Abstract:
A flexible tubing for an intravenous fluid delivery set including an elongate tubing member formed of aliphatic polyether polyurethane. The set may include connectors to a container and an intravenous needle, and additional connectors for components placed in line with the tubing, with hollow posts on the connectors, with the tubing ends adapted to friction fit over the posts. The posts may have outer diameters which are tapered from a first diameter to a second diameter, where the inner diameter of the tubing ends are less than the second diameter. A method of delivering therapeutic fluid is also shown including providing the delivery set, providing a flow path by forcing tubing ends over connector posts in an in-line arrangement, and then controlling the flow of the therapeutic fluid between the container and the intravenous needle through the fluid flow path.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention is directed toward intravenous fluid delivery sets.  
           [0002]    Intravenous fluid delivery sets (“IV sets”) are well known in the art which contain a variety of components which can be combined, as desired for a particular patient, to facilitate the delivery of fluids directly to a patient&#39;s bloodstream. Such IV sets are well known for use in connecting a container such as a bottle or bag containing a liquid (e.g., a saline solution) to an intravenous needle extending into a patient&#39;s vein and suitably secured to the patient at the entry point (e.g., taped to the back of the patient&#39;s hand).  
           [0003]    The IV sets typically include a tubing extending between hood assemblies, one of which is suitably connected to the container of liquid and the other of which is connected to the intravenous needle secured to the patient. Other components may also be provided for mounting at intermediate locations along the tubing, typically at breaks in the tubing between adjacent in-line tubing sections. Components in addition to the tubing and hood assemblies can include, for example, adapter, filters, clamps for selectively closing the tubing, back check valves, flow control devices for controlling the rate of flow of the liquid through the tubing and into the patient, needle-less connectors allowing for easy injection of a desired drug directly into the flow through the IV set, sight chambers allowing visual verification of the drip flow rate through the IV set, etc. IV sets which are not expected to rely upon gravity for flow may also include pump structures as well.  
           [0004]    Among the desirable features of IV sets are the ability to easily and reliably set up the IV set in a variety of different conditions (sometimes in time critical situations) and the ability to easily and reliable deliver the desired fluids, and control the delivery of those fluids, for periods of time thereafter.  
           [0005]    Heretofore, the components of IV sets have commonly been manufactured in large part with polyvinyl chloride (PVC). PVC tubings have been easily sealed to the other components using suitable solvents allowing easy bonding to a wide variety of materials, including acrylics, polycarbonates, and vinyls. However, some customers for IV sets have expressed a desire to avoid the use of PVC for a variety of reasons. It is, of course, desirable to provide customers with a product which meets their requirements.  
           [0006]    Materials other than PVC have been heretofore used with IV sets. For example, polyurethane tubings have been used in prior art IV sets. However, those IV sets have to date proven undesirable for a number of reasons, including an insufficient resistance to kinking of the tubings and an insufficient maintenance of clarity of the material. Of course, inadvertent kinking of a tubing could cause the flow of fluid to be cut off, with potentially disastrous results, and is a serious concern given the bending to which IV sets are commonly subjected (e.g., due to movement of the patient). Resistance to kinking requires an element of stiffness for the tubing, which can be difficult to balance with the contradictory requirement of flexibility for the tubing. Further, some tubings used in the market and formed of aromatic non-PVC materials can color during gamma radiation sterilization, for example, leaving a poor appearance after such handling. Clouding and/or coloring of the tubings can not only inhibit the desired ability to view inside the tubings to help verify proper flow, but can cause patients to incur increased stress if they interpret an unclear tubing to indicate a lack of sterility of the IV set being used to deliver fluids to their bloodstream.  
           [0007]    The present invention is directed toward overcoming one or more of the problems set forth above.  
         SUMMARY OF THE INVENTION  
         [0008]    In one aspect of the present invention, a flexible tubing for an intravenous fluid delivery set is provided, including an elongate tubing member formed of aliphatic polyether polyurethane.  
           [0009]    In one form of this aspect of the invention, the aliphatic polyether polyurethane is a polymer of dicylohexylmethanediisocyanate, poly(tetramethylene glycol) and 1,4-Butanediol.  
           [0010]    In another aspect of the present invention, an intravenous fluid delivery set is provided, including a first connector for connecting to a container, and an aliphatic polyether polyurethane elongated hollow tubing having open distal and proximate ends, at least one of which is adapted for a fluid tight connection to the connector.  
           [0011]    In another form of this aspect of the invention, the one or more connectors and the tubing define a fluid delivery path free of polyvinyl chloride.  
