US 2689415 A
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Description (OCR text may contain errors)
Sept- 21, 1954 H. T. HAvER ANATOMICAL INSTRUCTION MODEL Filed July 29, 1952 fillillf QW v l l l l:
INVENTOR. Harry 7'. Hover A TTOR/VEY Patented Sept.v 21, 1954 UNITED STATES PATENT OFFICE Claims.
The invention relates to a device for instructlng students of medicine and nursing, medical technicians, and the like, in the correct and most expedient technique of piercing veins for the sampling of blood, injection of fluids, etc. In particular, it relates to a life-like replica of a human arm or leg embodying natural appearance and feel which is exceptionally well suited for imparting essential knowledge and confidence to such students without the necessity of experimenting on a live patient.
An object of the present invention is to provide a realistic model of a human arm or leg which may be pierced repeatedly by needles without losing its natural appearance or effectiveness as a teaching aid. A further object is to provide such a replica from which needle marks may be readily removed. Another object is to provide such a replica in which the location of the veins may be determined by touch as in the human arm. Additional objects will become apparent as the following detailed description proceeds.
In Fig. 1 is illustrated an overall perspective view of an arm showing the insertion of the needle of a syringe into the tube simulating the cephalic Vein. Fig. 2 is a cross sectional View of the arm shown in Fig. 1 taken along lines 2-2. The present invention will be described particularly with respect to such an arm.
In accordance with a preferred embodiment of the present invention, the simulacrum of the arm I0 shown in Fig. 1 is a hollow rubber latex form (prepared in a manner hereinafter more fully described) with tubing I I, which simulates the cephalic vein, passing through the arm. It passes through wall A of cavity I2, through the `cavity itself (from about 0.020 to about 0.040
inch below the normal surface of the arm) and then through wall B. The dimensions of cavity I2 are not critical but should preferably be at least about three-fourths of an inch in depth, about two inches in length and at least about an inch and one-half in width. The cavity may have various geometrie shapes, e. g. the rectangular shown; it has been found that cavities which are triangularin cross-section, i. e. are wedge-shaped, are particularly `easy to produce by molding. Cavity I2 is filled with substance I3, such as Korogel which is an elastic, pliable polyvinyl molding jelly, hereinafter referred to in greater detail. Tube II preferably extends through the entire length of the arm, terminating in small valve I4, substantially concealed in the clenched fingers of the hand or in tion. It should be of greater diameter and should be inset at a greater depth at injection sites in the upper part of the arm than in the lower part, e. g. on the back of the hand.. These variations correspond, of course, to the nature 0f veins in a human arm. The actual tapering of the human veins is preferably simulated so that there exists an increased difliculty in locating and piercing them at locations in the lower regions of the arm and in the hand. Tapered tubing may be made by a careful dipping process known to those skilled in the art but it is equally satisfactory, for purposes hereof, and substantially less expensive to join lengths of different uniform diameter tubing at locations between the Various injection, sites. Thus, tubing II preferably comprises a length of largerI diameter tubing I5 which after passing through cavity I2 is connected to a smaller diameter tubing I6 at some location between cavities I 2 and I1 by coupling I8 which is a short length of tubing of any suitable material, e. g. glass, Tygon, etc. Diminution of the diameter of the artificial veins may thus be obtained at a plurality of locations along tube II depending upon the number of injection sites. It should be' understood that any number of such cavities may be located along the arm although only three are shown in the drawing and that several veins may be simulated although only two are illustrated. Additional dea thermo-fusible plastic scription of tube 20 which simulates a second vein, e. g. the basilic vein, is considered unnecessary; it is illustrated to show the manner in which more than one vein may be simulated and how a plurality of reductions in diameter of the tube may occur. Tube 20` comprises sections 2l and 22 joined by adapters 24 and 25.
-The fusible plastic material, e. g. Korogel, employed in cavities I2 and I1 does not readily adhere to the latex surface of such cavities.. `It is therefore ordinarily Y necessary to 4provide a means for retaining the plastic therein. This may be accomplished by forming such cavities with undercut sides into which the plastic may iiow While hot but which upon cooling will be retained by the rim or edge of the cavity'. Because `of the problems of .molding or casting undercuts it is preferred, however, to provide Tube II is preferably of gum rubber construc-` the cavities with projections which, along with the tube passing through the cavity, become imbedded in the plastic and form adequate retainembedded in the rubber, at several points along the arm. Instead of wire brackets, however, there may be. employed any suitable means for maintaining the tube in the desired position. Thus, pressure sensitive tape may be employed or the tube may be cemented to a wall with a suitable rubber adhesive. It is not essential that the tube be fixed to the wall in a more permanent manner than results from its passage through the several cavities; but to avoid any possibility of separation of the various lengths of tubing at the connections and consequent uid leakage, it is preferred that it have a minim-umf oftfreedom.- within the arm..
