Patent Publication Number: US-2007113911-A1

Title: Multi-lumen miniature ribbon tubing

Description:
FIELD OF THE INVENTION  
      The present invention relates to tubular conduits and, more particularly, to plural duct tubular conduits  
     BACKGROUND OF THE INVENTION  
      For conducting fluids to and from the human body or portions thereof (e.g., for delivering liquid nutrients, medicine, or blood), flexible rubber or polymer tubing has traditionally been used. Such tubing typically comprises an elongate cylindrical sidewall defining a hollow, cylindrical passageway having a relatively wide diameter (e.g., from 0.125 to 0.250 inches) through which the fluid travels. Such tubes are well adapted to delivering large amounts of a single fluid to or from a single location, but cannot be used to concurrently deliver multiple non-commingled fluids. Multiple tubes can be used to deliver multiple fluids, but this requires bundling the tubes together to avoid a “tangle” of tubes. Also, such bundled tubes are bulky, and cannot be used in situations involving the delivery of many different fluids and/or fluids to a very small or restricted destination location, e.g., a single organ. They also present a greater risk of contamination due to the increased total surface area requiring sterilization or disinfecting.  
      Since conventional tubes are impractical for doing so, multi-lumen tubes and catheters are used for delivering different fluids to and from the human body or other location. As shown in  FIGS. 1A and 1B , such tubes typically have a cylindrical outer wall and two or more interior lumens, i.e., separate longitudinal passageways. These tubes work well in certain applications, e.g., as catheters for delivering nutrients, but are impractical in situations where fluids have to be delivered to different locations. This is because the lumens are integral with the overall tube and, therefore, are necessarily co-terminus, i.e., have openings lying proximate to one another. This is because the lumens cannot be separated from one another.  
      Flat tubes or hoses have been used in certain situations where a generally flat outer shape is desired over a tubular outer shape. For example, as shown in  FIG. 1C , ribbon tubes are sometimes used in applications where a “low profile” is required. Also, flat hoses are available for garden use, and are believed to be less prone to kinking then conventional round hoses. As should be appreciated, however, such devices are not suitable for delivering multiple fluids within a clinical, laboratory, or other context.  
     SUMMARY OF THE INVENTION  
      An embodiment of the present invention relates to a multi-lumen, miniature ribbon tube. The ribbon tubing is generally flat in overall shape, and comprises a number of generally parallel, longitudinal lumens arranged sequentially one next to the other. Each lumen includes a tubular polymer sidewall defining a longitudinal fluid passageway or bore. (As used herein, “lumen” refers to a sidewall and passageway/bore in combination, while “fluid” refers to all freely flowable materials including liquids and gases.) The fluid passageways are each separated from one another by the sidewalls. The lumens are integrally formed, but may be provided with outwards-facing longitudinal grooves (upper and lower grooves between neighboring pairs of lumens) for facilitating longitudinal separation of the lumens from one another. The sidewall may be made of a medical grade Teflon®-type polymer, e.g., FEP or ETFE. The ribbon tubing may be as wide as 3.5 inches, and may have the following additional dimensions: a passageway diameter of about 0.005 to about 0.050 inches; and a minimum wall thickness of about 0.002 inches and more typically at least about 0.005 inches.  
