An expandable tamponade for treating penetrating wounds

Abstract

An expandable tamponade for treating penetrating wounds comprises an expandable foam 112, a housing 108 containing the expandable foam, wherein the foam is held in a first compressed state in the hous

Description

Field The present application generally relates to an expandable tamponade for treating penetrating wounds, such as stab and gunshot wounds. In particular, the present techniques relate to an expandable tamponade comprising an expandable foam. Background Blood loss from penetrating wounds, such as stab and gunshot wounds, can be fatal. A tamponade that enables first responders to reduce the blood loss from such wounds could save many lives. The applicant has therefore identified the need for improved techniques for reducing blood loss from penetrating wounds. Summary In a first approach of the present techniques, there is provided an expandable tamponade for treating penetrating wounds, the tamponade comprising: an expandable foam; a housing containing the expandable foam, wherein the foam is held in a first compressed state in the housing; and a valve for controlling fluid flow into and out of the housing, wherein when the valve permits fluid to flow into the housing, the foam expands and is held in a second expanded state in the housing. In the compressed state, the expandable foam is rigid to enable insertion of the tamponade into a wound tract. That is, when compressed, the foam is sufficiently rigid that it can be easily gripped, and thereby inserted and guided into the wound tract. Additionally, the rigid foam may allow a user to determine resistance to insertion of the tamponade into a wound. Thus, because a user holds the compressed foam, the user is provided with feedback on when the end of the wound tract is reached, which helps the user to know that the tamponade should not be inserted any deeper into the body. In the expanded state, in use, the expandable foam provides a pressure against the wound tract. Advantageously, the foam is rigid and compressed during insertion into a wound tract, and then expands to provide pressure against the wound tract, which helps to minimise bleeding. In an expanded state, the foam may have a cylindrical shape, or any other suitable shape, such as a conical shape, or a box shape. In the compressed state, the expandable foam may have a conical shape. This may aid the insertion of the compressed foam into a wound, in a similar way to how the point / tip of a knife aids insertion of the knife into an object. Thus, the tamponade may be held by a user such that the narrow end of the cone-shaped tamponade is inserted into a wound first. In some cases, the foam and the housing may be cone-shaped, such that in both the expanded and compressed states the tamponade is cone-shaped. In other cases, the foam and housing may have any shape but may be moulded into a cone shape when the foam is being compressed. The narrow end of the cone-shaped tamponade may help guide the tamponade through the wound tract. The expandable foam may be made from a reticulated foam and / or a melamine based foam. Advantageously, reticulated foams and melamine-based foams provide the desired properties that make the tamponade suitable for both insertion into a wound tract and providing a pressure inside a wound tract. That is, both types of foam are rigid enough, when in a compressed state, to be inserted into a wound, and expand by a sufficient amount to provide a sufficient pressure in a wound tract. It will be understood that these are example foam types that provide the desired properties, and are non-limiting. In the compressed state, the expandable foam may have a diameter of less than or equal to 10mm when the foam is in the compressed state. This diameter may ensure that the foam can be inserted easily into a wound tract, as an average wound tract has a diameter of less than 10mm. That is, the tamponade is unlikely to get stuck when being inserted into the wound tract when using a tamponade with a diameter of less than 10mm in a compressed state. The diameter of the foam in the compressed state may be substantially uniform along the length of the foam, or may vary. For example, the foam may be cone-shaped in a compressed state, and the diameter may be 10mm at the narrowest part of the cone or the widest part of the cone. In the expanded state, the expandable foam may have a diameter of at least 30mm along the length of the foam. In use, the expandable foam may exert a pressure of at least 100 MmHg on the wound tract. Advantageously, this means that the tamponade, when expanded, has a diameter that is sufficient for most wound sizes, while providing a pressure that is sufficient to stem bleeding from a penetrating wound. The housing may be an expandable housing. That is, the housing may provide a tight fit around both the compressed and the expanded tamponade. When the tamponade expands, the housing may expand with the tamponade. Advantageously, this may make inserting the tamponade into a wound tract easier as there is no superfluous housing material to accommodate the foam in an expanded state. This can ensure that the tamponade housing does not get stuck while being inserted into the wound tract and may reduce friction between the housing and the wound tract. The housing may be a flexible housing. That is, the housing may be flexible enough to allow the foam to be housed in both a compressed and an expanded state. In particular, the housing may be flexible enough to allow air to be removed from the housing and the foam, such that the foam is held in a vacuum state to compress the foam. Advantageously, a flexible but not expandable housing material may provide a tighter seal for the foam. Additionally, a flexible but not expandable housing may be made from a thicker material and may therefore be more puncture resistant than an expandable material. This may be advantageous if the penetrating wound is caused by, for example, shrapnel that remains in the wound tract. The housing may be made from a biocompatible material. That is, the housing material may be safe to use in the human and / or animal body. Additionally, the housing material may comply with regulatory standards for medical devices. The housing may, for example, be made from latex. It will be understood that this is an example material and is non-limiting. In some cases, the valve may be a one way valve that allows fluid to enter the housing to enable the foam to expand. That is, the foam may be held in a compressed state within the housing by virtue of air / fluid being sucked out of the foam and housing. The one way valve may allow fluid to enter the housing but may prevent fluid from leaving the housing until required. This prevents inadvertent deflation or loss of pressure in the foam. That is, the one way valve may ensure that a pressure provided by the foam on the wound tract remains constant, even when there is additional strain on the foam and / or housing in some way, for example, during transport of a patient. In some cases, the valve may be a two way valve which can be used to control fluid flow into the housing (to enable expansion of the foam), and to control fluid flow out of the housing (to enable compression of the foam, and to prevent fluid flow out when the foam is expanded). Thus, the valve may ensure that fluid, such as air, that has entered the tamponade