InFigLZxis shown, somewhat more clearly, the relationshipv of the-thermally fusible substance it-int cavityi-2 tothe-rest of: the arm as well as Sow-the? cav-ityg. itself is-.disposed in the arm. The juncture between the surface of the thermally fusible subs-tance. the-cavity and the surface of the remainderof the simulacrum, comprising latex, issmooth andnon-obvious. Thus, these surfacesare` essentially continuous and the materia-1" in thecavity' is conformed to the contour ofthe arm. The veins il44 and 2@ are shown passing through the cav-ity immersed in the thermo-plastic material therein and essentially parallel-,tothe surface of the arm. Cavity i2 itselfis, as indicated above, ofthe same :materia-l. asthe rest of the arm, e. g. latex, and in the-,absencetofth'e thermo-plastic and the veins, cavity i2y appears-'simply asl an indication in the surface' of the arm.
The simulacrumof the arm is preferably yieldable andr made of. latex rubber although other. substancesA may; be used without departingfrom the scope of the invention. Thus, instead of rubber. other suitable materials, such as those em-ployedlin dolls,y man-ikins and prosthesis, may be employed; Various commercial polyvin-yl resins' are suitable for this purpose, for example, Geen-121 plasti'sol (a product of B. F. Good-rich Chem-ical Co.)-, Marvinol VR-lO (a producty of Nauga-tuc'k Chemical Div., U. S. Rubber 6o.). The' arm may of course be made of nor-i-yieldabley material such as plaster but it is obviouslylessrealistic insuch form and consequently-l not as suitable for its intended purpose. The entire arm mayi be. made from a molding jelly such as Korogel, which would eliminate thezn'eed-:forA cavities at injection sites. Such simulacraare not sufficiently durable, however, to be-` of general applicability.
A- simple technique for the manufacture ofV a latex* simulacrumof` anr arm such as is shown in the drawingfisasfollows: A person thrusts his arm up to.' theshoulder: intoa long narrow bag containing moltenagar-molding composition and the-bag, with arm in place, is then immersed incold water forY about one-half hour to set the composition. Before-withdrawing the arm thebagis slit at the wrist to permit the large part of. the; hand to pass out. After the arm is removed, the' mold is tied at the location where the slit was made to reform the mold. Plaster or other material suitable for a temporary p.osi'tivee.. g. wax, is then poured into the agar mold. After. allowing. the same to set, the
agar mold is removed and the temporary plaster positive remains. Cavities are then cut in the arm at the desired locations and a negative plaster piece mold, i. e. a mold comprising numerous pieces to permit accurate reproduction of undercuts in the arm, is prepared. For a detailed description of the technique of preparing piece molds see Molding and Casting by Carl Dame Clark (1938) John O. Lucas Co., pages 144 et seq. Brom the plaster piece mold may then be prepared any number of latex arms by pouring the liquid rubber and permitting the same to build up to at least about 1/8" and preferably to atleast about 1/4 thickness. When the rubber is substantially coagulated, finely divided vermiculite or molten wax is poured into the. arm within the mold to prevent shrinkage. When the rubber has completely coagulated, the negative piece mold may be removed. In a modification of the above technique the temporary positive. containing the cavities maybe immersed in aV bag containing agar-molding composition,` removed after the composition has set, and after introducinga suitable coabulating agent, the
liquid latex may be pouredv directly into the agar mold until a rubber positive of desired `thicknessis produced. A- simple agar-composition suitable for use in accordance with the above maybe prepared by mixing 40 parts of water, 8 partsl of powdered agar, 1 part. of boraX, andl 20 partsA of sorbitol.
The simulacrum may also be prepared by other techniques, e. g. slush molding, casting, dipping, spraying, etc. The method of preparation constitutes no part of the present invention, however, and further detail is considered unnecessary. It is highly desirable and preferred.-
that the simulacrum be hollow in order to-facilitate insertion and removal of the gum rubber tubes. After the tubing is placed in a hollow simulacrum, it is preferably lled with a suitable packing to give the arm weight and body.
For this purpose granular vermiculite, sawdust, etc. may be used.
Solid simulacre. having vein-simulating conduits bored therein and a short connecting length of gum rubber tube or the like within the cavities at injection sites into which needlesmay be inserted may be employed in accordance herewith. This embodiment has particular appeal from the practical standpoint since the problem of removing entire lengths of tubing when only the section of tube at a point of injection must be replaced-is eliminated. The apertures in the walls of thecavities can, in such a case, be provided with suitable female fittings to receive the male ends of a replacementl tube.
