WO2008011675A1

WO2008011675A1 - Medical practice device

Info

Publication number: WO2008011675A1
Application number: PCT/AU2007/001034
Authority: WO
Inventors: Jagdeep Heer; Kyriakos Tanousis
Original assignee: Simulation Medical
Priority date: 2006-07-27
Filing date: 2007-07-26
Publication date: 2008-01-31

Abstract

A medical or veterinary training device, comprising: a plurality of elements arranged in layers, wherein at least two elements are bonded together at adjacent surfaces; wherein at least one of the plurality of elements is adapted to simulate at least one material property of human or animal skin; and wherein at least one non-skin element is adapted to simulate at least one material property of a human or animal tissue or tissue component.

Description

MEDICAL PRACTICE DEVICE

BACKGROUND TO THE INVENTION

The invention relates to a device for demonstrating, teaching, and practicing techniques in the area of medicine. In particular the device is suitable for demonstrating, teaching, and practicing techniques such as the administration of an injection, drawing blood, and cannulization. The device is suitable for use by a wide range of people, including a medical trainer, a trainee in a healthcare profession, and a patient learning how to self- administer an injectable medicine, for example epinephrine.

In this specification where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was publicly available, known to the public, part of common general knowledge, or was known to be relevant to an attempt to solve any problem with which this specification is concerned at the priority date of the present invention.

While the invention will be described with reference to the administration of injections, it will be readily understood by the person skilled in the art that the invention is not so limited but extends to techniques such as cannulization and the taking of blood samples.

Injections generally

An injection is the introduction of a substance, such as a fluid, into the body, usually by means of a syringe and needle, which is pierced through the skin so as to allow the substance contained within the syringe to be forced through the needle into the body. As is well known in the medical arts, a wide variety of substances may be injected, such as, for example, a test substance (as in. determining allergic sensitivity or immunity to a disease), an anaesthetic, a therapeutic drug, a nutrient (such as in cases where intravenous feeding is necessary), blood, or blood plasma, etc.

Injections are usually described in terms of the location or tissue type into which the injection is made. An intracutaneous injection is the introduction of a small amount of fluid into the subcutis, the layer of skin directly below the dermis and epidermis (which are collectively referred to as the cutis, or cuticle layers). The subcutis and cutis together are referred to as the cutaneous layers and comprise the skin. A subcutaneous injection is directed to the tissues immediately below the skin, which in mammals is generally a fatty layer. Due in part to the relatively restricted circulationln the cutaneous and subcutaneous tissues, substances administered intra- or subcutaneously tend to be absorbed slowly. Intracutaneous and subcutaneous injections are commonly self-performed by patients.

When quicker absorption of a drug is required, an intramuscular injection or intravenous injection may be used. Intramuscular injections pierce the cutaneous and subcutaneous layers and penetrate the muscle beneath. For example, most vaccines are delivered by intramuscular injection, so that the immunogen will be accessible to the circulating cells of the immune system while still being somewhat restricted to the site of injection. Intravenous injections pierce the cutaneous and subcutaneous layers and penetrate a vein located in or below the subcutis, often within the fatty layer below the subcutis and above underlying muscle or between muscle groups. Generally, intramuscular or intravenous injections are delicate procedures and are administered by a trained medical professional. However, self-administration of these types of injections is becoming increasingly common for patients who require such injections on a routine basis.

Prior art practice devices Efficient administration of an injection requires a degree of skill and dexterity that can only be achieved with practice. Without practice, various deleterious effects may occur, for example, the injection can cause pain, tissue damage, excessive bleeding leading to haematoma, the introduction of an air embolus, and may be of limited effectiveness if the proper site of injection (such as a vein) is missed. Furthermore, for people self- administering medication, there can be an added mental barrier associated with piercing their own skin and other tissues. Accordingly trainee professionals such as doctors, veterinarians, paramedics and nurses as well as human patients who must self-administer medicine must spend a great deal of time practicing the administration of injections.

In the past, oranges were often used for practicing and teaching the administration of injections. However the skin and peel of an orange does not have the look and feel of skin and flesh. Furthermore they do not have any structures that approximate a blood vessel, such as a vein and are therefore of limited value for practicing intravenous injections.

A number of devices currently exist for teaching and practicing medical techniques and procedures. For example, medical mannequins which have the appearance of a real body, or specifically designed anatomical mock-ups of limbs are commonly used in medical schools for learning a range of clinical skills. Some high-tech medical mannequins have realistic skin, and 'see-through' portions showing internal body structures such as bones, muscles, nerves and veins. The 'feel' of the mannequin is such that correct intramuscular injection sites can be palpated. A visual indicator, such as a green light, indicates correct injection technique and positioning - a buzzer and flashing red light warn students if they have pushed the needle in too deep or if the needle position is incorrect

The simulator intravenous arm from Kyoto Kaguku Co.Ltd is a life-like simulator for injection practice. It accurately reproduces vein location and blood is pumped around the veins by an electric pump for a realistic effect, including induction of back-flow into the injection needle. The simulator intravenous arm thus allows the practice of administration of injections and blood collection from the basilic, median antebrachial and cephalic veins.

