Patent Application
20210378877
The present invention relates to compositions and applicators for treating injured tissue in a mammalian patient, such as a human and methods of using the same.
There are a large number of medical procedures that result in injuries to blood vessels. Similarly, there are numerous examples of bleeding caused by traumatic injuries, hematological disorders, and from unknown causes. When the site of bleeding is not readily accessible, such as an injured vessel located deep within the flesh, or inside a body cavity, a simple and effective method of hemorrhage control that can access the site within the body and seal the injured vessel is needed. Similarly, tissue may be divided by either traumatic injury or surgical procedure, and require sealing to approximate the edges of the injury in order to restore function. The same problems may also occur in regards to open wounds, or damaged tissue inside the respiratory, alimentary, reproductive, urinary, auditory and digestive tracts as well as other tissue tracts that communicate with the outside of the body such as tear ducts. Current sealing products and devices have one or more deficiencies, usually due to their inadequate performance, or their reliance upon non-natural components that interfere with normal healing, or fundamental difficulties with conveniently and effectively applying them.
The need for improved technologies to address these injuries is significant. For example, in the case of blood vessels that have been deliberately punctured as part of a diagnostic and/or therapeutic procedure (such as cardiac catheterization, balloon angioplasty, vascular stenting and the like), over seven million such procedures are currently performed every year, but with a 9% overall complication rate and a 1-3% major complication rate (See Millennium Research Group: Global Markets for Vascular Closure Devices 2006). These complications can lead to significant morbidity, increased expense, a requirement for additional procedures and/or devices, extended time in the medical facility and conversion of outpatients to inpatients. Commercially available products now available only reduce the major complication rate by one half of one percent (See Arora et al: Am Heart J. 2007 April; 153(4):606-11) to 2.4%. Nevertheless, despite this poor performance, even these devices are currently used since the costs and consequences of procedure-induced complications is so high (See Resnic et al: Am J Cardiol. 2007 Mar. 15; 99(6):766-70).
Not only are there the above described complications associated with therapy itself, closure of the access hole(s) created in the blood vessel is a significant source of additional complications, including uncontrolled hemorrhage, pseudoaneurysm, hematoma, arteriovenous fistula, arterial thrombosis, infection, and retained devices (See Meyerson et al: Angiographic Access Site Complications in the Era of Arterial Closure Devices Vasc Endovasc Surg, 2002; 36 (2) 137-44). These additional complications may lead to prolonged closure procedures, hospitalization, the requirement for surgical repair, and even tissue loss or death.
Currently, the primary means of closing the access hole in the vessel has been to allow a natural blood clot to form at the puncture site. This has generally been accomplished by manual compression, but various products have recently been developed in an attempt to reduce the time required to achieve vascular closure. Such devices automate the application of pressure over the injury site, suture the hole in the vessel, clip the hole shut, or apply some sort of patch or pad that allegedly increases the formation of a natural clot at the site. These devices are convenient and gaining in popularity, but their overall safety appears over estimated. Indeed, far from being risk free, these devices may be associated with unique levels of hemorrhagic and cardiac risks including myocardial infarction, stroke and death (See Rao, S. Implications of bleeding and blood transfusion in percutaneous coronary intervention. Rev Cardiovasc Med. 2007, 8 Suppl 3:S18-26.).
Significant risks have been reported to be associated with all classes of vascular closure devices. Most seriously, the severity and the difficulty in treating complications are generally greater when vascular closure devices are used (See Nehler et al. Iatrogenic vascular injuries from percutaneous vascular suturing devices. J. Vasc Surg 2001 May; 33(5):943-7; Castelli et al: Incidence of vascular injuries after use of the Angio-Seal closure device following endovascular procedures in a single center. World J Surg. 2006 March; 30(3):280-4.). The use of such devices is even associated with higher risks among patients having complications of pseudoaneurysms, failure to successfully treat such pseudoaneurysms, blood loss, transfusions, extensive operations to correct the problems and arterial infections (See Sprouse et al. The management of peripheral vascular complications associated with the use of percutaneous suture-mediated closure devices. J Vasc Surg. 2001 April; 33(4):688-693.). Moreover, some of these complications can be deadly, particularly in patients with diabetes, obesity and previously implanted devices (all conditions commonly found in patients in whom such closure devices are frequently used) (See Hollis and Rehring. Femoral endarteritis associated with percutaneous suture closure: new technology, challenging complications. J Vasc Surg. 2003 July: 38(1):83-7.). Accordingly, there remains a great need to develop a vascular closure system that avoids the problems associated with use of known vascular closure devices.
Another medical situation involving treatment of injured internal tissue is the repair of herniations. There are numerous types and locations of hernia, and the surgical repair techniques vary widely depending thereon. Both open and endoscopic procedures are currently in use, and may involve the use of sutures alone or sutures in combination with various kinds of meshes or supports for the injured tissue. Major complications for most hernia repair procedures include pain and the requirement to re-do the repair (See American College of Surgeons. When you need an operation About Hernia Repair, available at: http://www.facs.org/public_info/operation/hernrep.pdf).
Similarly, there is also a need to improve the therapeutic options for treatment of simple bleeding conditions such as epistaxis, which requires professional medical treatment in 1 of 7 people in their lifetime (See Evans: Epistaxis, emedicine (2007) available at www.emedicine.com/EMERG/topic806.htm). In fact, epistaxis is frequently cited as the most common ENT emergency (See Hussain et al: Evaluation of aetology and efficacy of management protocols of epistaxis. Ayub Med Coll Abottabad, 2006 October-December; 18(4):63-6) The difficulty in treating these cases is evidenced by the fact that 1.6 out of every 10,000 patients are hospitalized for epistaxis that is refractory to normal treatment (See Viehweg et al: Epistaxis: diagnosis and treatment, J. Oral Maxillofac Surg 2006 March; 64(3):5 11-8). Current treatment options include packing, chemical cauterization, electrocautery, surgical ligation and embolization (See: Ortiz & Bhattacharyya: Management pitfalls in the use of embolization for the treatment of severe epistaxis, Ear Nose Throat J. 2002 March; 82(3):178-83.) Frequently, multiple treatments with different technologies are required to effectively treat this often life-threatening condition (See Siniluoto et al: Embolization for the treatment of posterior epistaxis. An analysis of 31 cases. Arch Otolaryngol Head Neck Surg. 1993 August; 119(8):837-41; Gifford & Orlandi: Epistaxis. Otoloaryngol Clin North Am. 2008 June; 41(3):525-36, vii).
There are now in use a number of newer haemostatic agents that have been developed to overcome the deficiencies of traditional bandages that have been utilized in the above addressed medical procedures and medical emergencies. These haemostatic agents include the following:
Liquid fibrin sealants, such as Tisseel VH, have been used for years as an operating room adjunct for hemorrhage control. See J. L. Garza et al., J. Trauma 30:512-513 (1990); H. B. Kram et al., J. Trauma 30:97-101(1990); M. G. Ochsner et al., J. Trauma 30:884-887 (1990); T. L. Matthew et al., Ann. Thorac. Surg. 50:40-44 (1990); H. Jakob et al., J. Vasc. Surg., 1:171-180 (1984). The first mention of tissue glue used for hemostasis dates back to 1909. See Current Trends in Surgical Tissue Adhesives: Proceedings of the First International Symposium on Surgical Adhesives, M. J. MacPhee et al., eds. (Lancaster, Pa.: Technomic Publishing Co; 1995). Liquid fibrin sealants are typically composed of fibrinogen and thrombin, but may also contain Factor XIII/XIIIa, either as a by-product of fibrinogen purification or as an added ingredient (in certain applications, it is therefore not necessary that Factor XIII/Factor XIIIa be present in the fibrin sealant because there is sufficient Factor XIII/XIIIa, or other transaminase, endogenously present to induce fibrin formation). As liquids, however, these fibrin sealants have not proved useful outside certain specific procedures.
Dry fibrinogen-thrombin dressings having a collagen support (e.g. TachoComb™, TachoComb™ H and TachoSil available from Hafslund Nycomed Pharma, Linz, Austria) are also available for operating room use in many European countries. See U. Schiele et al., Clin. Materials 9:169-177 (1992). While these fibrinogen-thrombin dressings do not require the pre-mixing needed by liquid fibrin sealants, their utility for field applications is limited by a requirement for storage at 4° C. and the necessity for pre-wetting with saline solution prior to application to the wound. These dressings are also not effective against high pressure, high volume bleeding. See Sondeen et al., J. Trauma 54:280-285 (2003).
A dry fibrinogen/thrombin dressing for treating wounded tissue is also disclosed in U.S. Pat. No. 6,762,336. This particular dressing is composed of a backing material and a plurality of layers, the outer two of which contain fibrinogen (but no thrombin) while the inner layer contains thrombin and calcium chloride (but no fibrinogen). While this dressing has shown great success in several animal models of hemorrhage, the bandage is fragile, inflexible, and has a tendency to break apart when handled. See McManus et al., Business Briefing: Emergency Medical Review 2005, at 78.; Kheirabadi et al., J. Trauma 59:25-35 (2005). In addition, U.S. Pat. No. 6,762,336 teaches that this bandage should contain 15 mg/cm2 of fibrinogen to successfully pass a porcine arteriotomy test that is less robust than that disclosed in this application (see Example XI). Moreover, although U.S. Pat. No. 6,762,336 discloses that bandages comprising two layers of fibrinogen, each with a concentration of 4 mg/cm2 to 15 mg/cm2 may provide effective control of hemorrhage, it further teaches that “fibrinogen dose is related to quality. The higher dose is associated with more firm and tightly adhered clots. While lower fibrinogen doses are effective for hemorrhage control during the initial 60 minutes, longer term survival will likely depend on clot quality.”
Other fibrinogen/thrombin-based dressings have also been proposed. For example, U.S. Pat. No. 4,683,142 discloses a resorptive sheet material for closing and healing wounds which consists of a glycoprotein matrix, such as collagen, containing coagulation proteins, such as fibrinogen and thrombin. U.S. Pat. No. 5,702,715 discloses a reinforced biological sealant composed of separate layers of fibrinogen and thrombin, at least one of which also contains a reinforcement filler such as PEG, PVP, BSA, mannitol, FICOLL, dextran, myo-inositol or sodium chlorate. U.S. Pat. No. 6,056,970 discloses dressings composed of a bioabsorbable polymer, such as hyaluronic acid or carboxymethylcellulose, and a haemostatic composition composed of powdered thrombin and/or powdered fibrinogen. U.S. Pat. No. 7,189,410 discloses a bandage composed of a backing material having thereon: (i) particles of fibrinogen; (ii) particles of thrombin; and (iii) calcium chloride. U.S. Patent Application Publication No. US 2006/0155234 A1 discloses a dressing composed of a backing material and a plurality of fibrinogen layers which have discrete areas of thrombin between them. To date, none of these dressings have been approved for use or are available commercially.
Minimally invasive procedures often have strict requirements for attaining hemostasis. For the most part, the body cavities being treated are reached by either natural orifices or by small holes, and thus the instruments that can reach the treatment sites are themselves of a small diameter. This limits their complexity and dexterity, with a resulting limit on the general effectiveness of hemostatic products that can be used. The primary tools include direct pressure, sometime supplemented with a small amount of gauze at the tissue-instrument interface, and cautery. Should these tools fail, the only option is to convert the ‘closed’ minimally-invasive surgical procedure to a traditional ‘open’ one, with the attendant disadvantages of increased risk to the Patient, increased Patient morbidity, increased surgical time and increased costs. Thus any invention that improves the chances of achieving hemostasis during a minimally invasive procedure is highly desirable. Furthermore, current limitations on the ability to achieve hemostasis using the available endoscopic products limits the number of operations that can be initiated as endoscopic procedures, placing a further value on more capable endoscopic hemorrhage control technologies.
The same is true for procedures that involve treating wounds, whether medical or traumatic, that involve wound ‘tracts’ that lead from the exterior surface of the body deep into tissue. Current technologies for treating these situations are few and minim ally effective, and further improvements highly desirable. It is even the case that open wounds or open surgical procedures may benefit from treatment with more effective, convenient, ready to use and economical hemostatic technologies.
A number of different techniques, including the use of liquid fibrin sealant, have been proposed for sealing punctures in blood vessels, including those made to secure vascular access. For example, U.S. Pat. No. 7,357,794 discloses devices, systems and methods for acute or chronic delivery of substances or apparatus to extravascular treatment sites. U.S. Pat. No. 7,335,220 discloses apparatus and methods for sealing a vascular puncture using an expanding lyophilized hydrogel plug. U.S. Pat. No. 7,300,663 discloses adhesion and sealing of tissue with compositions containing polyfunctional crosslinking agents and protein polymers. U.S. Pat. No. 7,399,483 discloses a carrier with solid fibrinogen and solid thrombin. U.S. Pat. No. 7,335,220 discloses apparatus and methods for sealing vascular punctures. U.S. Pat. No. 7,115,588 discloses methods for treating a breach or puncture in a blood vessel. U.S. Pat. No. 7,008,442 discloses vascular sealant delivery devices using liquid formulations. U.S. Pat. No. 6,890,342 discloses to methods and apparatus for closing vascular puncture using a guidewire and/or other surgical implement extending from the wound on which a haemostatic material is moved into contact with an area of the blood vessel surrounding the wound. U.S. Pat. No. 6,818,008 discloses percutaneous puncture sealing method using flowable sealants. U.S. Pat. No. 6,699,262 discloses a percutaneous tissue track closure assembly and method using flowable materials. U.S. Pat. No. 6,613,070 discloses sealing vascular penetrations with haemostatic gels. U.S. Pat. No. 6,500,152 discloses a device for introducing a two-component liquid fibrin adhesive into a puncture channel. U.S. Pat. No. 6,325,789 also discloses a device for sealing puncture wounds using liquid or paste fibrin sealant. U.S. Pat. No. 5,814,066 discloses methods of reducing femoral arterial bleeding using percutaneous application of liquid fibrin sealant. U.S. Pat. Nos. 5,725,551, 5,486,195 and 5,443,481 each disclose the use of two component liquid fibrin sealant for artery closure. U.S. Pat. No. 5,649,959 discloses an assembly for sealing a puncture in a vessel which maintains the fibrinogen and thrombin separately. To date, however, all of these remain little-used in therapy, most likely due to the difficult and time consuming preparation requirements for two-component liquid fibrin sealant compositions.
