Abstract:
An apparatus and method for preventing the occurrence of free fluid in a fluid delivery system consists of a valve having a sealing element and elongate body disposed within the lumen of a flexible tube. The elongate body of the valve if further disposed within the inlet port of a connector. The perimeter of the sealing element and lumen of the flexible tube provide a tight seal preventing fluid flow when the flexible tube is in a relaxed state or when the longitudinal axis of the flexible tube is in alignment with the axis of the inlet port. The medical fluid is allowed to flow when the longitudinal axis of the flexible tube is not in alignment, e.g., when angularly stretched, with the axis of the inlet port.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a device for preventing fluid free flow through a tube assembly of a fluid delivery system. More specifically, the present invention relates to an anti-free flow device, that prevents fluid free flow when the tube assembly is disengaged from a rotary pump, while allowing fluid flow the tube assembly is engaged with the pump.  
           [0002]    1. Field of the Invention  
           [0003]    Many individuals in hospitals or nursing homes cannot orally take nourishment or medication. These individuals, or medical patients, typically receive medical fluids containing the requisite nourishment and/or medication intravenously or-enterally via a tube assembly of a fluid delivery system. In such a fluid delivery system, gravity is used to feed the medical fluid from a container, e.g., a plastic pouch, through the tube assembly and into the patient. More recently, pumps, e.g., rotary peristaltic pumps, have been added to fluid delivery systems to regulate the rate that the medical fluid is infused into the patient.  
           [0004]    Although these peristaltic pumps have allowed better control of the administration of the medical fluid, the use of the pumps have increased the risk that a medical patient is overmedicated or overfed. This risk arises whenever the tube assembly is disengaged from the pump, and the medical fluid is free to flow through the tube assembly under the force of gravity, in a situation known as fluid free flow.  
           [0005]    To prevent the occurrence of free flow, many fluid delivery systems include valves or occluders which automatically block the passage of fluid whenever the tube assemblies are disengaged from the pumps. Although many of such valves and occluders are effective, they are also mechanically complicated and add to the overall cost of the tube assembly. Furthermore, many of these valves and occluders cannot be retrofitted to existing tube assemblies or easily incorporated into existing tube assembly designs. Other valves and occluders incorporate additional mechanical parts to the tube assembly, thus, making them more complex and difficult to use.  
           [0006]    Thus, there is a need for a mechanically simple anti-free flow device that is compatible with existing tube assembly designs. An example of tube assembly that can be retrofitted with the anti-free flow device is the COMPAT® enteral delivery sets distributed by Novartis Nutrition Corporation (Minneapolis, Minn.).  
         SUMMARY OF THE INVENTION  
         [0007]    A primary object of the present invention to provide an apparatus and method for occluding the tube assemblies of feeding delivery sets to prevent free flow.  
           [0008]    Another object of the present invention to provide an anti-free flow device which is simple to make, use and easily incorporated into existing tube assembly designs.  
           [0009]    According to the present invention, there is provided a feeding delivery system that includes a container holding a medical fluid to be infused; a tube assembly containing a device for preventing free flow; and a pump, e.g., a rotary peristaltic pump, for pumping the medical fluid into the patient. The tube assembly includes components, such as a roller clamp, a drip chamber, an anti-free flow device, a connector and a spike, as well as medical grade tubing to connect these components in series. In addition to these components, other optional components can be incorporated into the tube assembly, e.g., a y-port fitting or roller clamp.  
           [0010]    When the tube assembly is installed within the rotary peristaltic pump, the drip chamber and the connector are oriented, e.g., parallel to each other. The section of tubing connecting the drip chamber to the connector is wrapped, or stretched, around the rotor of the peristaltic pump.  
           [0011]    When the tube assembly is installed within the rotary peristaltic pump and both the drip chamber and connector are each engaged with the pump, the section of tubing between the drip chamber and connector is stretched around the rotor of the peristaltic pump. The axes of the outlet port of the drip chamber and the inlet port of the connector are oriented, e.g., parallel to each other. The anti-free flow device consists, e.g., of a sealing element and an elongate body such that the elongate body is partially disposed within the inlet port of the connector. The longitudinal axis of the anti-free flow device resides in an non-parallel configuration with respect to the axis of the inlet port of connector. The longitudinal axis of the anti-free flow device and the axis of the inlet port of the connector intersect to form an angle, e.g., an acute example. The stretching of the tubing causes the tube to deform in the vicinity of the sealing element. This deformation allows the fluid to flow freely past the sealing element.  
