Abstract:
A device for mixing and ejecting a multi-component reactive mixture, which will not clog after a single and subsequent uses, is disclosed. The device has a cylindrical mixing space defined by upper, lower, and side walls. There are two entry ports into the mixing space defined by and tangent to the side wall. Two fluid component sources are fluidly connected to the entry ports and are pressurized such that two fluids, which react with each other, separately enter the mixing space. The side wall of the mixing space imparts a rotational motion to the fluids, which causes the fluids to thoroughly mix together before being ejected out through the exit orifice in either a spray or stream form. A valve stem may be provided, which is configured and dimensioned to substantially occupy the mixing space and to seal the two entry ports when it is in the closed position.

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of mixing and dispensing reactive components. In particular, the present invention relates to an apparatus and method for mixing and dispensing a plurality of fluid components that together form a tissue adhesive, such that clogging of the apparatus is avoided. 
     BACKGROUND OF THE INVENTION 
     A surgical adhesive is used in lieu of physical means, such as sutures or staples, to bind together two edges or sides of a laceration. Biologically and non-biologically based surgical adhesives are made by mixing a first reactive fluid component (e.g., fibrinogen) with a second reactive fluid component (e.g., thrombin), which react with each other to harden into the adhesive. Upon contact the two fluid components react relatively quickly, in the order of seconds, to harden into the tissue adhesive. If it is only partially mixed, the adhesive will not sufficiently harden over the entire area to which it is applied thus, resulting in weak spots. It is, therefore, desirable to apply a thoroughly mixed solution to the target site before the solution has gelled or hardened. Furthermore, it is desirable to minimize the amount of time required to thoroughly mix the fluid components together, thereby minimizing the amount of contact time between the two substances prior to delivery to the target site. 
     Several methods and devices exist for mixing and applying biologically based and synthetic tissue adhesives. One method is to directly apply a layer of the first fluid component to the target site, directly apply a layer of the second fluid component on top of the first fluid component layer, mechanically mix the two fluid components together using a surgical instrument and spread the mixed adhesive over the target area. A variation of this method is to premix the two fluid components, immediately thereafter draw the adhesive mixture into a delivery syringe and apply the mixture to the target site. Both of these methods suffer from multiple deficiencies, not the least of which is that it is very difficult to thoroughly mix the fluid components and apply the mixed adhesive before the adhesive begins to gel and harden, resulting in a nonuniform adhesive layer with weak spots. 
     More recent devices and methods utilize one device for bringing the fluid components together, mixing the fluid components and applying the mixed adhesive in either an aerosol or a stream form to the target site. The more recent devices and methods can be broken down into two general types: 1) devices that bring the two fluid components together, mix them within the device and then dispense the mixed adhesive; and 2) devices that separately atomize the two fluids outside the device such that the atomized fluids contact and mix together before being deposited on the target site. 
     An example of the first type is described in U.S. Pat. No. 4,735,616 to Eibl et al. This device has two parallel fluid component syringes fluidly connected to two channels that extend through a manifold into a mixing needle. The two fluid components flow through their respective channels and enter the mixing needle, where they contact for the first time. The high surface area within the mixing needle creates turbulents that cause the fluid components to become thoroughly mixed within the needle. A second example of this type of device is described in U.S. Pat. No. 5,116,315 to Copozzi et al. This device has two parallel fluid component syringes connected to one end of a Y-manifold and a mixing assembly detachably locked onto the second end of the Y-manifold. The mixing assembly has two separate and adjacent parallel channels, each separately fluidly connected to the two fluid component syringes, via the Y-manifold, and both of which terminate into a single annular channel within the mixing assembly. The annular channel is connected to a disk shaped mixing space having three inclined vanes disposed about an exit orifice. In use, the two fluid components pass through the Y-manifold, through the two separate parallel channels in the mixing assembly, through the singular annular channel, where the fluid components first contact and begin mixing, through the mixing space, where the fluid components impinge upon the vanes that impart a spiraling motion to the fluids causing the fluids to become thoroughly mixed, and out of the exit orifice in an atomized spray. A problem experienced with these types of devices is that they typically become clogged after a short period of non-use, because the un-ejected, mixed or partially mixed, adhesive hardens within the device. 
     An example of the second type of devices is described in U.S. Pat. No. 5,368,563 to Lonneman et al. Similar to the first type of devices, Lonneman et al. disclose a device having two parallel syringes connected to a manifold. However, the manifold has two separate exit orifices adjacent and in close proximity to each other. In use, the two fluid components exit from the corresponding exit orifices in a swirling atomized spray. The atomized fluid components mix with each other while airborne without the need for an internal mixing chamber. While the Lonneman et al. design alleviates the clogging problem of the first type of devices, it has been found that it does not adequately mix the two fluids, particularly at the peripheries of the two atomized spray cones, thus resulting in an adhesive layer having weak spots. 
