Abstract:
A novel shunt comprises: a first lumen having a first end and a second end, wherein the first lumen is composed of a polydimethylsiloxane material; a bulb-shaped portion positioned on each of the first end and the second end; a reinforcing spring extending along the first lumen from the first end and the second end; and a second lumen having a first end and a second end, wherein the first end is connected to a center portion of the first lumen and the second end is connected to a valve.

Description:
RIGHTS OF THE GOVERNMENT 
     The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty. 
    
    
     TECHNICAL FIELD 
     This disclosure relates generally to shunts. In particular, it relates to shunts for vascular injuries. 
     BACKGROUND 
     Shunts have found increased use in the treatment of traumatic vascular injuries and the like, particularly as a result of activities in Iraq and Afghanistan. In such circumstances, shunts are used to treat combat-related vascular injuries. Shunts in the arterial position allow for perfusion of the extremity during transport or fixation of associated orthopedic injuries. For injury patterns involving an artery and vein, shunts placed in the venous position provide drainage and decrease venous hypertension that can compound tissue ischemia and bleeding. 
     In many cases, shunts are used to treat vascular injuries resulting from improvised explosive devices, explosive munitions, high velocity weapons, and other high energy trauma. In such circumstances, shunts provide a damage control adjunct that can be applied at forward echelon locations to restore fluid flow and the like until such injuries can be treated more fully at medical treatment facilities. 
     The temporary shunts currently employed in these situations provide some advantages but suffer from several deficiencies. Reports from wartime and civilian medical centers confirm the effectiveness of temporary vascular shunting in the setting of vascular injury; however, these same reports describe random use of a number of devices, none of which are designed for treating vascular injuries. As such, currently available shunts are of suboptimal size, length, and diameter. Moreover, they have no capability for injection into the injured vessel and have no name recognition among trauma surgeons. Many of the currently used shunt technologies were designed and approved for use in carotid surgery for perfusion of the brain for a short period of time, rather than for temporary use in complex trauma-related vascular injury. They provide poor patency, and are not of comparable vessel size which leads to a reduction in efficacy, even for temporary use. As a result of these and other problems, the shunts currently used to treat traumatic vascular injuries are difficult to use and insert into damaged blood vessels. Similarly, in the case of the Vascutek® shunt that recently received FDA approval for use in trauma-related vascular injury, military surgeons report undesired complications because the shunt lacks the features necessary for appropriate trauma-related care. These limitations result, at least in part, from the fact that these shunts were not designed to treat traumatic vascular injuries. In aggregate, these deficiencies in technology generate the need for a trauma-specific extremity vascular shunt. 
     SUMMARY 
     The shunts disclosed herein overcome these limitations and provide vastly improved treatment for vascular injury and similar trauma. These shunts, referred to as trauma specific-vascular injury shunts (TS-VIS), provide a short-term (&lt;24 hours) implantable device that can be used by qualified medical personnel to temporarily restore blood flow to a person&#39;s injured extremity following a complex trauma-related vascular injury. The TS-VIS can remain in place for several hours or longer to restore perfusion in the affected body area until the patient can be transported to a tertiary care or similar medical treatment facility where a permanent vascular repair can be accomplished, at which time the TS-VIS is removed. The TS-VIS is designed for use by qualified medical personnel. It can be used to treat military and civilian trauma-related vascular injuries and it significantly improves the salvage of damaged limbs by restoring and maintaining the flow of blood and fluid to those limbs until the vascular injuries can be permanently repaired. 
     The TS-VIS includes unique novel features for treating traumatic vascular injuries to create a device optimally designed for temporary traumatic vascular injury repair. As such, it provides a single shunt that is designed for treatment of vascular injury and can be recognized and used by trauma surgeons and other trained medical personnel to treat traumatic vascular injuries, thus ending the current use of a myriad of suboptimal, non-trauma devices. 
     The TS-VIS represents an important breakthrough in the management of extremity blood vessel trauma. The improved design enables medics and others to properly insert TS-VIS shunts to restore blood flow in damaged blood vessels. It also enables unit-level medics and others to treat patients with traumatic vascular injuries at the scene of the injury or trauma and restore blood flow until patients are transported to medical treatment facilities for surgery and repair of those injuries. As a result of the use of the TS-VIS, unnecessary loss of limb and other injuries can be avoided. 