Liquid fibrin sealant has also been used to treat epistaxis, endoscopic sinus surgery and endonasal surgery ((See Vaiman et al. Fibrin glue treatment for epistaxis. Rhinology. 2002 June; 40(2):99-91; Vaiman et al. Use of fibrin glue as a haemostatic in endoscopic sinus surgery. Ann Otol Rhinol Laryngol, 2005 March; 114(3): 237-41; Vaiman et al. Fibrin sealant: alternative to nasal packing in endonasal operations. A prospective randomized study. Isr Med Assoc J. 2005 September; 7(9):571-4.). All these reports indicate that liquid fibrin sealant may be used with some success at controlling hemorrhage from various locations just inside the nose all the way into the sinuses. However, the time and efforts associated with preparing such sealants make them less than ideal for daily clinical use. Their effectiveness may be further limited by the difficulties in combining their application with direct pressure during the period required for fibrin formation.
Accordingly, there remains a need in the art for compositions of solid hemostatic materials and effective, convenient means of applying them to achieve hemostasis and sealing of both internal and external wounded tissue, particularly highly vascularized tissue, and single blood vessels. Additionally, treatment of tissues that have been divided (e.g. due to accident, pathology or surgical intervention) and require re-approximation to promote healing would also benefit from such materials and applicators capable of adequate tissue sealing.
The assessment of such materials requires new techniques that go beyond those previously disclosed for testing haemostatic dressings. The ability of dressings to seal an injured blood vessel has been determined by an ex vivo porcine arteriotomy (EVPA) performance test, which was first described in U.S. Pat. No. 6,762,336. The EVPA performance test evaluates the ability of a dressing to stop fluid flow through a hole in a porcine artery. While the procedure described in U.S. Pat. No. 6,762,336 has been shown to be useful for evaluating haemostatic dressings, it failed to replicate faithfully the requirements for success in vivo. More specifically, the procedure disclosed in U.S. Pat. No. 6,762,336 required testing at 37° C., whereas, in the real world, wounds are typically cooler than that. This decreased temperature can significantly reduce the rate of fibrin formation and its haemostatic efficacy in trauma victims. See, e.g., Acheson et al., J. Trauma 59:865-874 (2005). The test in U.S. Pat. No. 6,762,336 also failed to require a high degree of adherence of the dressing to the injured tissue. A failure mode in which fibrin forms but the dressing fails to attach tightly to the tissue would, therefore, not be detected by this test. Additionally, the pressure utilized in the procedure (200 mHg) may be exceeded during therapy for some trauma and surgery patients. The overall result of this is that numerous animal tests, typically involving small animals (such as rats and rabbits), must be conducted to accurately predict dressing performance in large animal, realistic trauma studies and in the clinical environment.
In order to minimize the amount of time and the number of animal studies required to develop dressings intended to treat accessible traumatic injuries, an improved ex vivo testing procedure has been developed. To accomplish this, the basic conditions under which the dressing test was conducted were changed, and the severity of the test parameters was increased to include testing at lower temperatures (i.e. 29-33° C. vs. 37° C., representing the real physiologic challenge at realistic wound temperatures (Acheson et al., J. Trauma 59:865-874 (2005)), higher pressures (i.e. 250 mmHg vs. 200 mmHg), a longer test period (3 minutes vs. 2 minutes) and larger sized arterial injuries (U.S. Pat. No. 6,762,336 used an 18 gauge needle puncture, whereas the revised procedure used puncture holes ranging from 2.8 mm to 4 mm×6 mm). A new test has also been developed to directly measure adherence of the dressing to the injured tissue. Both these tests showed greatly improved stringency and are thus capable of surpassing the previous ex vivo test and replacing many in vivo tests for efficacy. These newer tests are described in U.S. patent application Ser. No. 11/882,874, the disclosure of which is herein incorporated by reference in its entirety.
The newer tests described in U.S. patent application Ser. No. 11/882,874 were designed to simulate trauma-derived, accessible wounds with high pressure and flow characteristics. Therefore, for the evaluation of methods and compositions for treating wounded internal tissue, it was preferable to develop additional assays to more accurately simulate the peripheral vasculature and the effects of surrounding tissue.
It is therefore an object of the present disclosure to provide solid dressings that can treat wounded internal mammalian tissue. It is a further object to provide novel dressings for treating internal wounded tissue, manufacturing of the same, and methods of using the same. It is further an object of the present disclosure to provide methods of treating wounded internal mammalian tissue, particularly human tissue. Other objects, features and advantages of the present invention will be set forth in the detailed description of preferred embodiments that follows, and will in part be apparent from that description and/or may be learned by practice of the present invention. These objects and advantages will be realized and attained by the compositions and methods described in this specification and particularly pointed out in the claims that follow.
In accordance with these and other objects, a first embodiment of the present disclosure is directed to a haemostatic material having a cylindrical shape having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator, wherein said cylindrical shaped haemostatic material is suitable for treating internal wounded tissue.
In a further embodiment, a haemostatic material for treating wounded internal tissue in a mammal comprising a cylindrical haemostatic material having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator wherein said cylindrical haemostaic material is made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical pre-chilled mold having a temperature between 12° C. and −196° C.
In a further embodiment, a haemostatic material for treating wounded internal tissue in a mammal comprising a cylindrical haemostatic material having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator wherein said cylindrical haemostaic material is made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical pre-chilled mold, and freezing said material, which is stable for at least 24 hours at a temperature below 0° C.
In a further embodiment, a haemostatic material for treating wounded internal tissue in a mammal comprising a cylindrical haemostatic material having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator wherein said cylindrical haemostaic material is made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical pre-chilled mold; wherein said fibrinogen component is present in an amount between 1 and 37.5 mg/ml and said fibrinogen activator is present in an amount between about 0.01 to about 1.0 U/mg fibrinogen component; wherein said liquid combination is thereafter frozen and lyophilized.
A haemostatic material cast a cylinder consisting essentially of, a fibrinogen component, a fibrinogen activator, and water, wherein said haemostatic material is made by combining said fibrinogen component, fibrinogen activator, and water at 0° C.-12° C., into a cylindrical mold, freezing said fibrinogen component, fibrinogen activator, water, and cylindrical mold, and maintaining said frozen fibrinogen component, fibrinogen activator, water, and cylindrical mold at a temperature of below 0° C. for at least 24 hours, wherein fibrin formation of γ-γ dimers is less than about 5%.
In a further embodiment, a haemostatic material for treating wounded internal tissue in a mammal comprising a cylindrical haemostatic material having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator wherein said cylindrical haemostaic material is made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical pre-chilled mold; wherein said fibrinogen component is present in an amount between 1 and 37.5 mg/ml and said fibrinogen activator is present in an amount between about 0.01 to about 1.0 U/mg fibrinogen component; wherein said liquid combination is thereafter frozen and lyophilized and contains less than about 5% γ-γ dimer.
In a further embodiment, a haemostatic material for treating wounded internal tissue in a mammal comprising a cylindrical haemostatic material having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator wherein said cylindrical hemostatic material is made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical pre-chilled mold; wherein said fibrinogen component is present in an amount between 0.15 and 37.5 mg/ml and said fibrinogen activator is present in an amount between about 0.01 to about 1.0 U/mg fibrinogen component; wherein said liquid combination is thereafter frozen and lyophilized and contains less than about 3% γ-γ dimer.
In a further embodiment, a haemostatic material for treating wounded internal tissue in a mammal comprising a cylindrical haemostatic material having a larger height than the radius, and consisting essentially of a fibrinogen component and a fibrinogen activator wherein said cylindrical haemostaic material is made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical pre-chilled mold; wherein said fibrinogen component is present in the combined solution at concentrations of between 1 and 37.5 mg/ml; wherein following lyophilization the fibrinogen component was present in an amount between 3 and 75 mg/cm2 and in both cases, said fibrinogen activator was present in an amount between about 0.01 to about 1.0 U/mg fibrinogen component; wherein said liquid combination is thereafter frozen and lyophilized and contains less than about 3% γ-γ dimer.
In a further embodiment, a haemostatic material comprising a fibrinogen component fibrinogen activator and water, frozen in a cylindrical form having a larger height than the radius, and made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical mold; wherein said fibrinogen component is present in an amount between 1 mg/ml and 37.5 mg/ml, which corresponds to a dose of fibrinogen component in an amount between 3 and 75 mg/cm2, and in both cases, said fibrinogen activator is present in an amount between about 0.01 to about 10.0 U/mg fibrinogen component and freezing said mold, and maintaining said frozen mixture at a temperature of below 0° C. for at least 24 hours, wherein fibrin formation of the γ-γ dimer is less than about 5%.
In a further embodiment, a haemostatic material comprising a fibrinogen component fibrinogen activator and water, frozen in a cylindrical form having a larger height than the radius, and made by combining liquid fibrinogen component and liquid fibrinogen activator at about 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical mold; wherein said fibrinogen component is present in an amount between 1 mg/ml and 37.5 mg/ml, which corresponds to a dose of fibrinogen component in an amount between 3 and 75 mg/cm2, and in both cases, said fibrinogen activator is present in an amount between about 0.01 to about 10.0 U/mg fibrinogen component and freezing said mold, and maintaining said frozen mixture at a temperature of below 0° C. for at least 24 hours, wherein fibrin formation of the γ-γ dimer is less than about 1%.
Another embodiment is directed to a method for treating wounded internal tissue in a mammal comprising applying to wounded internal tissue at least one cylindrical haemostatic material consisting essentially of a fibrinogen component and a fibrinogen activator for a time sufficient to join or approximate said wounded tissue and/or to reduce the flow of fluid from said wounded tissue, wherein said haemostatic material is cast or formed from a single aqueous solution containing the fibrinogen component and the fibrinogen activator, wherein said fibrinogen component is present in an amount between 0.15 and 37.5 mg/ml and said fibrinogen activator is present in an amount between about 0.01 to about 1.0 U/mg fibrinogen component; wherein said liquid combination is thereafter frozen and lyophilized, wherein said fibrinogen component is present in a dose of between 3 and 15 mg/cm2.
Another embodiment is directed to a method for treating wounded internal tissue in a mammal comprising applying to wounded internal tissue at least one cylindrical haemostatic material consisting essentially of a fibrinogen component and a fibrinogen activator for a time sufficient to reduce the flow of fluid from the wounded tissue, wherein the haemostatic material is cast or formed from a single aqueous solution containing the fibrinogen component and the fibrinogen activator.
Another embodiment is directed to a method for treating wounded internal tissue in a mammal comprising applying to wounded internal tissue at least one cylindrical haemostatic material consisting essentially of a fibrinogen component and a fibrinogen activator for a time sufficient to reduce the flow of fluid from the wounded tissue, wherein the haemostatic material is cast or formed as a single piece and wherein said fibrinogen component is present in an amount between 0.15 and 37.5 mg/ml and said fibrinogen activator is present in an amount between about 0.01 to about 1.0 U/mg fibrinogen component; wherein said liquid combination is thereafter frozen and lyophilized, wherein said fibrinogen component is present in a dose of between 3 and 15 mg/cm2.
Additional embodiments are directed to the design of applicators suitable for use of the hemostatic materials and facilitating their use on various tissues, whether accessing the site to be treated via a conventional ‘open’ surgical technique or by an endoscopic, minimally invasive-type approach. When the product format is for endoscopic use an applicator may have one or more of several kinds of features designed to hold the product firmly to the applicator tip and allow it to be pressed onto the site to be treated until such time as the application has complete and to then release the product from the applicator. This may be achieved by the use of clamps, quills, hook and loop fasteners, or a suitable break-away layer, or the product may be affixed by some kind of thread that can be withdrawn so as to no longer hold it to the applicator when desired.
A further embodiment is a haemostatic device comprising an applicator that is rod-like in shape, having a handle, and a cylindrical haemostatic material disposed of on the non-handle end; wherein the cylindrical haemostatic material is made by combining a liquid mixture of aqueous fibrinogen component and aqueous fibrinogen activator having a temperature of 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical mold; freezing said cylindrical mold, liquid mixture, and applicator and lyophilizing said frozen liquid mixture, said applicator, and optionally said cylindrical mold.
A further embodiment is a haemostatic device comprising an applicator that is rod-like in shape, having a handle, and a non-resorbable material disposed of on the non-handle end; wherein the cylindrical haemostatic material is made by combining a liquid mixture of aqueous fibrinogen component and aqueous fibrinogen activator having a temperature of 12° C. to 0° C., and preferably 4° C.+/−2° C. into a cylindrical mold; freezing said cylindrical mold, liquid mixture, and applicator and lyophilizing said frozen liquid mixture, said applicator, and optionally said cylindrical mold, wherein said fibrinogen component is present in an amount between 1 mg/ml and 37.5 mg/ml in said liquid mixture, which corresponds to a dose of fibrinogen in an amount between 3 and 75 mg/cm2, and in both cases, said fibrinogen activator is present in an amount between about 0.01 to about 10.0 U/mg.
A further embodiment is a method for using a haemostatic applicator wherein said applicator is rod-like in shape and having a handle, a haemostatic material disposed of on the non-handle end, and wherein the haemostatic material is cast as a cylinder having a height greater than the radius from a liquid mixture of aqueous fibrinogen component and aqueous fibrinogen activator having a temperature of 12° C. to 0° C., and preferably 4° C.+/−2° C.; freezing said applicator and lyophilizing said frozen applicator; wherein said haemostatic material is applied to a wound surface via the applicator for a period sufficient to form a fibrin clot and said applicator is removed thereafter.
Another embodiment would include an applicator that is rod-like in shape, which may have one or more of the following additional features: a handle, a trigger-release to free the product from the end.
A further embodiment is a haemostatic device comprising an applicator that is rod-like in shape, having a handle, and a cylindrical haemostatic material disposed of on one end of the non-handle end of the applicator, wherein said cylindrical haemostatic material is cast as a cylinder having a height greater than the radius from a liquid mixture of aqueous fibrinogen component and aqueous fibrinogen activator having a temperature of 12° C. to 0° C., and preferably 4° C.+/−2° C.; freezing said applicator and lyophilizing said frozen applicator; wherein said haemostatic material is applied to a wound surface via the applicator for a period sufficient to form a fibrin clot and said applicator is removed thereafter.
In the embodiments disclosed above, fibrinogen component is preferably human fibrinogen derived from plasma, transgenic, or recombinant sources, or bovine or fish based fibrinogen. Fibrinogen activator is preferable human thrombin derived from plasma, transgenic, or recombinant sources, or bovine or fish based thrombin.