           [0012]    In still another form of this aspect of the invention, the connector is a female connector that each includes a cylindrical recess adapted to securely receive one of the proximate or distal tubing ends therein.  
           [0013]    In an alternate form of this aspect of the invention, the connector has a hollow post and the tubing end has an inner diameter less than the post outer diameter and is adapted for friction fit over the male connector post.  
           [0014]    In another form of this alternate form including a connector post, the hollow post has an outer diameter that is tapered from a first diameter to a second diameter, and the elongated hollow tubing distal or proximate end inner diameter is less than the second diameter.  
           [0015]    In still another form of the alternate form including a connector post, the tubing has an inside diameter on the order of 0.095″ and an outside diameter on the order of 0.150″. In a further form, the outer diameter of the hollow post tapers from a first outer diameter at the end of the post to a second outer diameter on the order of 0.134″, the first outer diameter being less than 0.134″.  
           [0016]    In yet another form of this aspect of the invention, multiple connectors and tubings are provided utilizing over the post friction fits.  
           [0017]    In yet another aspect of the present invention, a method of delivering therapeutic fluid is provided, including providing an intravenous fluid delivery set, providing a fluid flow path between a therapeutic fluid container and a patient using the delivery set, and controlling the flow of the therapeutic fluid between the container and an intravenous needle or catheter through the fluid flow path. The provided delivery set includes first and second connectors, at least one set component chosen from the group of filters, valves, flow control devices, needle-less connectors and pumps, and first and second aliphatic polyether polyurethane hollow tubings. The flow path is provided by (1) connecting the first connector to a container of therapeutic fluid, (2) connecting the second connector to an intravenous needle in a patient, (3) connecting the proximate end of the first tubing to the first connector and connecting the distal end to the third connector of one of the at least one component, and (4) connecting the distal end of the second tubing to the second connector and connecting the proximate end to the fourth connector of one of the at least one component.  
           [0018]    In another form of this aspect of the invention, the step of providing an intravenous fluid delivery set comprises providing connectors which each have a cylindrical recess adapted to securely receive the proximate and distal tubing ends therein.  
           [0019]    In an alternate form of this aspect of the invention, the step of providing an intravenous fluid delivery set includes (1) providing the connectors each with a hollow post with a selected outer diameter and (2) providing the tubings with the open ends having inner diameters less than the selected outer diameter, where the tubing connecting steps comprise forcing the tubing ends over the hollow posts. With this alternate form, the selected outer diameter may be tapered from a first diameter to a second diameter, with the inner diameter of the tubing ends being less than the second diameter. With this alternate form, the first and second tubings may having an inside diameter on the order of 0.095″ and an outside diameter on the order of 0.150″, and the selected outer diameter may taper from a first outer diameter at the ends of the posts to a second outer diameter on the order of 0.134″, said first outer diameter being less than 0.134″.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]    [0020]FIG. 1 is a partially exploded perspective view illustrating the use of a fluid delivery set embodying the present invention;  
         [0021]    [0021]FIG. 2 is an exploded view showing the connection of a tubing and connector according to the present invention;  
         [0022]    [0022]FIG. 3 is an exploded view showing an alternative connection of a tubing and connector according to the present invention;  
         [0023]    [0023]FIG. 4 is a plan view showing another arrangement of a fluid delivery set embodying the present invention; and  
         [0024]    [0024]FIG. 5 illustrates the chemical composition of an aliphatic polyether polyurethane from which tubing of the present invention may be made. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    An assembled intravenous fluid delivery set  10  embodying the present invention is illustrated in FIG. 1. The set  10  may be particularly adapted for delivering a fluid from a container  12  (e.g., a bottle or bag) to an intravenous needle  14  secured in a vein of a patient  16 . It should be understood, however, that sets embodying the present invention can be used in a variety of applications, including neonatal tubing sets and blood tubing sets. In applications where fluid (e.g., blood) is extracted from a patient, the container  12  may be a suitable receptacle for the fluid, whereas when therapeutic fluid is being provided to the patient, the container  12  dispenses the fluid (e.g., a saline solution and/or prescribed drugs).  