     In one embodiment, a shunt comprises: a first lumen having a first end and a second end, wherein the first lumen is composed of a polydimethylsiloxane material; a bulb-shaped portion positioned on each of the first end and the second end; a reinforcing spring extending along the first lumen from the first end and the second end; a second lumen having a first end and a second end, wherein the first end is connected to a center portion of the first lumen and the second end is connected to a valve. 
     In another embodiment, a method of repairing a damaged vessel with a temporary vascular injury shunt comprises the steps of: inserting a bulb-shaped portion at one end of the shunt into one portion of the damaged vessel; inserting a bulb-shaped portion at the other end of the shunt into the other portion of the damaged vessel; securing each of the bulb-shaped portions within the respective portions of the damaged vessel by a clip, a rubber band, vessel loops, and/or a suture; and pulling the shunt away from each portion of the damaged vessel so that the clip, the rubber band, the vessel loop, and/or the suture is adjacent to each bulb-shaped portion. 
     In a further embodiment, a method of treating traumatic vascular injuries, comprises the steps of: inserting the first end and the second end of the shunt into respective portions of a damaged vessel; securing the first and second ends of the shunt in the respective portions of the damaged vessel; monitoring the flow of blood through the shunt; providing blood, medicine, contrast, media, and/or other fluid to the traumatic vascular injury via the shunt; transporting the patient to a medical treatment facility; and permanently repairing the traumatic vascular injury. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  discloses an embodiment of a shunt. 
         FIG. 2  is a cross-sectional view taken along line II-II of  FIG. 1 . 
         FIG. 3  is a side perspective of an expanded portion of the shunt of  FIG. 1 . 
         FIG. 4  is a side cross-sectional view taken along line IV-IV of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     In one embodiment, a TS-VIS  100  includes a first lumen  101 , a bulb-shaped portion  102  positioned on each end of the first lumen  101 , a reinforcing spring  103  disposed within the first lumen  101 , and a second lumen  104  with a valve  105 , as shown in  FIG. 1 . The first lumen  101  comprises a medical grade tubing made of a biocompatible platinum-catalyzed polydimethylsiloxane (PDMS) material. This material is generally clear so medical personnel and others can monitor the flow of blood through the TS-VIS  100  visually and use Doppler instruments to measure blood flow through the TS-VIS  100 . This material also makes the TS-VIS  100  rigid enough so that it retains its shape during and after insertion, but also is flexible enough to give the TS-VIS  100  the capability of being manipulated during insertion. This material also provides improved patency and eliminates clotting that occurs in shunts made of other materials, such as polytetrafluoroethylene (PTFE) and expanded polytetrafluoroethylene (ePTFE). In contrast, the PDMS material used in the TS-VIS  100  largely eliminates clotting. 
     In one embodiment, the TS-VIS  100  has a length of 30 cm. This length is well-suited for bridging missing segments of blood vessels under varied circumstances and it avoids further vessel damage that can occur from over-stretching a shunt to bridge a larger gap than the shunt was designed to handle. This length also enables medical personnel and others to connect damaged blood vessels while providing enough slack in the shunt to bridge bones and other injuries that orthopedic surgeons and others can repair without disrupting the flow of blood in the repaired vessel. This configuration also enables the TS-VIS  100  to be employed in a straight or looped configuration depending upon the nature of the injury to be treated and the gap to be bridged by the TS-VIS  100 . 
     The bulb-shaped portions  102  are positioned on each end of the first lumen  101 . The bulb-shaped portions  102  are made of a PDMS medical grade tubing or similar materials. The bulb-shaped portions  102  are configured to facilitate their insertion into a vessel insertion site. This configuration is a marked improvement over existing shunt designs and not only enables medical personnel to quickly and accurately position the TS-VIS  100  in injured vessels, but also reduces or eliminates the trauma to those vessels that typically results from the use of current shunts. The design of the bulb-shaped portions  102  also prevents clotting in repaired vessels and provides vastly increased patency in the TS-VIS  100 , as compared to current shunts used to treat traumatic vascular injuries. In one embodiment, the bulb-shaped portions  102  are cone-shaped and have an outer surface  107  that tapers from an outer diameter of about 5.5 mm at the distal end  108  of the bulb-shaped portions  102  to about 6.5 mm at the proximal end  109  of the bulb-shaped portions  102 . This configuration facilitates easy, atraumatic insertion of the TS-VIS  100  within a vessel and it improves shunt stability after placement, particularly under adverse conditions such as those found in combat environments and the like where patients may be in shock or experiencing extreme drops in blood pressure. It also improves the patency of the TS-VIS  100  in excess of 24 hours, if necessary. The wall thickness of the bulb-shaped portions  102  is about 1 mm. However, the configuration, shape, dimensions, and thickness of the bulb-shaped portions  102  may be varied depending on the nature of the injury to be treated. In one embodiment, the bulb-shaped portions  102  are formed integrally with the first lumen  101 , for example during an extrusion process. In another embodiment, the bulb-shaped portions  102  may be formed separately and affixed to the first lumen  101 , for example, by adhesive, welding, and the like. 