and expanded the foam remains inside the tamponade housing. For example, when a patient with a penetrating wound has been treated with the tamponade in the field and is then moved, the valve may ensure that the tamponade cannot deflate during transport or when pressure is otherwise applied to the wound. The valve may enable the tamponade to be easily removed when a patient has reached a treatment centre, such as a hospital, because the tamponade can be compressed again. Making the tamponade easily removable also ensures that the tamponade can be removed without inflicting further damage to the wound. The valve may be connectable to a pump for removing air / fluid from the tamponade, to thereby compress the foam and housing. The valve may be connectable to a fluid source for inserting fluid into the tamponade, to thereby expand the foam and housing. The valve may be connectable to a pump and / or fluid source via a single connection or separate connections. The tamponade may further comprise a fastening mechanism for fastening the tamponade to a patient. In some cases, the fastening may be coupled to the housing. For example, the housing may comprise a hilt or similar component which may be in close proximity or in contact with a wound opening, and the fastening may be coupled to the hilt. The fastening mechanism may comprise one or more of: a strap for strapping the tamponade in position on the patient; at least one hook for insertion into skin of the patient; a strap and at least one hook for insertion into skin of the patient; and adhesive for adhering the tamponade to skin of the patient. The housing may comprise a retention mechanism on an external surface of the housing for retaining the tamponade within a wound tract. For example, the retention mechanism may comprise bristles or Velcro (RTM) or similar components which grip and / or increase friction, thereby making it more difficult for the tamponade to slip out of the wound tract. In a second approach to the present techniques, there is provided a first responder kit, the kit comprising: at least one expandable tamponade of the type described herein, wherein each tamponade is provided in a removable wrapper. Providing the tamponade in a removable wrapper has several advantages. Firstly, a removable wrapper ensures that the tamponade is and remains sterile before being applied to a wound in the field. Secondly, the removable wrapper protects the tamponade from other outside contaminants or influences. The removable wrapper may also retain the tamponade in a compressed state. That is, the tamponade may be provided in a first responder kit in a compressed state. For example, the foam of the tamponade may be held in a vacuum in the tamponade housing and the wrapper ensures that the vacuum seal remains intact until the tamponade can be applied. Providing the tamponade in a compressed state means that a user in the field needs no additional tools or instruments to apply the tamponade to a patient. This is because the foam of the tamponade provides both the rigidity required to insert the tamponade into a wound tract and the expandable properties to apply pressure to the wound tract. Advantageously, in some cases, there is no need to inflate the foam or tamponade in any way as the pressure is simply provided by the foam being released from a vacuum state and expanding. However, the tamponade may be further inflated by inserting further fluid into the housing of the tamponade. This further fluid may provide an additional increased pressure on the wound when the pressure provided by the foam is not sufficient. Additionally, inserting further fluid may be desirable to inflate and deploy the tamponade more quickly, instead of waiting for the foam to expand. The removable wrapper may retain the compressed tamponade in a conical shape. Advantages of the conical shape are as described above. The removable wrapper may comprise a rigid portion for ensuring that the foam retains the desired conical shape. Alternatively, when the tamponade has been placed inside the wrapper, the wrapper may be sealed around the tamponade in a conical shape. Together with ensuring that the tamponade and foam are sealed and remain in a vacuum state, the removable wrapper then ensures that the tamponade is ready for use in the field. The features described above with respect to the first approach apply equally to the second approach and therefore, for the sake of conciseness, are not repeated. Brief description of the drawings Implementations of the present techniques will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a schematic drawing of the components of one embodiment of the expandable tamponade; Figure 2 shows an ideal curve of diameter as a function of pressure exerted for a foam used in the tamponade; Figure 3A shows an expandable tamponade packaged in a removable wrapper; Figure 3B shows the expandable tamponade in a compressed state; Figure 3C shows the expandable tamponade in an expanded state; Figure 4 shows a fastening mechanism for fastening the tamponade to the patient, the fastening mechanism comprising a strap for strapping the tamponade in position on the patient; Figure 5A shows a fastening mechanism for fastening the tamponade to the patient, the fastening mechanism comprising at least one hook for insertion into skin of the patient; Figure 5B shows the fastening mechanism of Figure 5A when the at least one skin hook is further attached to a strap; Figure 6A shows a fastening mechanism for fastening the tamponade to a patient, the fastening mechanism comprising an adhesive strip for adhering the tamponade to the skin of the patient; Figure 6B shows a fastening mechanism for fastening the tamponade to a patient, the fastening mechanism comprising an adhesive blister for adhering the tamponade to the skin of the patient; Figure 6C shows the fastening mechanism of Figure 6B; Figure 7 shows a bristle internal retention mechanism; Figure 8 shows a Velcro (RTM) internal retention mechanism; Figure 9 shows a clip fastening mechanism; and Figure 10 shows a treasury tag fastening mechanism. Detailed description of the drawings Broadly speaking, embodiments of the present techniques provide an expandable tamponade for treating penetrating wounds. Advantageously, the present techniques provide an expandable tamponade comprising foam inside a housing wherein the foam can be compressed to enable the tamponade to be inserted into a wound tract, and expanded to exert pressure onto the wound tract and thereby stem bleeding. Figure 1 shows a schematic drawing of the components of one embodiment of the expandable tamponade. The expandable tamponade 100 comprises: an expandable foam 112; a housing 108 containing the expandable foam, wherein the foam is held in a first compressed state in the housing 108; and a valve 104 for allowing a fluid into and out of the housing, wherein when the valve 104 permits fluid to flow into the housing 108, the foam expands and is held in a second expanded state in the housing. In the compressed state, the expandable foam 112 is rigid to enable insertion of the tamponade 100 into a wound tract. That is, when compressed, the foam is sufficiently rigid that it can be easily gripped, and thereby inserted and guided into the wound tract. Additionally, the rigid foam may allow a user to determine resistance to insertion of the tamponade into a wound. Thus, because a user