A similar paediatric injection training arm is available from Gaumard Scientific and is typically attached to a child-size mannequin. The training arm contains anatomically located venous grooves which are fitted with soft latex tubes closely simulating the consistency of the veins. A translucent, pliable latex skin, which is removable and washable, is stretched over the venous structure. The paediatric training arm is also equipped with (1) subcutaneous injection areas on the volar side of the forearm and the lateral side of the upper arm; (2) an intramuscular injection site in the deltoid area; (3) two veins in the dorsum of the liand for additional intravenous training techniques.

However the mannequin and injection training arms are typically too complex, require high maintenance, and are too expensive to allow convenient and economical practice of advanced clinical skills. Furthermore, component parts for assembly of these devices are often made of relatively expensive materials. For example, leather or suede are often used for simulation skin, and some even use cultured cells as components. As a result, these complex and expensive training tools are only used by medical schools and other teaching and research institutes.

The Venipuncture Pad is a soft-tissue, strap-on pad for use in practicing venipuncture, but is specifically designed to be strapped on to the antecubital fossa of the right arm. It includes replaceable veins that are self-sealing and rechargeable via a one-way valve supplied with mock blood under pressure. However this type of pad is relatively expensive and complex, particularly for trainees who may not be able to afford the cost nor need such a complex device. Furthermore it is designed only for use in the antecubital fossa of the arm, and it does not simulate the layers of skin, fat and muscle that the trainee will encounter when carrying out a medical technique such as administering an injection or cannulization.

MedWorldwide and LifeForm also provide simple, multi-layered, soft tissue pads representing epidermis, dermis, fat layer, and muscle layer. The epidermis layer may be peeled back or the pad squeezed to release injected liquid. It can also be strapped onto a base-plate which is then attached to a real arm for role playing. However while these simple pads allow the practice of intradermal, subcutaneous, and intramuscular tissue injection techniques they are not adapted for teaching or practicing intravenous injection. Furthermore, none of the simple soft tissue pads currently available simulate the connective fascia between or surrounding some tissues; the sensation of piercing connective tissue is an important aspect in the successful practice of medical injection techniques that is not provided by the commercially available training aids.

Accordingly (here is a need for a simple, low cost device for demonstrating, teaching and practicing medical techniques such as the administration of injections, cannulisation and taking of blood samples. There is further a need for such a device that is manufactured from inexpensive component parts but that still renders an accurate simulation of human or animal anatomy, particularly its consistency and other material properties.

SUMMARY OF THE INVENTION

Therefore, in one aspect of the invention, there is provided a device suitable for the demonstration, practice and teaching of skin-penetrating needle techniques, the device comprising a skin simulating layer; and at least one blood-vessel simulating tube, wherein at least one tube is adapted to contain a blood-simulating fluid. Preferably the device will further comprise a muscle simulating layer, bone simulating layer, and a fat simulating layer. Even more preferably, the layers are bonded together using a bonding agent that simulates the consistency of human or animal connective fascia; in some embodiments, double-sided tape is a preferred bonding agent.

In a second aspect of the invention, there is provided a device suitable for attachment to a limb for the practice and teaching of intradermal, subcutaneous, intramuscular and intravenous techniques, the device including a pad comprising: a dense first layer adapted to prevent needle stick injury as well as simulating bone, which in use is located adjacent the limb; a second layer adjacent to the first layer simulating muscle tissue; a third layer adjacent to the second layer simulating fat tissue; and a fourth layer adjacent to the third layer simulating skin. Preferably, the device will include a means for attaching the pad to a limb. Preferably, one or more tubes simulating blood vessels are disposed intermediate at least two of the layers, the tubes being adapted to retain a fluid simulating blood. In some instances, the tubes may penetrate or pass through, in whole or in part, one or more tissue- simulating layers.

According to another aspect of the invention, there is provided a medical or veterinary training device, comprising: a plurality of elements arranged in layers, wherein at least two elements are bonded together at adjacent surfaces; wherein at least one of the plurality of elements is adapted to simulate at least one material property of human or animal skin; and wherein at least one non-skin element is adapted to simulate at least one material property of a human or animal tissue or tissue component. The device may comprise a plurality of non-skin elements which may for example each simulate a different human or animal tissue. In some embodiments, bonding is effected by a bonding agent disposed between the adjacent surfaces and bonding may for example simulate human or animal fascia between and appropriate to the adjacent simulated tissues. In some preferred embodiments, the bonding agent is double-sided tape. In some embodiments of the invention, the device further comprises at least one tube disposed within the device; wherein the at least one tube is adapted to simulate at least one material property of a human or animal blood vessel. The tube may for example be substantially elastomeric. The material property may for example be selected from the group consisting of consistency, resiliency, density, size, thickness, depth, and color.

In some embodiments, at least one element comprises expanded foam rubber and the tube may for example comprise silicone. In some embodiments, at least one of the elements is adapted to simulate fatty tissue. In some embodiments, at least one of the elements is adapted to simulate muscle tissue. In some embodiments, at least one of the elements is adapted to simulate bony tissue.

