Abstract:
A radiographic composition for promoting the formation of clots in blood includes a zeolite and iodine. A device for promoting the clotting of blood at an internal wound site includes a catheter; a delivery instrument insertable through the catheter; a radioopaque blood clotting agent that deliverable through the delivery instrument; and a positive pressure apparatus that can dispense the blood clotting agent to the wound site through the delivery instrument. A system for radiographically imaging an internally bleeding wound includes means for delivering a radioopaque blood clotting agent and means for radiographically imaging the radioopaque blood clotting agent. A method of imaging an internally bleeding wound includes the steps of inserting a catheter into a patient; advancing the catheter to a point adjacent the bleeding wound; depositing a radioopaque zeolite at the bleeding wound; and imaging the radioopaque zeolite to monitor blood-clotting caused by the zeolite.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to blood clotting agents and, more particularly, to blood clotting agents having radio-opacity and devices incorporating such agents as materials for use in monitoring and controlling blood flow. 
       BACKGROUND OF THE INVENTION 
       [0002]    Various techniques can be utilized to view the internal body structures of humans and animals. Such techniques include magnetic resonance imaging (MRI) and radiography. In MRI techniques, pharmaceutical compositions comprising paramagnetic ions are captured within zeolite structures either as “free” ions within zeolite cages or as complexes with appropriate complexing agents. The free ions are typically charged species that lack ligands, although interactions between species are also possible. Such interactions may be in the form of counterion interactions within the structures of the capturing zeolite or between captured ions and the structure of the capturing zeolite itself. The paramagnetic ions are typically ions derived from complexes of gadolinium (viz., diethylenetriamine penta-acetic acid complexes of trivalent gadolinium), which are incorporated into the zeolite using ion-exchange methods. The gadolinium/zeolite is then orally or intravenously administered to a patient and imaged. 
         [0003]    Radiographic methods involve the introduction of a radiographic contrast agent into tissue and the subsequent tracking of the agent using x-ray imaging techniques. One type of radiographic contrast agent is an aqueous suspension of barium sulfate, which is swallowed by a patient or administered as an enema. The contrast agent is then imaged to determine its movement through the digestive tract. Another type of radiographic contrast agent is based on iodine bound in a non-ionic or in an ionic compound, which may be administered intravenously, intraarterially, intrathecally, or intraabdominally. Typical non-ionic compounds include iodipamide and iohexyl, although other compounds based on (2,3-dihydroxypropyl)isophthalamides may also be utilized. In intravenous or intraarterial applications, the iodine-based compounds may be imaged and used to map the flow of blood. 
         [0004]    Blood is a liquid tissue that includes red cells, white cells, corpuscles, and platelets dispersed in a liquid phase. The liquid phase is plasma, which includes acids, lipids, solubilized electrolytes, and proteins. The proteins are suspended in the liquid phase and can be separated out of the liquid phase by any of a variety of methods such as filtration, centrifugation, electrophoresis, and immunochemical techniques. One particular protein suspended in the liquid phase is fibrinogen. When bleeding occurs, the fibrinogen reacts with water and thrombin (an enzyme) to form fibrin, which is insoluble in blood and polymerizes to form clots. 
         [0005]    Controlling the flow of blood from compromised tissue is of concern when either traumatic injury is sustained or when surgical procedures are undertaken. The location of the bleed site can make controlling bleeding easier; on the other hand, the location can sometimes make controlling the bleeding considerably more difficult. When the blood is emanating from an indiscernible internal location and is pooling within adjacent tissue and accumulating around organs, the bleed site can be especially difficult to locate and treat. 
         [0006]    Once the location of the bleed site is discerned, the site must be closed to prevent further blood loss. Sponges or balloon-type devices can be used to exert pressure against the bleed site and to absorb blood. More invasive procedures such as suturing or stapling can also be used, although some types of tissue typically do not respond favorably to such techniques. In situations in which sponging, blocking, suturing, or stapling are less than adequate, seepage can occur, which may result in excessive and unnoticed blood loss. 
