interacts with the tube to occlude the tube to substantially prevent fluid inside the tube from flowing through the tube.

[0003] A removable cassette for a peristaltic pump includes a cassette body and an occluder disposed at least partially in the cassette body and configured to be movable between an occluding position and a non-occluding position. The occluder includes an occluder body and an anti-ejection member integrally formed on the occluder body. The anti-ejection member is configured to substantially prevent the removal of the cassette from the peristaltic pump when the occluder is in the non-occluding position.

[0012] Embodiment(s) of the removable cassette for a peristaltic pump, as disclosed herein, advantageously include an occluder movable between an occluding position and a non-occluding position, where the occluder includes an anti-ejection member that substantially prevents removal of the removable cassette from the peristaltic pump when the occluder is in the non-occluding position. The occluder is relatively simple in design and generally does not include overly delicate and/or intricate parts that may be jammed or easily broken during operation and/or routine maintenance of the cassette. The peristaltic pump including the cassette also may advantageously provide feedback to a user thereby indicating to the user that the occluder is in the occluding position so that the cassette may be ejected from the pump. Further, the peristaltic pump including the cassette is relatively easy to assemble and to use.

[0013] As defined herein, the term “occlusion point” refers to an area or region on a tube at which the tube may be occluded by the occluder.

[0014] As also defined herein, the term “occluding position” refers to the position of the occluder in the cassette where the tube supported by the cassette is occluded at the occlusion point, thereby substantially preventing fluid from flowing through the tube at the occlusion point. The term “non-occluding position” refers to the position of the occluder in the cassette where the tube supported by the cassette is not occluded at the occlusion point, thereby allowing fluid to flow through the tube at the occlusion point.

[0015] As further defined herein, the term “ejection position” refers to the position of an anti-ejection member formed on the occluder where the anti-ejection member does not interface with a pump body retaining feature formed on the cassette body, thereby allowing the cassette to be removed from the pump body. The term “anti-ejection position” refers to the position of the anti-ejection member where the anti-ejection member interfaces with the pump body retaining feature, thereby preventing the cassette from being removed from the pump body.

[0016] Referring now to FIGS. 1 and 2, together, a peristaltic pump assembly is generally depicted at 10. Pump assembly 10 includes a removable and disposable cassette 12 assembled with a pump body 14. The pump body 14 includes a display 16 that corresponds with a keypad 18 for inputting user information such as, for example, patient identification number, drug identification number, operator identification number, or the like. The display 16 also provides visual feedback to the operator or user of the pump 10 regarding, for example, the amount of medication administered to the patient, the flow rate of the medication, and the time for medication administration.

[0017] The pump body 14 also includes a cassette receiving portion 20 formed adjacent to the display 16. The cassette receiving portion 20 includes a partial cavity 22 defined by a floor (not shown) and two opposed walls 26, 28. A roller mechanism 29, including an assembly of satellite rollers 30 arranged in a planetary configuration, is housed within the cavity 22. The roller mechanism 29 is attached to a pump motor (not shown) through a bore (not shown) formed through the first opposed wall 26. In a non-limiting example, each roller 30 is slip-fit onto a respective pin (the backs of which are shown at 102 in FIG. 1) supported by a yoke 100 (shown in FIGS. 1 and 2). The yoke 100 is mounted to a drive shaft (not shown), which is operated by the pump motor. As the yoke rotates, the rollers 30 rotate as an assembly. It is to be understood that, since the rollers 30 are slip-fit onto the pins, the rollers 30 are also free to rotate individually in response to rotational forces imparted thereto from the rotational movement of the drive shaft. Details of an example of the pump body 14 including an example of the roller mechanism 29 may also be found in U.S. application Ser. Nos. 11/862,302 and 11/862,326 filed concurrently herewith, which are commonly owned by the Assignee of the present disclosure, and are incorporated herein by reference in their entirety.