In some embodiments, at least one tube is disposed between adjacent elements which may for example be between the skin-simulating layer and an adjacent layer. The tube may be disposed within a groove or recess in at least one element. Some embodiments further comprise at least one simulated human or animal body fluid disposed within the at least one tube and the simulated human or animal body fluid may for example be simulated blood. In some preferred embodiments, there is further provided a simulated body fluid reservoir communicatingly connected with the at least one tube. Some embodiments comprise a fitting communicatingly attached to at least one exposed end of the at least one tube. A fitting may for example be selected from the group consisting of one-way valves, two-way valves, and Luer fittings and may be adapted to communicate with an external accessory which may for example be a fluid pump adapted to pressurize the simulated body fluid within the at least one tube. In some embodiments, optionally at least one tube and / or at least one layer is adapted to simulate a characteristic appropriate to the application, such as species, age, physiological state, pathology, etc.

In some embodiments, at least one element is optionally substantially elastomeric, polymeric, plant-derived, animal-derived, or man-made. In some preferred embodiments, at least one element is optionally substantially elastomeric.

Ln another aspect of the invention, there is provided a method for manufacturing a device of any of the preceding claims, comprising:

(a) selecting a particular device application based on characteristics such as species, age, physiology, pathology;

(b) selecting an element for a skin simulating layer, and optionally at least one tissue- simulating layer, and optionally at least one blood-vessel simulating tube to simulate the characteristics of the application in (a);

(c) selecting at least one bonding agent to bond adjacent elements into layers of a composite;

(d) bonding at least two elements in layers, optionally with the at least one blood-vessel simulating tube disposed between two adjacent layers, with the at least one bonding agent so as to form a composite to simulate the application.

The method may further comprise a step of: (e) cutting and shaping the composite into a final form.

The bonding agent may for example simulate at least one type of fascia present in the application. A plurality of devices may be cut in final form from a larger length of composite and cutting may be performed by any suitable means, for example, using water jet technology or compression press cutting. Some embodiments comprise a step of communicatively attaching at least one fitting to at least one exposed end of the at least one tube.

A device according to the present invention may be used for practicing a wide variety of techniques. By way of example only, it may be used in relation to administration of injections, cannulization, and taking of blood samples. For example the device of the present invention allows a trainee the experience of taking blood samples or injecting or cannulising a limb without having to practice on a living patient. In particular, water, saline or other fluids may be injected to simulate an intradermal, subcutaneous, intramuscular or intravenous injection.

DETAILED DESCRIPTION

Layers

The different layers of the device replicate the anatomical layers such as skin, fascia, fat, muscle and bone. The differences in resistance of the layers mimic the resistance felt when piercing a needle through skin, fat and muscle. In actual injection practice, various tissues have representative material properties, such as consistency, and resistance to puncture by and passage of a needle or other object. Further realism may be obtained by simulating the fascia that surrounds tissues and/or connects adjacent tissues.

The layers of a device according to the present invention may be composed of any suitable materials. For example, in some applications relating to animal simulations, real skin from ^■ an animal of that species may be used. Such skin may optionally be pre treated in order to increase the pliability and provide for a better simulation of the skin as if it were alive. Similarly, one or more other layers of the device may comprise any other suitable material, such as animal or plant derived products, or man-made products, such as elastomers or other types of polymers. In some embodiments, a bone layer may comprise an actual bone, or an artificial bone (for example made from a cast) of the species of the application.

The fascia typically presents as a thin, relatively firm layer that provides a momentary resistance to penetration that is higher than the tissue the fascia surrounds. Accordingly, a thin, relatively viscous or rigid layer is preferably disposed between certain layers of the present invention. In some preferred embodiments, this layer comprises the bonding agent that connects adjacent layers. A surprising and unexpected benefit is obtained when the bonding agent used is double-sided tape; since double-sided tape effectively and economically simulates connective fascia.

In some embodiments, one or more layers are adapted to simulate particular characteristics of certain species, or physiological states, such as age, nutritional status, physiological status, pathology, disease state, etc. Thus in some embodiments, the connective tissue and skin structure of a dog, cat or horse is simulated. This is very different to that of a human as canine skin is much more loose and flexible and is attached to an underlying thin sheet of muscle.

Li other embodiments, fascia or other connective tissue may be simulated by a layer of material attached to one of the other simulating layers. Thus, for example, in some embodiments, the simulated fat layer may comprise on one surface a sheet of material which .is less easy to penetrate, and so simulates the resistance and then 'popping through' sensation of piercing fascia with a needle. Similarly, in other embodiments, the connective tissue or fascia may be simulated by a completely separate layer which may or may not be attached, or adhered to any other layer. In one embodiment, a first layer is adapted to prevent needle stick injury to a person wearing the device. For example, a hard, dense layer of vulcanized rubber or another comparatively rigid polymer, such as hard plastic, may be suitable and could simulate bone. This hard, dense layer would typically be from 5mm to 7mm in thickness. Alternatively some grades of materials such as mylar or Kevlar which are thin and flexible but resist piercing by a needle may be suitable. In some preferred embodiments, a preferred material for this layer is acrylic.

In a preferred embodiment, a second layer is typically of a thickness and density that simulates muscle. For example certain densities of expanded foam rubber may be suitable. Typically this layer would be from 4mm to 7mm in thickness, but may be substantially thicker or thinner depending upon the muscle type or size to be simulated or depending on the depth of muscle penetration required to simulate the particular anatomy desired.

