|Publication number||US3546643 A|
|Publication date||Dec 8, 1970|
|Filing date||Jan 16, 1969|
|Priority date||Jan 16, 1969|
|Publication number||US 3546643 A, US 3546643A, US-A-3546643, US3546643 A, US3546643A|
|Inventors||Virostek Catherine A|
|Original Assignee||Virostek Catherine A|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Referenced by (27), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Dec. :sg-197.07 .A.v|ROsTEK 3,546,643
VPAD FOR SURGICAL INSTRUMENTS OR THE LIKE Filed Jan. 16, 1969 Fig PRIOR ART 34 Fig. 5
C E IZJVNTOR.
ATHERIN /QUSTEK F lg. 6
United States Patent Office 3,546,643 PAD FOR SURGICAL INSTRUMENTS OR THE LIKE Catherine A. Virostek, 3148 Yorkshire Road, Cleveland Heights, Ohio 44118 Filed Jan. 16, 1969, Ser. No. 791,627 Int. Cl. H01f 7/02 U.S. Cl. 335-303 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention The present invention relates to pads for supporting instruments or tools and more particularly relates to pads for supporting surgical instruments in an operating room during surgery.
The prior art Pads for supporting surgical instruments by magnetic attraction have been proposed by the prior art. The prior art proposals generally consisted of a mat having a number of embedded magnets. The magnets were spaced and covered by a sheath. The pads were flexible and provided .major surfaces on which the instruments were placed.
Some prior mats have been made with reinforced plastics. The plastics used have included natural and synthetic rubber. Usually the magnets were flat, rectangular platelike members having a thickness about the same as the mat material so that the major surfaces of the magnets Were ilush with the surrounding mat. The reinforcing fabric engaged, or was closely adjacent the major surfaces of these magnets.
The mat has previously been encapsulated by the sheath. The sheath material impregnated the fabric and adhered to the magnets and mat. This sheath was normally relatively thin and formed of the same substance used in the mat. The pads cured to produce a thin skin-like layer about the exterior of the sheath.
As noted the sheath was usually molded about the mat. Perhaps because of the construction of the molding equipment or high heat conductivity of the magnets, or both, the sheath material along the major surfaces of the magnets was of smaller cross-sectional thickness than the sheath material spaced from the magnets.
Such pads have commonly been used to support surgical instruments. Hence they were often placed on a surgery patient during surgery. For this reason the pads were provided with structure to accommodate pins or clips by which they were attached to a gown or the like covering the patient. This structure wasusually in the form of 'molded-in parts providing spaced holes having reinforced boundaries for the reception of the pins or clips.
Pads for surgical instruments of the type proposed by the prior art have been generally unsatisfactory for a number of reasons. In the rst place, anesthetics used in operating room are sometimes of a highly explosive nature and it is therefore necessary to electrically ground objects in the operating room to prevent electrical static 3,546,643 Patented Dec. 8, 1970 discharges which in the form of sparks, can cause explosions. Secondly, the pads have readily split and torn due to rolling or folding and consequently have had short useful lives.
Commonly, equipment and personnel in operating rooms are electrically grounded to insure against static electrical discharges. Even the surgery patient is electrically grounded, either by strapping the patient to the operating table with electrically conductive straps, or by grounding the patients body through the operating table itself. The instrument pads have not, however, been grounded in the past because the plastic material of the pads was a poor conductor. Hence the prior art instrument pads were subject to accumulations of charge which were not dissipated through conduction of the pads, and it. was possible for a static electrical charge to develop upon the instrument pad itself giving rise to the danger of an explosion.
Another reason for these pads being unsatisfactory was their relatively brief useful life. The problem of short life of these pads was due to splitting and tearing caused by folding the pads. Pads of the type referred to were frequently placed in an autoclave for sterilization and in many instances the autoclave was of such small internal dimensions that the instrument pad had to be tightly rolled up or folded in order to be inserted. It has been found that even though the magnets were spaced apart to provide flexibility, prior art pads tended to split adjacent the ends of the magnets and the pads would then easily tear from split to split. Furthermore, the spacing of the magnets has encouraged tight rolling or folding of the pads even when not necessary.