[0018] As shown in FIG. 1, a flexible tube 34, which is also disposable, is disposed in the cassette 12. In response to rotational movement of the rollers 30, portions of the flexible tube 34 that are in contact with the rollers 30 compress or are otherwise occluded against a race 36 (shown in FIG. 3) of the cassette 12. As a result, fluid is temporarily retained in the tube 34 between the occluded points. In this manner, fluid is urged through the tube via peristaltic wave action. The design of the cassette 12 will be described further in conjunction with FIGS. 3 and 4 below.

[0019] In a non-limiting example, the tube 34 may be classified as substantially flexible so that the tube may be compressed and/or occluded by the rollers 30. In an embodiment, the tube 34 is made of a polymeric material. Non-limiting examples of suitable polymeric materials include silicones, AUTOPRENE (an opaque thermoplastic rubber with high wear resistance derived from SANTOPRENE, commercially available from Advanced Elastomer Systems, a subsidiary of ExxonMobil Chemical located in Houston, Tex.), VITON (a black fluoroelastomer with resistance to concentrated acids, solvents, ozone, radiation and temperatures up to 200° C. with good chemical compatibility, commercially available from DuPont Performance Elastomers located in Wilmington, Del.), TYGON (good chemical resistance with a clear finish, commercially available from Saint-Gobain Performance Plastics Corporation located in Akron, Ohio), PROTHANE II (a transparent, blue, polyester, polyurethane tubing with good chemical resistance, commercially available from Randolph Austin Company located in Manchaca, Tex.), and/or the like, and/or combinations thereof. The inner diameter of the tube 34 may be selected based on the desirable flow rates and the desirable viscosities of the fluid that will flow therethrough.

[0020] A pump body retaining feature 35 (shown in FIG. 2) is located in the cassette receiving portion 20 of the pump body 14. The pump body retaining feature 35 is configured to matingly engage a cassette retaining feature 56 (shown in FIGS. 1 and 4) formed on the cassette 12. When the attaching mechanism 35 and coupling member 56 are engaged, the cassette 12 is secured to the pump body 14. In a non-limiting example, the pump body retaining feature 35 may be a clip movable between a closed position and an opened position. The closed position refers to the position of the pump body retaining feature 35 where the pump body retaining feature 35 engages the cassette retaining feature 56. The opened position refers to the position of the pump body retaining feature 35 when the pump body retaining feature 35 is moved away from the closed position.

[0021] With reference to FIGS. 3 and 4, the removable cassette 12 generally includes a cassette body 38, a removable occluder 40 at least partially disposed therein, and a cover 42 disposed over the cassette body 38. The cover 42 substantially secures the removable occluder 40 in the cassette body 38 when the occluder is assembled therewith.

[0022] The cassette body 38 is a single, integrally formed piece of polymeric material and may be fabricated using, for example, injection molding, cast molding, and/or the like. The cassette body 38 includes a base 44 having a wall 46 substantially normal to the base 44 and surrounding at least a portion of the perimeter of the base 44. The cassette body 38 further includes two opposed ends 48, 50. An inlet 52 is formed at the first end 48 and is configured to receive a first end of the tube 34. An outlet 54 is formed in the cassette body 38 at the second end 50, where the outlet 54 is configured to receive a second end of the tube 34. An assembly of the tube 34 with the cassette body 38 is shown in FIGS. 5A and 5B.

[0023] With reference to FIGS. 3-5B, the race 36 is integrally formed in the cassette body 38 and is positioned substantially normal to the base 44 and projects outwardly therefrom. The race 36 includes an occlusion surface 37 for the tube 34 to occlude the tube 34 when the rollers 30 force the tube 34 against the occlusion surface 37 during operation of the pump 10. Formed on the other side of the race 36 is a slide surface 64, which is a substantially smooth surface for slidable movement of the occluder 40 when the occluder 40 is assembled with the cassette body 38. The assembly of the occluder 40 with the cassette body 38 will be described in more detail below in conjunction with FIGS. 7A-7D.