In a further preferred embodiment, a third layer is typically thinner and less dense than the second layer and simulates fat. Certain densities of expanded foam rubber may also be suitable for this layer. Typically this layer would be from 3mm to 5 mm in thickness, but may be substantially thicker or thinner depending upon the application. For example, if the trainee requires training in injecting obese patients, the fat layer might be much thicker.

In an even further preferred embodiment, a fourth layer of the pad is the outer layer simulating skin. This layer may be unitary or may be a composite such as a non-expanded polymer coating over a thin layer of expanded polymer. This layer would have a density greater than the fat layer but less than the muscle layer. Typically this layer would be from lmm to 3mm in thickness. Again, the thickness may be substantially thicker or thinner depending upon the application. For example, veterinary applications may require skin 2 to 4 centimeters thick to simulate elephant hide. . In some embodiments, the outer (skin) layer mimics the skin's resistance to wear from the application of isopropyl alcohol which is commonly applied prior to injections or venipuncture.

The various layers comprising the device may be of any suitable thickness and consistency and will vary with the intended application. Thus, for example, they may vary to mimic different species and different anatomical sites, thus for example, the face, deltoid, gluteal regions, etc. Furthermore, the various layers may be of different thicknesses to simulate various patient physiological states, such as obesity, cachexia, malnourishment, pregnancy, lactation, etc.

Even further, the various layers may incorporate inclusions to mimic anatomical landmarks or other features; likewise, such features may be incorporated into the intermediate space between layers. Such anatomical landmarks are frequently useful to trainees in learning to make injections into the locations of such features, for example, in the neck. Anatomical landmarks or features that are simulated may include bone, cartilage, ligament, tendon, nerve, muscle, lymph duct or node, organ or gland, and the like, and may even include simulations of artificial objects such as pacemakers, implanted defibrillators, artificial joints or valves, screws, rods, filaments, surgical instruments. Even further, these inclusions may simulate objects present as the result of traumatic accidental injury, such as pieces of wood, stone, or metal, or of violent injury, such as teeth, claws, bullets, shrapnel, blades, and the like.

In some embodiments^', the device comprises layers with specified thickness, density, and materials to simulate layers such as skin, fat, muscle, and bone layers and to mimic actual tissue feedback from needle piercing procedures and palpation. Thus as a needle is pierced through the layers or into a tube, a trainee feels the same or similar resistance that they would feel if injecting a real patient.

Further, the various layers of the device and the simulated vessels may be of any suitable colour, and would usually simulate the colour of skin in the population (whether human or animal) to be simulated. Thus, in some embodiments, the outer (skin) colour may be dark, and in others, it may be light. The outer (skin) layer may also comprise hair to further add to the realistic effect. This may be particularly important in certain applications for certain anatomical sites and in certain species. In some embodiments, the outer (skin) layer may be transparent to facilitate learning by the user. In some embodiments, the user may see all layers of the product from the sides (this allows the user to be aware of approximate depths of each layer and can therefore judge the depth of the needle when injecting the different layers of human anatomy). In others, it will be opaque so as to require the user to palpate the vessel in question.

Simulated Vessels

The tubes simulating blood vessels may be at any suitabl e location within the device. The location will usually be dependent on the intended application. Thus, for example in some embodiments, such a tube may be located intermediate a third and a fourth layer (or intermediate a second and a third layers to simulate a deeper vessel) and are typically located within grooves in the layers. However, in some applications, it may be necessary to simulate vessels that are transiting between layers or loop into and then out of a layer. Typically the veins are palpable. This can be achieved by controlling not only the location of the tube(s), but also the diameter and material of construction of the tubes. In reality, the 'feel' or palpability of a blood vessel in a patient depends upon a number of factors such as the age and weight of the patient and any relevant disease state. In a preferred embodiment the device of the present invention includes tubes of different diameters, compositions, and wall thicknesses to simulate the differing feel of blood vessels. For example a blood vessel in an older person with arteriosclerosis could be simulated by a small diameter tube or tube with a comparatively thick wall made of a comparatively rigid material. A blood vessel in a younger person could be simulated by a larger diameter, thinner walled tube having higher elasticity.

In some embodiments, the tubes may also have other characteristics which simulate the variety of vessel types found in patients. Thus for example, using particular polymers, certain tubes may be more or less friable, or leaky or prone to rupture or extravassation, etc.

The tubes may be of any suitable diameter; in human applications, the diameter of the tubes simulating such veins may typically range from about 1mm to about 3mm. However smaller and larger diameters are also contemplated, particularly in veterinary applications of the invention. Thus for example, a very fine diameter may be used for a device which simulates a kitten's cephalic vein, but a much thicker device may be used to simulate the jugular vein of a horse. In some embodiments, the tubes may be housed in a ridge that is mostly rigid, to stimulate bone. For example, to simulate the commonly-used tail vein in cattle medicine.

Preferably the tubes are made of a polymer. In one preferred embodiment the tube is self- sealing after puncture with a needle. Many silicone based polymers would be suitably self sealing and it is estimated that an appropriate silicone tube could be punctured a suitable number of times (for example, over 500 times) before it develops permanent fluid leakage that renders it no longer usable.