     There thus remains a need in the art for a device that can thoroughly mix the reactive fluid components of a tissue adhesive and deliver the mixed adhesive to a target site without clogging after only a single use. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards an apparatus for mixing and ejecting a multi-component fluid mixture, such as a medical adhesive, which will not become clogged after only a single use. The device has a body portion having a mixing space defined therein. The mixing space is defined by at least an upper wall, a side wall and an exit orifice. The side wall defines at least two entry ports to the mixing space. The device further has at least two fluid component sources fluidly connected to the at least two entry ports and a means for forcing the at least two fluid components into the mixing space. The at least two fluid components separately enter the mixing space through the at least two entry ports; the side wall imparts rotational motion to the at least two fluid components; the at least two fluid components become thoroughly mixed into the multi-component fluid mixture; and the multi component mixture exits the mixing space from the exit orifice. Alternatively, a valve stem, with a distal end and a proximal end and movably extending through the body portion into the mixing space, may be provided. The distal end of the valve stem is configured and dimensioned to substantially occupy the mixing space when the stem is in a closed position. In the closed position the distal end seals the at least two entry ports and forces substantially all fluid components remaining in the mixing space out through the exit orifice. In the open position the distal end is withdrawn from the mixing space, thereby allowing the at least two fluid components to enter the mixing space as previously described. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view illustrating a device for mixing and spraying a dual component medical adhesive constructed according to the principles of the present invention; 
     FIG. 2 is a perspective view of the body portion  12  of the embodiment illustrated in FIG. 1; 
     FIG. 3 is a plan view of insert  14  of the embodiment illustrated in FIG. 1; 
     FIG. 4 is a cross-sectional view of the insert shown in FIG. 3; 
     FIG. 5 is a schematic, in cross-sectional view, of the embodiment of the present invention illustrated in FIG. 1; 
     FIG. 6 illustrates, in plan view, the embodiment of the present invention illustrated in FIG. 1; 
     FIG. 7 illustrates, in cross-sectional view, an alternative embodiment of the present invention; 
     FIG. 7A illustrates an enlarged cross-sectional view of area  7 A shown in FIG. 7 
     FIG. 8 illustrates, in cross-sectional view, another alternative embodiment of the present invention; and 
     FIG. 9 illustrates, in cross-sectional view, another alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of a medical mixing device  10  in accordance with the principles of the present invention, capable of mixing and delivering a medical adhesive to a target area without clogging after multiple uses, is shown in FIGS. 1-7. Mixing device  10  has a body portion  12 , an insert  14 , a first fluid component syringe  16  and a second fluid component syringe  18 . A handle member  21  may be provided to facilitate simultaneous ejection of the first and second fluid components out of syringes  16  and  18  respectively. 
     Referring to FIGS. 1 and 2, body portion  12  has a void  20  (best shown in FIG. 2) configured to receive insert  14 , two standard luer locks  22  and  24  for detachably connecting syringes  16  and  18 , a first conduit  26  and a second conduit  28  extending through body portion  12 . Each conduit  26  and  28  has a first end,  30   a  and  30   b , connected to luer locks  22  and  24 , and a second end,  32   a  and  32   b , connected to void  20 . Any suitable fluid connector may be used in place of luer locks. 
     Void  20 , best shown in FIG. 2, is cylindrically shaped and has an upper, substantially planar face  34  and a side face  36  perpendicular to upper face  34 . Second ends  32   a  and  32   b  (FIG. 1) of conduits  26  and  28  connect to void  20  at the intersection of side ace  36  and upper face  34  and at opposite ends of a diameter of upper face  34 . The skilled artisan will readily recognize that shapes other than cylindrical may be used for void  20  and insert  14 , and that conduits  26  and  28  may connect to void  20  in many different locations without deviating from the scope of the present invention. 
     Referring to FIGS. 3 and 4, insert  14  is a cylindrically shaped piece of suitable material, such as medical grade plastic, that has a substantially planar top surface  38  and a side surface  40 . The skilled artisan will readily recognize that shapes other than cylindrical and that material other than medical grade plastic may be used for insert  14  without deviating from the scope of the present invention. Top surface  38  has a cylindrically shaped cavity  42  therein, which is defined by a side wall  44  with thickness A and a bottom wall  46  with diameter B. Bottom wall  46  has an orifice  48  with diameter C and length D (dimensions best shown in FIG.  4 ). Channels  50  and  52 , cut into top surface  38 , extend from mouths  54   a  and  54   b , into cavity  42  at openings  55   a  and  55   b , which are tangent to side wall  44  and opposite each other. In this embodiment, each of the channels  50  and  52  have the same width E (FIG.  3 ), and the same height equal to thickness A of side wall  44  (FIG.  4 ). Mouths  54   a  and  54   b , which are wider than width E, are provided to facilitate connecting the channels to second ends  32   a  and  32   b  of conduits  26  and  28 , as discussed in more detail below. A skilled artisan will readily recognize that the height of channels  50  and  52  may be greater or less than thickness A of side wall  44  and that the width of mouths  54   a  and  54   b  may also be varied without deviating from the scope of the present invention. 
     Referring to FIG. 5, insert  14  fits into void  20  (FIG. 2) such that bottom wall  46 , side wall  44  and upper face  34  define a cylindrical mixing space  56  with an exit orifice  48  defined by bottom wall  46 . Second ends  32   a  and  32   b  of conduits  26  and  28  connect to channels  50  and  52  via mouths  54   a  and  54   b , thereby defining two separate, continuous fluid passages or ports from first and second fluid component syringes  16  and  18  through body portion  12  into cylindrical mixing space  56 . The skilled artisan will readily recognize that body portion  12  and insert  14  may be molded from a single piece of material or multiple pieces of material in order to create mixing space  56 , channels  50  and  52  and conduits  26  and  28 . Cylindrical mixing space  56  may take on other shapes, such as conical for example, without deviating from the scope of the present invention. 
     Referring to FIG. 6, the two fluid components pass through first and second conduits  26  and  28  respectively, through first and second channels  50  and  52  respectively, into mixing space  56 , tangent to side wall  44  and from opposite sides of mixing space  56 . Side wall  44  imparts a rotational motion to each of the fluid components about the central axis thus, mixing the fluids together. The mixed fluids are ejected out exit orifice  48  in a substantially aerosol form. 
     It has been found that a device having the dimensions in Table 1 will deliver an even spray pattern of a thoroughly mixed medical adhesive and the device may be used multiple times without clogging, even when several minutes pass between uses (dimensions are best shown in FIGS.  3  and  4 ). 
     