[0024] Cassette retaining feature 56 (shown in FIGS. 3 and 4) is disposed adjacent to the inlet 52 formed in the cassette body 38. As mentioned above, the cassette retaining feature 56 is matingly engageable with the pump body retaining feature 35 included with the pump body 14 (shown in FIG. 2). Generally, the cassette retaining feature 56 is designed to complement or otherwise mate with the pump body retaining feature 35. In a non-limiting example, the cassette retaining feature 56 is a ledge formed in the cassette body 38 and is configured to receive and hold the pump body retaining feature 35 (e.g., a clip) when the pump body retaining feature 35 engages the cassette retaining feature 56. In use, when the cassette 12 is assembled with the pump body 14, the pump body retaining feature 35 captures the cassette retaining feature 56 and releasably attaches the cassette 12 to the pump body 14. It is within the purview of the present disclosure that other configurations or designs for the pump body retaining feature 35 and the cassette retaining feature 56 may also be used to removably attach the cassette 12 to the pump body 14, as desired.

[0025] The cassette body 38 also includes an anti-ejection member-receiving slot 68 formed therein. As shown in FIG. 4, the anti-ejection member-receiving slot 68 may generally resemble a key hole slot, where the slot 68 includes a narrow portion 70 and a wider portion 74. It is to be understood that the key hole configuration of the slot 68 facilitates assembly of the occluder 40 with the cassette body 38. This assembly will be described in more detail below. It is further to be understood that anti-ejection member-receiving slot 68 is configured to receive an anti-ejection member 72 (shown in FIG. 2) formed on the occluder 40, and further operates as a guide for the anti-ejection member 72. More specifically, the slot 68 is configured to allow the anti-ejection member 72 to move into a position to substantially prevent removal of the cassette 12 when the occluder 40 is in the non-occluding position; or to move into a position to allow removal of the cassette 12 when the occluder 40 is in the occluding position. Movement of the anti-ejection member 72 will be described further in conjunction with FIGS. 6A and 6B.

[0026] As shown in FIG. 3, the occluder 40 generally includes an occluder body 76 and the anti-ejection member 72 integrally formed thereon, and is configured to be movable between the occluding position and the non-occluding position. In an embodiment, the occluder body 76 is convex in shape and substantially conforms to the shape of the slide surface 64 formed adjacent to the race 36. It is to be understood that other shapes (e.g., a flat shape) may also be used for the occluder body 76 as long as the cassette body 38 is formed to accommodate the shape of the occluder body 76.

[0027] The occluder 40 includes first and second opposed sides 78, 80, where the first side 78 is configured to slidably contact the slide member 64, and the second side 80 includes a toggle member 82 extending outwardly therefrom and located proximate to a first end 83 of the occluder 40. In an embodiment, the toggle member 82 is embossed or otherwise defined in the occluder body 76 such that the toggle member 82 protrudes from the second side 80. In this embodiment, when the occluder 40 is assembled with the cassette 12, the toggle member 82 extends outwardly from the occluder body 76 and through an opening 84 defined in the cassette body 38. In use, when the cassette 12 is assembled with the pump body 14, the toggle member 82 actuates movement of the occluder 40 between the non-occluding position and the occluding position, shown in FIGS. 5A and 5B, respectively. Further, when the user moves the toggle member 82 to allow the occluder 40 to move into the occluding position, the cassette 12 provides feedback to the user that the occluder 40 is in the occluding position. Non-limiting examples of feedback include tactile feedback, audible feedback, and/or the like, and/or combinations thereof. In a non-limiting example, a releasable locking feature, e.g., a detent, may be provided between the occluder 40 and the cassette body 38 that may audibly “click” and/or provide a feel to a user that the occluder 40 has been placed into the occluded position.

[0028] The occluder 40 also includes an occlusion slot 86 formed in the occluder body 76 proximate to a second end 88 of the occluder 40. The occlusion slot 86 is configured to substantially occlude the tube 34 when the occluder 40 is in the occluding position, and is further configured to substantially allow free flow of fluid through the tube 34 when the occluder is in the non-occluding position. In an embodiment, the occlusion slot 86 is a key hole slot having a narrow portion 90 and a wider portion 92. In this embodiment, and as shown in FIGS. 5A and 5B, the occlusion slot 86 receives the tube 34 in the wider portion 92 thereof when the occluder 40 is in the non-occluding position, and receives the tube 34 in the narrow portion 90 when the occluder 40 is in the occluding position.

