A non-biological blood simulant of use in simulation-based medical trauma training, for training firefighters, military personnel, and other rescue/emergency medical service personnel, and for use in the entertainment fields, such as in the movie making and personal gaming industries.
Training army personnel for various extreme situations is a crucial component of being prepared for combat missions. It is important that every participant in combat is trained to stop bleeding and conduct hemorrhage control. As of the time of this filing, four out of nine critical training procedures involve the use of animal blood. However, the use of animal blood creates an inherent biological hazard and requires the extensive use of live animals. The use of an artificial blood simulant would be a safer and less expensive route for training.
To be effective as a medical training tool, a blood simulant must be able to realistically reproduce situations that the trainee could encounter in the field. For example, the blood simulant should preferably approximate the viscosity, flow characteristics, and clotting properties to those of actual blood. For enhanced realism, the blood simulant may also mimic the appearance, tactile feel, and odor of actual blood.
In one aspect, a non-biological simulant liquid is disclosed. The simulant liquid includes about 30 to about 95 parts by weight of a polymer dispersion or a wax emulsion or dispersion, about 5 to about 70 parts by weight of a rheology modifying agent, and a pigment or a pigment combination. The non-biological simulant has a viscosity that is shear-dependent, such that the viscosity is from about 30 cP to about 300 cP at a shear rate from 0 s−1 to about 10 s−1, and such that the viscosity decreases when the shear rate increases. The pigment or pigment combination imbues the non-biological simulant with a color that approximates that of human or animal arterial or venous blood.
In another aspect, a non-biological simulant liquid includes about 30 to about 95 parts by weight of an alkali resistant acrylic polymer emulsion or a polyethylene wax emulsion, about 5 to about 70 parts by weight of a rheology modifying agent, the rheology modifying agent including a hydrophobic fumed silica dispersion, a water-based pigment combination, the pigment combination including magenta, yellow, and black pigments having a particle size of about 20 nm to about 150 nm, and a matting agent, the matting agent including a coarse-grained precipitated silica. The non-biological simulant has a viscosity that is shear-dependent, such the viscosity is from about 30 cP to about 300 cP at a shear rate from 0 s−ito about 10 s−1, and such that the viscosity decreases when the shear rate increases. The non-biological simulant has a color and an odor that approximates the odor of human or animal arterial or venous blood. When the non-biological simulant liquid forms a dried residue, the dried residue has a low gloss appearance that approximates the appearance of dried human or animal arterial or venous blood.
In yet another aspect, a training system is disclosed. The training system includes a water-based non-biological blood simulant capable of forming a solid or semisolid residue representative of clotting blood and a simulant gauze including a clotting agent, the clotting agent including a superabsorbent material. Contact between the simulant gauze and the non-biological blood simulant induces formation of the solid or semisolid residue.
Other aspects of the invention will be readily apparent in view of the descriptions and examples presented herein.
The non-biological simulant liquid (NBSL) disclosed herein is not suitable for use as a biological blood substitute. It simulates blood only with respect to look, feel, smell, flow characteristics, etc., but does not simulate the biological functionality of blood in a living organism.
The NBSL mimics the rheological profile of blood (as used herein, the term “blood” refers to human or animal arterial or venous blood), including blood's non-Newtonian properties with respect to static and dynamic viscosity, as seen in
To achieve these properties, the NBSL is formed of a combination of a polymer dispersion or a wax emulsion/dispersion, a rheology modifying agent; and a pigment or a pigment combination. As used herein, the term “wax emulsion/dispersion” should be understood to include both liquid-in-liquid mixtures and solid-in-liquid mixtures. The NBSL may further include a matting agent to give the NBSL an appearance, when dried, that mimics the appearance of dried blood. The NBSL may further include an odor agent to give the NBSL an odor that approximates the odor of human or animal arterial or venous blood. The NBSL may be paired with a simulant gauze incorporating an absorbent material, and in one embodiment a superabsorbent material, such that together, the NBSL and the simulant gauze can be used as a training system to simulate an emergency first aid situation involving bodily injury. Contact between the simulant gauze and the NBSL causes the NBSL to form a solid or semisolid residue, which may have an appearance and other characteristics similar to that of dried, clotted blood.
The polymer dispersion or the wax emulsion/dispersion component of the NBSL is a water-based emulsion or dispersion, which is selected so as to provide mechanical strength to the NBSL when “clotting” to form a semi-solid/solid mass when the water is removed (for example, if the NBSL interacts with a superabsorbent material) that has a consistency approximate to that of dried blood. The polymer/wax element of the polymer dispersion or wax emulsion/dispersion component may form micelles when the component is in liquid form, and these micelles may serve as a binder when the NBSL is dried to a residue. The polymer dispersion or the wax emulsion/dispersion forms about 30 to about 95 parts-by-weight of the NBSL. In one embodiment, the polymer dispersion or the wax emulsion/dispersion is about 40 to about 60 parts of the NBSL.