      Using the minimum wall thickness and passageway diameter, a 3.5-inch wide ribbon tube according to the present invention would have well more than 200 lumens, each providing a separate fluid passageway. Tubing having a larger wall thickness and/or larger passageway diameter would have fewer lumens, but still typically at least six, and more typically at least twenty lumens. In each case, this would enable a multiplicity of fluids to be delivered to one location, a single fluid to be delivered to multiple locations, or any combination thereof. Because the distal ends of the lumens can be separated from one another, each can be directed to a different localized destination location. At the same time, the central portion of the tubing (i.e., the portion where the lumens remain connected) provides a compact, unitary tubing unit that can be easily routed without tangling, kinking, etc. Additionally, if the distal ends of some or all of the lumens are left connected together, they can be conveniently terminated into one mass, multi-lumen connector that provides a single common connection (i.e., one fluid source for all the lumens), multiple connections (i.e., different fluid sources for the different lumens), or a combination of the two. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:  
       FIGS. 1A and 1B  are cross-sectional views of prior art multi-lumen tubes or catheters;  
       FIG. 1C  is a cross-sectional view of a prior art flat tube;  
       FIG. 2  is a perspective view of miniature ribbon tubing according to an embodiment of the present invention;  
       FIG. 3A  is a cross-sectional view of the ribbon tubing of  FIG. 2  taken along line  3 A- 3 A;  
       FIG. 3B  is a cross-sectional view of the ribbon tubing in  FIG. 2  with a slightly larger pitch;  
       FIG. 4  is a schematic view of the ribbon tubing in use for delivering fluids, at a source end;  
       FIG. 5  is a perspective view of the ribbon tubing in use, at a destination end;  
       FIG. 6  is a cross-sectional view of an alternative embodiment of the ribbon tubing; and  
       FIGS. 7A and 7B  are top plan views of tubing connectors. 
    
    
     DETAILED DESCRIPTION  
      With reference to  FIGS. 2-5 , an embodiment of the present invention relates to a multi-lumen, miniature ribbon tube  10 . The ribbon tubing  10  is generally flat in overall shape, and comprises a number of generally parallel, generally tubular lumens  12  arranged sequentially one next to the other. In other words, the lumens  12  are laterally sequentially arranged in parallel to form a generally flat outer periphery  14 . (By “generally flat,” it is not meant that the top and bottom of the ribbon tubing is necessarily flat or without contours/features, although that could be the case; instead, it is meant that the tubing is significantly wider than it is thick.) Each lumen  12  includes a polymer sidewall  16  and a hollow, longitudinal fluid passageway or bore  18  extending down through the center of the sidewall  16 . The fluid passageways  18  will typically be separated from one another, i.e., not in fluid communication. (By “fluid,” it is meant any flowable material including liquids and gases.)  
      The longitudinal passageways  18  will typically be circular in cross section. However, passageways having different cross sections are possible. For example, the passageways could be elliptical or polygonal in cross section. In either case, the passageways have a maximum dimension  20 , by which it is meant the maximum straight-line lateral distance across the passageway. In the case of a passageway with a circular cross section, the maximum dimension  20  is the inner diameter of the lumen, as shown in  FIG. 3A . Typically, the inner diameter (or other maximum dimension) will be from about 0.005 to about 0.050 inches, where “about” refers to manufacturing tolerances typically on the order of ±1 on the least significant digit, e.g., 0.005±0.001 inches. The polymer sidewall may be as thin as about 0.002 inches, but for increased sturdiness will more typically have a thickness of at least about 0.005 inches up to about 0.015 inches. A wall thickness of more than about 0.015 inches is possible, e.g., up to a maximum of about 0.050 inches. The pitch  22  of the tubing (meaning the distance between the longitudinal axes of neighboring passageways) will typically be at least 1.5 times the maximum dimension  20 . Thus, with an inner diameter  20  of about 0.005 inches, the pitch would be at least about 0.007 inches. More typically, with an inner diameter of about 0.005 inches and a wall thickness of about 0.005 inches, the pitch would be at least about 0.012 inches.  
      To provide for relative compactness, the ribbon tubing  10  will typically be around 3.5 inches wide or less. With an inner diameter of about 0.005 inches, a wall thickness of about 0.005 inches, and a pitch of about 0.012 inches, a 3.5-inch wide length of the ribbon tubing  10  would include at least 280 lumens  12 . Because each lumen  12  defines a separate longitudinal fluid passageway  18 , a length of such a tubing could be used to deliver a number of different fluids from one location to another, one fluid from one location to a plurality of different localized destination locations, or any combination thereof, all in a convenient, compact, easy-to-route, and easy-to-terminate package.  