The noted splitting was believed to be principally caused by folding or rolling the pads for placement in an autoclave but may have been aggravated by the temperature ranges to which the pads were subjected. In any event, since one pad may be required to be sterilized several times during a single operation, the pads were subject to frequent folding and temperature cycling and their life expectancy was brief.
Several constructional factors are believed to contribute to the tendency of prior art instrument pads to split and tear. First, because the magnets were generally rectangular plate-like members, the corners and short edges of the magnets stressed the reinforcing fabric and sheath material unduly when the pad was rolled or folded. Secondly, since the reinforcing fabric was disposed adjacent or upon the major surfaces of the magnets and the fabric was fixed with respect to the magnets, the fabric tended to be cut or ruptured by the short edges of the magnets and the reinforcing fabric was adhered to the surfaces of the magnets, the reinforcing fabric was anchored to the magnets and held against flexing movement as the magnets bore against the fabric during folding. This contributed to rupturing of the fabric. Fourthly, because of the reduced thickness of the sheath material covering the major surfaces of the magnets, the plastic material in these regions lacked the yieldability of the sheath remote from the magnets and these reduced thickness regions were readily overstressed and split when the pad was rolled or folded.
SUMMARY OF THE INVENTION Thel present invention provides a new magnetized pad for supporting surgical instruments during an operation which: (1) eliminates the possibility of an electrical lspark and explosion due to static electrical charge acfolded, for example, during placement in a container such as an autoclave.
The new surgical instrument pad comprises a plastic mat in which a number of magnets are embedded. The major surfaces of the magnets are flush with the major surfaces of the mat. The magnets are plate-like members defining major surfaces which do not have relatively short edges. The major surfaces are bounded at least in part by nonlinear sides devoid of corners and short edges. These surfaces are preferably cylindrical. Because of their shapes, the magnets do not exert undue stress on the sheath at localized areas when the pad is folded.
A sheath of plastic material extends about the mat to define continuous exterior major surfaces of the mat upon which instruments are disposed. The sheath has an embedded reinforcing fabric. This fabric is surrounded by the plastic material and is thus spaced from the magnets. The reinforcing material is therefore not directly engaged by the magnets at any time and furthermore is not unduly restrained in the vicinity of the magnets as in prior art devices.
Surgical instrument pads constructed in accordance with the invention are incapable of developing static electrical charges when supported by a grounded object, such as a patient or the operating table, because the pad is capable of dissipating such charges to ground. To this end theplastic sheath material is impregnated with an electrically conductive material providing conductive paths through which any charge tending to be built up on the pad is conducted away from the pad through the grounded pad supporting object.
Accordingly, a principal object of the present invention is the provision of a new and improved instrument pad lwhich is incapable of maintaining a static electrical charge and which is extremely long lived despite frequent rolling or folding.
Other objects and advantages of the present invention will become apparent from a consideration of the following detailed description thereof made with reference to the accompanying drawings which form a part of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of an instrument pad constructed in accordance with the prior art proposals;`
FIG. 2 is a cross-sectional view seen from the plane indicated by the line 2-2 of FIG. l;
FIG. 3 is a view of a portion of the prior art pad of FIG. 1 illustrating a typical failure and shown on a larger scale than that of FIG. l
FIG. 4 is a cross-sectional view seen from the plane indicated by the line 4 4 of FIG. 3;
FIG. 5 is a plan view of an instrument pad constructed in accordance with the present invention; and
FIG. 6 is a cross-sectional view seen from the plane indicated by the line 6--6 of FIG. 5.
DESCRIPTION OF A PRIOR ART PAD struction provides a relatively thin rectangular or square pad having major surfaces 11a, 11b upon which surgical linstruments are disposed and maintained in place by magnetic attraction.
As best seen in FIG. 2, the mat 12 includes a body 15 composed of a sheet of pliable plastic material, such as silicon rubber, in which the magnets 13 are embedded. The body 15 and the magnets 13 are surrounded by a reinforcing fabric 16 preferably composed of fine synthetic fibers, such as nylon or the like, woven into a screen-like cloth or net.