         [0007]    The available methods of monitoring the flow of blood from internal bleed sites, as indicated above, as well as available methods of stopping blood flow all have drawbacks and limitations. There is a need for improved systems, methods, and devices that can quickly monitor and address the bleeding or hemorrhaging associated with internal wounds. Regarding procedures and devices for monitoring and stopping the bleeding, the need for a quick, effective imaging and clotting technique has been long recognized in both human and veterinary surgery. 
         [0008]    Based on the foregoing, it is a general object of the present invention to provide compositions, devices, and systems for imaging and controlling internal bleeding and methods of their use that overcome the problems with or improve upon the prior art. 
       SUMMARY OF THE INVENTION 
       [0009]    According to one aspect, the present invention resides in a radiographic composition for promoting the formation of clots in blood. Such a composition comprises a zeolite and an associated compound having an effective amount of iodine present in ionic form. The iodine, which may be from iodipamide, iohexyl, or the like, provides a radioopaque quality to the composition (i.e., the zeolite/iodine composition can be radiographically imaged using x-rays). Prior to being used in a patient, a moisture content of zeolite/iodine composition is adjusted by drying, re-hydrating, or a combination of drying and re-hydrating. Adjusting the moisture enables the composition to have a specific moisture content, which enables the exothermic effects of the composition in blood to be controlled, thereby preventing the composition from becoming so hot as to cause discomfort in the patient during use. 
         [0010]    In a second aspect, the present invention resides in a device for promoting the clotting of blood at an internal wound site. The device comprises a catheter; a delivery instrument that can be inserted through the catheter; a radioopaque blood clotting agent that can be delivered through the delivery instrument; and a positive pressure apparatus such as a pump or syringe that can dispense the blood clotting agent to the wound site through the delivery instrument. The radioopaque blood clotting agent comprises a molecular sieve material (preferably a zeolite) and preferably an iodine compound. Depositing the radioopaque blood clotting agent at the bleeding wound site causes the molecular sieve material to come into contact with blood, which clots the blood. The radioopacity of the blood clotting agent allows it to be imaged as the clotting is taking effect. 
         [0011]    In a third aspect, the present invention resides in a system for radiographically imaging an internally bleeding wound. Such a system comprises means for delivering a radioopaque blood clotting agent to the internally bleeding wound and means for radiographically imaging the radioopaque blood clotting agent. Means for delivering the blood clotting agent to the internally bleeding wound may be a conduit, and the blood clotting agent may be delivered through the conduit using a positive pressure device such as a pump or a syringe. Means for radiographically imaging the blood clotting agent may be an x-ray apparatus. 
         [0012]    In a fourth aspect, the present invention resides in a method of imaging an internally bleeding wound. The method includes the steps of inserting a catheter into a patient; advancing the catheter to a point adjacent the bleeding wound; depositing a radioopaque zeolite from a delivery instrument in the catheter at the bleeding wound; imaging the radioopaque zeolite to monitor blood-clotting caused by the zeolite. The radioopaque zeolite is imaged using x-rays. 
         [0013]    In the preferred embodiments of the present invention, the zeolite is found to be particularly effective in causing blood to clot. The compositions, devices, methods, and systems of the present invention are especially useful in controlling bleeding. One advantage of the present invention is that upon use of any of the compositions or devices of the present invention to address the flow of blood from a blood vessel or an internal organ, the clotting effect can be monitored radiographically. 
         [0014]    Another advantage of the present invention is that the devices described herein can be easily retracted from the patient with little adverse effect. In particular, the devices can be easily and cleanly pulled away from the wound while leaving only the zeolite necessary for clotting remaining at the bleed site. 
         [0015]    Another advantage is that the small particle size of the zeolite material produces a less drastic exothermic reaction than does a larger particle size. The porous nature of the zeolite still allows liquid blood constituents to be wicked away to cause thickening of the blood, thereby facilitating the formation of clots. Because the initial moisture content of the zeolite is controlled in a preferred embodiment, a less aggressive drawing of moisture from the blood can be realized, which thereby tempers any exothermic effects due to the absorption of water by the zeolite experienced at the wound site. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a perspective view of a blood clotting device, of the present invention, capable of dispensing a blood clotting agent. 