         [0026]    In the particular application illustrated in FIG. 1, various parts of the fluid delivery set  10  are illustrated in an in-line arrangement providing a fluid path between the container  12  and intravenous needle  14 , including three tubings  20 ,  22 ,  24 , a roller clamp  26  and an integral needle-less connector  28 . However, it should be understood that while FIG. 1 shows a set  10  in use with the particular illustrated components, the set  10  may be provided in kit form with additional components such as previously described (e.g., filters, back check valves, sight chambers, etc.), which components may or may not be used in a particular instance due to the conditions of the particular use. Preferably the above-mentioned additional components are free of polyvinyl chloride (PVC) so as to define a fluid delivery path free of PVC. For example, a polycarbonate (non PVC) sight chamber is available from Borla S.p.A. of Torino, Italy.  
         [0027]    [0027]FIG. 2 illustrates a connector  30  and an end of a tubing (identified as tubing  20  for illustration purposes). Both the tubing  20  and connector  30  include openings  32 ,  34  therethrough which, when connected, cooperate to define the desired fluid path. The connector  30  includes a hollow post  36  over which the end of the tubing  20  is friction fit (i.e., secured by mechanical interference, not chemical bonding). Before forcing the tubing end over the post  36 , a suitable solvent (e.g., a cyclohexane and methylene chloride blend) may be placed on the post  36 , which solvent acts as a lubricant as the tubing  20  slides over the outer surface of the post  36 .  
         [0028]    While reference herein is made to a connector  30  such as shown in FIGS. 1 and 2 in which a discrete structure preferably of a semi-rigid to substantially rigid non PVC material including but not limited to acrylic, acrylonitrile butadiene styrene (ABS), or polycarbonate is provided, the discussion of the connectors  30  (with hollow posts  36 ) herein should be recognized as pertaining to a wide variety of connecting structures. For example, the connector could comprise one or more hollow posts integral to a component (e.g., roller clamp  26  and integral needle-less connector  28 ) allowing direct connection of tubings to those components, or the connector could comprise a discrete adapter structure which includes a hollow post for connecting to a tubing and an adapter for connecting to a component. That is, the connector could be a hollow post integrally provided on an intravenous needle, or could be a separate adapter structure (such as illustrated in FIG. 1) which includes a hollow post  36  for securing to a tubing  24  with a hollow adapter  38  configured to attach to the attachment structure of the intravenous needle  14 . The adapter  38  preferably has a hollow tapered post configuration similar to that described below for the hollow post  36 .  
         [0029]    It should also be understood that, as used herein, “connection” of a tubing to some other element may not be a direct connection between the tubing end and that element, but may comprise the disclosed connection of the tubing to a connector which is itself otherwise, directly or indirectly, suitably connected to that element.  
         [0030]    As shown in FIG. 2, the hollow post  36  has an outer diameter which is greater than the inner diameter of the tubing  20 . More specifically, the tubing  20  has an inner diameter A and the outer diameter of the post  36  tapers from B to C, where A is less than C. Such a configuration requires that the tubing  20  stretch as it is forced over the post  36 , thereby providing a tight securement around the post  36  and a suitable friction force between the surfaces preventing the tubing  20  from being pulled off the post  36 .  
         [0031]    The end of the post  36  may also include a rounded tip  40  to further ease the end of the tubing  20  over the post  36 , where the rounded tip  40  at its end has a diameter which is preferably no more than the inner diameter A of the tubing  20 .  
         [0032]    [0032]FIG. 3 illustrates another connector  42  and an end of a tubing (identified as tubing  20  for illustration purposes) which may be used within the broad scope of the invention. Both the tubing  20  and connector  42  include openings  32 ,  44  therethrough which, when connected, cooperate to define the desired fluid path. The connector  30  includes a recessed cylindrical opening  46  into which the end of the tubing  20  is secured. While some friction fit may occur, with this connector  42  it is preferred that a suitable conventional adhesive also be used to provide a suitable secure bond between the tubing  20  and the connector  42 . The outer portion  48  of the recessed cylindrical opening  46  may be tapered to assist in guiding the end of the tubing  20  into the opening  46 .  
         [0033]    Still other connectors could be used within the scope of the invention, including securing the annular end face of the tubing to a surface surrounding an opening to the fluid path. While such a connection would not generally be as preferred as those illustrated in FIGS.  2 - 3 , with the use of suitably secure adhesive it could still be used within the broad scope of the present invention.  
         [0034]    [0034]FIG. 4 simply illustrates another application of the fluid delivery set  10  of the present invention, with two tubings  50 ,  52  being secured in accordance with the above description to opposite connectors of a roller clamp  54 , with hood adapter assemblies  56 ,  58  similarly secured to the other ends of the tubings  50 ,  52 . The hood adapter assemblies  56 ,  58  may be particularly suited for directly connecting to, for example, a fluid container and intravenous needle.  