       
         
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Width E of 
                   
                   
               
               
                 Height A 
                 Diameter B of 
                 Openings 
                 Diameter C 
                 Length D of 
               
               
                 of Wall 44 
                 Mixing Space 
                 55a and 55b 
                 of Orifice 48 
                 Orifice 48 
               
               
                 (in) 
                 56 (in) 
                 (in) 
                 (in) 
                 (in) 
               
               
                   
               
             
             
               
                 0.020 
                 0.047 
                 0.010 
                 0.016 
                 0.01 
               
               
                   
               
             
          
         
       
     
     In some applications it may be desirable to spray the adhesive onto the target site and in other applications it may be desirable to apply a stream to the target site. While not wishing to be bound by theory, it is believed that a rotating fluid, with sufficient angular momentum, exiting an orifice will atomize upon exit. Therefore, for delivering a mixed medical adhesive in a spray from cylindrical mixing space  56 , as shown in FIGS. 5 and 6, it is believed that the ratio of Diameter B (FIG. 4) of mixing space  56  to Width E (FIG. 3) of openings  55   a  and  55   b  should be sufficiently large such that the fluid components rotate about the central axis, but not so large such that the fluids will lose angular momentum before reaching exit orifice  48 . It is believed that ratio B:E should be between about 2 to about 5 and preferably about 4, for fluid components having similar viscosities in the range between about 5 and about 30 centipoise and preferably approximately 8 centipoise when injected at approximately 30 p.s.i. (normal delivery pressure expected from syringes). 
     Again, while not wishing to be bound by theory, it is believed that a fluid having a sufficiently low angular momentum and/or a sufficiently low linear velocity will exit an orifice as a stream. It is believed that increasing length D (FIG. 4) of exit orifice  48  the embodiment described in Table 1 to about 0.04-0.08 in. will sufficiently reduce the angular momentum of the fluid components such that the mixed adhesive will exit as a stream rather than as a spray. Alternatively, it is believed that fixing the ratio B:E between about 1 to about 3 and preferably about 2 allows for sufficient rotation and mixing of the fluid components within mixing space  56  and also allows for delivery of the mixed adhesive as a stream. 
     As shown in FIG. 7, an alternative embodiment of medical mixing device  10  utilizes a conically shaped mixing space  58 , which is defined by conical side wall  60 , upper wall  62  and cylindrical exit orifice  64 . Exit orifice  64  has Length F (FIG. 7A) and Diameter G and conical sidewall  60  has interior angle  65  relative to central axis  63  (FIG.  7 A). First and second openings  66   a  and  66   b  connect to mixing space  58  tangent to conical side wall  60 . Openings  66   a  and  66   b  are in fluid communication with first and second conduits  26  and  28  via channels  50  and  52 , thereby defining two separate continuous fluid passages or ports from first and second fluid component syringes  16  and  18  through body portion  12  into conical mixing space  58 , as discussed previously. Openings  66   a  and  66   b  have width E equal to the width of channels  50  and  52  as previously described. In this alternative embodiment, it is preferred that entry passages  66   a  and  66   b  have width E of channels  50  and  52 , but do not extend the entire height of conical side wall  60 . In use, the first and second fluids enter conical mixing space  58  from openings  66   a  and  66   b , conically shaped side wall  60  imparts rotational flow about the central axis  63  of mixing space  58  causing the two fluid components to thoroughly mix together, and the mixed fluid ejects from exit orifice  64  in an atomized form. 
     It has been found that a device having the dimensions in Table 2 will deliver an atomized spray of a thoroughly mixed medical adhesive and the device may be used multiple times without clogging. It is believed that increasing length F of exit orifice  64  of the embodiment described in Table 2 to about 0.04-0.08 inches, preferably 0.04 inches, will sufficiently reduce angular momentum of the fluid components such that the mixed adhesive will exit as a stream rather than a spray. 
     