It is to be understood that the foregoing general description and the following detailed description of preferred embodiments are exemplary and explanatory only and are intended to provide further explanation, but not limitation, of the invention as claimed herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. All patents and publications mentioned herein are incorporated by reference.
As used herein, use of a singular article such as “a,” “an,” and “the” is not intended to excluded pluralities of the article's object unless the context clearly and unambiguously dictates otherwise.
“Patient” as used herein refers to human or animal individuals in need of medical care and/or treatment.
“Endoscopic” as used herein refers to one or more surgical procedures employing small incisions used to pass viewing tools, surgical and probing, biopsy and surgical instruments, but not the Surgeon's hands, into one or more body cavities or surgical sites. It incorporates laparoscopic surgery, minimally invasive and keyhole surgery as types of endoscopic surgery.
“Wound” or “wounded tissue” as used herein refers to any damage to any internal tissue of a patient which results in the loss of blood from the circulatory system and/or any other fluid from the patient's body. The tissue may be any mammalian internal tissue, such as an organ or blood vessel. A wound may be in a soft internal tissue, such as an organ, or in hard internal tissue, such as bone. The “damage” may have been caused by any agent or source, including traumatic injury, infection or surgical intervention.
“Resorbable material” as used herein refers to a substance that is broken down spontaneously and/or by the mammalian body into components which are consumed or eliminated in such a manner as not to interfere significantly with wound healing and/or tissue regeneration, and without causing any significant metabolic disturbance.
As used herein the terms “kittner” and or “Kittner”, singular or pleural, refers to a device resembling the conventional endoscopic surgical tissue probe or dividing device that has one or more shafts and ends intended to manipulate or apply pressure to the patient's tissues. As used herein, such the term may also apply to a similarly-shaped device that is tipped with some form of hemostatic mixture or product to be applied to injured tissue.
“Stability” as used herein refers to the retention of those characteristics of a substance that determine activity and/or function.
“Suitable” as used herein is intended to mean that a substance (or mixture of substances) does not adversely affect the stability or function of the dressings or any component thereof, nor producing any unacceptable effects upon Patients when the dressings are applied.
“Binding agent” as used herein refers to a compound or mixture of compounds that improves the adherence and/or cohesion of the components of the haemostatic material of the dressings.
“Solubilizing agent” as used herein refers to a compound or mixture of compounds that improves the dissolution of a protein or proteins in aqueous solvent.
“Filler” as used herein refers to a compound or mixture of compounds that provide bulk and/or porosity or structure to the haemostatic material.
“Release agent” as used herein refers to a compound or mixture of compounds that facilitates removal of a dressing from a manufacturing mold.
“Foaming agent” as used herein refers to a compound or mixture of compounds that produces gas when hydrated under suitable conditions, or a suitable gas infused into a material resulting in it being altered into a foam.
“Solid” as used herein is intended to mean that a haemostatic material or dressing will not substantially change in shape or form when placed on a rigid surface and then left to stand at room temperature for 24 hours.
“Frozen” as used herein is intended to mean that a haemostatic material or dressing will not substantially change in shape or form when placed on a rigid surface and then left to stand at 0° C. for 24 hours, but will substantially change in shape or form when placed on a rigid surface and then left at room temperature for 24 hours.
“Substantially homogeneous” as used herein is intended to mean that the haemostatic material has a uniform composition throughout, within the tolerances described herein. Thus, a “substantially homogeneous” haemostatic material according to the present invention may be composed of a plurality of particles, provided that each of those particles has the same composition.
“γ-γ dimer” as used herein, means covalently cross-linked fibrinogen γ chains. Since the resulting structure has a higher apparent molecular weight then single γ chains, and can be separated from the α and β chains by molecular weight, the relative amount of γ-γ versus free γ chains in a sample can be determined. Further, since the formation of γ-γ dimers from γ chains occurs late in the transformation of fibrinogen to insoluble fibrin, it can be used to quantify the amount of fibrin in a sample.
As used herein, “fibrin” refers to fibrin polymers, predominantly cross-linked via their gamma chains that are substantially insoluble under physiological conditions.
“About” as used herein means within 10% of a stated number.
As used herein, “consisting essentially of” is intended to mean that the fibrinogen component and the fibrinogen activator are the only necessary and essential ingredients of the haemostatic material when it is used as intended to treat wounded internal tissue. Fibrinogen component may contain Factor XIII and other co-purifying plasma proteins, whether these are essential to the functioning of the fibrinogen component or not. Accordingly, the haemostatic material may contain other ingredients in addition to the fibrinogen component and the fibrinogen activator as desired for a particular application, but these other ingredients are not required for the solid dressing to function as intended under normal conditions, i.e. these other ingredients are not necessary for the fibrinogen component and fibrinogen activator to react and form enough fibrin to reduce the flow of blood and/or fluid from normal wounded tissue when that dressing is applied to that tissue under the intended conditions of use. If, however, the conditions of use in a particular situation are not normal, for example the patient is a hemophiliac suffering from Factor XIII deficiency, then the appropriate additional components, such as Factor or some other transaminase, may be added to the haemostatic material without deviating from the spirit of the present invention.
The haemostatic materials of the present invention may be formed or cast in any shape or form suitable for a given application. For example, the haemostatic material may be formed or cast in the shape of a cone or cylinder or a multi-faceted rod or the like. Such a shape is particularly suitable for use in applications where the damage to the tissue being treated is a hole to be plugged or sealed, e.g. a vein which has been intentionally punctured as part of a medical procedure, such as angioplasty. In such applications, the haemostatic material may alternatively be in the shape of a disk, optionally with a hole for use in conjunction with a guide wire.
In suitable situations, a haemostatic material may be formed in a mold to conform to a specified shape for use in a specified type of setting. Shapes may include circular, oval, square, multi-faceted rod, or other shapes as necessary. Furthermore, the haemostatic material may comprise a length, a width, and a depth, such that a three-dimensional haemostatic material may properly seal a wound.
Typical situations may arise when an endoscope makes an incision and requires a haemostatic material of a particular shape and size for a particular surgery. Such a haemostaic material may be pre-formed to that suitable surgery. Such haemostatic material may comprise a backing or no backing, and may comprise a release mechanism or none.
Suitable ranges and optimization of the composition of the material may comprise about 1 mg/ml to about 37.5 mg/ml of the fibrinogen component in the liquid mixture used to form the material and comprise fibrinogen activator at about 0.01 U/mg to about 10 U/mg fibrinogen component. Other suitable ranges and optimization of the composition of the final lyophilized material may comprise about 0.1 mg of fibrinogen/cm2 of the area of the material, to about 75.0 mg of fibrinogen/cm2 of the area of the material, and comprise fibrinogen activator at about 0.01 U of thrombin/mg of fibrinogen component to about 10 U of thrombin/mg fibrinogen component.
In a preferred embodiment, a haemostatic material is cast as a rod or a cylinder. The casting shape is important for use in surgical or trauma settings wherein a wound is three-dimensional in nature, and bleeding is occurring from the various dimensions. Compare the following two examples, a tissue sample being a cube, having dimensions of 2″, is cut on one face, removing a small layer of tissue on the single face. The wound, being two-dimensional, can be closed by applying pressure to the wound, or alternatively using a flat haemostatic dressing to stop the bleeding. However, if that same cube tissue, is punctured with a ½″ diameter probe to a depth of 1.5″, the wound would not have a single surface, but surfaces along multiple dimensions that may be bleeding. A material that would have the same shape as the puncture wound would allow for haemostasis with regard to all surfaces of the wound, and provides greater closure of the wound.
However, no such haemostatic bandage currently exists, due in part to the numerous technical difficulties in manufacturing such a bandage. When a typical “flat” bandage, i.e. having dimensions of 2″×2″ and having a thickness of a few mm, at most, is placed into a mold, frozen, and then lyophilized, the process of lyophilization is relatively easy. There is a large surface area for contact with a cooling/heating surface, and there is a large surface area for sublimation to occur, with relatively small amount of depth for the water to sublimate through.
Compare a “flat” bandage to a rod or cylinder, having a total volume of 1 ml, 3 ml, 5 ml, 10 ml, etc., as manufactured in an ordinary and standard syringe of said volumes. In each case, the total height is much larger than the radius, and the height would be much greater than the thickness of a “flat” bandage. Thus, in making such a rod or cylinder of haemostatic material, a cylindrical mold, having a height of about 1-3 cm and a radius of about 1-5 mm is filled with an aqueous solution of fibrinogen and an aqueous solution of thrombin as described in the Examples herein. The mold is capped, inverted to mix, and then frozen in liquid nitrogen or other suitably cold environment. To freeze, the reduced temperature must go through the mold, in this case, a plastic material from the syringe, and then through the liquid solution therein. The material freezes from the outside in. Then, to evacuate the aqueous liquid, the frozen mold is placed in a lyophilizer so that the liquid can sublimate, thus drying the material.
However, as one end of the mold is capped and the sides are solid, only the top portion, i.e. a small portion of the rod or cylinder is open to the air, and thus there is very little surface area for the sublimation process to occur, as compared to the “flat” bandages. This requires that the concentrations and quantities of the fibrinogen component and fibrinogen activator and the lyophilization process combine so that the structure of the dried rod or cylindrical haemostatic material is supported. If the material is dried improperly, or improper quantities or ratios of fibrinogen component and fibrinogen activator are utilized, the crystal structure of the dried product is compromised and the material will not stay in the cylindrical shape. This may occur because sublimation starts at the top portion that is open to the lyophilizer, and removing water from that portion, before water is removed from deeper portions of the rod or cylinder. As the moisture is pulled from deeper portions of the rod, it wants to re-adhere to the already dried portions that it must travel through. If the rate of reabsorption of water released from the deeper parts of the structure into the upper parts is too high, these parts will dissolve and their crystals collapse and undergo physical shape changes causing the upper portions of the mass to collapse. Frequently this results in the pores in the collapsed portion of the mass to be diminished in size, further aggravating the difficulty in lyophilization and leading to more collapse, plus a resulting mass that is slow to dissolve when water is added due to the lack of suitable pores via which water may move into the mass.
A resulting rod or cylinder is usually put through a two phase lyophilization cycles to properly dry the product and ensure stable storage conditions for the rod haemostatic material. Accordingly, the resulting rod shaped haemostatic material, must be made from aqueous solutions under conditions that prevent the formation of fibrin both during manufacture and during both the low (primary) and high (secondary) lyophilization phases. It is expected that some conversions of α, β, and/or γ chains occurs, and that the formation of γ-γ dimers is less than about 9%. In particular, it is envisioned that the amount of γ-γ dimer formation is less than about 7%, 5%, 4%, 3%, 2%, and 1%. In particular, it is preferred that there is less than about 0.5% or even 0.1% γ-γ dimer formation, thus nearly every molecule of fibrinogen and thrombin is available to convert to fibrin upon activation by an aqueous fluid. “Substantially free” of fibrin shall mean that the material comprises less than 3% γ-γ dimer. Occasionally higher levels of % γ-γ dimers in the final product may be acceptable, when the majority of the % γ-γ dimers were contributed by the fibrinogen component itself and not by the formation of new γ-γ dimers during the manufacture or storage of the rod haemostatic material.
After lyophilizations, the rod haemostatic material is susceptible to falling out of the cylindrical mold if inverted. It is appropriate for small tabs, or other mechanism to be present on the inside of the cylindrical mold to prevent the rod haemostatic material from falling out when ready for use. Examples of these designs are depicted, for example, in
Accordingly, production of a haemostatic rod provides for certain and numerous advantages in surgical and trauma uses where the injury is three-dimensional. Indeed, the rods may be manufactured with certain wound sizes in mind that are typically encountered, whether they are intentional from surgical procedures, or whether they are from typical injuries seen in trauma patients. It is particularly noted that in certain embodiments the shape of the rod may further be circular, elliptical, irregular, multi-curved, multifaceted, as is necessary for the particular injury to be treated. These modifications may be molded or cast, or be modified to the particular shape as needed by a medical professional.
In a particular embodiment, it is particularly preferred to combine fibrinogen and thrombin into an aqueous solution in a cylindrical mold and freeze material in the mold. Thereafter, it is advantageous to store the mold, frozen at a temperature of less than 0° C. for at least 24 hours. It is particularly understood that the frozen molds may be maintained at such temperatures for at least 24 hours, 7 days, at least 14 days, at least 30 days, at least six months, and at least a year, before the frozen mold is lyophilized, and wherein the frozen aqueous solution has less than 5% γ-γ dimer formation, and in some embodiments less than 1% formation. It may be preferred to store such molds at temperatures of about −20° C., or −80° C., or another temperature for long term storage.
It may be suitable to utilize a pre-chilled mold in some circumstances. A mold may be placed on top of dry ice or other suitably cold material in some embodiments. Accordingly, the pre-chilled mold is suitably utilized at a temperature of about −196° C., −80° C., −68° C., −40° C., −20° C., 0° C., and at temperatures up to about room temperatures. Pre-chilled molds may also fall into temperature ranges in-between these temperatures, as transfer between a cold environment and a warmer environment may slightly warm the mold. Preferred embodiments include a pre-chilled mold at between 12° C. and −68° C.
A method of using such rod shaped haemostatic material comprises manufacture of a rod shaped haemostatic material having a radius and a length, wherein an injury tissue has a similar radius and length, and a rod shaped haemostatic material is inserted into said injured tissue and held for a sufficient amount of time to reach haemostasis.
It is envisioned that typical surgical wounds and injuries are known in the art and that the particular sizes of injuries are known. It is therefore envisioned to manufacture rod shaped haemostatic materials that fit within these injuries.
Suitable ranges and optimization of the composition of the material may comprise about 0.1 mg/cm2 to about 450.0 mg/cm2 fibrinogen component and comprise about 0.01 U/mg of fibrinogen to about 10 U/mg of fibrinogen of a fibrinogen activator. Stated another way, the ratio of thrombin to fibrinogen may be about 0.01 to 10 U(Thrombin):mg of Fibrinogen. In preferred embodiments, the amount of material comprises about 5 to about 75 mg/cm2 fibrinogen component and about 0.01 U/mg to about 1.0 U/mg fibrinogen activator. Stated another way, in preferred embodiments, the ratio of thrombin to fibrinogen may be about 0.01 to 1 U(Thrombin)/mg of Fibrinogen.