If the polymer dispersion or the wax emulsion/dispersion component is a polymer dispersion, the polymer dispersion may be a polyurethane dispersion, a urethane acrylic dispersion, an acrylic dispersion, a polyvinyl dispersion, or a combination thereof. Suitable commercially-available polyurethane dispersions include BERMODOL® PUR 2130, BAYHYDROL® 2342, BAYBOND® XP 2469, and IMPRANIL® DLP. Suitable acrylated polyurethane dispersions include UCECOAT® 7689 and BAYHYDROL® 2317. Suitable acrylic dispersions include BAYHDYROL® 2546, JONCRYL® 537, JONCRYL® HRC 1645, and JONCRYL® 8383. Suitable polyvinyl dispersions include RESYN® 1025, RESYN® 1072, and DUR-O-SET® C 310.
If the polymer dispersion or the wax emulsion/dispersion component is a wax emulsion/dispersion, suitable wax emulsion/dispersions include MICHEM® Emulsion 77030, MICHEM® Emulsion 61335, MICHEM® Emulsion 24930, JONWAX® 26, and JONWAX® 28.
The combination of the polymer dispersion or the wax emulsion/dispersion component and the rheology modifying agent provides the NBSL with a rheological profile that approximates the non-Newtonian behavior of blood, as shown in
The rheology modifying agent may be a water-based silica dispersion, an acrylic copolymer dispersion, a cellulose-based product, a clay-based product, or any material known in the art as useful for the manipulation of the rheological profile of liquid. In one embodiment, the rheology modifying agent is a hydrophobic fumed silica dispersion provided at 35-70 parts, for example AERODISP® WR 8520 (which can be equivalently formulated from 20% AEROSIL® R972 in water). In addition to the rheological impact, hydrophobic fumed silica dispersions provide additional anti-settling and stability enhancement benefits to the NBSL. In one instance, NBSL samples incorporating AERODISP® WR 8520 were stored for four to six months, and no phase separation was observed. Other suitable dispersion/emulsion-type rheology modifying agents include AEROSIL® R200, AERODISP® W7520, VISCOATEX® 730, and RHEOTECHTM 4800. Other suitable rheology modifying agents include cellulose-based BERMOCOLL® EHM 200, BERMOCOLL® EHM 300, and BERMOCOLL® EBS 411 FQ, and clay-based OPTIGEL® WX, LAPONITE® RD, and LAPONITE® RDS. Cellulose and clay-based rheology modifying agents should be used in smaller percentages as compared to dispersion/emulsion-type agents, for example at or below about 10 parts.
Two attributes to consider in the selection of an appropriate pigment include the quality of the visual appearance as compared to blood (in both liquid and dried forms) and the ability of the pigment to remain in suspension and avoid settling despite long-term storage. The pigments of the NBSL have a particle size of about 20 nm to about 150 nm, which allows them to remain in suspension and resist settling for extended periods of time due to their small size. Red, magenta, yellow, and/or black pigments can be used in combination to approximate the visual appearance of blood. In one embodiment, the NBSL includes from about 0.1 to about 5 parts by weight of a magenta pigment, from about 0.1 to about 5 parts by weight of a yellow pigment, and from 0 to about 0.5 parts by weight of a black pigment (or more preferably from about 0 to about 0.3 parts). The inclusion or exclusion of black pigment is dependent upon whether the NBSL is designed to simulate arterial or venous blood, where black pigment is included only for venous-type NBSLs. Only a small amount of black pigment should be used as compared to pigments of the other colors to both maintain the realism of the appearance of the NBSL in liquid form and to ensure that the NBSL dries as a dark, flaky solid, where the darkness varies depending on the thickness of the NBSL such that the dried NBSL is darker at thicker points. In one embodiment, the NBSL includes about 0.75 parts magenta pigment, about 0.90 parts yellow pigment, and (if venous) about 0.015 parts black pigment to emulate bovine blood.
Water-based pigments of the type designed for use with ink jet printers are suitable for incorporation into the NBSL, such as those produced by Clariant International, Ltd., under their HOSTAJET® product line. Alternatively, other pigment dispersions or coloring agents may be used, such as those designed for paint and general use applications, but they may be less effective in terms of color retention and settlement avoidance.