By the term rubber latex, as employed herein, it is intended to includerubber latex whether concentrated or not and either natural or synthetic. condition, or it may be vulcanized in the moreusual way to a soft product after disposition and drying.
Korogel, which is a plasticized thermally fusible polyvinyl resin is preferred as thellerfin.
sary tov re-surface the area of injection by fusion` after. a substantial number. ofholes have'been-` It may be vulcanized in the dispersed made and students are able to observe from a concentration of marks where the proper injection should be made.
The vein simultating conduits are preferably of gum rubber but other materials which have suflicient elasticity to seal the puncture made by a needle can also be used. Thus, for example, Tygon tubing (a modified vinyl resin product of U. S. Stoneware Co., Inc.) has a certain amount of self-sealing ability and may be used. Its transparency is particularly in its favor. But its elasticity is much less than that of `gum rubber and, therefore, it cannot withstand a comparable number of injections without leaking fluid. Other materials will suggest themselves to one skilled in the art.
A primary purpose of the present invention is to train persons to correctly insert a needle into the vein. The trainee making an injection after a large number of others have done so can readily determine the proper injection location by observing that area containing the most needle marks. This is not fair to teacher or student. In accordance, herewith, such marks may be quickly and eifectively removed by the application of heat to the injection site. A preferred method is simply to pass a heated spatula or other suitably smooth implement over the area. The complete resurfacing operation takes only a few minutes and after permitting the material to completely solidify, the arm is unblemished and ready for the next student. Such resurfacing ordinarily need only be done after a days use.
Whereas the foregoing description has been directed to a complete arm or leg, it should be understood that it is within the scope of the invention to employ portions of an arm or leg embodying the novel features herein described.
The veins in a human arm tend to roll or side-slip under the skin and tissue when pressure is exerted thereon. This may be simulated in the arm of theV present invention by inserting beneath the tube, within the cavity, a, layer of sponge rubber. Another method of simulating this is to immerse the tube, in a narrow channel within the Korogel, in a heavy liquid such as mercury.
Having thus described my present invention, what I claim as novel and desire to protect by Letters Patent is as follows:
l. An anatomical model comprising a simulacrum of a human limb; a concavity in the surface of said simulacrum; a vein simulating conduit beneath the surface of said simulacrum which passes through said concavity with at least that portion of the conduit passing through said concavity being capable of sealing itself after puncture by a needle; and a fusible plastic substance, which is penetrable by a needle substantially as is human skin and subcutaneous tissue, disposed within said concavity above said conduit.
2. An anatomical model comprising a yieldable simulacrum of a human limb, a concavity in the surface of said simulacrum; a vein-- simulating conduit beneath the surface of said simulacrum, which conduit is capable of substantially sealing itself after puncture by needle, extending through said concavity; and a fusible plastic substance, which is penetrable by 3, needle substantially as is human skin and subcutaneous tissue, disposed within said concavity above said conduit and molded to the contour of said simulacrum.
3. The anatomical model of claim 2 wherein the simulacrum substantially comprises latex rubber.
4. The anatomical model of claim 2 wherein the fusible plastic substance comprises a thermally fusible polyvinyl resin.
5. The anatomical instruction model of claim 2 wherein at least that portion of the conduit which passes through the concavity comprises gum rubber.
6. An anatomical instruction model comprising a substantially hollow, thin-walled, latex rubber simulacrum of a human limb; a concavity in the surface of said simulacrum, 9, vein-simulating conduit comprising a gum-rubber tube within said simulacrum extending through said concavity; and a thermally fusible plastic supstance penetrable by a needle substantially as is human skin and subcutaneous tissue, disposed within said concavity above said conduit and molded to the contour of said simulacrum.
7. The anatomical instruction model of claim 6 wherein the diameter of the vein-simulating conduit is substantially less in the lower section of the limb than in the upper section.
8. The anatomical instruction model of claim 6 wherein the vein simulating conduit terminates in the lower section of the limb in a means for permitting air to escape as the tube is illed with liquid and substantially preventing liquid escape.
9. The anatomical instruction model of claim 6 wherein the vein simulating conduit comprises a plurality of sections of tubing joined. together, the diameter of each succeeding section diminishing as the conduit passes down the limb.
10. The anatomical instruction model of claim 6 wherein the limb is an arm and said hollow thin-walled simulacrum is filled with a packing material to render the same solid and realistic to the senses of sight and touch.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,034,446 Saxe Mar. 17, 1936 2,095,511 Oberto Oct. 12, 1937 2,207,153 Judovich July 9, 1940 2,213,270 Chase Sept. 3, 1940 2,288,296 Munro June 30, 1942 2,324,702 Hoffman et al July 20, 1943