The haemostatic material may also optionally contain one or more suitable fillers, such as sucrose, lactose, maltose, silk, fibrin, collagen, albumin (natural or recombinantly produced), polysorbate (Tween™), chitin, chitosan and its derivatives (e.g. NOCC-chitosan), alginic acid and salts thereof, cellulose and derivatives thereof, proteoglycans, hyaluron and its derivatives, such as hyaluronic acid, glycolic acid polymers, lactic acid polymers, glycolic acid/lactic acid co-polymers, and mixtures of two or more thereof.
The haemostatic material may also optionally contain one or more suitable solubilizing agents, including detergents and tensides. Illustrative examples of suitable solubilizing agents include, but are not limited to, the following: sucrose, dextrose, mannose, trehalose, mannitol, sorbitol, albumin, hyaluron and its derivatives, such as hyaluronic acid, sorbate, polysorbate (Tween™), sorbitan (SPAN™) and mixtures of two or more thereof.
The haemostatic material may also optionally contain one or more suitable foaming agents, such as a mixture of a physiologically acceptable acid (e.g. citric acid or acetic acid) and a physiologically suitable base (e.g. sodium bicarbonate or calcium carbonate). Other suitable foaming agents include, but are not limited to, dry particles containing pressurized gas, such as sugar particles containing carbon dioxide (see, e.g., U.S. Pat. No. 3,012,893) or other physiologically acceptable gases (e.g. Nitrogen or Argon), and pharmacologically acceptable peroxides. Such a foaming agent may be introduced into the aqueous mixture of the fibrinogen component and the fibrinogen activator, or may be introduced into an aqueous solution of the fibrinogen component and/or an aqueous solution of the fibrinogen activator prior to or after mixing, or it may be introduced into the lyophilized mixture during or after hydrating, or upon hydration of the material when applied to, or just prior to application to, wounded tissue. Alternatively, the inventive haemostatic materials may be ground to particles of a predetermined size and then combined with a suitable foaming agent.
The haemostatic material may also optionally contain a suitable source of calcium ions, such as calcium chloride, and/or a fibrin cross-linker, such as a transaminase (e.g. Factor XIII/XIIIa) or glutaraldehyde.
The haemostatic materials described in the various embodiments herein are prepared by mixing aqueous solutions of the fibrinogen component and the fibrinogen activator under conditions which minimize the activation of the fibrinogen component by the fibrinogen activator and thus are substantially free of fibrin. This aqueous mixture of the fibrinogen component and the fibrinogen activator may then be frozen until used to treat wounded tissue.
Indeed, as described herein, the rod shaped haemostatic material can be stored frozen and the frozen mixture may then subjected to a process, such as lyophilization or freeze-drying, to reduce the moisture content to a predetermined effective level, i.e. to a level where the dressing is solid and therefore will not substantially change in shape or form upon standing at room temperature for 24 hours. Similar processes that achieve the same result, such as drying, spray-drying, vacuum drying and vitrification, may also be employed, either alone or in combination.
As used herein, “moisture content” refers to levels determined by procedures substantially similar to the FDA-approved, modified Karl Fischer method (Centers for Biologics Evaluation and Research, FDA, Docket No. 89D-0140, 83-93; 1990 and references cited therein) or by near infrared spectroscopy. Suitable moisture content(s) for a particular inventive haemostatic material may be determined empirically by one skilled in the art depending upon the intended application(s) thereof.
For example, in certain embodiments of the present invention, higher moisture contents are associated with more flexible solid dressings. Thus, in solid dressings intended to be deformed in use, it may be preferred for the haemostatic material to have a moisture content of at least 6% and even more preferably in the range of 6% to 44%.
Similarly, in other embodiments of the present invention, lower moisture contents are associated with more rigid solid dressings. Thus, in solid dressings intended to be used as formed or cast, it may be preferred for the haemostatic material to have a moisture content of less than 6% and even more preferably in the range of 1% to 6%.
Accordingly, illustrative examples of suitable moisture contents for the inventive haemostatic materials include, but are not limited to, the following (each value being ±0.9%): less than 53%; less than 44%; less than 28%; less than 24%; less than 16%; less than 12%; less than 6%; less than 5%; less than 4%; less than 3%; less than 2.5%; less than 2%; less than 1.4%; between 0 and 12%, non-inclusive; between 0 and 6%; between 0 and 4%; between 0 and 3%; between 0 and 2%; between 0 and 1%; between 1 and 16%; between 1 and 11%; between 1 and 8%; between 1 and 6%; between 1 and 4%; between 1 and 3%; between 1 and 2%; and between 2 and 4%.
The fibrinogen component in the haemostatic material may be any suitable fibrinogen known and available to those skilled in the art. The fibrinogen component may also be a functional derivative or metabolite of a fibrinogen, such the fibrinogen α, β and/or γ chains, soluble fibrin I or fibrin II, and further including human fibrinogen, human fibrin I, human fibrin II, human fibrinogen α chain, human fibrinogen β chain, human fibrinogen γ chain, fibrin protofibrils, fibrin fibrils, fibrin fibers, and mixtures of two or more thereof. A specific fibrinogen (or functional derivative or metabolite) for a particular application may be selected empirically by one skilled in the art. As used herein, the term “fibrinogen” is intended to include mixtures of fibrinogen and small amounts of Factor XIII/Factor XIIIa, or some other such transaminase. Such small amounts are generally recognized by those skilled in the art as usually being found in mammalian fibrinogen after it has been purified according to the methods and techniques presently known and available in the art, and typically range from 0.1 to 20 Units/mL. However mixtures with little or no Factor XIII may be suitable to treat wounds that contain or exute sufficient amounts of a suitable transaminase. Conversely, Factor XIII or another suitable transaminase may be added to a source of fibrinogen that has been manufactured so as to be substantially free of Factor XIII or other transaminases, such as a recombinant or transgenically produced fibrinogen, or a plasma-derived fibrinogen in which the endogenous Factor XIII has been removed or purified away or inactivated.
Preferably, the fibrinogen employed as the fibrinogen component is a purified fibrinogen suitable for introduction into a mammal. Typically, such fibrinogen is a part of a mixture of human plasma proteins which include Factor XIII/XIIIa and have been purified to an appropriate level and virally inactivated. A preferred aqueous solution of fibrinogen for preparation of a solid dressing contains around 37.5 mg/mL fibrinogen at a pH of around 7.4±0.1. Suitable fibrinogen for use as the fibrinogen component has been described in the art, e.g. U.S. Pat. No. 5,716,645, and similar materials are commercially available, e.g. from sources such as Sigma-Aldrich, Enzyme Research Laboratories, Haematologic Technologies and Aniara.
The fibrinogen component should be present in the inventive haemostatic materials in an amount effective to react with the fibrinogen activator and form sufficient fibrin to reduce the flow of fluid from wounded internal tissue. According to certain preferred embodiments of the present invention, when the haemostatic material is frozen, the fibrinogen component is present in an amount of from 4.70 mg to 18.75 mg (±0.009 mg) per square centimeter of the surface(s) of the haemostatic material intended to contact the wounded internal tissue.
According to other preferred embodiments, when the haemostatic material is a solid, regardless of form, the fibrinogen component is present in an amount of from 5.00 mg to 450.00 mg (±0.009 mg) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated. Greater or lesser amounts, however, may be employed depending upon the particular application intended for the solid dressing.
For example, when the haemostatic material is in the shape of a rod or cylinder, the fibrinogen component is more preferably present in an amount of from 3.00 mg to 75.00 mg (±0.009 mg) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated. Alternatively, when the haemostatic material is in the shape of a flat sheet or disk, the fibrinogen component is more preferably present in an amount of from 5.00 to 56.00 mg (±0.009 mg) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated.
The fibrinogen activator employed in the haemostatic materials of the present invention may be any of the substances or mixtures of substances known by those skilled in the art to convert fibrinogen (or a fibrinogen equivalent) into fibrin. Illustrative examples of suitable fibrinogen activators include, but are not limited to, the following: thrombins, such as human thrombin or bovine thrombin, and prothrombins, such as human prothrombin or prothrombin complex concentrate (a mixture of Factors II, VII, IX and X); snake venoms, such as batroxobin, reptilase (a mixture of batroxobin and Factor XIIIa), bothrombin, calobin, fibrozyme, and enzymes isolated from the venom of Bothrops jararacussu; and mixtures of any two or more of these. See, e.g., Dascombe et al., Thromb. Haemost. 78:947-51 (1997); Hahn et al., J. Biochem. (Tokyo) 119:835-43 (1996); Fortova et al., J. Chromatogr. S. Biomed. Appl. 694:49-53 (1997); and Andriao-Escarso et al., Toxicon. 35: 1043-52 (1997).
Preferably, the fibrinogen activator is a thrombin. More preferably, the fibrinogen activator is a mammalian thrombin, although bird and/or fish thrombin may also be employed in appropriate circumstances. While any suitable mammalian thrombin may be used, the thrombin employed is preferably a frozen or lyophilized mixture of human plasma proteins which has been sufficiently purified and virally inactivated for the intended use of the solid dressing. Suitable thrombin is available commercially from sources such as Sigma-Aldrich, Enzyme Research Laboratories, Haematologic Technologies and Biomol International. A particularly preferred aqueous solution of thrombin for preparing the inventive haemostatic materials contains thrombin at a potency of between 10 and 2000±50 International Units/mL, and more preferred at a potency of 25±2.5 International Units/mL. Other constituents may include albumin (generally about 0.1 mg/mL) and glycine (generally about 100 mM±0.1 mM). The pH of this particularly preferred aqueous solution of thrombin is generally in the range of 6.5-7.8, and preferably 7.4±0.1, although a pH in the range of 5.5-8.5 may be acceptable.
In addition to the inventive haemostatic material(s), the solid and frozen dressings of the present invention may optionally further comprise one or more support materials. As used herein, a “support material” refers to a material that sustains or improves the structural integrity of the solid or frozen dressing and/or the fibrin clot formed when such a dressing is applied to wounded tissue. The support material may be an internal support material or a surface support material. Moreover, in the case of the latter, if the dressing is in a form that has a wound facing side, the support material may be on the wound facing side or it may be on the non-wound facing side or both, impeded within the dressing, or any two or three of these options.
Any suitable resorbable material known and available to those skilled in the art may be employed in the present invention. For example, the resorbable material may be a proteinaceous substance, such as silk, fibrin, keratin, collagen and/or gelatin. Alternatively, the resorbable material may be a carbohydrate substance, such as alginates, chitin, cellulose, proteoglycans (e.g. poly-N-acetyl glucosamine), glycolic acid polymers, lactic acid polymers, or glycolic acid/lactic acid co-polymers. The resorbable material may also comprise a mixture of proteinaceous substances or a mixture of carbohydrate substances or a mixture of both proteinaceous substances and carbohydrate substances. Specific resorbable material(s) may be selected empirically by those skilled in the art depending upon the intended use of the solid dressing.
According to certain preferred embodiments of the present invention, the resorbable material is a carbohydrate substance. Illustrative examples of particularly preferred resorbable materials include, but are not limited to, the materials sold under the trade names Vicryl™ (a glycolic acid/lactic acid copolymer) and Dexon™ (a glycolic acid polymer). These suitable resorbable materials may be advantageously mixed into an aqueous solution and dried and lyophilized as internal support structures or as a backing support structure.
Any suitable non-resorbable material known and available to those skilled in the art may be employed as the support material. Illustrative examples of suitable non-resorbable materials include, but are not limited to, plastics, silicone polymers, paper and paper products, latex, gauze plastics, non-resorbable suture materials, latexes and suitable derivatives thereof.
According to other preferred embodiments, the support material comprises an internal support material. Such an internal support material is preferably fully contained within the haemostatic material(s) of a solid or frozen dressing. The internal support material may take any form suitable for the intended application of the haemostatic material. For example, according to certain embodiments, the internal support material may be particles or strands of a predetermined suitable size or size range, which are dispersed throughout the haemostatic material. Alternatively, a sheet or film or internal support material may be included in the solid or frozen haemostatic material.
According to still other preferred embodiments, the support material may comprise a backing material on the surface(s) of the dressing opposite the wound-facing surface. As with the internal support material, the backing material may be a resorbable material or a non-resorbable material, or a mixture thereof, such as a mixture of two or more resorbable materials or a mixture of two or more non-resorbable materials or a mixture of resorbable material(s) and non-resorbable material(s).
According to still other preferred embodiments, the dressing comprises both a backing material and an internal support material in addition to the haemostatic material(s). According to still other preferred embodiments, the dressing comprises both a front support material and an internal support material in addition to the haemostatic layer(s). According to still other preferred embodiments, the dressing comprises a backing material, a front support material and an internal support material in addition to the haemostatic layer(s).
According to certain preferred embodiments, the haemostatic material(s) may also contain a binding agent to maintain the physical integrity of the haemostatic material(s). Illustrative examples of suitable binding agents include, but are not limited to, sucrose, mannitol, sorbitol, gelatin, hyaluron and its derivatives, such as hyaluronic acid, maltose, povidone, starch, chitosan and its derivatives, and cellulose derivatives, such as carboxymethylcellulose, as well as mixtures of two or more thereof.
According to certain embodiments of the present invention, particularly where the solid or frozen dressing is manufactured using a mold, the dressings may also optionally further comprise a release layer in addition to the haemostatic material(s) and support layer(s). As used herein, a “release layer” refers to a layer containing one or more agents (“release agents”) which promote or facilitate removal of the solid or frozen dressing from a mold in which it has been manufactured. A preferred such agent is sucrose, but other suitable release agents include gelatin, hyaluron and its derivatives, including hyaluronic acid, mannitol, sorbitol and glucose. Alternatively, such one or more release agents may be contained in the haemostatic material.
The haemostatic material and any layer(s) may be affixed to one another by any suitable means known and available to those skilled in the art. For example, a physiologically-acceptable adhesive may be applied to a backing material (when present), and the haemostatic material subsequently affixed thereto.
In certain embodiments of the present invention, the physiologically-acceptable adhesive has a shear strength and/or structure such that the backing material can be separated from the fibrin clot formed by the haemostatic layer after application of the dressing to wounded tissue. In other embodiments, the physiologically-acceptable adhesive has a shear strength and/or structure such that the backing material cannot be separated from the fibrin clot after application of the bandage to wounded tissue.