           [0017]      FIG. 2  is a sectional view of one exemplary embodiment of a conduit for use with the device of  FIG. 1 , the conduit having a wax coating to prevent the absorption of aqueous body fluids by the blood clotting agent. 
           [0018]      FIG. 3  is a sectional view of another exemplary embodiment of a conduit for use with the device of  FIG. 1 , the conduit having a frangible membrane to prevent the absorption of aqueous body fluids by the blood clotting agent. 
           [0019]      FIG. 4  is a schematic representation of a system, of the present invention, for imaging radiographic zeolite. 
           [0020]      FIG. 5  is a schematic representation of a system, of the present invention, utilizing a plurality of apparatuses that image radiographic zeolite to determine parameters of an internal wound. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Disclosed herein are devices, methods, and systems for delivering radioopaque hemostatic materials to internal wounds to promote the clotting of blood, thereby providing for the cessation of blood flow from the wound. The devices can be inserted subcutaneously through ports during invasive and minimally invasive surgical procedures to supply the radioopaque hemostatic (blood clotting) agents to bleeding wound sites. By contacting the blood with the blood clotting agent at the wound site, at least portions of the liquid phases of the blood are absorbed, thereby promoting clotting. The radioopaque attributes of the blood clotting agents allow the blood flow to be radiographically monitored before, during, and after clotting takes effect. The blood clotting agent is preferably a particulate molecular sieve material having an associated radioopaque component that can be maintained in direct contact with blood emanating from a wound. 
         [0022]    The molecular sieve material used in the present invention may be a synthetic polymer gel, cellulose material, porous silica gel, porous glass, alumina, hydroxyapatite, calcium silicate, zirconia, zeolite, or the like. Exemplary synthetic polymers include, but are not limited to, stylene-divinylbenzene copolymer, cross-linked polyvinyl alcohol, cross-linked polyacrylate, cross-linked vinyl ether-maleic anhydride copolymer, cross-linked stylene-maleic anhydride copolymer or cross-linked polyamide, and combinations thereof. 
         [0023]    The molecular sieve material is preferably a zeolite. Other molecular sieve materials that may be used include, but are not limited to, faujasite. As used herein, the term “zeolite” refers to a crystalline form of aluminosilicate having the ability to be dehydrated without experiencing significant changes in the crystalline structure. The zeolite may include one or more ionic species such as, for example, calcium and sodium moieties. Typically, the preferred zeolite is a powdered, friable material that is less than about 75% by weight silicon oxide, and preferably less than about 65% by weight silicon oxide; less than about 50% by weight aluminum oxide, and preferably less than about 40% by weight aluminum oxide; less than about 30% by weight sodium oxide, and preferably less than about 20% by weight of sodium oxide; less than about 30% by weight of calcium oxide, and preferably less than about 20% by weight of calcium oxide. The calcium portion contains crystals that are about 5 angstroms in size, and the sodium portion contains crystals that are about 4 angstroms in size. The preferred molecular structure of the zeolite is an “A-type” crystal, namely, one having a cubic crystalline structure that defines round or substantially round openings. The median size of the zeolite particle used is about 7 microns. However, the present invention is not limited in this regard as other sizes of zeolite particle are within the scope of the invention. 
         [0024]    The zeolite may be mixed with or otherwise used in conjunction with other materials having the ability to be dehydrated without significant changes in crystalline structure. Such materials include, but are not limited to, magnesium sulfate, sodium metaphosphate, calcium chloride, dextrin, polysaccharides, combinations of the foregoing materials, and hydrates of the foregoing materials. 
         [0025]    Zeolites for use in the disclosed applications may be naturally occurring or synthetically produced. Numerous varieties of naturally occurring zeolites are found as deposits in sedimentary environments as well as in other places. Naturally occurring zeolites that may be applicable to the compositions described herein include, but are not limited to, anal cite, chabazite, heulandite, natrolite, stilbite, and thomosonite. Synthetically produced zeolites that may also find use in the compositions and methods described herein are generally produced by processes in which rare earth oxides are substituted by silicates, alumina, or alumina in combination with alkali or alkaline earth metal oxides. One zeolite material found to be particularly useful in practicing the present invention is Molsiv Adsorbents 5A, manufactured by UOP LLC of Des Plaines, Ill. However, the present invention is not limited in this regard as other zeolite materials can be substituted without departing from the broader aspects of the present invention. 