The architecture of the tubes that simulate the vessels may vary for any suitable reason, for example, to simulate various levels of difficulty in vein architecture. Thus, for example, in some species, the vessels at certain anatomical sites are notoriously difficult to access. Furthermore, in some embodiments, the tubes further simulate the anatomical characteristics of the vessel in question, such as for example, the path taken by the vessel, its depth, thickness, any branches, and so on, for example the (cephalic, basilic, etc veins in humans). In some embodiments a variety of different types of vessel-simulating tubes will be present together. Thus, for example, arteries with veins, each of varying wall thickness, diameter, and depth to simulate the real situation.

The vessels may also vary in depth in order to simulate type of vessel, such as veins (superficial) or arteries (deeper). In some embodiments, various physiological alterations are also simulated, for example, by varying the diameter, or other characteristics of the vessels. Thus, in some embodiments, the vessels may be more friable, or may demonstrate age-related anatomical changes, such as for example, in pediatric, geriatric, or normal healthy adult populations.

In some embodiments, the vessels may be movable, for example, to simulate geriatric veins and other vessels that require the practitioner to manually tether the vessel before injecting.

In some embodiments, the device incorporates connective fittings, such as Luer fittings, at the ends of vessels to allow universal fitment of hospital equipment (e.g. syringes, cannulas, IV bags...etc.) and extensions. Thus, the tubes can readily be adapted for use with other medical systems or devices.

In some embodiments, the device further comprises a valve system disposed within and/or at the ends of the tubes to allow blood flow in only one direction (as in veins). Such an embodiment is useful for a variety of reasons, for example, for simulating the taking of arterial blood gases. Preferred embodiments may further comprise a pump to simulate pulse and may increase tube pressure for flashback. In other embodiments, the device comprises a two-way valve system to allow refilling or use of the device in either direction of flow.

Blood simulant

The fluid simulating blood may be retained within the tube under slight pressure to provide the appropriate feeling of resistance when a trainee injects fluid into the tube. In one preferred embodiment of the present invention, each tube is sealed or blocked at one end, the other end extending out from the pad and adapted to be attached to a syringe for manually increasing the fluid pressure in the tube. Equally, though in other embodiments, the tube may be sealed at both ends, with for example a capping device.

The fluid in the tube typically has the viscosity and flow characteristics of blood. For example a solution of glycerol of appropriate viscosity could be used. The fluid should not be too viscous, otherwise it will hold open puncture holes in the tube and prevent self- sealing.

Simulated blood may have any suitable characteristics as required for the intended application and such characteristics may be designed to change in use. Thus, for example, the fluid may be bright red to simulate arterial blood and darker red or purple to simulate venous blood. In some embodiments associated with practicing emergency procedures, the colour of the blood may change during a set period to simulate an emergency situation in which the oxygenation status of the patient is rapidly changing. Such an embodiment will be useful for example in simulating the feeling of time pressure in practicing the emergency technique.

In some embodiments, there is provided at least one mock-blood reservoir to increase the amount of fluid withdrawal, increase the flash-back affect, and increase the number of uses before the device must be refilled. Any suitable mechanism may be used for such a reservoir, some examples include, an IV bag, a syringe attached to the vessel-simulating tubing via connector, or other reservoir.

Attachment means

The device itself as a whole may be of any suitable shape. In those embodiments that are intended to be strapped to a body part of a human or animal, then preferably they are appropriately shaped so as to readily fit on those parts. Thus, for example, in humans, the shape may be designed for the forearm, gluteal, thorax and so on.

In a particularly preferred embodiment the pad is elongated so that in use it may be located along the entire length of the simulated limb, such as a person's thigh, calf, upper arm or lower arm.

Equally, it may simulate another anatomical site, such as the ear of a rabbit, the tail of a cow etc. Some embodiments may simulate an artificial device located beneath the surface of the skin, such as an injection port for chronic intravenous therapy (such as chemotherapy). The device may be attached, for example, by straps at either end of the pad, the straps being secured by any convenient means such as buckles or hook and loop (Velcro) fastener. Straps are preferred in some embodiments because a strap may perform the function of a tourniquet and many injection techniques require the application of a tourniquet.

Alternatively the pad may wrap around a limb, the longitudinal edges being secured by, for example, Velcro straps.

Those embodiments that comprise a strapping system may also comprise the ability to readily remove the strapping system so that the device can be used as a stand alone unit, without a partner.

In some embodiments, the device is able to be attached (for example strapped) to a piece of furniture in order to maintain its position during use. Thus for example, it may be strapped to the arm of a chair to simulate the arm of a patient sitting for venupuncture. In other embodiments, the device comes with a stand to which it can be attached to hold it steady for use. Embodiments such as these increase the ease of use of the device by a single person.

In some embodiments, there is provided an integral acrylic/plastic base layer that serves as a protective layer to prevent accidental needle injury to users and also serves as a bone layer for feedback. Such an acrylic/plastic layer can also be modified to allow direct incorporation of a strapping system. Such an acrylic/plastic layer can also be modified with a slip resistant material or layer to allow usage of the injection pad as a stand alone unit, on a flat surface. In some further embodiments, the device may be adapted to be a component of a larger simulator. Thus for example, it may be a swappable, detachable forearm on a mannequin, or it may comprise a swappable or detachable component of a forearm itself. Attachment may be in any suitable way, for example, as a superficial attachment or into a dedicated recess such as the unit becomes an integral part of the mannequin.