Suitable fibrinogen components and suitable fibrinogen activators for the haemostatic materials may be obtained from any appropriate source known and available to those skilled in the art, including, but not limited to, the following: from commercial vendors, such as Sigma-Aldrich and Enzyme Research Laboratories; by extraction and purification from human or mammalian plasma by any of the methods known and available to those skilled in the art; from supernatants or pastes derived from plasma or recombinant tissue culture, viruses, yeast, bacteria, or the like that contain a gene that expresses a human or mammalian plasma protein which has been introduced according to standard recombinant DNA techniques; and/or from the fluids (e.g. blood, milk, lymph, urine or the like) of transgenic mammals (e.g. goats, sheep, cows) that contain a gene which has been introduced according to standard transgenic techniques and that expresses the desired fibrinogen and/or desired fibrinogen activator.
According to certain preferred embodiments of the present invention, the fibrinogen component is a mammalian fibrinogen such as bovine fibrinogen, porcine fibrinogen, ovine fibrinogen, equine fibrinogen, caprine fibrinogen, feline fibrinogen, canine fibrinogen, murine fibrinogen or human fibrinogen. According to other embodiments, the fibrinogen component is bird fibrinogen or fish fibrinogen. According to any of these embodiments, the fibrinogen component may be recombinantly produced fibrinogen or transgenic fibrinogen.
According to certain preferred embodiments of the present invention, the fibrinogen activator is a mammalian thrombin, such as bovine thrombin, porcine thrombin, ovine thrombin, equine thrombin, caprine thrombin, feline thrombin, canine thrombin, murine thrombin and human thrombin. According to other embodiments, the thrombin is bird thrombin or fish thrombin. According to any of these embodiments, the thrombin may be recombinantly produced thrombin or transgenic thrombin.
As a general proposition, the purity of the fibrinogen component and/or the fibrinogen activator for use in the solid dressing will be a purity known to one of ordinary skill in the relevant art to lead to the optimal efficacy and stability of the protein(s). Preferably, the fibrinogen component and/or the fibrinogen activator has been subjected to multiple purification steps, such as precipitation, concentration, diafiltration and affinity chromatography (preferably immunoaffinity chromatography), to remove substances which cause fragmentation, activation and/or degradation of the fibrinogen component and/or the fibrinogen activator during manufacture, storage and/or use of the solid dressing. Illustrative examples of such substances that are preferably removed by purification include: protein contaminants, non-protein contaminants, such as lipids; and mixtures of protein and non-protein contaminants, such as lipoproteins. The fibrinogen component and/or fibrinogen activator and/or the inventive haemostatic materials may also be subjected to suitable sterilization treatments, including, but not limited to, treatment with one or more of the following: heat, gamma radiation, e-beam radiation, plasma radiation and ethylene oxide.
The amount of the fibrinogen activator employed in the solid dressing is preferably selected to optimize both the efficacy and stability thereof. As such, a suitable concentration for a particular application of the solid dressing may be determined empirically by one skilled in the relevant art.
According to certain preferred embodiments of the present invention, when the fibrinogen activator is human thrombin, the amount of human thrombin employed is between 0.03 and 16.10 Units (all values being ±0.009) per square centimeter of the surface(s) of the haemostatic material intended to contact the wounded internal tissue. Greater or lesser amounts, however, may be employed depending upon the particular application intended for the solid dressing.
For example, when the haemostatic material is a solid in the shape of a rod or cylinder, the fibrinogen activator is more preferably present in an amount of from 0.01 Units to 7.50 Units (±0.009 Units) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated and most preferable between 0.1 and 1.0 (+/−0.09 Units). Alternatively, when the haemostatic material is a solid in the shape of a flat sheet or disk, the fibrinogen activator is more preferably present in an amount of from 0.03 Units to 16.10 Units (±0.009 Units) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated. Still alternatively, when the haemostatic material is a powdered solid, either loose or compressed, the fibrinogen activator is more preferably present in an amount of about 1.3 Units (±0.09 mg) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated. Still alternatively, when the haemostatic material is frozen, the fibrinogen activator is more preferably present in an amount of about 1.3 Units (±0.09 mg) per square centimeter of the surface(s) intended to contact the wounded internal tissue being treated.
According to still other preferred embodiments of the present invention, when the fibrinogen activator is human thrombin, the amount of human thrombin employed is between 0.0087 and 1.0000 Units (all values being ±0.00009) per milligram of the fibrinogen component. Greater or lesser amounts, however, may be employed depending upon the particular application intended for the solid dressing.
For example, when the haemostatic material is a solid in the shape of a rod or cylinder, the fibrinogen activator is more preferably present in an amount of about 0.1 Units (±0.09 Units) per milligram of the fibrinogen component. Alternatively, when the haemostatic material is a solid in the shape of a thin disk, the fibrinogen activator is more preferably present in an amount of from 0.1 Units to 1.00 Units (±0.009 Units) per milligram of the fibrinogen component. Still alternatively, when the haemostatic material is frozen, the fibrinogen activator is more preferably present in an amount of about 0.07 Units to 0.10 Units (±0.009 Units) per milligram of the fibrinogen component.
During use of the inventive haemostatic materials, the fibrinogen component and the fibrinogen activator are preferably activated at the time the dressing is applied to the wounded tissue by the endogenous fluids of the patient escaping from the hemorrhaging wound. Alternatively, in situations where fluid loss from the wounded tissue is insufficient to provide adequate hydration of the protein mass, the fibrinogen component and/or the fibrinogen activator may be activated by a suitable, physiologically-acceptable liquid, optionally containing any necessary co-factors and/or enzymes, prior to or during application of the dressing to the wounded tissue.
In some embodiments of the present invention, the inventive haemostatic materials may also contain one or more supplements, such as growth factors, drugs, polyclonal and monoclonal antibodies and other compounds. Illustrative examples of such supplements include, but are not limited to, the following: fibrinolysis inhibitors, such as aprotinin, tranexamic acid and epsilon-amino-caproic acid; antibiotics, such as tetracycline and ciprofloxacin, amoxicillin, and metronidazole; anticoagulants, such as activated protein C, heparin, prostacyclins, prostaglandins (particularly (PGI2), leukotrienes, antithrombin III, ADPase, and plasminogen activator; steroids, such as dexamethasone, inhibitors of prostacyclin, prostaglandins, leukotrienes and/or kinins to inhibit inflammation; cardiovascular drugs, such as calcium channel blockers, vasodilators and vasoconstrictors, such as epinephrine; chemoattractants; local anesthetics such as bupivacaine; and antiproliferative/antitumor drugs such as 5-fluorouracil (5-FU), taxol and/or taxotere; antivirals, such as gangcyclovir, zidovudine, amantidine, vidarabine, ribaravin, trifluridine, acyclovir, dideoxyuridine and antibodies to viral components or gene products; cytokines, such as alpha- or beta- or gamma-Interferon, alpha- or beta-tumor necrosis factor, and interleukins; colony stimulating factors; erythropoietin; antifungals, such as diflucan, ketaconizole and nystatin; antiparasitic gents, such as pentamidine; anti-inflammatory agents, such as alpha-1-anti-trypsin and alpha-1-antichymotrypsin; anesthetics, such as bupivacaine; analgesics; antiseptics; hormones; vitamins and other nutritional supplements; glycoproteins; fibronectin; peptides and proteins; carbohydrates (both simple and/or complex); proteoglycans; antiangiogenins; antigens; lipids or liposomes; oligonucleotides (sense and/or antisense DNA and/or RNA); and gene therapy reagents. In other embodiments of the present invention, the backing layer and/or the internal support layer, if present, may contain one or more supplements. According to certain preferred embodiments of the present invention, the therapeutic supplement is present in an amount greater than its solubility limit in fibrin.
The inventive haemostatic materials, and the solid and frozen dressings containing them, may be applied to any internal wounded tissue in a mammal using any of the suitable techniques and/or devices known and available to one skilled in the medical arts. For example, when used to treat vascular punctures, the haemostatic material(s) may be applied via a catheter, either with or without a guide wire. The inventive materials and dressings may also be applied in conjunction with endoscopic techniques, including endoscopic surgery, laparoscopic surgery and tele-robotic/tele-presence surgery. According to such embodiments, it is preferable to use a “plunger” or “tamper” to facilitate passage of the inventive materials through surrounding tissue to the wounded internal tissue being treated. The inventive materials and dressings may also be applied manually.
It is understood that there are advantages in providing for an applicator that is capable of securing to a haemostatic material, and in-particular, to a rod shaped haemostatic material in surgical and trauma settings. For example, certain surgical processes including: soft tissue sealing, parynchymal organ sealing, vascular access blood vessel puncture site sealing, hernia repair, epistaxis, and adhesion prevention. An applicator has the ability to aid the medical professional in maneuvering the haemostatic material to the wound site and providing pressure to ensure haemostasis.
Accordingly, certain kittner probes and other similar devices are intended to be utilized with the inventive materials as described in the embodiments herein. The kittner or probe device has a shaft and at one end of the shaft, a mechanism for securing a haemostatic material to said shaft. For example, a thread, staple, hook and loop, quills, clamps, pins, may be attached to one end of the shaft. These devices may then be secured to the haemostatic material.
In the case where the haemostatic material is rod shaped, one end of the rod is secured to one end of the applicator shaft. It may be advantageous to have a resorbable or non-resorbable material on the end of the rod that is in contact with the end of the shaft, thus aiding in securing the haemostatic material to the shaft and in its removal. For example, a non-resorbable material may be secured to the rod with a release layer between the rod and the non-resorbable material. The non-resorbable material may have a tab, or other feature that can be easily secured to a thread, staple, hook and loop, quill, clamp, pin, etc. Then, the rod material may be guided into place in the injured tissue, appropriate pressure applied and the shaft removed to leave the rod shaped haemostatic material in place.
In some embodiments, the rod or shaft is hollow and within the hollow shaft is are situated one or more release mechanisms. For example, where a thread is secured to the haemostatic material, that thread may pass through the haemostatic material, and into the hollow shaft, and once the haemostatic material is applied to an internal wounded surface, the thread may be pulled or removed, thus allowing the applicator to be removed but the haemostatic material to stay in place. Removal of the thread, however, would not limit the ability of a medical professional to continue applying pressure to the haemostatic material.
Similarly, the hollow shaft allows for means to secure and also detach the haemostatic material to the end of the applicator. This allows for movement of tweezers, scissors, clamps, latches, and removal of sutures, staples and other securing mechanisms.
For example, in view of
Where the wound is a deep wound and of three dimensions, the haemostatic material can be inserted into said wound to fill the wound opening. Accordingly, in view of
In view of
In view of
In view of
In view of
The following examples are illustrative only and are not intended to limit the scope of the invention as defined by the appended claims. It will be apparent to those skilled in the art that various modifications and variations can be made in the methods of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
The following is a list of acronyms used in the Examples below:
The ability of the dressings to seal an injured blood vessel was determined by modifications of an ex vivo porcine arteriotomy (EVPA) performance test, which was first described in U.S. Pat. No. 6,762,336. The EVPA performance test evaluates the ability of a dressing to stop fluid flow through a hole in a porcine artery. While the procedure described in U.S. Pat. No. 6,762,336 has been shown to be useful for evaluating haemostatic dressings, it failed to replicate faithfully the requirements for success in vivo. More specifically, the procedure disclosed in U.S. Pat. No. 6,762,336 required testing at 37° C., whereas, in the real world, wounds are typically cooler than that. This decreased temperature can significantly reduce the rate of fibrin formation and its haemostatic efficacy in trauma victims. See, e.g., Acheson et al., J. Trauma 59:865-874 (2005). The test in U.S. Pat. No. 6,762,336 also failed to require a high degree of adherence of the dressing to the injured tissue. A failure mode in which fibrin forms but the dressing fails to attach tightly to the tissue would, therefore, not be detected by this test. Additionally, the pressure utilized in the procedure (200 mHg) may be exceeded during therapy for some trauma patients. The overall result of this is that numerous animal tests, typically involving small animals (such as rats and rabbits), must be conducted to accurately predict dressing performance in large animal, realistic trauma studies and in the clinical environment.
In order to minimize the amount of time and the number of animal studies required to develop the present invention, an improved ex vivo testing procedure was developed. To accomplish this, the basic conditions under which the dressing test was conducted were changed, and the severity of the test parameters was increased to include testing at lower temperatures (i.e. 29-33° C. vs. 37° C., representing the real physiologic challenge at realistic wound temperatures (Acheson et al., J. Trauma 59:865-874 (2005)), higher pressures (i.e. 250 mmHg vs. 200 mmHg), a longer test period (3 minutes vs. 2 minutes) and larger sized arterial injuries (U.S. Pat. No. 6,762,336 used an 18 gauge needle puncture, whereas the revised procedure used puncture holes ranging from 2.8 mm to 4 mm×6 mm).
In order to apply the haemostatic test articles to the surface of an injured artery surrounded by a tissue stimulant, the test articles were housed in cylindrical molds made of 10 or 3 mL polypropylene syringes (Becton Dickinson) with the luer-lock end removed. The plungers were withdrawn to the 6 mL and 2 mL mark respectively. For dressings utilizing a backing, the support material was cut and placed into each mold and pushed down until it was adjacent to the plunger. Once prepared the molds were placed upright and surrounded by dry ice, leaving the opening exposed at the top. 1 ml of fibrinogen and 0.15 mL of thrombin (with or without backing material dispersed within) were dispensed into the 10 mL molds and 1 ml of fibrinogen and 0.15 mL of thrombin (with or without support material dispersed within) were dispensed into the 3 mL molds, which were allowed to freeze for 5 minutes. The molds were then placed into the −80° C. freezer for at least two hours before being placed into a pre-cooled Genesis™ lyophylizer (Virtis, Gardiner, N.Y.). The chamber was sealed and the temperature equilibrated. The chamber was then evacuated and the dressings lyophilized via a primary and secondary drying cycle.
They were subsequently performance tested in a modified EVPA assay (Deep Tissue EVPA). Briefly, in one version, a plastic foam form was slipped over the artery. This covering had a hole in it that corresponded to the hole in the artery and the surrounding tissue (
Deep Tissue EVPA Testing
Equipment and Supplies:
1. Materials and Chemicals
2. Artery Cleaning and Storage
1. Store arteries at −20° C. until used.
2. Thaw arteries at 37° C. in H2O bath.
3. Clean fat and connective tissue from exterior surface of artery.
4. Cut the arteries into ˜5 cm segments.
5. The arteries may be refrozen to −20° C. and stored until use.
3. Artery Preparation for Assay
1. Turn the artery inside-out so that the smooth, interior wall is facing outwards.
2. Stretch a size 13 O-ring over a 20 cc syringe or a size 10 O-ring over a 10 cc syringe with an approximately 0.6 cm (0.25 in) hole drilled into one side.