     The reinforcing spring  103  is made of stainless steel or a similar material. It also may be made of a wire mesh material. The reinforcing spring  103  extends along the length of the first lumen  101  from each bulb-shaped portion  102 . In one embodiment, the reinforcing spring  103  can be formed within the first lumen  101  during extrusion of the first lumen  101 . The reinforcing spring  103  is disposed entirely within the first lumen  101  so that no portion of the reinforcing spring  103  extends beyond an outer surface or an inner surface of the first lumen  101 , as shown in  FIG. 2 . In one embodiment, the reinforcing spring  103  does not extend along the entire length of the first lumen  101 , so that a center portion  111  of the first lumen  101  is not reinforced by the reinforcing spring  103 , as shown in  FIG. 1 . In this embodiment, the unreinforced center portion  111  of the first lumen  101  is about 1 cm in length. However, the non-reinforced center portion  111  of the first lumen  101  may be greater or less than 1 cm, depending on the nature of the injury to be treated and the configuration of the TS-VIS  100 . The unreinforced center portion  111  provides a region on the TS-VIS  100  that medical personnel can grasp with a hemostat, forceps, clamps, or similar instrument to position the TS-VIS  100  for insertion in a vascular wound without damaging the TS-VIS  100  or impairing its patency. The reinforcing spring  103  prevents kinking of the first lumen  101  after the TS-VIS  100  is inserted into a blood vessel. It also keeps the first lumen  101  open when the TS-VIS  100  is disposed in a looped or coiled configuration. In another embodiment, the reinforcing spring  103  does not extend completely through the bulb-shaped portions  102  at the distal ends of the first lumen  101 . 
     The second lumen  104  is attached at the center portion  111  of the first lumen  101 . The second lumen  104  can be attached to the first lumen  101  by welding, melting, or other attachment means. In one embodiment, the second lumen  104  is about 10 cm long and has an outer diameter of about 3 mm, an inner diameter of about 2.5 mm, and a wall thickness of about 0.25 mm. The valve  105  is positioned on the end of the second lumen  104  that is distal to the first lumen  101 . In one embodiment, the valve  105  is a one piece valve, such as a Maximus® MP1000 valve connector with a luer lock, made by Medegen, Inc., 930 South Wanamaker Avenue, Ontario, Calif. The second lumen  104  and the valve  105  provide an injection port that facilitates the injection of medications and contrast media into the TS-VIS  100  and the repaired blood vessel. This also enables medical personnel to inject de-clotting agents and medicines such as medicines for limb salvage at a site that is best suited for that injury and eliminates the need to establish an alternate port or injection site for treatment of that injury. Contrast media for angiograms and the like can be injected through the second lumen  104  without the need to insert a catheter or other device into the wound or damaged limb. The luer lock of the valve  105  provides a means to secure medicines, blood, and other fluids to the second lumen  104  without the need for medical personnel to remain on station. If the second lumen  104  is not used for injection or supply of medicines, blood, fluid, contrast media, or other fluids, the valve seals the second lumen  104 . When a syringe or other instrument is connected to the valve  105 , the valve opens to permit medicines, blood, fluid, contrast media, or other fluids to be supplied through the second lumen  104 . 
     As shown in  FIG. 2 , the first lumen  101  has a circular or generally circular cross-section. In one embodiment, the outer diameter  101   a  of the first lumen  101  is about 5.5 mm and the inner diameter  101   b  is about 4.0 mm, producing a total wall thickness of about 1.5 mm, or a thickness in a single wall  106  of about 0.75 mm. This configuration provides improved perfusion to injured limbs while ensuring the patency of the TS-VIS  100  and avoidance of a ballooning effect in the non-reinforced portion of the first lumen  101 . The configuration of the TS-VIS  100 , including the outer diameter  101   a , inner diameter  101   b , and wall thickness  106  of the first lumen  101 , may be varied depending on the nature of the injury to be treated so that the TS-VIS  100  may be used in the large arteries and veins of the proximal lower extremities and the small arteries and veins of the upper extremities. For example, a smaller unit with outer diameter  101   a  of the first lumen  101  is about 4.0 mm and the inner diameter  101   b  is about 2.5 mm, producing a wall thickness  106  of about 1.5 mm. 