The matting agent is used to modify the opacity of the NBSL and enhance the realism of the appearance of the NBSL by reducing the glossiness of the NBSL. The matting agent may be a silica, wax, micronized polymer, micronized high density polyolefin, micronized polypropylene, or other material or combination of materials which, upon inclusion in a liquid composition, reduces the glossiness of the composition in dried form. Examples of several suitable matting agents are AQUAMAT® 208, AQUAMAT® 272, CERAFLUOR® 1000, CERAFLUOR® 920, CRAVYLLAC® WN-1875, ACEMATT® TS 100, ACEMATT® 3300, ACEMATT® HK 450, AQUAMATTE® 31, PROPYLMATTE® 31, and PROPYLMATTE® 450. Most matting agents significantly affect the glossiness of the NBSL in dried form, but either do not or otherwise only minimally impact the color/appearance of the NBSL aside from the gloss level.
To emulate the appearance of dried blood, sufficient matting agent should be added to achieve a gloss at or below about 10 GU at a 60° angle. In one embodiment, the NBSL includes from about 0.25 to about 1.25 parts of the matting agent. It was found that the addition of more than 1% matting agent does not significantly affect the gloss level of the resultant NBSL, but that the addition of significant amounts of matting agent (for example 4% or 8%) may, for some matting agents, affect the viscosity and/or color of the resultant NBSL.
Blood has a metallic odor, and providing the NBSL with an odor agent to emulate the smell of blood enhances the realism of training exercises that use the NBSL. In one embodiment, the odor agent is vinyl pentyl ketone (VPK) (IUPAC Name: 1-octene-3-one; CAS Number 4312-99-6), which has an odor that approximates the metallic odor of blood. Notably, VPK is an irritant, so its inclusion may raise safety concerns both in the production process and the ultimate use of the NBSL. The amount of odor agent required is dependent upon the inherent odor of the NBSL absent the odor agent. In an embodiment where the NBSL is otherwise substantially odorless, it is sufficient for the VPK to form from about 0.0002% to about 0.1% of the NBSL. In one embodiment, the NBSL includes about 0.02% VPK.
Various formulations of the NBSL were prepared in accordance with the principles outlined above, and combinations were evaluated for a variety of characteristics as compared to blood, including rheological profile, color and appearance in liquid form, color and appearance in dried (solid/semisolid) form, solid strength after drying, and smell. Several formulations of the NBSL in accordance with the properties described above are illustrated in the table below:
Referring now to
The superabsorbent material may take any of a variety of forms, including a superabsorbent polymer (SAP), a superabsorbent fiber (SAF), a polyacrylic acid, or a combination thereof.
In one embodiment, the gauze 10 is a multi-layer laminate (see
While the disclosed training system is contemplated for use without any further specialized training equipment, it is contemplated that the training system may also be used in conjunction with other training devices, such as a mannequin equipped with SkedCo's FIELD EXPEDIENT BLEEDING SIMULATION SYSTEM™ (FEBSS), to more realistically simulate actual emergency scenarios. For example, to simulate various wounds that may be encountered in a battlefield, the NBSL can be pumped through artificial blood vessels of an FEBSS to a simulated gunshot wound on a mannequin, where the trainee's goal is to treat the wound using the gauze. The FEBSS/other training aid may be capable of simulating both arterial bleeding (pulsating output) and venous bleeding (constant output) at various flow rates.
For embodiments of the training system intended for use in conjunction with an FEBSS, materials for the NBSL and gauze should be selected to avoid clogging the hoses and openings of the FEBSS. For example, it was found that for embodiments incorporating an SAF-based gauze, a load of SAF of about 10 to about 450 gsm is functional, and a load of about 40 to about 350 gsm is optimal to establish an effective, realistic clot. However, a load of about 90 to 150 gsm, or about 110 gsm, may be more practical when taking into consideration the impact on the FEBSS equipment is being used, because higher loads are more likely to either clog the tubing, result in the release of some of the SAF into the tubing and/or simulated wound, or otherwise make the equipment difficult to clean. A three inch by thirty inch piece of gauze incorporating a 110 gsm load of SAF was found to be able to effectively stop the flow of several tested formulations of the NBSL out of a simulated gunshot wound for over 20 minutes, under both steady and pulsating flow conditions, with only negligible amounts of SAF release into the simulated wound and FEBSS supply lines of the FEBSS, and without clogging the FEBSS supply lines.
This application claims the benefit of U.S. Provisional Application No. 61/906,049 filed Nov. 19, 2013, the entirety of which is hereby incorporated by reference.
This invention was made with government support under Contract No. W81XWH-11-C-0073-P00001, awarded by the U. S. Army. The government has certain rights in the invention.
Number | Date | Country | |
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61906049 | Nov 2013 | US |