           [0012]    When the tube assembly is accidentally disengaged and no longer under tension, e.g., when the connector is no longer seated in the rotary peristaltic pump, the tubing relaxes to its original state prior to assemblage into the pump. The longitudinal axis of the anti-free flow device becomes collinear with the axis of the inlet port of the connector. A tight seal forms around the sealing element of the anti-free flow device thus preventing fluid from flow past the sealing element and onto the patient.  
           [0013]    Numerous, other objects, features and advantages of the present invention will readily become apparent from the following detailed description, from the claims and from the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an exemplary embodiment of the present invention.  
         [0015]    [0015]FIG. 1 is a front elevational view of an exemplary embodiment of a fluid delivery system;  
         [0016]    [0016]FIG. 2 is a front elevational view of an exemplary embodiment of a tube assembly for use with the fluid delivery system of FIG. 1;  
         [0017]    [0017]FIG. 3 is a perspective view of an exemplary embodiment of an anti-free flow device in accordance with the present invention for use with the tube assembly of FIG. 2;  
         [0018]    [0018]FIG. 4 a  is a front elevational view of the anti-free flow device of FIG. 3 within the tube assembly of FIG. 2 in a relaxed state;  
         [0019]    [0019]FIG. 4 b  is an enlarged view of the section circled in FIG. 4 a;    
         [0020]    [0020]FIG. 5 a  is a front elevational view of the anti-free flow device of FIG. 3 within the tube assembly of FIG. 2 in a stretched state; and  
         [0021]    [0021]FIG. 5 b  is an enlarged view of the section circled in FIG. 5 a.    
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0022]    Referring to FIG. 1 a front elevational view of an exemplary embodiment of fluid delivery system  10  in accordance with the present invention is illustrated. The fluid delivery system  10  consists of pump  12  and tube assembly  14  assembled together in their intended operative manner.  
         [0023]    The pump  12  can be any type of pump appropriate for controlling the flow of medical fluid through the tube assembly  14  and into a patient. For example, peristaltic pumps are commonly used, as known in the art, to accomplish such a task. The pump  12  selectively allows a metered amount of medical fluid to flow downstream or distally from the pump  12 . Any type of peristaltic pump, for example a rotary peristaltic pump, can be used in conjunction with the anti-free flow device of the present invention. The pump, as depicted in FIG. 1., is a rotary peristaltic pump. The pump  12  has rotor  16  which engages the tube assembly  14  with rollers (not shown). Each revolution or partial revolution of the rotor  16  causes a specific amount of medical fluid to flow through the tube assembly  14 . Also shown on the pump  12  is control panel  18  which allows a user to observe and adjust the rate of rotation for the rotor  16 . A faster rate of rotation per period allows a larger quantity medical fluid to be administered to the patient. First bracket  20  and second bracket  22  are formed within the housing of the pump  12  and are located above the rotor  16 . The first bracket  20  and second bracket  22 , e.g., are used to engage various components of the tube assembly  14  which are discussed in further detail below.  
         [0024]    Referring to FIG. 2, a front elevational view of the tube assembly  14  in accordance with an exemplary embodiment of the present invention is depicted.  
         [0025]    As used herein, the term “proximal” refers to the end of the tube assembly  14  closest to the supply container  26 , and “distal” refers to the end of the tube assembly  14  furthest away from the supply container  26 . Additionally, as used herein, the term “downstream” means in the direction of or nearer the patient. Likewise, as used herein, “upstream” means in the direction of or nearer the supply container  26 .  
         [0026]    The tube assembly  14  consists of a plurality of discrete, or integrally formed, components connected in series via sections of tubing. For example, at one end of the tube assembly  14  is supply container  26 . The supply container  26  can be, e.g., a rigid bottle or a flexible pouch to hold the medical fluid that is to be administered to a patient enterally or parenterally. When in use, the supply container  26  is typically hung from a support (not shown) above the patient, e.g., five or six feet from off the floor.  