         [0026]    The radioopacity of the zeolite is derived from the association of an iodine-based compound with the zeolite structure. The association may be either by binding the iodine-based compound to the zeolite using a binding agent, by blending the compound with the zeolite, or by incorporating the compound into the crystalline structure of the zeolite. Iodine compounds suitable for use with the zeolite include, but are not limited to, iodipamide, iohexyl, compounds based on 5-amino-2,4,6-triiodo-N,N′-bis(2,3-dihydroxypropyl)isophthalamide as building blocks, compounds based on 5-acetylamino-2,4,6-triiodo-N,N′-bis(2,3-dihydroxypropyl)isophthalamide as building blocks, combinations of the foregoing, and the like. The present invention is not limited in this regard, however, as other iodine-based compounds are within the scope of the present invention. 
         [0027]    Various other materials may be mixed with, associated with, or incorporated into the zeolite/iodine compounds to maintain an antiseptic environment at the wound site or to provide functions that are supplemental to the clotting functions of the zeolites. Exemplary materials that can be used include, but are not limited to, pharmaceutically-active compositions such as antibiotics, antifungal agents, antimicrobial agents, anti-inflammatory agents, analgesics (e.g., cimetidine, chloropheniramine maleate, diphenhydramine hydrochloride, and promethazine hydrochloride), bacteriostatics, compounds containing silver ions, and the like. Still other materials that can be incorporated to provide additional hemostatic functions include ascorbic acid, tranexamic acid, rutin, and thrombin. Botanical agents having desirable effects on the wound site may also be added. 
         [0028]    In one embodiment of the present invention shown in  FIG. 1 , a device that can be used to facilitate the clotting of blood at an internal bleed site is shown at reference numeral  10  and is hereinafter referred to as “device  10 .” The device  10  is especially useful for delivering the radioopaque zeolites of the present invention to a wound to close the wound to prevent undesirable internal bleeding and the formation of hematoma (pooling of blood). The wound can be located using any suitable method. The device  10  comprises a catheter  12 , at least one delivery instrument such as a conduit  14  through which the radioopaque zeolite may be dispensed, and a positive pressure apparatus  16 . The conduit  14  is configured to be advanced through the catheter  12  or with the catheter to the wound site. The positive pressure apparatus  16  may be a syringe or the like, although the present invention is not limited in this regard as other devices (e.g., pumps, blowers, and the like) are within the scope of the invention. 
         [0029]    The catheter  12  is a tube that can be inserted through an access port such as a portal or a duct and into a subcutaneous environment such as a body cavity duct or vessel and advanced to a wound site. The conduit  14  comprises flexible tubing sufficient for allowing the radioopaque zeolite to flow therethrough in the direction indicated by an arrow  18  under pressure from the positive pressure apparatus  16 . Because the radioopaque zeolite (shown at  20 ) is preferably in particle or powder form, the inner surface of the conduit  14  is coated with or otherwise includes a suitable surface agent capable of facilitating the flow of the zeolite. One particular agent which the inner surface of the conduit  14  may be coated with is polytetrafluoroethylene (PTFE). 
         [0030]    Once the radioopaque zeolite  20  is deposited at the wound site, the catheter  12  and the conduit  14  may or may not be retracted from the access port. 
         [0031]    Referring now to  FIGS. 2 and 3 , the conduit  14  may be capped or otherwise prevented from receiving body fluids during the maneuvering of the device  10  in the subcutaneous environment. In  FIG. 2 , the conduit  14  may be capped using a wax plug or wax coating  30  to prevent the contact of the radioopaque zeolite  20  by both aqueous and non-aqueous body fluids. The wax coating  30  may be of a calculated thickness to allow the body heat of a patient into which the device  10  incorporating the wax coating  30  is inserted to melt the wax over a period of time. Preferably, the period of time is sufficient to allow the end of the conduit  14  to be positioned at the wound site without allowing body fluids to dissolve the wax. In  FIG. 3 , the conduit  14  may be capped with a thin membrane  34 , which can be ruptured by pressurizing the conduit to a calculated pressure. In such an embodiment, the membrane  34  is preferably integrally formed with the conduit  14  and is sufficiently frangible to allow for rupture while not breaking off in the patient. An inner surface of the membrane  34  may include a notch  35  or similar defect to facilitate the rupture of the membrane. The membrane  34  is also sufficiently durable to prevent the penetration of the body fluids into the conduit  14 , thereby preventing moisture accumulation by the zeolite  20 . 