      Because passageways  18  with a diameter  20  of about 0.005 inches will admit a relatively small volume of fluid, for certain applications where it is desired to transmit a greater volume of fluid, passageways with a diameter (or other maximum dimension) of from about 0.015 to about 0.050 inches may be used. For the latter, with a wall thickness of from about 0.015 to about 0.050 inches, there will be a minimum of six lumens  12  in a one inch-wide section of tubing  10 . At least this many lumens in a one inch-wide section of tubing would provide an acceptable balance between flexibility in delivering one or more fluids to different locations and a compact package or overall shape. For greater flexibility in terms of fluid delivery, a 3.5-inch wide section of tubing would provide at least twenty-three of the lumens  12 —still a compact overall package. With a smaller inner diameter  20  of about 0.015 inches and a wall thickness of from about 0.005 to about 0.015 inches, there would be at least twenty lumens  12  in a one inch-wide section of tubing  10 . Overall, it is believed that tubing  10  with at least twenty lumens  12  in a one inch-wide section would provide an optimal balance between flexibility in delivering fluids to different locations while preserving a compact outer package/periphery.  
      The sidewall  16  may be made of a polymer such as a medical grade fluoropolymer or other polymer, for example FEP (fluorinatedethylenepropylene) or ETFE (ethylene-tetrafluoroethylene). Other materials are possible. Between FEP and ETFE, FEP may be preferred for certain applications since it is stable at high temperatures and is generally impervious to acids and other caustic chemicals, and is more flexible than ETFE.  
      The ribbon tubing  10  may be provided with upper and lower outwards facing longitudinal grooves  24   a ,  24   b  between neighboring pairs of lumens  12  for facilitating frangibility and separation of the lumens  12  from one another. The grooves  24   a ,  24   b  will typically be formed during the manufacturing process, e.g., either as a feature in a mold for molded tubing or a feature in a die, forming roll, or the like for extrusion. As shown in  FIG. 3A , the grooves  24   a ,  24   b  may be relatively shallow. Alternatively, as shown in  FIG. 3B , the grooves  24   a ,  24   b  may be deeper, with the lumens  12  being more distinct from one another. It should be noted that given a set wall thickness, a shorter pitch  22  results in the tubing shown in  FIG. 3A , while a longer pitch results in the tubing shown in  FIG. 3B . In either case, the sidewall  16  may be configured so that the lumens  12  are frangible by hand and/or by the use of a machine or device, e.g., a blade or other sharp instrument. As suggested by  FIG. 2 , the tubing  10  may be provided with the lumens  12  pre-separated from one another proximate one or both ends of the tubing  10 .  
       FIG. 4  shows the tubing  10  in use on the supply end. Here, a first lumen  12   a  is connected to a first liquid or other fluid source  26   a , and a second lumen  12   b  is connected to a second fluid source  26   b . In addition, three other lumens  12   c - 12   e  are connected to a third fluid source  26   c . Assuming the lumen passageways are the same size, if each fluid source  26   a - 26   c  has the same source pressure, then each lumen  12   a - 12   e  will transfer fluid at the same flow rate. As such, to provide different volumes of fluids, all that is required is to combine some of the lumens  12  in parallel with a common source and destination. Thus, in  FIG. 4 , if each lumen  12   a - 12   e  admits a fluid at a flow rate of “X” given the same source pressure, then the three lumens  12   c - 12   e  connected in parallel will admit an effective flow rate of 3X. In  FIG. 4 , the lumens  12   a ,  12   b , and  12   c - 12   e  are shown as being separated from one another ( 12   c - 12   e  remain connected) proximate the end of the tubing  10  by the fluid sources  26   a - 26   c . As should be appreciated, this might be done for facilitating connection of the lumens to the fluid sources in cases where the fluid sources are spaced apart. However, the tubing  10  could be connected to multiple fluid sources without separating the lumens  12 , provided the coupling(s) to the fluid sources were closely proximate to one another. As shown in  FIG. 4 , despite the lumens  12   a - 12   e  being partially separated from one another, this is only proximate the end of the tubing, and the lumens remain connected to one another away from the fluid sources  26   a - 26   c . Thus, most of the tubing  10  remains unified, tangle-free, and easy to route and place in a laboratory, medical, or other setting.  