holds the compressed foam, the user is provided with feedback on when the end of the wound tract is reached, which helps the user to know that the tamponade should not be inserted any deeper into the body. The foam may comprise a plurality of pores and a compressed state then means that the pores of the foam are devoid of fluid. Fluid may mean air or another fluid, such as saline. When the fluid is air, the pores being devoid of air means that the foam may be vacuum-packed inside the housing. That is, the housing may be airtight and seal the foam against the surrounding air. The foam being rigid may also mean that inside the housing, there is a lower air pressure than a surrounding air pressure. For example, the surrounding pressure may be an atmospheric pressure and the air pressure inside the housing may be less than an atmospheric pressure. The pressure inside the housing being lower than an atmospheric pressure means that the housing and foam inside the housing are compressed by the atmospheric pressure and the rigid properties of the foam may be provided by the foam being subjected to this atmospheric pressure. That is, the foam may be compressed by a pressure difference between the inside of the housing and the surrounding atmosphere. In the expanded state, in use, the expandable foam 112 provides a pressure against the wound tract. Advantageously, is rigid and compressed during insertion into a wound tract, and then expands to provide pressure against the wound tract, which helps to minimise bleeding. In an expanded state, the foam may have a cylindrical shape, or any other suitable shape, such as a conical shape, or a box shape. This means that application of a vacuum is being used to store energy in an elastically compressible material. The stored energy is released when air is reintroduced, applying force to the walls of the wound tract through the expanded foam. Advantageously, the foam provides the pressure and there is no need for a mechanism, such as, for example, positive air pressure from an inflated balloon or the like inside the wound tract to stem the bleeding. As there is no positive air pressure in the wound, there are no concerns about bursting of, for example, a balloon. Additionally, there are no concerns about air leakage or loss of air pressure in the system. This is because the pressure provided is inherent to the expanded foam and no additionally pressurising mechanism is needed. That is, there is no need for the user to pump air or other fluids into a balloon or other system - a simple one-step release of a valve or plug is sufficient to activate / expand the foam and thus provide pressure on the wound tract. However, the tamponade may be further inflated by inserting further fluid into the tamponade. This further fluid may provide an additional increased pressure on the wound when the pressure provided by the foam is not sufficient. Additionally, inserting further fluid may be desirable to inflate and deploy the tamponade more quickly, instead of waiting for the foam to expand. Additionally, the rigid foam may relate resistance in the wound tract to a user inserting the tamponade, and thus the rigid foam may be used to detect an end of the wound tract and determine that the tamponade should not be inserted any further. The rigid foam also provides the user with a means of probing the wound site to palpate the wound tract and find the best path through tissue planes to reach the end of the wound tract. Ideally, the user may probe delicately using the rigid foam to avoid causing further damage or pain. The foam and / or housing may further comprise lines or markings that may act as a depth gauge by which insertion depth can be measured and reported / recorded. Insertion depth may be measured using the unexpanded foam. That is, the marking may indicate a measure of depth that is accurate for the unexpanded foam. Additionally or alternatively, markings may provide a measure of insertion depth for the expanded foam. When the foam expands, the pores of the foam fill with fluid and the volume of the foam increases. This increase in volume provides a force on the wound tract wherein the force acts to stem a bleeding inside the wound tract. When the fluid used to expand the tamponade is air, the pores of the foam may fill with air. For example, when the foam has been held inside a vacuum or at lower than atmospheric pressure inside the housing, opening the valve means that air can enter the housing and expand the foam. Upon opening the valve, the pressure inside the housing and foam is then similar to an atmospheric pressure and the resulting expansion of the foam provides a pressure on the wound tract. In an expanded state, the foam may then have a cylindrical shape, or any other suitable shape, such as a conical shape, or a box shape. The tamponade and foam may be provided in a compressed state to a user or a user can compress the foam of the tamponade before inserting the tamponade into the wound tract. For example, the user may use a syringe to draw air from the housing of the tamponade and thus the foam. Hence, the user may be required to prepare the tamponade for use before inserting the tamponade into a wound tract. It may be advantageous for the tamponade to be provided in a compressed state to the user. When the tamponade is already provided in a compressed state, no additional tools or instruments are necessary to insert and expand the tamponade in a user’s wound tract. This is because the tamponade may simply be provided in a vacuum-packed state and the foam of the tamponade may expand by letting air into the housing of the tamponade. In the compressed state, the expandable foam may have a conical shape. This may aid the insertion of the compressed foam into a wound, in a similar way to how the point / tip of a knife aids insertion of the knife into an object. Thus, the tamponade may be held by a user such that the narrow end of the cone-shaped tamponade is inserted into a wound first. In particular, a part of the foam that first enters the wound tract may be narrower than the end of the foam which enters the wound tract last. In some cases, the foam and the housing may be cone-shaped, such that in both the expanded and compressed states the tamponade is cone-shaped. In other cases, the foam and housing may have any shape but may be moulded into a cone shape when the foam is being compressed. The narrow end of the cone-shaped tamponade may help guide the tamponade through the wound tract. Advantageously, the tip of the foam may therefore be compressed to a greater extent and may help guide the tamponade through the wound tract. Additionally, the tip of the foam, and thus the tamponade, may be shaped to ease the tamponade into the wound, and the higher compression provides enough stability to navigate the wound tract. A shape that may help ease the tamponade into the wound may be hemispherical or rounded shape. In particular, inserting the tamponade into the wound tract and navigating the wound tract may be challenging, especially for complex wound geometries. Thus, a more compressed tamponade tip may also provide better haptic feedback to a user navigating the wound tract This may also help the user feel the end of the wound tract when inserting the tamponade and therefore signals the user to stop inserting the tamponade into the wound tract any further. It will be appreciated that this is a