Materials and Manufacture

The device can be manufactured so as to be alterable to a variety of applications. Equally though, application-specific versions of the device may also be manufactured. Such applications may be dependent on species, type of health care (such as nurses, doctors, surgeons, paramedics, dentists, veterinarians, etc), anatomical site, physiological state, age, pathology and so on. The material selected to simulate the desired application should replicate at least some of the material properties of the tissues simulated in the application. Relevant material properties include consistency, resiliency, density, size, thickness, depth, and color.

Preferably, the materials used in manufacturing the device are inexpensive and readily obtained commercially in an immediately useable form. Elastomeric polymers are preferred materials for both the tissue-simulating layers and vessels. For tissue-simulating layers, expanded foam rubbers of various densities and compositions are available in suitable consistencies, are easy to work with (i.e., to cut and shape), and are easily obtained in the commercial market. Examples of suitable expanded foam rubbers include EVA, such as EVA 30, PE, such as PE 30. Natural elastomers are also preferred, for example natural gum sheet is a preferred skin-simulating material. Tubing for the vessels preferably comprises silicone. T240 and T238 silicone tubing are examples of preferred tubing for the vessels.

Some embodiments further comprise at least one two-way valve or connector connected to at least one end of a tube which allows the addition of caps, syringes, and any other accessory products (e.g. reservoir bag, ABG pulse pump, pressure inducer for flashback... etc.) with universal connectivity. Such a two-way valve system may also allow for increased efficiency of production by allowing the entire device (all layers and tubing) to be cut in one uniform process. All valves and fittings (e.g., Luer fittings) usable in the present invention are commercially available, for example from medical supply houses. Valves and fittings are preferably attached to the tubes using appropriate glues or solvents as are well known to one skilled in the art.

In some embodiments, the device is adapted to form a component of or to be attached to a simulated body or body part, such as a pre-formed arm. In such cases, accessory equipment that might be connected directly to the device are preferably connected indirectly to the device by way of the simulated body part. For these embodiments, the device is adapted to receive the input (fluids, etc.) from connectors on the simulated body part.

Assembly may be performed in any suitable way. Typically, a material for each layer is selected to best simulate the layers present in the tissues of the desired application. The layers are laid down sequentially with a bonding agent in between each layer, as desired, and pressed together. Vessel-simulating tubes are typically sandwiched between layers, as is the case for blood λ'essels in most applications. However, the tubes may be disposed within grooves, holes, or recesses cut into the layers as is desired to simulate the particular application. These grooves may be cut in any convenient way, including for example hand or machine-operated cutting or grinding technologies. For ease of manufacture, and to avoid lengthy cure periods, rapid-setting bonding agents are preferred. Even further, as indicated above, the bonding agent preferably simulates the material properties of the type of fascia or connective tissue, if any, that exists between tissue layers in the application. Bonding agents include any of a multitude of glues and/or solvents suitable for joining elastomeric polymers as are well known to one skilled in the art. Preferably, the bonding agent is double-sided tape.

Thus, for example, in some embodiments, incorporation of double-sided tape as the bonding agent prevents layers from coming apart, prevents trapping of air in between layers, and simulates a fascia layer of connective tissue between layers that allows user feedback to know the needle has traversed a layer. Furthermore, using such double-sided tape is much faster and provides more consistent manufacture than the use of glue or similar techniques.

In some embodiments, the bonding agent is absent from all or part of the intermediate space between two layers. Such embodiments include, for example, applications in which the adjacent tissues are not connected firmly across their entire surface and applications mimicking pathological states in which connectivity is absent. In one embodiment, an area (such as a circular area) of adjacent tissue layers is left without bonding agent to simulate the presence of a cyst. In this embodiment, the circular area may be filled with fluid prior to use of the device so as to expand into a fluid sphere and allow a trainee to practice draining the "cyst."

In another aspect of the invention, there is provided a method of manufacturing a device according to the present invention. The method comprises the steps of (a) selecting a particular device application based on characteristics such as species, age, physiology, pathology, etc

(b) selecting a skin simulating layer, at least one tissue-simulating layer (if desired), and where required, at least one blood-vessel simulating tube to simulate the characteristics of the application in (a);

(c) selecting bonding agent(s) to join the layers and simulate the type(s) of fascia present in the application; and

(d) assembling the layer(s) and tube(s) with the bonding agent(s) so as to simulate the application.

In some embodiments, the substrate is fully assembled with veins already in situ before cutting final shapes. This greatly simplifies mass production. For example, expanded foam rubbers may be obtained as large sheets and silicone tubing may be obtained.in long lengths. Thus, a large number of substrate units may be cut from a single length of pre- bonded materials, or individual substrate units may be cut from the end of an endless length of pre-bonded materials, which for example may be formed from expanded rubber sheeting, double-sided tape, and rubber tubing dispensed from rolls into a pressing machine. In these embodiments, after cutting, exterior fittings, valves, accessories, etc., are affixed to the cut-offends of the integrated tubing.