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                   
                   
                 Width E of 
               
               
                   
                 Interior 
                 Length F of 
                 Diameter G of 
                 opening 66a 
               
               
                   
                 Angle 
                 Exit Orifice 64 
                 Exit Orifice 64 
                 and 66b 
               
               
                   
                 65 
                 (in) 
                 (in) 
                 (in) 
               
               
                   
                   
               
             
             
               
                   
                 30° 
                 0.015 
                 0.010 
                 0.03 
               
               
                   
                   
               
             
          
         
       
     
     As shown in FIG. 8, an alternative embodiment of medical mixing device  10  includes valve stem  68  slidingly extending through body portion  12 , which has an open position and a closed position (shown in closed position). Distal end  70  of valve stem  68  is configured to slide into and substantially occupy mixing space  56  when stem  68  is in the closed position. In the closed position, outer wall  75  of distal end  70  substantially abuts the side wall of mixing space  56 , thereby sealing openings  55   a  and  55   b . Also, when in the closed position tip  74  of distal end  70  substantially abuts bottom wall  46  of mixing space  56 . In the open position (not shown), distal end  70  is withdrawn from mixing space  56  such that the two fluid components may enter mixing space  56 , as described above. Also in the open position, tip  74  defines the upper wall of mixing space  56 . 
     In use valve stem  68  is slid into the open position, first and second component fluids are injected into mixing space  56 , become thoroughly mixed and are ejected from exit orifice  48 , as described above. After ejecting the desired amount of mixed adhesive, valve stem  68  is slid into the closed position, thereby forcing substantially all the fluid components remaining in mixing space  56  out exit orifice  48  and sealing openings  55   a  and  55   b . By forcing out fluid components remaining in mixing space  56 , very little, if any, of the fluid components remain in contact with each other within the device, thereby significantly reducing the chances that the device will clog. Also provided is spring  69 , which abuts against valve stem  68  at shoulder  71  and against clips  73   a  and  73   b . Spring  69  is biased to hold valve stem  68  in a closed position. Clips  73   a  and  73   b  lock into notch  72  to hold valve stem  68  in the open position. A skilled artisan will readily recognize that many different mechanisms are well known in the art for actuating and maintaining valve stem  68  in the closed and open positions. 
     Alternatively, as shown in FIG. 9, mixing space  90  is conically shaped. Valve stem  78  has distal end  80  configured to substantially occupy mixing space  90  in the closed position, such that the outer wall (not shown) of distal end  80  substantially interfaces conical wall  60 , thereby sealing openings  66   a  and  66   b . O-ring  76  is provided adjacent to the distal end to form a seal between valve stem  78  and body portion  12 . In the withdrawn or open position, tip  84  defines the upper wall of mixing space  90  and openings  66   a  and  66   b  are open such that the fluid components may enter mixing space  90 , as described above. 
     Although various embodiments of the present invention have been described, the descriptions are intended to be merely illustrative. Thus, it will be apparent to the skilled artisan that modifications may be made to the embodiments as described herein without departing from the scope of the claims set forth below. In particular, the construction of the invention may be from a single piece or from multiple pieces. Additionally, while the embodiments described herein have been described for mixing and ejecting medical adhesives, the skilled artisan will readily recognize that the principles of the present invention apply equally to the mixing and dispensing of multi-component reactive mixtures that will harden in a relatively short period of time.