         [0032]    Referring now to  FIG. 4 , a system in which the radioopaque zeolite is imaged is shown generally at  40  and is hereinafter referred to as “system  40 .” System  40  comprises the device  10  and an imaging apparatus  44 . In using the system  40 , the radioopaque zeolite  20  is deposited at or proximate the wound site (shown at  46 ) in a tubular organ  45  in which blood is present and the imaging apparatus  44  radiographically determines the flow of the zeolite as it is carried by the blood flow. As clots  50  form around or at the wound site  46 , a series of images of the radiographic zeolite  20  taken over time will indicate a cessation of the blood flow from the high pressure side of the wound site to the low pressure side of the wound site. Although the device  10  of the system  40  is shown as being inserted into a tubular organ (e.g., a blood vessel or an esophagus) to stop the flow of blood from the high pressure side, it should be understood that the system may be utilized by inserting the device directly into the subcutaneous environment to address bleeding from the low pressure side. 
         [0033]    Referring now to  FIG. 5 , system  40  may incorporate a plurality of imaging apparatuses. One exemplary embodiment of system  40  comprises a first imaging apparatus  44   a , a second imaging apparatus  44   b , and a third imaging apparatus  44   c . In utilizing three imaging apparatuses, three images may be radiographically obtained simultaneously. Using a suitable compilation technique, the radiographic data may be compiled to form a three-dimensional image of the wound site  46  for display on a suitable video apparatus. If a plurality of three-dimensional images is obtained over a period of time, the images may be sequentially viewed to illustrate the clotting of the blood over time. 
         [0034]    As an alternative to compiling several images for three-dimensional viewing of the wound site  46 , the first imaging apparatus  44   a , the second imaging apparatus  44   b , and the third imaging apparatus  44   c  may be operated in conjunction with a triangulation technique to accurately locate a wound site that can only be approximately located using cursory location methods. More specifically, standards can be developed (e.g., based on intensity of the imaged radioopaque zeolite) that enable distances to be calculated. By obtaining three or more values based on signal intensity from corresponding imaging apparatuses, a triangulation technique may be utilized to determine a conjunctive point that corresponds to a maximum intensity. Such a conjunctive point can be marked and subsequently determined to be a point of particular interest such as, for example, the point at which the radioopaque zeolite collects, which may be determined to be the point at which clotting is seeded. 
         [0035]    In any embodiment in which zeolite is utilized as the blood clotting agent, the control of the moisture content of the zeolite in the substrate is related to its effectiveness. The preferred moisture content is between about 5 and about 25% by weight, more preferably between about 7 and about 19% by weight, and most preferably between about 10 and about 15% by weight. The moisture content of the zeolite can be adjusted by drying and then re-hydrating, or a combination of drying and re-hydrating, such that the zeolite has the desired specific moisture content. Alternatively, the composition may be fully saturated with water and subsequently dried to a specific water content. In the drying of the zeolite, the bound water is removed to allow the crystalline structure of the zeolite to remain intact. In the re-hydration of the zeolite, the most active adsorption sites are hydrated first and then less active sites are hydrated. As the degree of hydration of the zeolite increases, the heat of hydration decreases. More specifically, when the composition is applied to the blood, water in the blood is adsorbed by the zeolite. Upon adsorption of this water, heat is generated. At higher levels of hydration (hydration of the zeolite prior to its application to blood), less heat is generated when the composition is applied to blood. Thus, when the composition is applied to blood directly at a wound site, the amount of heat transferred to the tissue surrounding the wound site is reduced. 
         [0036]    Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.