non-limiting example and other foam shapes are possible. The expandable foam may be made from a reticulated foam and / or a melamine based foam. Advantageously, a reticulated foam and a melamine based foam provide the desired properties that make the tamponade suitable for both insertion into a wound tract and providing a pressure inside a wound tract. That is, both types of foam are rigid enough, when in a compressed state, to be inserted into a wound, and expand by a sufficient amount to provide a sufficient pressure in a wound tract. It will be appreciated that these are non-limiting examples, and the foam may be made from any other suitable material. The foam may also be a biocompatible foam, such that when there is a tear in the housing, contact with foam is not harmful to a patient. Other properties of the foam may be desirable. For example, it may be desirable for the foam to be made from a hydrophobic material. This may be desirable to ensure that the foam material does not lose its properties that allow the foam material to expand and provide a pressure on the wound tract. That is, it may be desirable for the foam material and foam pores to retain their structural properties upon contact with water or bodily fluids present in a wound tract, such as blood or other fluids. Figure 2 shows an ideal curve of diameter as a function of pressure exerted for a foam used in the tamponade. In the compressed state, the expandable foam 112 may have a diameter of less than or equal to 10mm along some or all of the length of the compressed foam. That is, there is no point of the foam that has a diameter larger than 10mm. Some parts of the foam may have a diameter less than 10mm, for example, the tip of the foam. This diameter ensures that the foam can be inserted easily, as an average wound tract has a diameter less than 10mm. That is, the tamponade is unlikely to get stuck when being inserted into the wound tract when using a tamponade with a diameter of less than 10mm in a compressed state. It will however be appreciated that this is a non-limiting example and other tamponade and foam sizes and diameters are possible. For example, the tamponade and foam may be provided in different sizes, and a user may pick a suitable tamponade size based on, for example, nature of the wound, location of the wound, wound geometry and / or incident angle of the wound causing instrument (e.g. bullet or knife). As a non-limiting example, the device may be manufactured at a size “A”, say a diameter of 60mm and a length of 135mm. In this state the compressible material, i.e. the foam, is under no compressive stress and is in a relaxed state. Then, the foam is placed in the housing and air is removed. The foam is constrained / held to maintain the foam’s length, but allowed to compress under atmospheric pressure so that the foam’s diameter reduces to a new size “B” which may be 10mm or another suitable size to be insertable into a narrow wound opening. The tamponade and foam may be stored at this diameter for months or years and during that time, it is likely that the foam will creep or take on a compression set. It is therefore likely that the foam will not spring back immediately to diameter A when air is allowed to re-enter the housing. When air is allowed to re-enter the housing, the foam springs back towards the foam’s initial size as the foam recovers elastically. When the foam expands in a wound cavity / tract larger than the manufactured size of the foam (e.g. 70mm diameter), the foam will eventually reach size A (i.e. the initial manufactured / expanded size) and apply no pressure to the wound walls. When the tamponade is used in a wound cavity smaller than the manufactured / expanded foam size, the foam will apply a pressure to the wound walls. The applied pressure depends on the foam diameter inside the wound tract. That is, the pressure is relative to the diameter needed to fill the wound tract (diameter “C”). When the wound cavity / tract is a penetrating stab wound of approx. 50mm width, the walls will form a cavity of approximately 30mm diameter and this diameter may correlate to a pressure applied by the foam to the wound walls wherein the pressure is sufficient to slow or stop arterial bleeding. In the expanded state, the expandable foam may have a diameter of at least 30mm and, in use, may exert a pressure of at least 100 MmHg on the wound tract. Advantageously, this means that the tamponade, when expanded, has a diameter that is sufficient for most wound sizes, while providing a pressure that is sufficient to stem bleeding from a penetrating wound. However, it will be understood that these sizes and pressures are provided merely as non-limiting examples and other sizes and required pressure may be used. For example, the size of the tamponade and foam may be less when the patient is a child. Additionally, the required pressure to stem bleeding in a wound tract may be less or more depending on the location of the wound and the type of tissue that is injured. Other tissue types may be particularly susceptible to bleeding and may therefore require a higher pressure for a bleeding to be stopped. It will also be appreciated that both a size and softness of foam may be varied. When the foam has a larger diameter and is inserted into a smaller wound tract, this may automatically result in a higher pressure being applied to the wound tract. Therefore, in this case, it may not be necessary to vary the foam material to pick a tamponade with a foam that provides a greater pressure. The same may be true when a tamponade with smaller diameter but foam providing a higher pressure is used. The properties required of the foam can be described on a graph, as shown in Figure 2, as a compression profile (response to vacuum) which delivers diameters A, B and C at three respective pressures: (a) zero differential pressure (i.e. pressure inside the housing equal to surrounding pressure), (b) a vacuum of e.g. 0.9 Bar and (c) 130-200mmHg or a similar target based on typical blood pressure values. Diameter C and its associated pressure will be affected by the compression set of the material in question. The compression set of a material is the permanent deformation of the material remaining after squashing the material. That is, the expanded diameter inside the wound tract will depend not only on the material, the size of the foam and the size of the wound tract, but also on the compression set of the material used for the foam. Materials with low creep may perform best. That is, solid materials with a low tendency to undergo slow deformation while subject to persistent mechanical stresses are expected to perform best as foam materials. This is because these materials will not deform significantly when stored in a compressed state for a prolonged period of time. In other words, materials with a low creep will provide sufficient pressure to stem bleeding from a wound even when the foam has been compressed fora long time. This is because in these materials, the foam will “spring back” to substantially the same shape as before the foam has been compressed. Some foam materials are too dense for use in the tamponade - it is important that the foam material exhibits a large change in volume in response to externally applied pressure. For example, a ratio of 6:1 in expanded to compressed volume has proven useful but it should be obvious that a larger ration of 10:1 or