3. Pull the artery onto the syringe, taking care not to tear the artery or have a too loose fit. The artery should fit snugly to the syringe. Slide another O-ring of the same size onto the bottom of the syringe
4. Carefully pull both O-rings over the ends of the artery. The distance between the O-rings should be at least 3.5 cm.
5. Using the blade of some surgical scissors, gently scrape the surface of the artery in order to roughen the surface of the artery.
6. Use a 18-gauge needle to poke a hole through the artery over the site of the hole in the syringe barrel (see note above)
7. The tip of the biopsy punch is inserted through the hole in the artery. Depress the punch's plunger to make an open hole in the artery. Repeat a couple of times to ensure that the hole is open and free of connective tissue.
8. Patch holes left by collateral arteries. Generally this is done by cutting a patch from a latex glove and gluing it over the hole with cyanoacrylate glue. Allow the glue to cure for at least 10 minutes.
4. Solution and Equipment Preparation
1. Check to see that the water bath, block heater and incubation chamber are maintained at 37° C.
2. Make sure that there is sufficient 0.9% saline in the pump's reservoir for completion of the day's assays. Add more if needed.
3. Place 0.9% saline and 0.9% saline with a few drops of red food coloring added into containers in a water bath so that the solutions will be warmed prior to performing the assay.
4. Prepare the container for warming the arteries in the incubation chamber by lining with KimWipes™ and adding a small amount of water to keep the arteries moist.
5. Check the tubing for air bubbles. If bubbles exist, turn on the pump and allow the 0.9% saline to flow until all bubbles are removed.
5. Application of the Dressing
1. Slip either the warmed (at 37° C.) plastic foam form or the warmed tissue over the artery. Align the hole in it to correspond to the hole in the artery and the surrounding tissue (
2. Open the haemostatic dressing (Test Article) pouch and remove haemostatic dressing & Applicator.
3. Slowly wet the haemostatic dressing drop wise with 0.9% saline warmed to 29-33° C. or other blood substitute, taking care to keep the saline from running off the edges. Any obvious differences in wetting characteristics from the positive control should be noted on the data collection forms.
NOTE: By way of example, a representative (13-15 mg/cm2 of fibrinogen) 2.4×2.4 cm haemostatic dressing should generally be wet with 800 μl of saline or other blood substitute. The amount of saline used can be adjusted depending on the requirements of the particular experiment being performed; however, any changes should be noted on the data collection forms.
4. Immediately pass the dressing in the applicator down thru the hole in the foam to the artery surface. Depress the plunger by hand and hold by hand for 3 minutes, after which the applicator is withdrawn as the plunger was depressed further.
5. After polymerization, note the condition of the haemostatic dressing. Any variation from the positive control should be noted on the data collection form.
Exclusion Criterion:
The mesh support material must remain over the hole in the artery. If it has shifted during the polymerization and does not completely cover the hole the haemostatic dressing must be excluded.
Testing Procedure
1. Diagram of Testing Equipment Set-Up
The set-up of the testing equipment is shown in
2. Equipment and Artery Assembly
Fill the artery and syringe with red 0.9% saline warmed to 37° C., taking care to minimize the amount of air bubbles within the syringe and artery. Filling the artery with the opening uppermost can assist with this. Attach the artery and syringe to the testing apparatus, making sure that there are as few air bubbles in the tubing as possible. The peristaltic pump should be calibrated so that it delivers approximately 3 ml/min. If available, the PLC should be operated according to a pre-determined range of pressures and hold times as appropriate for the article being tested. If under manual control, the pressure/time profile to be followed is attained by manually turning the pump on and off while referencing the system pressure as read out by one or more pressure-reading components of the system. Following the conclusion of testing, the haemostatic dressing is subjectively assessed with regard to adhesion to the artery and formation of a plug in the artery hole. Any variations from the positive control should be noted on the data collection form.
Success Criteria
Haemostatic dressings that are able to withstand pressures for 3 minutes are considered to have passed the assay. When a haemostatic dressing has successfully passed the assay the data collection should be stopped immediately so that the natural decrease in pressure that occurs in the artery once the test is ended isn't included on the graphs. Should the operator fail to stop data collection, these points can be deleted from the data file to avoid confusing the natural pressure decay that occurs post-test with an actual dressing failure. The entire testing period from application of the haemostatic dressing to completion must fall within pre-established criteria. The maximum pressure reached should be recorded on the data collection form.
Failure Criteria
Haemostatic dressings that start leaking saline at any point during testing are considered to have reached the end of the assay. NOTE: Build failures that are caused by artery swelling can be ignored and the test continued or re-started (as long as the total testing time doesn't fall beyond the established limit).
When leakage does occur, the pressure should be allowed to fall ˜20 mmHg before data collection is stopped so that the failure is easily observed on the graphs. The pressures at which leakage occurred should be recorded on the data collection form. Should the data collection stop in the middle of the experiment due to equipment failure the data can be collected by hand at 5 second intervals until the end of the test or haemostatic dressing failure, whichever happens first. The data points should be recorded on the back of the data collection form, clearly labeled, and entered by hand into the data tables.
Exclusion Criteria
If the total testing period exceeds the maximum allowed for that procedure, regardless of cause, results must be excluded. If there are leaks from collaterals that can't be fixed either by patching or finger pressure the results must be excluded. If the test fails because of leaks at the O-rings, the results must be excluded. If the mesh support material does not completely cover the hole in the artery, the results must be excluded.
Adherence Performance Testing
Equipment and Supplies
Hemostat(s), Porcine artery and haemostatic dressing, optionally after performance of EVPA assay.
Preparation of the Artery+Dressing
After application of the dressing without completion of the EVPA Assay, the dressing is ready for the Adherence Assay and Weight Limit Test (if applicable). After application of the dressing and subsequent EVPA Analysis, the artery and syringe system is then disconnected slowly from the pump so that solution does not spray everywhere. The warmed, red saline solution from the EVPA Assay remains in the syringe until the Adherence Assay and Weight Limit Test (if applicable) is completed.
Performance of the Adherence Assay
1. After preparation of the artery and dressing (with or without EVPA analysis), gently lift the corner of the mesh and attach a hemostat of known mass to the corner.
2. Gently let go of the hemostat, taking care not to allow the hemostat to drop or twist. Turn the syringe so that the hemostat is near the top and allow the hemostat to peel back the dressing as far as the dressing will permit. This usually occurs within 10 seconds. After the hemostat has stopped peeling back the dressing, rate the adherence of the bandage according to the following scale:
90+%
~50%
Exclusion Criteria
The mesh support material must remain over the hole in the artery. If it has shifted during the polymerization and does not completely cover the hole the haemostatic dressing must be excluded.
Success Criteria
Dressings that are given an adherence score of 3 are considered to have passed the assay.
Failure Criteria
If a dressing does not adhere to the artery after application and/or prior to performing the EVPA assay, it is given a score of 0 and fails the adherence test. If a dressing receives a score ≤2, the dressing is considered to have failed the Adherence Assay.
Weight Held Performance Assay
After the initial scoring of the “Adherence Test”, weights may then be added to the hemostat in an incremental manner until the mesh support material is pulled entirely off of the artery. The maximum weight that the dressing holds is then recorded as a measure of the amount of weight the dressing could hold attached to the artery.
Similar to the need to evaluate a test article in the context of sealing and injury deep within surrounding tissue, there was also a need to test products that can seal injured tissue where the injured vessels are smaller and thinner-walled than an aorta. The following assay accomplishes this goal.
According to this modification, the porcine carotid artery is attached to a barbed female connector using cotton thread with the connective tissue side exposed. This is in contrast to the standard EVPA where the internal side is exposed. As the carotid arteries used in the VA model are more elastic and friable than the aorta, it is more difficult to treat or abrade the surface without damaging and compromising the artery. To ensure that no tears have occurred during the removal of the bulk of the connective tissue, the artery is connected to the barbed connector and solution is pumped into it. If the artery is intact, a 1.5 mm hole is punched into the artery using a biopsy punch.
After the artery is prepped, it is connected to the pump system and placed on top of a piece of foam with a concave “hollow” cut into the surface. This serves as a support for the artery during application of the FD and “compression” of the artery. The test article is applied to the top of the hole and wet with 37° C. 0.9% NaCl. The artery is covered with plastic wrap, and a weight warmed to ˜38-40° C. is then placed on top of the artery. The artery is partially compressed instead of being pressed flat because of the support of the foam.
After the weight has been applied for 5 min., it is then removed, and the pump is turned on. When the solution is coming out of the end of the artery, it is then clamped and allowed to pressurize until 250 mmHg or a leak occurs, whichever comes first.
In development of the assay, the following variables were considered and tested:
Tissue Selection:
In order to mimic a vascular access procedure, a tissue substrate that was elastic yet strong was needed. Contact with rendering companies such as PelFreeze and Animal Technologies revealed 2 types of arteries collected that could be potentially used to mimic the vascular access procedure: porcine renal arteries and porcine carotid arteries. These arteries were comparable in size to a human femoral artery. Both types were purchased to examine their usefulness. The porcine renal artery was too short in useable length (less than 2″), to small an internal diameter, and not as elastic as desired. The porcine carotid artery, however, was highly elastic and offered useable segments of 3-5″ without branching or collateral arteries.
Artery Hole Size:
To determine a size to use for the assay, the actual surgical procedure was mimicked insofar as possible. A hole was put into the artery using an 18-gauge needle. A 200 uL pipette tip was then pushed into the hole to the point where the diameter was ˜3.5 mm, just larger than a 10 F catheter. The tip was left in place for 2 hrs. and was then removed. The resulting hole was larger than the initial 18-gauge needle punch and, when compared to 2.8, 2.0, and 1.5 mm holes, was very similar to the 1.5 mm hole produced by the biopsy punch.
Surface Preparation:
In the EVPA assay, the interior surface of a porcine aorta is gently abraded using the edge of a pair of scissors to provide a “damaged” surface to which the FD would adhere, mimicking large trauma. For the vascular access procedure, obtaining a uniform, reproducible surface on which to test the FD was important. Starting with the familiar, the carotid artery was turned inside-out and abraded. However, this did not work as the carotid artery is highly elastic, and the scraping of the surface created tears that rendered the artery unusable. Using the exterior surface, the arteries that had the connective tissue carefully removed down to the level of the artery provided a surface that was uniform and best mimicked the vascular access procedure.
Integration of the Artery into the Pump System:
To best mimic the vascular access procedure, the use of the artery without any internal support to interfere with compression was desired. In order to incorporate the artery into the pump system, it was necessary to attach the artery at one end to the tubing and still have an open end to allow solution flow prior to pressurization. After examining different types of tubing and connectors, a barbed low-pressure female connector was chosen. The barb could be either ⅛″ or ¼″, depending upon the inner diameter of the carotid artery. To attach the artery to the barbed end, cable ties, o-rings, and thread were tested. Only the thread prevented leakage during pressurization.
Arterial Support:
In trying to partially-compress the artery on a flat surface, it became clear that some form of support was needed to prevent the artery from shifting during application of the FD and to prevent total compression of the artery. A variety of materials were tested, including gel packs, Styrofoam packaging material, and foam pieces. Foam pieces that had a concave trough cut into the top surface offered the best support: the trough held the artery in place, and it was cut just deep enough to allow partial compression of the artery.
Compression Method:
In the actual surgical procedure, hemostasis is more commonly achieved by manual compression of the artery for a period of ˜20 min. During this time, arterial flow is maintained. Application of a weight to the artery was tested in order to mimic this at the lab bench. Various weights in beakers just large enough to contain the weight were tested on arteries in the foam arterial support. With this set-up, both 200 g and 500 g weight inside a glass beaker (to provide a uniform surface for compression) just large enough to accommodate the weight proved to be ideal for compression. Weights lower or higher provided insufficient or too much compression, respectively.
Temperature Maintenance:
FXIII, a component of the FD that is responsible for cross-linking of fibrin monomers, is thermally labile, and the assay needs maintained around normal body and wound temperatures of 34-36° C. As this set-up cannot be easily transferred to an incubator as in the EVPA, another method had to be devised. Various methods were considered such as warmed gel packs, heating pads, and warming lamps. While these methods would produce a warmer-than-ambient temperature, they were difficult to control to the level that this assay requires. The most practical method was the use of a heat block set to 37° C. While a heat block can maintain a constant temperature for very long periods of time, they were not sufficient to warm the artery and FD to 34-36° in the 5 minute time frame of the assay. As the weight that is applied could be a potential heat source, it was warmed in the incubator prior to application, and this addition to the 37° C. heat block was sufficient to maintain the 34-36° C. temperature range.
Data Collection:
For this assay, the following pieces of data are collected: amount of saline required to wet the dressing, ease of wetting, artery temperature after the incubation period, maximum pressure obtained, failure mode (channel leak, leak through plug), qualitative assessment of the adherence of the dressing to the artery, and overall comments on dressing appearance (mottled, pre-formed fibrin, thin, etc.)
Test Protocol for Ex Vivo Porcine Carotid Artery Assay (EVPCA)
Equipment and Supplies
Materials and Chemicals
Preliminary Procedures
Artery Cleaning and Storage 1. Store arteries at −20° C. until used.
2. Thaw arteries at 37° C. in H2O bath.
3. Clean fat and connective tissue from exterior surface of artery.
4. The arteries may be refrozen to −20° C. and stored until use.
Artery Preparation for Assay
1. Make sure that all connective tissue is removed from the artery.
2. If any collateral arteries or other large holes are visible, cut the artery at the hole. If a small section of artery is produced from the cut, discard it. If 2 pieces are produced that are at least 1½″ long, both pieces may be used for assays.
3. Insert the barbed end of a low pressure connector, either ⅛″ or ¼″ depending upon the internal diameter of the artery, into the larger end of the artery.
4. Cut a piece of quilting or other heavy thread ˜6″ long. Using a square knot, tie the artery to the connector so that it does not come off of the connector.
Note: As it is possible to tear the artery during the cleaning process, it is important to “leak test” the artery prior to performing the assay.
5. Connect the artery to the male connector at the end of the tubing attached to the pump system.
6. Turn on the pump with the open end of the artery pointed upwards and allow the artery to fill with the red 0.9% NaCl. When the artery is full, clamp the artery closed using a hemostat.
7. Watch the artery as it pressurizes to see if any holes or tears are present. If a hole is present, turn off the pump, unclamp the artery over a beaker to catch the saline solution, and disconnect it from the pump system.