In some embodiments, vessel tubing is cut flush with the edge of the substrate or pad. This again simplifies the mass production of units. Many benefits arise from this approach, for example, it limits the amount of manual labour involved, allows each unit to be identical, decreases cost per unit, decreases manufacturing cycle time, allows large numbers to be made quickly. It also reduces the packaging space requirements thereby reducing packaging costs.

In some embodiments, the manufacturing method comprises the use of presses, high pressure water jet laser, blade, and saw technologies, and other technologies known in the art. Preferably, the cutting processes are automated and controlled electronically by computer so as to allow easy alteration, modification, and changeover of the control templates. Such technologies, such as a high powered waterjet or compression press cutting either of which may be controlled by computer, allow many electronically templated units to be cut at high speed and high accuracy from larger sheets of fully assembled materials.

Methods of Use

The present invention further includes a method for demonstrating, teaching or practicing medical techniques including administering injections, cannulization or taking of blood samples including the step of using a needle to pierce the device of the present invention. In one preferred embodiment, a pad with a pump attachment to simulate a pulse may be used to practice taking Arterial Blood Gas (ABG) samples.

In some embodiments, the device is used to simulate the injection of a non-fluid substance. This may for example be the sub-cutaneous application of a device such as a pump, or chip, controlled-release implant (such as Norplant), or any other suitable thing.

Kits

In another aspect of the present invention, a kit. is provided that includes instructional materials, practice injection devices, and a simulation device for a particular application to allow a trainee to obtain instruction and practice for that application.

In one preferred embodiment, a kit is provided to teach patients and other trainees to use emergency epinephrine injection systems, for example the Epipen system, in cases of anaphylaxis. In this embodiment, the kit provides a simulation device that simulates the ventral surface of a human thigh for intramuscular injection. Thus, the simulation device comprises four layers (simulated bone, muscle, fat, and skin) and does not include any vessels. The simulation device includes straps for affixing the device to the thigh of a practice subject. The kit also provides a simulated Epipen, and it provides an instructional CD/DVD showing the causes and signs of anaphylaxis, precautions to avoid anaphylaxis, correct use of the injection system (Epipen), how to recognize a successful treatment, and emergency procedures for in case the treatment fails. In other embodiments, other forms of epinephrine pen may be used, for example, the Twinject epinephrine pen which gives a double dose of epinephrine and has becoming more widely used in the recent past.

Examples

Various embodiments/aspects of the invention will now be described with reference to the drawings presented herein, in which,

Figure Ia is a drawing of a device according to one embodiment of the present invention, laid flat as when not in use, and

Figure Ib is a cross section plan view across AA' of Figure Ia.

Figure 2a is a drawing of a device according to a further embodiment of the present invention, laid flat as when not in use, and Figure 2b is a cross section plan view across AA' of Figure 2a.

Figure Ia shows one embodiment of a device (1) of the present invention designed to be attached to a person's forearm. The device comprises a pad (5) that is generally elongate, and, in this embodiment, about 24cms in length. One end of the.pad is approximately 12cms in width, narrowing at the other end to about 6cms in width; these and other measurements associated with this particular application may be changed according to the requirements of another application. In use the pad (5) is attached to a person's forearm by two buckled straps (15a, 15b), the narrow end of the pad being buckled adjacent the wrist (15a), the wider end (15b) being adapted to be buckled adjacent the elbow. The pad (5) is constructed of four layers of polymers, in which are embedded three silicone tubes (10a, 10b and 10c) of 3mm (10a), 2mm (10b) and lmm (10c) diameter respectively.

Figure Ib is a cross section plan view across AA' of Figure Ia. In this view can be seen the first layer (20a) consisting of acrylic, the second layer (20b) consisting of a layer of expanded foam rubber, the third layer (20c) consisting of a layer of foam rubber and the fourth layer (2Od). The tubes (10a, 10b, 10c) are embedded between the third layer (20c) and fourth layer (2Od).

Figure 2a shows one embodiment of a device of the present invention designed to be adaptable to attach to a body part. The device comprises a pad (35) that is generally elongate. In use the pad (35) may be attached to a body part by one or more straps which may pass through slits 36. The pad (35) is constructed of multiple layers of polymers, in which are embedded two silicone tubes (30a and 30b) of 5mm (30a) and 0.5 mm (30b) diameter respectively. The ends of the tubes (30a and 30b) are fitted with universal two-way connectors (31) at both ends of the pad. The connectors are adapted to be attached to a syringe of fluid (not shown) that simulates blood. The syringe can be used to pressurise the tube (35) with fluid and act as an extended mock blood reservoir.

Figure 2b is a cross section plan view across AA' of Figure 2a. In this view can be seen a skin layer (40a), a fat layer (40b), a muscle layer (40c) and a bone layer (4Od). The tubes (30a, 30b) are embedded between skin layer (40a) and fat layer (40b).

In one preferred embodiment of the present invention, the following components are used:

Tissue layer elements:

- Top Layer, 0.8mm Natural gum sheet.

- 2nd layer, 4mm thick beige EVA 30.

- 3rd layer, 7mm thick white PE 30.

Base layer, polystone 300 black acrylic sheet. 4.4mm thick.