higher may work as well or better. A lower ratio of e.g. 3:1 would mean that a 10mm diameter device would apply no pressure to a wound of 30mm diameter, and thus such a ration may not apply sufficient pressure to a wound tract of 30mm diameter. It will, however, be appreciated that a ratio of 3:1 may be sufficient for smaller wound tracts, and thus the required ration of expanded foam to compressed foam may depend on the application, wound type and wound size. Additionally, it will also be appreciated that the foam ideally exhibits this change in volume in a relatively short time frame when air is reintroduced into the housing. For example, the foam may expand within 30 seconds, or 60 seconds or any other suitable time frame. Shorter time frames such as 20 seconds may also be useful, but it will be appreciated that there is a balance between allowing first responder time to insert and adjust the foam during inflation, while inflation of the foam not taking so long that bleeding can continue for a prolonged period. Any elastically compressible material can be considered for use as the foam in this device. For example, polymer foams may be used if they have the required stiffness. Other materials and structures may include metallic lattices, sprung wire assemblies, elastic matrices, doped foams, composite reinforced open-cell materials or honeycombs. The housing 108 may be an expandable housing. Therefore, the housing may provide a tight fit around both the compressed and the expanded tamponade. When the tamponade expands, the housing may expand with the tamponade. Advantageously, this may make inserting the tamponade into a wound tract easier as there is no superfluous housing material to accommodate the foam in an expanded state. This can ensure that the tamponade housing does not get stuck while being inserted into the wound tract and may reduce friction between the housing and the wound tract. An expandable housing may, for example, be a balloon, such as a latex balloon, or any other suitable type of balloon. The housing 108 may be a flexible housing. That is, the housing may be flexible enough to allow the foam to be housed in both a compressed and an expanded state. In particular, the housing may be flexible enough to allow air to be removed from the housing and the foam, such that the foam is held in a vacuum state to compress the foam. That is, when the foam is in a compressed state, the flexible housing presses against the foam. In particular, when the foam is vacuum-sealed, or sealed at lower than atmospheric pressure inside the housing, the housing can shrink towards the foam. Advantageously, a flexible but not expandable housing material may provide a tighter seal around the foam. That is, a flexible but not expandable housing material may have a higher wall thickness, i.e. can be made from thicker material. This means, that any seal provided by the housing may be more secure and provide less risk of air leaking into the housing and expanding the foam before the foam can be inserted into the wound tract. Additionally, a flexible but not expandable housing may be made from a thicker material and may therefore be more puncture resistant than an expandable material. This may be advantageous if the penetrating wound is caused by, for example, shrapnel that remains in the wound tract. The housing may also be made from a flexible material that is specifically designed to be puncture resistant. The housing 108 may be made from a biocompatible material. That is, the housing material may be safe to use in the human and / or animal body. Additionally, the housing material may comply with regulatory standard for medical devices. Thus, the housing may, for example, be made from latex. Other biocompatible materials may be used. For example, nonlatex substitute materials may be used to form the housing. This may be advantageous if a patient has, for example, a latex allergy. The housing may also be made from a material that provides low friction when inserting the tamponade into a wound tract. However, ideally the housing material provides low friction while inserting the tamponade only and provides higher resistance / friction when removing the tamponade. That is, the housing material may provide friction against the wound tract in the direction of removal only. This is advantageous because in this way there is less risk of the tamponade being dislodged from or moving in the wound tract. In some cases, the valve 104 may be a one way valve that allows fluid to enter the housing to enable the foam to expand. That is, the foam may be held in a compressed state within the housing by virtue of air / fluid being sucked out of the foam and housing. The one way valve may allow fluid to enter the housing but may prevent fluid from leaving the housing until required. This prevents inadvertent deflation or loss of pressure in the foam. That is, the one way valve may ensure that a pressure provided by the foam on the wound tract remains constant, even when there is additional strain on the foam and / or housing in some way, for example, during transport of a patient. This may be advantageous to ensure that fluid, such as air, that has entered the tamponade and expanded the foam remains inside the tamponade housing. For example, when a patient with a penetrating wound has been treated with the tamponade in the field and is then moved, a one way valve may ensure that the tamponade cannot deflate during transport or when pressure is otherwise applied to the wound. The valve may be a standard valve, for example, the valve may be suitable for connection with a standard syringe. In this way, fluid can be inserted manually into the housing to (further) expand the tamponade. The valve may be connected to the housing 108 using a connector and / or tubing 106. The valve may be sealed using a plug 102 that can be inserted into a valve opening to seal the valve. In some cases, the valve may be a two way valve (not shown) which can be used to control fluid flow into the housing (to enable expansion of the foam), and to control fluid flow out of the housing (to enable compression of the foam, and to prevent fluid flow out when the foam is expanded). Thus, the valve may ensure that fluid, such as air, that has entered the tamponade and expanded the foam remains inside the tamponade housing. For example, when a patient with a penetrating wound has been treated with the tamponade in the field and is then moved, the valve may ensure that the tamponade cannot deflate during transport or when pressure is otherwise applied to the wound. The valve may enable the tamponade to be easily removed when a patient has reached a treatment centre, such as a hospital, because the tamponade can be compressed again. Making the tamponade easily removable also ensures that the tamponade can be removed without inflicting further damage to the wound. The further valve may be a standard valve, for example, the further valve may be suitable for connection with a standard syringe. In this way, fluid can be removed manually from the housing to compress the tamponade. The further valve may be connected to the housing using a connector and / or tubing. The further valve may be sealed using a plug that can be inserted into a valve opening to seal the further valve. The valve and connector and / or tubing may be sealed to the housing. The seal to the housing may be such that the airtight