For Arteries with Holes
For Arteries without Holes
Note:
After the artery has been inspected and any unwanted holes addressed, the test hole may then be punched in the artery
8. Insert a plastic strip into the open end of the artery so that it goes most of the way into the artery.
9. Using the biopsy punch, carefully punch a hole in the artery. Make sure that the punch connects with the plastic strip so that no additional holes are punched in the artery.
10. The punch should totally remove the center portion. If it does not, gently remove it with forceps or by re-cutting it using the biopsy punch.
11. Place the artery in the warmed, moistened container and place in the ˜40° C. incubation chamber to keep the artery moist prior to assay
Solution and Equipment Preparation
1. Turn on the heat block and check to see that it is maintained at 37° C.
2. Check to see that the water bath is maintained at 37° C. and incubation chamber is maintained at ˜40° C.
3. Make sure that there is sufficient 0.9% saline in the pump's reservoir for completion of the day's assays. Add more if needed.
4. Place 0.9% saline into containers in a 37° C. water bath so that the solutions will be warmed prior to performing the assay.
5. The peristaltic pump should be calibrated so that it delivers approximately 3 ml/min. If not, adjust the settings at this point.
6. Check the tubing for air bubbles. If bubbles exist, turn on the pump and allow the 0.9% saline to flow until all bubbles are removed.
Application of the FD or HD
1. Place a piece of foam with the concave surface on top of the heating block and cover with a piece of plastic wrap.
2. Remove an artery from the warming box and attach it to the pump system.
3. Allow the artery to rest in the concave hollow of the foam piece.
4. Open the haemostatic dressing pouch and remove haemostatic dressing(s). Place any extras in the vacuum desiccator.
5. Place the dressing, mesh support material side UP (or the side closest to the bottom of the mold if no support material is present), over the hole in the artery
6. Slowly wet the haemostatic dressing with an amount of saline appropriate for the article being tested
Note:
A standard (13-15 mg/cm2 of fibrinogen) 2.4×2.4 cm haemostatic dressing should be wet with 800 μl of saline or other blood substitute. A dressing of 1.5×1.5 cm would require 300 μl of saline or other blood substitute, and a 0.7×0.7 cm dressing would require 70 μl of saline or other blood substitute. The amount of saline used can be adjusted depending on the requirements of the particular experiment being performed; however, any changes should be noted on the data collection forms.
Note:
Wet the haemostatic dressing drop wise with 0.9% saline warmed to 37° C. or other blood substitute, taking care to keep the saline from running off the edges. Any obvious differences in wetting characteristics from the positive control should be noted on data collection forms.
7. Cover the artery with plastic wrap, taking care that the dressing doesn't slide around on the surface of the artery.
8. Place a warmed weight carefully on top of the dressing so that it does not shift off of the hole in the artery.
9. Allow the weight to remain on the artery on top of the 37° C. heat block for the duration of the polymerization time.
Note:
Time, pressure, and hole size can be altered according to the requirements of the experiment; changes from the standard conditions should be noted on the data collection forms.
10. After polymerization, carefully unwrap the artery and note the condition of the haemostatic dressing. Any variation from the positive control should be noted on the data collection form.
Exclusion Criterion:
The mesh support material must remain over the hole in the artery. If it has shifted during the polymerization and does not completely cover the hole the haemostatic dressing must be excluded.
Testing Procedure
A diagram of testing equipment set-up is shown in
Equipment and Artery Assembly
1. After the polymerization period is complete, carefully remove the plastic wrap so that the dressing is not disturbed.
2. Turn on the pump and gently lift the open end of the artery with a hemostat. Allow the artery to fill to the top with 0.9% NaCl. This is done to minimize air bubbles in the system.
3. The system should be operated according to a pre-determined range of pressures and hold times as appropriate for the article being tested. Should the pressure drop below the desired maximum during the hold period, the pump should be turned on again until the maximum pressure is achieved.
4. Should a leak in the system develop other than failure of the FD or HD (i.e. leaking from a hole in the artery, etc.), attempts to correct the problem should be taken. This might involve clamping the leak for the remainder of the assay. Should the attempts to fix the problem be ineffective, the test article will be excluded from analysis and called a “system failure” (See Exclusion Criteria below).
5. Following the conclusion of testing, the haemostatic dressing is subjectively assessed with regard to adhesion to the artery and formation of a plug in the artery hole. Any variations from the positive control should be noted on the data collection form.
Success/Fail and Exclusion Criteria
Success Criteria
1. Haemostatic dressings that are able to withstand various pressures for 3 minutes are considered to have passed the assay.
2. When a haemostatic dressing has successfully passed the assay the data collection should be stopped immediately so that the natural decrease in pressure that occurs in the artery once the test is ended isn't included on the graphs. Should the operator fail to stop data collection, these points can be deleted from the data file to avoid confusing the natural pressure decay that occurs post-test with an actual dressing failure.
3. The entire testing period from application of the haemostatic dressing to completion must fall within pre-established criteria.
Note:
For a single-step increase to maximum pressure the entire testing period should not exceed 15 minutes. Other time limits may be established for other test procedures, and should be noted on the data collection forms.
4. The maximum pressure reached should be recorded on the data collection form.
Note:
Typical challenge is 250 mmHg for three minutes in one step, but that may be altered based on the article being tested. The pressure, for example, may be increased in “steps” with holds at various pressures until the 250 mmHg is achieved. One example is increasing the pressure in 50 mmHg increments with a 1 minute hold at each step to ensure that the FD or HD can hold these pressures.
Failure Criteria
1. Haemostatic dressings that start leaking saline at the point of FD or HD attachment at any point during testing are considered to have failed the assay.
NOTE: Build failures that are caused by artery swelling can be ignored and the test continued or re-started (as long as the total testing time doesn't fall beyond the established limit)
2. When leakage from the FD or HD does occur, the pressure should be allowed to fall ˜20 mmHg before data collection is stopped so that the failure is easily observed on the graphs.
3. The pressures at which leakage occurred should be recorded on the data collection form.
4. Should the data collection stop in the middle of the experiment due to equipment failure the data can be collected by hand at 5 second intervals until the end of the test or haemostatic dressing failure, whichever happens first. The data points should be recorded on the back of the data collection form, clearly labeled, and entered by hand into the data tables.
Exclusion Criteria
1. If the total testing period exceeds the maximum allowed for that procedure, regardless of cause, results must be excluded.
2. If there are leaks from holes that can't be fixed by clamping or finger pressure the results must be excluded.
3. If the mesh support material does not completely cover the hole in the artery, the results must be excluded
For all dressings, ERL fibrinogen lot 3130 was formulated in CFB. The final pH of the fibrinogen was 7.4±0.1. The fibrinogen concentration was adjusted to 37.5 mg/ml. Once prepared the fibrinogen was placed on ice until use. Thrombin was formulated in CTB. The final pH of the thrombin was 7.4±0.1. The thrombin was adjusted to deliver 0.1 units/mg of Fibrinogen or 25 Units/ml thrombin. For the group with shredded support material dispersed within, it was cut into approximately 1 mm×1 mm pieces and dispersed within the thrombin solution prior to filling the molds. Once prepared the thrombin was placed on ice until use. The temperature of the fibrinogen and thrombin prior to dispensing was 4° C.±2° C. Cylindrical molds made of 10 or 3 mL polypropylene syringes (Becton Dickinson) with the luer-lock end removed were used. The plungers were withdrawn to the 6 mL and 2 mL mark respectively. For dressings utilizing a support material, the support material was cut and placed into each mold and pushed down until it was adjacent to the plunger. Once prepared the molds were placed upright and surrounded by dry ice, leaving the opening exposed at the top. 1 ml of fibrinogen and 0.15 mL of thrombin (with or without support material dispersed within) were dispensed into the 10 mL molds and 1 ml of fibrinogen and 0.15 mL of thrombin (with or without support material dispersed within) were dispensed into the 3 mL molds, which were allowed to freeze for 5 minutes. The molds were then placed into the −80° C. freezer for at least two hours before being placed into the freeze dryer and lyophilized as described above. The compositions are shown in Table 3.1 below.
Upon removal from the lyophylizer, both groups were performance tested in a modified EVPA assay as described in Example 1 above. Briefly, a plastic foam form was slipped over the artery. This covering had a hole in it that corresponded to the hole in the artery and the surrounding tissue. Warm saline was added to the surface of the dressing and the mold was immediately passed down thru the hole in the foam to the artery surface. The plunger was then depressed and held by hand for 3 minutes, after which the mold was withdrawn as the plunger was depressed further. At this point the artery was pressurized and the assay continued as described in Example 1 above.
Results
150 mm Hg
Conclusions:
Dressings that included no support material or a DEXON™ mesh support material performed well, with all passing the EVPA test at 250 mmHg. When the support material was dispersed throughout the composition, the dressings also performed well, with the large size (10 mL mold) dressings holding the full 250 mmHg of pressure, while the smaller held up to 150 mmHg of pressure. This indicates that the use of a support material may be optional, and it's location may be on the ‘back’ of the dressing, or dispersed throughout the composition, as desired.
The results demonstrate that the dressings were effective at the highest pressure tested regardless of size, and that they functioned effectively regardless of the presence or absence of the support material. Higher performance was associated with the presence of support material, and a larger applicator.
Dexon™ Mesh support material was cut to fit into and placed into each PETG 1.5×1.5 cm mold. Fifteen microliters of 2% sucrose was pipetted on top of each of the four corners of the support material and the molds were placed inside a −80° C. freezer. PETG 1.5×1.5 cm molds that did not contain support material were also placed inside the −80° C. freezer. In a third group, the same amount of support material was cut into small pieces (approximately less than 2 mm×2 mm) and placed into PETG 1.5×1.5 cm molds (these dressings are referred to as having their support material ‘dispersed’). Once completed the molds were placed in a −80° C. freezer. All molds remained in the −80° C. freezer for at least 60 minutes. Enzyme Research Laboratories (ERL) Fibrinogen lot 3130 was formulated in 100 mM Sodium Chloride, 1.1 mM Calcium Chloride, 10 mM Tris, 10 mM Sodium Citrate, and 1.5% Sucrose (Fibrinogen complete buffer). In addition, Human Serum Albumin was added to 80 mg/g of total protein and Tween 80 (non-animal source) was added to 15 mg/g total protein. The final pH of the fibrinogen was 7.4+/−0.1. The fibrinogen concentration was adjusted to 36.56 mg/ml and 14.06 mg/ml. Once prepared the fibrinogen was placed on ice until use. Thrombin was formulated in 50 mM Sodium Chloride, 40 mM Calcium Chloride, 10 mM Tris and 100 mM L-Lysine. The final pH of the thrombin was 7.4+/−0.1. The thrombin was adjusted to deliver 0.01, 0.1 or 1 units/mg of Fibrinogen or 2.5, 25 or 250 Units/ml thrombin. Once prepared the thrombin was placed on ice until use. The temperature of the fibrinogen and thrombin prior to dispensing was 4° C.+/−2° C. Molds were removed from the −80° C. freezer and placed on a copper plate that was placed on top of dry ice. A repeat pipettor was filled with fibrinogen and second repeat pipettor was filled with thrombin. Simultaneously 0.8 ml of fibrinogen and 133 micro liters of thrombin were dispensed into each mold. Once the molds were filled, they were returned to the −80° C. freezer for at least two hours before being placed into the freeze dryer. The final fibrinogen dose the groups was between 5 mg/cm2 to 13 mg/cm2. Table 4.1 shows the experimental design.
The performance of the test articles was determined using the EVPCA assay as described in Example 2 above.
Results:
Enzyme Research Laboratories (ERL) Fibrinogen lot 3170P was formulated in 100 mM Sodium Chloride, 1.1 mM Calcium Chloride, 10 mM Tris, 10 mM Sodium Citrate, and 1.5% Sucrose (Fibrinogen complete buffer). In addition, Human Serum Albumin was added to 80 mg/g of total protein and Tween 80 (non-animal source) was added to 15 mg/g total protein. The final pH of the fibrinogen was 7.4+/−0.1. The fibrinogen concentration was adjusted to 37.5 mg/ml. Once prepared the fibrinogen was placed on ice until use. Thrombin was formulated in 150 mM Sodium Chloride. 40 mM Calcium Chloride, 10 mM Tris and 100 mM L-Lysine. The final pH of the thrombin was 7.4+/−0.1. The thrombin was adjusted to deliver 0.1 units/mg of Fibrinogen or 25 Units/ml thrombin. Once prepared the thrombin was placed on ice until use. The temperature of the fibrinogen and thrombin prior to dispensing was 4° C.+/−2° C.
Cylindrical molds made of 3 mL polypropylene syringes (Becton Dickinson) with the luer-lock end removed were used. The plungers were withdrawn to the 1.0 ml mark.
Cylindrical molds were placed on dry ice. There were two groups of cylindrical molds prepared with one cylindrical mold per group. One group did not have any support material, and the second group contained shredded support material (0.1 gm Dexon™ mesh) dispersed within it. A repeat pipettor was filled with fibrinogen and second repeat pipettor was filled with thrombin. Simultaneously 0.5 ml of fibrinogen and 75 micro liters of thrombin were dispensed into each cylindrical mold. Once each cylindrical mold was filled, they were transferred to a −80° C. freezer until tested. Table 5.1 shows the experimental design.
The performance of the test articles was determined using a modified EVPCA assay. The EVPCA assay was modified to further enhance the faithfulness of the assay to the actual conditions that may be encountered in vivo. By surrounding the test blood vessel by closely fitting material, we can replicate the use of these inventions in sealing an injury deep inside tissue. To further enhance this replication of such a clinical setting, tissue was substituted for the plastic foam that was wrapped around the vessel. The tissue may be chosen to best replicate the intended anatomical location. In this Example commercial meat was used to simulate the leg muscle of a patient undergoing a vascular access procedure. Sufficient tissue was used to simulate a depth of several inches of muscle tissue. Other than this modification, and the employment of an application device as described was carried out as described in Example #2. The results are shown in table 5.2
Results:
ERL fibrinogen was formulated in CFB and adjusted to a final fibrinogen concentration of 37.5 mg/ml with a pH of 7.4±0.1. Thrombin (manufactured in-house) was formulated in CTB and adjusted to a final thrombin concentration of 0.1 units/mg of fibrinogen or 25 Units/ml thrombin, with a final pH of 7.4±0.1. Once prepared, the final fibrinogen and thrombin solutions were placed on ice and cooled to 4° C.±2° C.