         [0027]    At the bottom of the supply container  26  is outlet  28  which allows medical fluid to exit therefrom. Connected to the outlet  28  is first tube section  30 . The first tube section  30  connects the supply container  26  to drip chamber  32 . Second tube section  34  connects the drip chamber  32  to connector  36 . Third tube section  38  links the connector  36  with patient connection  40 . Aside from providing a physical means of attachment between the tube assembly  14  and pump  12 , the drip chamber  32  also functions a feedback mechanism signaling to the pump  12  the rate the medical fluid is being administered.  
         [0028]    For example, when the tube assembly  14  is for parenteral use, the patient connection  40  is a needle. When the tube assembly  14  is for enteral use, the patient connection  40  is a balloon catheter that connects to a stoma with a visceral organ, such as the stomach of the patient.  
         [0029]    The tube sections  30 ,  34  and  38  are each made of a flexible, resilient material. The tube sections  30 ,  34  and  38  can be of identical or different materials. Examples of such materials include, but are not limited to, silicone, rubber, polyvinyl chloride, polyurethane, latex, neoprene or any other suitable medical grade material of the like. For example, the tube sections  30  and  38  can be made of polyvinyl chloride whereas the tube section  34  can be made of silicone.  
         [0030]    Inserted within the lumen of the second tube section  34  is anti-free flow device  42  which is described in more detail below.  
         [0031]    Referring back to FIG. 1 both the drip chamber  32  and the connector  36  are sized and shaped such that each can be attached to the first bracket  20  and the second bracket  22  of the housing of the pump  12  respectively. The section of tubing between the drip chamber  32  and the connector  36 , the second tube section  34 , is stretched around the rotor  16 . The second tube section  34  connects outlet port  44  of the drip chamber  32  to inlet port  46  of the connector  36 . The inlet port  46  serves as the entry to the bore (not shown) within the connector  36 . The bore extends through the entire length of the connector  36  and provides a passage for the medical fluid to flow there through.  
         [0032]    Referring now to FIG. 3, a perspective view of the anti-free flow device  42  is shown. The anti-free flow device  42  includes sealing element  52  and elongate body  54 . The sealing element  52  and the elongate body  54  resemble, e.g., the head and stem of a nail.  
         [0033]    The sealing element  52 , e.g., is disc-like, or circular, and has a diameter that is equal to or slightly greater than the inside diameter of the lumen of the tubing assembly  14  when the tubing assembly is relaxed or not placed under any tension. Perimeter  58  of the sealing element  52  and the inner wall of the lumen of the tubing assembly  14  create a fit, or a seal, preventing fluid from passing the sealing element  52  as shown in FIG. 4 (discussed in detail below). The sealing element  52  has top surface  60  which is oriented against the flow of the medical fluid within the tubing assembly  14 . Top surface  60  can be planar or curved, e.g., convex or concave.  
         [0034]    The elongate body  54  of the anti-free flow device  42  functions as a stem for the sealing element  52 . The elongate body  54  can be rigid and does not bend whenever the second tube section  34  is pulled laterally or deformed. The shape of the elongate body  54  can be, e.g., tapered.  
         [0035]    Located optionally along the length of the sealing element  52  are a plurality of grooves  62 . The grooves  62 , e.g., can be of any length and can run along the entire length of the anti-free flow device  42 , including the exterior surface of the elongate body  54 , shown as grooves  62   a , or partially along the sealing element  54  shown as grooves  62   b . The grooves  62  are oriented with respect to each other such that none of the grooves  62  are perpendicular to the adjacent groove. For example, in FIG. 3, each groove  62   a  and its adjacent groove  62   b  form an angle of 60°. If there were three grooves then the grooves would be spaced 120° apart. Any number of grooves in any angle of spacing can be used provided that no two adjacent grooves are perpendicular to each other.  