     As shown in  FIG. 3 , the bulb-shaped portion  102  includes a tapered outer surface  107 . In one embodiment, the tapered outer surface  107  is a continuous linear surface that tapers outwardly from an outer diameter of about 5.5 mm at the distal most portion  108  of the bulb-shaped portion  102  to an outer diameter of about 6.5 mm at the proximal most portion  109 . In other embodiments, the outer surface  107  can have a non-linear tapered surface that forms, for example a regular or irregular convex or concave surface, depending upon the nature of the injury to be treated. As shown in  FIG. 3 , the proximal portion  109  of the bulb-shaped portion  102  has a generally straight or flat rear surface  110 . In other embodiments, the rear surface  110  of the proximal outer edge  109  may have a curved configuration depending on the nature of the injury to be treated. Additionally, the curvature of the proximal portion  109  may be varied, as desired. The configuration of the TS-VIS  100 , including the bulb-shaped portion  102  and the tapered outer surface  107  may be varied depending on the nature of the injury to be treated. The bulb-shaped portion  102  will have a maximum measurement of about 5.0 mm, and tapering to a wall thickness  108  of about 1.5 mm. 
     In one embodiment, the TS-VIS  100  can be used to repair a damaged blood vessel in the following manner. One bulb-shaped portion  102  of the TS-VIS  100  is inserted into one portion of the damaged blood vessel. Then, the other bulb-shaped portion  102  is inserted into the other portion of the damaged blood vessel. An elastic or rubber band, clip, vessel loops, and/or a suture is then wrapped around the outer surface of each portion of the damaged vessel behind the proximal portion  109  of each bulb-shaped portion  102 . This causes the blood vessel to be drawn inward behind the proximal portion  109  of each bulb-shaped portion  102 , adjacent to the rear surface  110  to secure each bulb-shaped portion  102  of the TS-VIS  100  within the respective portion of the damage blood vessel. After the ends of the damaged blood vessel are clipped or secured around the bulb-shaped portions  102 , each bulb-shaped portion  102  can be slid back against the bands or clips to secure the TS-VIS  100  inside the respective portions of the blood vessel with the rear surfaces  110  of each bulb-shaped portion  102  adjacent to the clipped or banded portion of the damaged vessel. This also minimizes the portion of the TS-VIS  100  that is disposed within the damaged vessel to the minimum amount needed to secure the TS-VIS  100  and restore blood flow. If the length of the TS-VIS  100  exceeds the length needed to bridge the gap in the damaged blood vessel, the first lumen  101  can be coiled in a looped or S-shaped configuration. This capability permits surgeons and other medical personnel to examine and repair bone, tissue, and other damaged portions of the wound without disrupting the flow of blood through the repaired vessel. It also permits patients to be transported from injury sites to medical treatment facilities without the TS-VIS  100  becoming kinked or losing its patency during transport. Because the PDMS material of the TS-VIS  100  is clear, visual observation can be made of the flow of blood through the TS-VIS  100  and the repaired vessel. In addition, blood flow through the TS-VIS  100  and the repaired vessel also can be monitored by Doppler instruments. After the patient is transported to a medical treatment facility, surgeons can repair broken bones and other damaged tissue while the TS-VIS  100  maintains perfusion to the injured limb, thereby reducing the incidence of limb loss and further injury. After bones and other trauma have been repaired, the damaged vessel can be permanently repaired, for example with a permanent graft of piece of vein and the like. The TS-VIS  100  may be removed to facilitate permanent repair of the damaged vessel. 
     The foregoing disclosure has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the various embodiments and forms disclosed herein. Persons skilled in the art will realize and appreciate that many modifications and variations are possible in light of the above teaching. For example, the design, configuration, dimensions, and materials of the TS-VIS may be varied, as desired, depending on the application and intended use of the shunts. The disclosed embodiments were chosen and described to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best use the invention in various embodiments and with various modifications suited to the particular use contemplated. The scope of the invention is to be defined by the following claims.