Cylindrical molds were prepared by cutting off the luer-lock ends of 3, 10, and 20 ml polypropylene syringes (Becton Dickinson) and withdrawing the syringe plungers to the 2.5, 8, and 15 ml markings, respectively. The molds were then placed upright and surrounded by ice, leaving the open ends exposed at the top, and resorbable DEXON™ backing material was added to the molds as a support material. For half of these molds, the DEXON™ backing material was shredded into small pieces of approximately 1 mm×1 mm in size which were placed into the syringe; for the rest the DEXON™ backing material was kept intact and rolled into a tube which was slid down into the syringe barrel.
The 3 ml syringes were manufactured by dispensing 0.20 ml of thrombin (at 4° C.±2° C.) followed by 1.3 ml of fibrinogen (at 4° C.±2° C.) into the cooled syringes. The 10 ml and 20 ml syringes were made in the same manner but using 0.82 ml of thrombin with 6.0 ml of fibrinogen for the 10 ml syringes and 1.64 ml of thrombin with 12.0 ml of fibrinogen for the 20 ml syringes. Immediately after each syringe was filled, it was removed from the ice and the contents were mixed by placing a thumb over the opening and inverting the syringe 3 times. The syringe was then immersed in liquid nitrogen and frozen for 2 minutes. After freezing, the syringes were placed at −80° C. for at least two hours before being lyophilized in the freeze-dryer.
Additionally, 12 mm×75 mm and 17 mm×100 mm polypropylene tubes were also used as molds. These tubes were placed on ice to cool. For the 12 mm×75 mm tubes, 0.41 ml of thrombin (at 4° C.±2° C.) and 2.59 ml of fibrinogen (at 4° C.±2° C.) were dispensed while for the 17 mm×100 mm tubes, 0.68 ml of thrombin (at 4° C.±2° C.) and 4.32 ml of fibrinogen (at 4° C.±2° C.) were dispensed into the cooled tubes. Immediately after each tube was filled, it was removed from the ice and the contents were mixed by placing a thumb over the opening and inverting the tube 3 times. The tube was then immersed in liquid nitrogen and frozen for 2 minutes. After freezing, the syringes were placed at −80° C. for at least two hours before being lyophilized in the freeze-dryer.
Testing Procedures:
Pigs were anesthetized and rendered cold and coagulopathic according to the method of: Bochicchio G, Kilbourne M, Kuehn R, Keledjian K, Hess J, Scalea T. Use of a modified chitosan dressing in a hypothermic coagulopathic grade V liver injury model. Am J Surg. 2009; 198:617e22. The pigs were then given a Grade V thru and thru liver injury by use of a 1″ diameter electric drill into the fundus of the liver. The resulting injury was a full thickness wound that included laceration of multiple large blood vessels with a significant blood loss and corresponding drop in blood pressure.
Immediately following injury, the injury site was treated with a 20 ml syringe described above. The first animal was treated with a syringe filled with material that included shredded backing material. The second was treated with material containing an intact rolled-up sheet of backing material.
The material was applied by inserting the open end of the syringe into the liver wound, and advancing the plunger of the syringe to expel the rod-like material within, while simultaneously withdrawing the syringe barrel from the wound site in order to deliver the material to the entire depth of the wounded tissue. Once this application was complete the manual pressure was applied to the wound site for approximately 150 seconds.
Upon removal of pressure complete hemostasis was observed. The animals were observed for approximately one hour, during which hemostasis was uninterrupted and their blood pressures stable.
ERL fibrinogen was formulated in CFB and adjusted to a final fibrinogen concentration of 37.5 mg/ml with a pH of 7.4±0.1. Thrombin (manufactured in-house) was formulated in CTB and adjusted to three thrombin concentrations: 1.0 units/mg of fibrinogen (or 250 Units/ml thrombin), 0.1 units/mg of fibrinogen (or 25 Units/ml thrombin), and 0.01 units/mg of fibrinogen (or 2.5 Units/ml thrombin), all of which were adjusted to a final pH of 7.4±0.1. Once prepared, the final fibrinogen and thrombin solutions were placed on ice and cooled to 4° C.±2° C.
Cylindrical molds were prepared by cutting off the luer-lock ends of 1, 3, and 10 ml polypropylene syringes (Becton Dickinson) and withdrawing the syringe plungers to their respective full volume capacities. The syringes were then placed upright and surrounded by ice, leaving the open ends exposed at the top. The 1 ml syringes were manufactured by mixing 0.14 ml of thrombin (at 4° C.±2° C.) and 0.86 ml of fibrinogen (at 4° C.±2° C.) and transferring the mixture to the cooled syringes. The 3 ml and 10 ml syringes were made in the same manner but using 0.41 ml of thrombin with 2.59 ml of fibrinogen for the 3 ml syringes and 1.36 ml of thrombin with 8.64 ml of fibrinogen for the 10 ml syringes. Immediately after each syringe was filled, it was immersed in liquid nitrogen and frozen for 2 minutes. After freezing, the syringes were placed in a −80° C. freezer for at least two hours before being lyophilized in the freeze-dryer. The final fibrinogen dose in all groups was 5 mg/cm2 to 13 mg/cm2.
A splenic injury was created by using a hemostat to pierce the spleen and create an opening down into the organ, and then expanding it using the hemostat in order to produce mild to moderate bleeding, avoiding pulsatile bleeding if possible. Initial bleeding was assessed as mild to moderate or pulsatile for approximately 30 seconds. Shed blood was suctioned from the cavity, and a 3 mL syringe was applied with manual pressure to the injured surface of the spleen for 3 minutes, followed by compression and examination to record the effects of treatment. The initial treatment was determined by the surgeon to include at least 1 syringe inside the wound, followed by 3 minutes of manual compression while holding the spleen together. Hemostasis was evaluated immediately after the cessation of application pressure. The results of this evaluation are presented below in Table 7.1.
The liver injury used to test 3 mL syringes was performed in a manner similar to the splenic injury model above. The liver of each subject was injured using a hemostat to pierce the liver and create an opening down into the organ. Treatment consisted of the application of a 3 mL syringe to the injury site of the liver, followed by 3 minutes of manual compression while holding the liver together and examination to record the effects of treatment. Hemostasis was evaluated immediately after the cessation of application pressure. The results of this evaluation are presented below in Table 2.
Another liver injury was also performed and was created using a drill with a 1″ auger bit, with the goal of producing a Grade 3 or greater hepatic injury. Treatment consisted of the application of a 10 mL syringe to the injured surfaces of the liver, followed by compression and examination to record the effects of treatment. The initial treatment was determined by the surgeon to include at least 1 syringe inside the wound, followed by 3 minutes of manual compression while holding the liver together.
Hemostasis was evaluated immediately after the cessation of application pressure, and 5 minutes after the initial application of the syringe. The results of this evaluation are also presented below in Table 7.2.
The kidney injury used to test 3 mL syringes was performed in a manner similar to the splenic injury model above. The kidney of each subject was injured using a hemostat to pierce the liver and create an opening down into the organ.
Treatment consisted of the application of a 3 mL syringe to the injury site of the kidney, followed by 3 minutes of manual compression while holding the kidney together and examination to record the effects of treatment. Hemostasis was evaluated immediately after the cessation of application pressure. The results of this evaluation are presented below in Table 7.3.
In order to assess the performance of hemostatic applicators in vitro, the Mild to Moderate Hemorrhage Assay (MMHA) was developed to more closely model the application of a hemostatic agent to an injury site using an applicator compared to the previously developed EVPA assay. This assay could then be used to evaluate the ability of the hemostatic applicator to stop the flow of fluid through a hole(s) in an animal tissue or tissue-like substrate. The assay could be adapted for use with a variety of tissues or tissue-like substrates and could be used to model different types of bleeding by varying the size and number of holes made in the tissue substrate, as well as the flow rate of the fluid being pumped through it.
The basic apparatus employed in the assay is shown in
In order to test the performance of applicators in this assay, a pre-made FD was cut into small pieces of about 5 mm in diameter. The DEXON™ backing material was removed from some of the pieces while the rest had the backing material intact. These pieces were applied to a 2.8 mm hole in the sausage casing using one of the following applicators: a 2 ml serological pipette with a circular piece of the plastic hook surface of Velcro cut and glued onto the end, a 5 ml serological pipette with a flat-tipped silicone plug in the end, and a 5 ml serological pipette with a round-tipped silicone plug in the end. All of the applicators were held firmly against the casing holes for 5 minutes.
The results of this evaluation showed that when used with FD pieces that contained the backing material, all three applicator types held a pressure of 3 psi (˜150 mmHg). Additionally, the flat-tipped silicone and the Velcro applicators held for 3 minutes at 3 psi (˜150 mmHg) and 5 minutes at 5 psi (˜250 mmHg). The adherence was also tested and shown to be excellent, yielding adherence scores of 4.0.
The same FDs used for these applicators were also tested in the EVPA and Adherence assays. They all exhibited excellent performance, passing 100%, with adherence scores of 4.0.
ERL fibrinogen was formulated in CFB and adjusted to a final fibrinogen concentration of 37.5 mg/ml with a pH of 7.4±0.1. Recombinant thrombin (Zymogenetic's RECOTHROM®) was reconstituted with the supplied diluent (0.9% sodium chloride) according to the manufacturer's instructions to a concentration of 1000 units/ml with a pH of 6.0±0.1. The thrombin solution was then diluted in CTB and adjusted to a final thrombin concentration of 0.1 units/mg of fibrinogen (25 units/ml thrombin), with a final pH of 7.4±0.1. Once prepared, the final fibrinogen and thrombin solutions were placed on ice and cooled to 4° C.±2° C.
Cylindrical molds were prepared by cutting off the luer-lock ends of 1, 3, 5, 20, 30, and 60 ml polypropylene syringes (Becton Dickinson) and withdrawing the syringe plungers to their respective full volume capacities. The syringes were then placed upright and surrounded by ice, leaving the open ends exposed at the top. The 1 ml syringes were manufactured by mixing 0.14 ml of thrombin (at 4° C.±2° C.) and 0.86 ml of fibrinogen (at 4° C.±2° C.) and transferring the mixture to the cooled syringes. The rest of the syringes were made in the same manner but using 0.41 ml of thrombin with 2.63 ml of fibrinogen for the 3 ml syringes, 0.69 ml of thrombin with 4.38 ml of fibrinogen for the 5 ml syringes, 2.75 ml of thrombin with 17.5 ml of fibrinogen for the 20 ml syringes, 4.13 ml of thrombin with 26.25 ml of fibrinogen for the 30 ml syringes, and 8.25 ml of thrombin with 52.50 ml of fibrinogen for the 60 ml syringes. Immediately after being filled, the 1, 3, 5, and 20 ml syringes were frozen by immersion in a dry ice/ethanol mixture for 5 minutes. The 30 and 60 ml syringes were frozen by immersion in liquid nitrogen for 1 minute. After freezing, the syringes were placed at −80° C. for at least two hours before being lyophilized in the freeze-dryer.
The splenic injuries were achieved with the use of scissors, while the liver injury was achieved with the use of a drill with a 1¼″ auger bit, with the goal of producing a Grade 3 or greater injury.
Treatment consisted of the application of a syringe appropriate to the size of the injured surface, followed by compression and examination to record the effects of treatment. The initial treatment was determined by the surgeon to include at least 1 syringe inside the wound, followed by 3 minutes of manual compression while holding the organ together.
Hemostasis was evaluated immediately after the cessation of application pressure, and 5 minutes after the initial application of the syringe. The results of this evaluation are presented below in Table 9.1.
STB purified fibrinogen was formulated in CFB and adjusted to a final fibrinogen concentrations ranging between 8.4 mg/ml and 25.5 mg/ml with a pH of 7.4±0.1. Recombinant thrombin (Zymogenetic's RECOTHROM®) was reconstituted with the supplied diluent (0.9% sodium chloride) according to the manufacturer's instructions to a concentration of 1000 units/ml with a pH of 6.0±0.1. The thrombin solution was then diluted in CTB and adjusted to a final thrombin concentration of 0.1 units/mg of fibrinogen (25 units/ml thrombin), with a final pH of 7.4±0.1. Once prepared, the final fibrinogen and thrombin solutions were placed on ice and cooled to 4° C.±2° C.
Cylindrical molds were prepared by pulling the plunger back to the end on both Merit Medical 20 ml X-Change syringes and Qosina 20 ml Open ended syringes. The syringes were then placed upright and surrounded by ice, leaving the open ends exposed at the top. Table 10.1 shows the concentration and dose of the fibrinogen used. All groups had a final thrombin concentration of 0.1 units/mg of fibrinogen.
After being filled, the syringes were frozen by immersion in a dry ice/ethanol mixture for 5 minutes. After freezing, the syringes were placed at −80° C. for at least two hours before being lyophilized in the freeze-dryer.
STB purified fibrinogen was formulated in CFB and adjusted to a final fibrinogen concentrations ranging from 8.72 mg/ml to 43.6 mg/ml with a pH of 7.4±0.1. Thrombin (manufactured in-house) was formulated in CTB and adjusted to a final thrombin concentration of 0.1 units/mg of fibrinogen or 25 Units/ml thrombin, with a final pH of 7.4±0.1. Once prepared, the final fibrinogen and thrombin solutions were placed on ice and cooled to 4° C.±2° C.
Cylindrical molds were prepared by cutting off the luer-lock end of a 3 ml polypropylene syringes (Becton Dickinson) and withdrawing the syringe plungers to the 2.5 ml markings, respectively. The molds were then placed upright and surrounded by ice, leaving the open ends exposed at the top. Table 11.1 shows the concentration and dose of the fibrinogen used. All groups had a final thrombin concentration of 0.1 units/mg of fibrinogen.
Immediately after each syringe was filled, it was removed from the ice and the contents were mixed by placing a thumb over the opening and inverting the syringe 3 times. The syringe was then immersed in liquid nitrogen and frozen for 2 minutes. After freezing, the syringes were placed at −80° C. for at least two hours before being lyophilized in the freeze-dryer.
Although embodiments of the invention have been described in considerable detail, those skilled in the art will appreciate that numerous changes and modifications may be made to the embodiments and preferred embodiments of the invention and that such changes and modifications may be made with out departing from the spirit of the invention. It is therefore intended that the appended claims cover all equivalent variations as fall within the scope of the invention.
| Number | Date | Country | |
|---|---|---|---|
| 61801393 | Mar 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16247135 | Jan 2019 | US |
| Child | 17148228 | US | |
| Parent | 14776705 | Sep 2015 | US |
| Child | 16247135 | US |