properties of the housing are maintained. For example, when the housing is made from latex or another polymer, the connector and / or tubing may be heat-sealed to the housing. The valve may be connectable to a pump for removing air / fluid from the tamponade, to thereby compress the foam and housing. The valve may be connectable to a fluid source for inserting fluid into the tamponade, to thereby expand the foam and housing. The valve may be connectable to a pump and / or fluid source via a single connection or separate connections. Figure 3A shows an expandable tamponade packaged in a removable wrapper. The tamponade may be provided in a first responder kit, the kit comprising: at least one expandable tamponade of the type described herein, wherein each tamponade is provided in a removable wrapper 110. Providing the tamponade in a removable wrapper has several advantages. Firstly, a removable wrapper ensures that the tamponade is and remains sterile before being applied to a wound in the field. Secondly, the removable wrapper protects the tamponade from other outside contaminants or influences. The removable wrapper may be a standard foil wrapper, or any other suitable type of wrapper. The removable wrapper 110 may also retain the tamponade in a compressed state. That is, the tamponade may be provided in a first responder kit in a compressed state. For example, the foam of the tamponade may be held in a vacuum in the tamponade housing and the wrapper 110 ensures that the vacuum seal remains intact until the tamponade can be applied. Providing the tamponade in a compressed state means that a user in the field needs no additional tools or instruments to apply the tamponade to a patient. This is because the foam of the tamponade provides both the rigidity required to insert the tamponade into a wound tract and the expandable properties to apply pressure to the wound tract. Advantageously, there is no need to inflate the foam or tamponade in any way as the pressure is simply provided by the foam being released from a vacuum state and expanding. However, the tamponade may be further inflated by inserting further fluid into the tamponade. This further fluid may provide an additional increased pressure on the wound when the pressure provided by the foam is not sufficient. Additionally, inserting further fluid may be desirable to inflate and deploy the tamponade more quickly, instead of waiting for the foam to expand. The removable wrapper may retain the compressed tamponade in a conical shape, as shown in Figure 1, where the wrapper 110 may comprise a rigid portion for retaining the conical shape of the tamponade. Alternatively, when the tamponade has been placed inside the wrapper, the wrapper may be sealed around the tamponade in a conical shape. For example, the wrapper may be heat sealed around the tamponade. The wrapper’s seal then restricts movement of the tamponade along the seal of the wrapper. That is, the seal may provide sufficient force on the foam to maintain the foam in the conical shape. Sealing the tamponade in the removable wrapper may thus provide a highly effective way of both preserving a vacuum inside the tamponade’s housing and providing a conical shape to the foam. Moreover, the wrapper’s heat seal may allow for easy removal of the tamponade in the field. Advantages of the conical shape are as described above. The removable wrapper may comprise a rigid portion for ensuring that the foam retains the desired conical shape. Together with ensuring that the tamponade and foam are sealed and remain in a vacuum state, the removable wrapper then ensures that the tamponade is ready for use in the field. The features described above with respect to the tamponade apply equally to the first responder kit and therefore, for the sake of conciseness, are not repeated. Figure 3B shows an expandable tamponade in a compressed state. The features of the expandable tamponade in a compressed state are as described above with respect to the tamponade and therefore, for the sake of conciseness, are not repeated. Figure 3B shows what the expandable tamponade 100 may look like when taken out of the wrapper by a user. The connector and / or tubing 106 may extend far enough from the housing to enable comfortable insertion and release of a valve for air or another fluid to enter the housing. That is, the length of tubing may, among other things, be such that it is possible to comfortably reach the valve even when the tamponade is inserted into a wound. On the other hand, the length of tubing may be such that a risk of accidently getting caught on the tubing and removing the tamponade is reduced. It will be appreciated that the length of tubing may be attached for different types of tamponades, different types of wounds, or different types of emergency setting, such that the length of tubing is convenient for the specific use case. Figure 3C shows the expandable tamponade in an expanded state. It is clear from Figure 3C that the expanded foam has a significantly greater volume than the unexpanded foam shown in Figure 3B. The features of the expandable tamponade in an expanded state are as described above with respect to the tamponade and therefore, for the sake of conciseness, are not repeated. Figure 4 shows a fastening mechanism for fastening the tamponade to the patient, the fastening mechanism comprising a strap for strapping the tamponade in position on the patient. The tamponade may further comprise a fastening mechanism for fastening the tamponade to a patient. In some cases, the fastening may be coupled to the handle. For example, the handle may comprise a hilt or similar component which may be in close proximity or in contact with a wound opening, and the fastening may be coupled to the hilt. The fastening mechanism may be a Velcro (RTM) / hook and loop fastener strap 402 for securing the tamponade to a patient. The strap may, for example, be wrapped around the patient and secured by pressing two ends of the strap 402 together. In another example, the strap may be secured by threading through a loop and pulling the strap back on itself and then securing the strap using the Velcro (RTM) / hook and loop fastener. In another example, the strap may be used as a tourniquet and further comprise a windlass for tightening the tourniquet. Figure 5A shows a fastening mechanism for fastening the tamponade to the patient, the fastening mechanism comprising at least one hook for insertion into skin of the patient. In this embodiment, fastening of the tamponade is provided by at least one skin hook 502. The at least one skin hook may be a barbed hook that digs into a patient’s skin. The at least one skin hook may be mounted on a hilt 506 of the tamponade. That is, the tamponade may further comprise a hilt 506 that may contact the patient’s skin when the tamponade is inserted into a wound tract. The at least one skin hook 502 may be part of the hilt. For example, the hilt may further comprise a push-down mechanism 504 for deploying the at least one skin hook. The skin hook may be attached to the push-down mechanism and may dig into the patient’s skin when the push-down mechanism is pushed down towards the patient’s skin. Figure 5B shows the fastening mechanism of Figure 5A when the at least one skin hook is further attached to a strap. The at least one skin hook 502’ may be connected to the tamponade via a strap 506. The strap 506 may be