Silicone tube for veins:

- Large T2402.5mm (inner diam) x 1.0 mm (wall thickness) silicone tube.

- Small T238 2.5mm (inner diam) x 0.75 mm (wall thickness) silicone tube.

Adhesives:

- Venture tape- 514cw High performance double coated clear tape (SA tape). - Silicone adhesive is used in small amounts to secure the veins into their grooves.

The components are assembled as follows:

- Laminate, 3 bottom layers with SA tape making sure there are no air gaps.

Apply SA tape to Gum "Do not stick gum layer on at this stage".

- Water jet all layers to size.

- Cut tracks for veins to required depth.

- Cut Silicone tube to length and place in track, use small amount of silicone glue to secure tube in place.

- Remove backing from gum layer and stick neatly to top of unit.

- Clean edge of acrylic layer to remove any burrs.-Attach Luer fittings to exposed tube ends using silicone glue.

The word 'comprising' and forms of the word 'comprising' as used in this description does ' not limit the invention claimed to exclude any valiants or additions.

Modifications and improvements to the invention will be readily apparent to those skilled in the art. Such modifications and improvements are intended to be within the scope of this invention.

Claims

CLAIMSWhat we claim is:

1. A medical or veterinary training device, comprising: a plurality of elements arranged in layers, wherein at least two elements are bonded together at adjacent surfaces; wherein at least one of the plurality of elements is adapted to simulate at least one material property of human or animal skin; and wherein at least one non-skin element is adapted to simulate at least one material property of a human or animal tissue or tissue component.

2. The device of claim 1 comprising a plurality of non-skin elements.

3. The device of claim 2 wherein the plurality of non-skin elements each simulate a different human or animal tissue.

4. The device of claim 1 wherein bonding is effected by a bonding agent disposed between the adjacent surfaces.

5. The device of claim 4 wherein the bonding agent simulates human or animal fascia between and appropriate to the adjacent simulated tissues.

6. The device of claims 4 or 5 wherein the bonding agent is double-sided tape.

7. The device of any of the preceding claims further comprising at least one tube disposed within the device; wherein the at least one tube is adapted to simulate at least one material property of a human or animal blood vessel.

8. The device of claim 7 wherein the tube is substantially elastomeric.

9. The device of any of the preceding claims wherein the material property is selected from the group consisting of consistency, resiliency, density, size, thickness, depth, and color.

10. The device of any of the preceding claims wherein at least one element comprises expanded foam rubber.

11. The device of claim 7 wherein the tube comprises silicone.

12. The device of any of the preceding claims wherein at least one of the elements is adapted to simulate fatty tissue.

13. The device of any of the preceding claims wherein at least one of the elements is adapted to simulate muscle tissue.

14. The device of any of the preceding claims wherein at least one of the elements is adapted to simulate bony tissue.

15. The device of claims 7 wherein the at least one tube is disposed between adjacent elements.

16. The device of claim 7 wherein the at least one tube is disposed between the skin-simulating layer and an adjacent layer.

17. The device of claim 7 wherein the at least one tube is disposed within a groove or recess in at least one element.

18. The device of claim 7 further comprising at least one simulated human or animal body fluid disposed within the at least one tube.

19. The device of claim 18 wherein the simulated human or animal body fluid is simulated blood.

20. The device of claims 18-19 further comprising a simulated body fluid reservoir communicatingly connected with the at least one tube.

21. The device of claim 7 further comprising a fitting communicatingly attached to at least one exposed end of the at least one tube.

22. The device of claim 21 wherein the fitting is selected from the group consisting of one-way valves, two-way valves, and Luer fittings.

23. The device of claim 21 wherein at least one fitting is adapted to communicate with an external accessory.

24. The device of claim 23 wherein the external accessory is a fluid pump adapted to pressurize the simulated body fluid within the at least one tube.

25. The device of claim 1 wherein optionally at least one tube and / or at least one layer is adapted to simulate a characteristic appropriate to the application, such as species, age, physiological state, pathology, etc.

26. The device of claim 1 wherein at least one element is optionally substantially elastomeric, polymeric, plant-derived, animal-derived, or man-made.

27. The device of claim 26 wherein at least one element is optionally substantially elastomeric.

28. A method for manufacturing a device of any of the preceding claims, comprising:

(b) selecting an element for a skin simulating layer, and optionally at least one tissue-simulating layer, and optionally at least one blood-vessel simulating tube to simulate the characteristics of the application in (a); (c) selecting at least one bonding agent to bond adjacent elements into layers of a composite;

29. The method of claim 28 further comprising a step of:

(e) cutting and shaping the composite into a final form.

30. The method of claim 28 wherein the bonding agent simulates at least one type of fascia present in the application.

31. The method of claim 29 wherein a plurality of devices are cut in final form from a larger length of composite.

32. The method of claim 29 wherein cutting is performed optionally using water jet or compression press cutting technology.

33. The method of claim 28 further comprising communicatively attaching at least one fitting to at least one exposed end of the at least one tube.

34. The method of claim 28 wherein at least one element is optionally substantially elastomeric, polymeric, plant-derived, animal-derived, or man-made.

5. The method of claim 28 wherein at least one element is substantial!}' elastomeric.