         [0035]    In accordance with the present invention, the tubings are made of aliphatic polyether polyurethane.  
         [0036]    More specifically, in a preferred form, the tubings (e.g.,  20 ,  22 ,  24 ) used in accordance with the present invention may be made of extruded polyurethane made from a non-aromatic, ether based, aliphatic polymer resin, such as that commercially available under the trade designation Tecoflex EG 85A from Thermedics, Inc. of Woburn, Mass. (Thermedics is the owner of U.S. Pat. Nos. 4,523,005 and 4,447,590, the complete disclosures of which are hereby incorporated by reference). FIG. 5 hereof illustrates such a polymer including the components from which it may be made. Specifically, the polyurethane is a polymer of dicylohexylmethanediisocyanate, poly(tetramethylene glycol), and 1,4-Butanediol. The preferred durometer hardness for the tubing is about 77 Shore A.  
         [0037]    In accordance with the present invention, the material may also be free of diethyl hexyl phthalate (DEHP), which is a plasticizer which can undesirably cause extraction and reduced potency with some drugs (e.g., nitroglycerine).  
         [0038]    The above described aliphatic polyether polyurethane material avoids clouding or discoloration such has occurred, for example, when prior art polyurethane tubings were sterilized.  
         [0039]    While the size of the tubings could vary according to particular needs, a preferred form made with the above described polyurethane has an inside diameter (A) on the order of 0.095″ and an outside diameter on the order of 0.150″ (providing a nominal wall thickness of 0.0275″ and a ratio of wall thickness divided by inside diameter of about 0.29). The hollow posts  36  of the components such as the connector  30  illustrated in FIG. 2 may then have an outer diameter which includes a rounded end beginning at the very end at a diameter of at least about 0.095″ to an outer diameter (B) of about 0.119″, with the post  36  then relatively smoothly tapering to an outer diameter (C) of about 0.134″. Such a structure allows the end of a tubing (e.g.,  20 ,  22 ,  24 ) to be relatively easily pushed over the end of the post  36  while at the same time thereafter providing a strong friction securement therebetween. A shoulder  35  may be provided on the conncector to positively limit the position of the end of the tubing (e.g.,  20 , 22 , 24 ). Such fittings have, for example, been found to have a tubing pull off force greater than eight pounds with an effective bond strength greater than or equal to PVC solvent sealed bonds used in the prior art, while also providing required kink resistance and allowing easy connection between tubing and post.  
         [0040]    Another preferred form, usable in neonatal applications, made with the above described polyurethane has an inside diameter (A) on the order of 0.054″ and an outside diameter on the order of 0.084″ (providing a nominal wall thickness of 0.015″ and a ratio of wall thickness divided by inside diameter of about 0.28). Still another preferred form, usable for example in blood applications, made with the above described polyurethane has an inside diameter (A) on the order of 0.120″ and an outside diameter on the order of 0.170″ (providing a nominal wall thickness of 0.025″ and a ratio of wall thickness divided by inside diameter of about 0.21). Testing of such tubings has been found to provide an adequate pull off force when friction fit over posts in such applications.  
         [0041]    Of course, variations on the mechanical interference fit described above could also be used in accordance with the invention. For example, a portion of the outer surface of the post  36  could be cylindrical rather than tapered, with the cylindrical portion having an outer diameter greater than the tubing inner diameter (A). As another example, small raised ribs could be provided on the outer diameter of the posts.  
         [0042]    Tests have been performed to evaluate tubings and connectors in accord with the above structure against prior art tubings made with PVC. The below table illustrates the results of this testing:  
                                                                         MECHANICAL PROPERTIES   PVC   PU                                        Average Values/Material                   Tensile Strength (psi)   2900   4400           Ultimate Elongation (%)   400   1300           100% Modulus (psi)   1600   700           KINK RESISTANCE (dia.-inches)   0.500   0.560           COMPRESSION TESTING (ml/min)           Roller Clamp           initial   243.3   185.9           10 minutes   243.6   188.2            6 hours   238.0   189.54           24 hours   230.3   194.2           initial   233.5   194.1           10 minutes   233.7   193.0            6 hours   235.1   196.9           24 hours   226.8   198.1                      
 
         [0043]    It should thus be appreciated that fluid delivery sets made according to the present invention may be provided at reasonable cost to customers who desire to avoid PVC materials (without incurring drawbacks such as undesirable coloring, kinking and/or compression) and such sets may be readily assembled for use in a variety of applications.  
         [0044]    Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.