adjustable, such that the at least one skin hook 502’ can hold the tamponade in place when the strap is pulled taut. Figure 6A shows a fastening mechanism for fastening the tamponade to a patient, the fastening mechanism comprising an adhesive strip for adhering the tamponade to the skin of the patient. In this embodiment, fastening of the tamponade may be provided by at least one adhesive strip 602 or any other suitable adhesive. The adhesive may be covered by a peelable layer that may be peeled off the adhesive when the tamponade is inserted into a wound. There may be two adhesive strips 602, each on opposite sides of the tamponade when inserted into the wound. The at least one adhesive strip may be pressed onto a patient’s skin to attach the adhesive strip to the patient. The adhesive of the adhesive strip may be any suitable adhesive that ensures that the tamponade remains in place when inserted. The adhesive may also be skin-friendly. Additionally, the adhesive may be a type of adhesive that can easily be removed by applying a solvent solution to dissolve the adhesive. This is advantageous because the adhesive can then be easily removed before or during surgery, when the penetrating wound is treated further. Figure 6B shows a fastening mechanism for fastening the tamponade to a patient, the fastening mechanism comprising an adhesive blister for adhering the tamponade to the skin of the patient. In this embodiment, fastening of the tamponade may be provided by an adhesive / glue that is applied to a hilt 612 of the tamponade and the user’s skin. The adhesive / glue 610 may be stored in a packet or blister 608 that is attached to the hilt. When the blister is broken by a user, glue may be released from the blister onto the patient’s skin and the hilt 612 of the tamponade such that the portion of the hilt contacting the patient’s skin is glued to the skin. The blister may be such that a breakable portion of the blister packet is on the side of the hilt facing the patient’s skin, and another portion of the blister packet is on the opposite side to the breakable portion. The other portion of the blister packet may then be pushed in to break the breakable portion of the blister packet and release the glue onto the patient’s skin and the part of the hilt contacting the patient’s skin. The glue may be cyanoacrylate glue. Alternatively, glue may be provided in a bottle or other container separate to the tamponade and applied to the patient’s skin and the tamponade hilt to attach the hilt to the patient’s skin. The user may hold the hilt still and press the hilt to the patient’s skin such that the glue may set and securely attach the hilt to the patient’s skin. Figure 6C shows the fastening mechanism of Figure 6B when the glue 616 is further attached to a strap 614. That is, the strap may be glued to a patient’s skin. The strap 614 may be adjustable, such that the glue 616 can hold the tamponade in place when the strap is pulled taut. Figure 7 shows a bristle internal retention mechanism. The balloon may comprise a retention mechanism on an external surface of the housing for retaining the tamponade within a wound tract. For example, bristles 702 may be attached to an exterior of the balloon. The bristles may be angled such that the tamponade is easy to insert but difficult to remove while inflated. This is because, when attempting to remove the tamponade, the bristles act as barbs that latch into a patient’s tissue in the wound tract. The bristles might be located on the whole of the housing. Alternatively, the bristles might be located at the tip of the housing only to anchor the tamponade to the patient’s wound. Additionally or alternatively, the retention mechanism may comprise similar components which grip and / or increase friction, thereby making it more difficult for the tamponade to slip out of the wound tract. Figure 8 shows a Velcro (RTM) internal retention mechanism. A surface 802 of the housing contacting the wound tract may comprise Velcro (RTM) spots 804 to provide resistance to the tamponade exiting the wound tract. The hooks of the Velcro (RTM) spots may be angled such that the tamponade is easy to insert but difficult to remove. There may be one Velcro (RTM) spot only or there may be a plurality of Velcro (RTM) spots. The spots may have any suitable shape, such as, for example, a circular, rectangular, elliptical or any other suitable shape. There may be a higher density per surface area of spots at the tip of the tamponade to ensure that the tamponade is anchored to the wound tract when inserted. The spots may have a size that is small compared to the size of the tamponade and / or the wound tract. Having a small size minimises the risk of one of the spots contacting an artery or other sensitive tissue inside the wound tract. However, if the spots do contact an artery inside the wound tract, the surrounding foam of the tamponade should provide sufficient pressure to stem any bleeding from the artery. Additionally or alternatively, the retention mechanism may comprise similar components which grip and / or increase friction, thereby making it more difficult for the tamponade to slip out of the wound tract. Figure 9 shows a clip fastening mechanism. The clip 902 may clip onto a patient’s skin. The clip may be part of a hilt of the tamponade or may be attached to a strap which is in turn attached to the tamponade. The strap may be adjustable, such that the clip can hold the tamponade in place when the strap is pulled taut The clip may comprise additional hooks 904 that may pierce the patient’s skin when the hook is applied and provide additional traction to keep the tamponade in place. Figure 10 shows a treasury tag fastening mechanism. The tag 1000 may be attached to the tamponade via a strap or cord or other suitable attachment means. The tag may comprise a needle 1002 for threading the tag through a patient’s skin. The tag may further comprise a retaining portion 1004 connected to a cord 1006 for retaining the tag in place when the needle has been threaded through a user’s skin. The retaining portion 1004 may resist the tag moving by being attached to the cord 1006 (which is in turn attached to the tamponade), and by the retaining portion having a size larger than a hole created by the needle in at least one dimension. For example, the retaining portion may have a longitudinal shape. When threaded through the needle hole, the long side of the longitudinal portion may facing in a direction perpendicular to a hole created by the needle when the cord attached to the retention means is being pulled upon. The retention means 1004 may be housed inside the needle 1002 when the needle is being threaded through a patient’s skin. When the needle has been threaded to a patient’s skin, the retention means may be removed from the needle to keep the tag in place. Those skilled in the art will appreciate that while the foregoing has described what is considered to be the best mode and where appropriate other modes of performing present techniques, the present techniques should not be limited to the specific configurations and methods disclosed in this description of the preferred embodiment. Those skilled in the art will recognise that present techniques have a broad range of applications, and that the embodiments may take a wide range of modifications without departing from any inventive concept as defined in the appended claims.