         [0036]    Although the exemplary embodiment of the anti-free flow device  42  as shown in FIG. 3 resembles a nail, it is appreciated that one of ordinary skill in the art can develop alternative shapes for the anti-free flow device  42  in accordance with the spirit of the present invention. For example, the anti-free flow device can take on the shape of an egg, a disk, a ball and stem and a bullet.  
         [0037]    [0037]FIGS. 4 a  and  4   b  show a front elevational view of the anti-free flow device  42  assembled within the lumen of the second tube section  34  of the tube assembly  14 . FIG. 4 a  also shows the tube assembly  14  in a relaxed state which would be the state if the tube assembly  14  were not assembled with the pump or if the tube assembly  14  were accidentally disengaged. The anti-free flow device  42  is oriented such that the sealing element  52  is against the flow of the medical fluid within the tube assembly  14 . The elongate body  54  is partially disposed within the bore of the connector  36  entering through the inlet port  46 . “Partially disposed” means that some length of the elongate body  54  is within the bore of the connector. The elongate body  54  can be fixed or freely movable within the bore. For example, in an alternative part, the anti-free flow device  42  and the connector  36  can be integrally formed or be of a single construction.  
         [0038]    The anti-free flow device  42  effectively prevents a free-flow condition whenever the tube assembly  14  is in a relaxed state which occurs whenever the second tube section  14  is not stretched or under tension. For example, a relaxed state occurs when the tube assembly  14  is inserted into the pump  12  or when the connector  36  become s disengaged from the pump  12  after the tube assembly  14  has already been connected to the pump  12 .  
         [0039]    When the tube assembly  14  is in a relaxed state, the perimeter of the sealing element  52  forms a seal with the lumen of the second tube section  34  to prevent the flow of medical fluid. In the relaxed state, the longitudinal axis, labeled B, of the second tube section  14  is axially aligned to axis, A, of the inlet port  46  of the connector  36 . “Axial alignment” refers to the alignment between axes A and B, e.g., when the axes A and B are collinear or parallel.  
         [0040]    When the tube assembly  14  is engaged in the pump  12 , the second tube section  34  is in a stretched or flexed state, e.g., when stretched at an angle, and pulled laterally such that the axis B of the second tube section  34  is no longer in axial alignment with the axis A of the inlet port  45  of the connector  36 . As shown in FIGS. 5 a  and  5   b , the second tube section  34  is pulled towards the left of the connector  36 . The axis A and axis B intersect to form angle α. When α is greater than 0°, e.g., 10°, 15°, 30°,45° or 60° the seal between the perimeter  58  of the sealing element  52  and the lumen of the second tube section  34  is temporarily breached to form passage  72  that allows the flow of medical fluid. Medical fluid flows through the lumen of the second tube section  34  into the passage  72  and along the grooves  62  of the anti-free flow device  42  and into the bore. Specifically, the passage  72  results from the reversible mechanical deformation of the second tube section  34  in the vicinity of the sealing element. Once the axes A and B are no longer in axial alignment, the sealing element  52  facilitates the flow of medical fluid by acting as a pivot point or lever that accentuates the passage  72 .  
         [0041]    During the engagement of the tube assembly  14  within the pump  12 , the anti-free flow device  42  is stationary and remains in place regardless of what angle α is. In an alternative exemplary embodiment, the stretched state of the second tube segment  34  causes the elongate body  54  of the anti-free flow device  42  to pull out from the bore of the connector  36  such that the elongate body  54  is not as substantially disposed as it were prior to the stretching. Once again, the passage  72  is accentuated by allowing the anti-free flow device  42  to pull out of the connector  36 . In this exemplary embodiment, the longitudinal axis of the anti-free flow device  42  is in axial alignment with the axis A when the second tube section  34  is in a relaxed state. The longitudinal axis of the anti-free flow device  42  is out of axial alignment with the axis A when the tube section is under a state of tension. The acute angle of intersection between the longitudinal axis of the anti-free flow device and the angle a can be the same or different in this exemplary alternative embodiment.  
         [0042]    It is understood that while the present invention has been described in conjunction with the detailed description thereof that the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the following claims. Other aspects, advantages and modifications are within the scope of the claims.