[0029] With reference again to FIG. 3, the occluder 40 further includes the anti-ejection member 72 formed on an edge 94 of the occluder body 76 located proximate to the second end 88. The anti-ejection member 72 is generally a tab projecting from the edge 94 and extending substantially perpendicular thereto. The anti-ejection member 72 is configured to substantially prevent removal of the cassette 12 from the peristaltic pump 10 when the occluder 40 is in the non-occluding position, and is further configured to allow removal of the cassette 12 from the peristaltic pump 10 when the occluder 40 is in the occluding position. This may be accomplished by causing the anti-ejection member 72 to either lock or unlock the cassette retaining feature 56. In a non-limiting example, as shown in FIG. 6A, when the occluder 40 is in the occluding position, the anti-ejection member 72 moves into an ejection position. In this position, the anti-ejection member 72 does not interface with the pump body retaining feature 35, thereby allowing the cassette 12 to be removed from the pump 10. In another non-limiting example, as shown in FIG. 6B, when the occluder 40 is in the non-occluding position, the anti-ejection member 72 is in an anti-ejection position. In this position, the anti-ejection member 72 interfaces with the pump body retaining feature 35, thereby substantially locking the cassette 12 to the pump body 14. This prevents the cassette 12 from being removed or ejected from the pump 10.

[0030] A method of assembling the cassette 12 is shown in FIGS. 7A-7D. The method generally includes providing the cassette body 38 and providing the occluder 40 as described above, and at least partially disposing the occluder 40 in the cassette body 38. An embodiment of a method of disposing the occluder 40 in the cassette body 38 may be accomplished as set forth below.

[0031] Referring now to FIG. 7A, the occluder 40, including the tube 34 (which is schematically depicted in FIG. 7A) disposed or otherwise threaded through the slot 86, is positioned substantially perpendicular to a plane X parallel to the cassette body 38 (e.g., plane X includes points defined by ends 48 and 50 (shown in FIG. 7B) of the cassette body 38). In more detail, the second end 88 of the occluder 40 including the anti-ejection member 72 is positioned substantially perpendicularly to the anti-ejection member-receiving slot 68 at a first side 96 of the base 44 of the cassette body 38. It is to be understood that the end 88 including the anti-ejection member 72 is substantially complementarily shaped with the anti-ejection member-receiving slot 68 so that the occluder 40 can easily slide therein. The positioning of the second end 88 is such that the anti-ejection member 72 is substantially aligned with the wide portion 92 of the slot 68.

[0032] Second, as shown in FIG. 7B, the occluder 40 is passed through the anti-ejection member-receiving slot 68 until the anti-ejection member 72 is exposed on a second, opposed side 98 of the base 44.

[0033] Third, and as shown in FIG. 7C, the occluder 40 is rotated counter-clockwise about 90° relative to the base 44 so that a side edge 94 (shown in FIG. 3) of the occluder body 76 is substantially aligned with the plane X. When the occluder 40 is rotated into the cassette body 38, the toggle member 82 is received through the opening 84 for access thereto by a user of the cassette 12.

[0034] Fourth, and as shown in FIG. 7D, the tube 34, already disposed through the slot 86 (best seen in FIG. 3) formed in the occluder 40, is fed through the inlet 52 formed in the cassette body 38 and through the outlet 54. The cover 42 is then disposed over the cassette body 38 and secured thereto via latching, snapping, welding, and/or the like, and/or combinations thereof. When the cover 42 is secured to the cassette body 38, the occluder 40 is substantially secured therein.

[0035] It is to be understood that the term “couple/coupled” or the like is broadly defined herein to encompass a variety of divergent coupling arrangements and assembly techniques. These arrangements and techniques include, but are not limited to (1) the direct coupling between one component and another component with no intervening components therebetween; and (2) the coupling of one component and another component with one or more components therebetween, provided that the one component being “coupled to” the other component is somehow operatively coupled to the other component (notwithstanding the presence of one or more additional components therebetween).

[0036] While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.