Claims

1. An expandable tamponade for treating penetrating wounds, the tamponade comprising:an expandable foam;a housing containing the expandable foam, wherein the foam is held in a first compressed state in the housing; anda valve for controlling fluid flow into and out of the housing, wherein when the valve permits fluid to flow into the housing, the foam expands and is held in a second expanded state in the housing.

2. The tamponade as claimed in claim 1 wherein, in the compressed state, the expandable foam is rigid to enable insertion of the tamponade into a wound tract.

3. The tamponade as claimed in claim 1 or 2 wherein, in the expanded state, in use, the expandable foam provides a pressure against a wound tract.

4. The tamponade as claimed in any preceding claim wherein, in the compressed state, the expandable foam has a conical shape.

5. The tamponade as claimed in any preceding claim wherein the expandable foam is made from a reticulated foam and / or a melamine based foam.

6. The tamponade as claimed in any preceding claim wherein, in the compressed state, the expandable foam has a diameter of less than or equal to 10mm along a length of the foam.

7. The tamponade as claimed in any preceding claim wherein, in the expanded state, the expandable foam has a diameter of at least 30mm and, in use, exerts a pressure of at least 100 MmHg on a wound tract.

8. The tamponade as claimed in any preceding claim wherein the housing is an expandable housing.

9. The tamponade as claimed in any preceding claim wherein the housing is a flexible housing.

10. The tamponade as claimed in any preceding claim wherein the housing is made from a biocompatible material.

11. The tamponade as claimed in claim 10 wherein the housing is made from latex.

12. The tamponade as claimed in any of claims 1 to 11 wherein the valve is a one wayvalve that allows fluid to enter the housing.

13. The tamponade as claimed in any of claims 1 to 11 wherein the valve is a two way valve.

14. The tamponade as claimed in any preceding claim further comprising a connection for connecting the valve to a pump for removing fluid from the housing, to thereby compress the foam.

15. The tamponade as claimed in any preceding claim further comprising a connection for connecting the valve to a fluid source for inserting fluid into the housing, to thereby expand the foam.

16. The tamponade as claimed in any preceding claim further comprising a fastening mechanism for fastening the tamponade to a patient.

17. The tamponade as claimed in claim 16 wherein the fastening is coupled to the housing.

18. The tamponade as claimed in claim 16 or 17 wherein the fastening mechanismcomprises a strap for strapping the tamponade in position on the patient.

19. The tamponade as claimed in claim 16 or 17 wherein the fastening mechanism comprises at least one hook for insertion into skin of the patient.

20. The tamponade as claimed in claim 16 or 17 wherein the fastening mechanism comprises a strap and a hook for insertion into skin of the patient.

21. The tamponade as claimed in claim 16 or 17 wherein the fastening mechanism comprises adhesive for adhering the tamponade to skin of the patient.

22. The tamponade as claimed in any preceding claim wherein the housing comprises a retention mechanism on an external surface of the housing for retaining the tamponade within a wound tract.5 23. A first responder kit, the kit comprising:at least one expandable tamponade as claimed in any of claims 1 to 22 wherein each tamponade is provided in a removable wrapper.

24. The kit as claimed in claim 23 wherein the removable wrapper retains the tamponade 10 in a compressed state.

25. The kit as claimed in claim 22 or claim 23 wherein the removable wrapper retains the compressed tamponade in a conical shape.15

Images