       FIG. 5  shows an example of the tubing  10  in use on the destination end. Here, lumen  12   a  is connected to one location  28   a  on a biological or other subject  30 . The subject could be an organ or other body part, a chemical apparatus, a machine, or any other device or object with which tubing is used. Similarly, lumen  12   b  is connected to a different, second location  28   b , and lumens  12   c - 12   e  are connected at a third location  28   c . Although the tubing  10  has been indicated for use in delivering fluids between various fluid sources  26   a - 26   c  and a destination subject  30 , the tubing  10  could also be used to simultaneously deliver fluids in both directions. For example, lumens  12   c - 12   e  could be used to deliver fluid to the subject  30  from a fluid source  26   c , while lumen  12   a  could be used to draw in fluid from the subject  30  at the location  28   a  and to deliver the sampled fluid to a device for analysis or monitoring.  
      The tubing  10  may be connected to a source or destination using standard tube fittings or other connectors dimensioned to correspond to the shape and size of the tubing  10 . As noted above, if the distal ends of some or all of the lumens are left connected together, they can be conveniently terminated into one mass, multi-lumen connector  50  (see  FIG. 7A ) that provides a single common connection (e.g., one fluid source for all the lumens), a connector that provides multiple connections (e.g., different fluid sources for the different lumens), or a connector  52  (see  FIG. 7B ) that provides a combination of the two.  
      The tubing  10  may be manufactured by molding, but more typically by extrusion. To form the passageways  18 , the sidewall  16  may be extruded over a plurality of wire-like, longitudinal metal supports, each of which has a cross section corresponding to the desired cross section of the passageways  18 . Once the polymer sidewall is set, the metal supports are stretched/elongated (typically by at least 25%) and then pulled axially away and out from the sidewall, leaving the passageways  18 . If a forming roll is used as part of the extrusion process, adhesion between the supports and sidewall may be lowered by deepening the forming roll concavities that in combination define the outer periphery of the tubing  10 .  
      The tubing  10  may take the form of non-stacked tubing. By “non-stacked” tubing, it is meant that not only are the lumens  12  laterally sequentially arranged in parallel to form a generally flat outer periphery  14 , but that the tubing  10  only has lumens so arranged, and does not have any lumens dissimilarly arranged, e.g., lumens stacked atop one another.  
      An embodiment of the present invention may also be characterized as a length of tubing have an outer wall and a plurality of longitudinal interior walls connected to the outer wall, with the passageways being defined by the outer wall and interior walls. Here, the outer wall would be considered the portion of the tubing separating the passageways from the exterior of the tubing, and the interior walls would be considered the portion of the tubing separating the passageways from one another.  
       FIG. 6  shows an alternative embodiment of the ribbon tubing  40 . Here, one or more of the passageways  42  would each be provided with a bendable support  44  extending down the length of the passageway. The bendable support  44  could be a small-diameter, generally stiff metal wire, i.e., a wire that maintains its shape but is capable of being easily bent. Such supports would allow the ribbon tubing  40  to be formed or bent into different configurations, shapes, or pathways, and would also help with rolls of the tubing remaining rolled up in storage and transportation. The supports could be provided as a byproduct of the manufacturing process, simply by leaving one or more of the above-described extrusion supports in place instead of removing them to form the passageways.  
      Since certain changes may be made in the above-described multi-lumen, miniature ribbon tubing, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description or shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.