The magnets 13 are rectangular plate-like members disposed in rows in the body 15 and spaced apart sufficiently so that the body 15 fiexes relatively freely. The magnets lie flat in the body 1S and have major surfaces 13a, 13b which are liush with major surfaces 15a, 15b of the body 15. It is evident that the magnets 13 are of substantially the same thickness as the body 15.
The structure defined by the mat 12 and magnets 13 is encapsulated in the sheath 14. The material of the sheath is also a plastic such as silicon rubber and is molded in place. The fabric 16 is of a suiciently loose weave that the sheath material permeates the fabric and thus the body and sheath are bonded together adjacent the fabric 16. The sheath material is also fixed on or close to the major surfaces 13a, 13b as a result of the sheath material fiowing through the fabric.
As seen in FIG. 2, the sectional thickness of the sheath 14 at locations 14a, immediately adjacent the major surfaces of the magnets is less than the sectional thickness of the sheath portions 14b remote from the magnets. This difference in sectional thickness is exaggerated in FIG. 2 for the purpose of illustration. It is believed the reason for the smaller sectional thickness of sheath material adjacent the magnets is due partly to the molding process or equipment and also to heat transfer characteristics of the metallic magnets differing from those of the mat 12.
When the pad has been formed in the manner described, it is suitably cured to produce a thin skin 21 which forms the exterior of the pad.
In use, pads such as the pad 10, are disposed on a supporting object in the operating room, often on the body of the surgery patient. The magnets 13 attract and maintain surgical instruments in position when placed on the pad.
As shown in FIG. 1, the pad 10 defines circular holes 25 near the corners. These holes permit the pad to be clipped or pinned in placed on the patient, operating table, or the like. Commonly, the holes 25 have circular boundaries which are reinforced by rigid grommet-like members (not shown) which are molded into the mat 12.
It may be necessary to place an instrument pad 10 in an autoclave a number of times during a single operation for sterilization. Oftentimes the pad 10 is rolled or folded when placed in the autoclave. Since the magnets 13 are extremely rigid compared to thematerial of the sheath and mat, folding or rolling the pads 10 causes the corners and short edges of the magnets 13 to stress the fabric 16 and sheath 14. Because the fabric 16 is adhered to the major surfaces 13a, 13b of the magnets along with the sheath material, bending of the pad 10 itself stresses the sheath and fabric adjacent the magnets.
After a relatively short period of use, the corners and short edges of the magnets cut the fabric 16 adjacent these edges of the major surfaces and split open the sheath. It should be noted that the relatively long sides of the magnets contribute to the high stresses on the sheath and fabric at the short edges of the magnet because of the lengthwise rigidity of the magnets and bending of the plastic pad adjacent the long sides of the magnets. This split condition of the sheath and fabric is illustrated in FIGS. 3 and 4.
It is believed that splitting of the sheath is due at least in part to the reduced sectional thickness of the sheath portions 14a adjacent the magnets 13 as a result of the reduced yieldability of these portions. EIn addition to this phenomenon, the pad material between near ends of adjacent magnets is tensioned heavily when the pad is rolled or folded which further reduces the ability of this material to resist rupturing.
Once the sheath 14 has split open adjacent the ends of several magnets, a tear line develops along the line of splits. This condition usually requires the instrument pad to be replaced.
In addition to the problems of splitting and tearing of instrumentl pads outlined above, the priorv art pad has a tendency` to naccumulate static electrical charges. This is due to the fact that the plastic material forming the mat is a poor electrical conductor. Because certain anesthetics are highly explosive, equipment and personnel in operating rooms are electrically grounded. The surgery patient is also electrically grounded by contact with the operating table itself or rby electrically conductive straps which secure the patient to the operating table. Due to the poor conductivity of the material forming the prior art pad 10, the pad itself is incapable of dissipating a static electrical charge even though electrically connected to a grounded object. For this reason the possibility exists that a static charge on an instrument pad can be dissipated by an electrical spark and result in an explosion in the operating room.
DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION FIGS. and 6 illustrate an instrument pad 30 constructed in accordance with the present invention. The pad 30 is defined by a flexible mat 31, magnets 32 embedded in the mat 31, and a sheath 33 surrounding the mat 31 and magnets 32.
The mat 31 is a sheet-like member of molded plastic material, such as silicon rubber, in which the magnets 32 are embedded. The magnets 32 are arranged in diagonally extending rows in the mat 31 (as viewed in the drawings). The thicknesses of the mat 31 and magnets 32 are substantially the same so that major surfaces 32a, 32b of the magnets are flush with major surfaces 31a, 31b of the mat 31.
The diagonal rows of magnets produce a staggered relationship *between magnets in adjacent longitudinal and transverse rows. This staggered relationship between the rows avoids extreme transverse or longitudinal tensioning of the material between adjacent magnets when the pad is rolled or folded.
The magnets 32 are fiat cylindrical members which lie fiat in the mat 31. Since the magnet sides 34 are nonlinear, the major surfaces 32a, 32b are devoid of corners or short edges. Preferably the magnets 32 are spaced no less than one half inch part to insure adequate flexibility of the pad 30 for rolling or folding.
The sheath 33 completely surrounds the mat 31 and magnets 32 and is formed by sheets 40, 41 composed in part of silicon rubber or equivalent plastic material. The sheets 40, 41 are bonded together at their juncture 42 which extends along the sides of the pad 30. The sheets 40, 41 are essentially identical and each includes reinforcing fabric 43 preferably comprised of woven Dacron fibers which is surrounded by the plastic material forming the sheets. As is seen in FIG. 6, the fabric 43 is spaced from the magnets 32 by a layer of sheet material. The sheets 40, 41 may be suitably adhered to the major surfaces 32a, 32b of the magnets 32 and the major surfaces 31a, 31b of the mat 31 to produce a unitary composite pad construction.
As seen in FIG. 5 the pad 30 is connectable to its support, `which may be the surgery patient, by engaging fasteners (not shown) with boundaries of holes 4S defined in the pad. Only a pair of holes 45 are provided and these are located adjacent the sides of the pad medially of its ends. Suitable grommet-like reinforcing parts 46 are fixed in the mat to strengthen the `boundaries of the holes.
The lower end (as viewed in the drawings) of the pad is defined by a semicircular apron-like area defining a surface particularly suited for placement of sponges used during surgery.
Even though the sheets 40, 41 are bonded to the mat 31 and magnets 32, the fabric 43 is maintained spaced away from the magnets 32 and accordingly the edges of the magnets do not directly contact the fabric 43 when the pad 30 is rolled or folded. Hence, the edges of the magnets do not cut through the fabric. Additionally, because the sheets 40, 41 are reinforced with the fabric 43, the cross-sectional thickness of the sheath is substantially uniform across the major surfaces of the pad, and therefore, does not contain regions of reduced yieldability adjacent the magnets which might otherwise result in splitting of the sheath. The magnets 32 are configured to be devoid of short edges and corners and for this reason the magnets do not produce extremely high point stresses on the sheath when the pad is rolled or folded. Additionally, as noted, since the magnets are staggered, longitudinal or transverse rolling or folding will not cause undue pad tensions between the magnets. Hence, because of the construction of the pad 30 as described, and due to the configurations of the magnets, splitting and tearing of the pad is insured against despite frequent rolling and folding. The new instrument pad therefore has a relatively long life compared to the prior art constructions.
The new instrument pad 30 is also incapable of maintaining a static electrical charge when connected to a grounded object. To this end the major surfaces of the pad 30 define electrically conductive paths which conduct static electricity to ground when the pad is electrically grounded. This is so because the sheets 40, 41 are impregnated with electrically conducting material, such as great numbers of minute particles 50 of copper or like conductive metal which establish electrically conductive paths along the major surfaces of the pad. Hence, when the pad is connected to an electrically grounded object, any static charge tending to be developed on the pad is dissipated by conduction to the grounded object supporting the pad before any significant charge level exists.
It can now be seen that a new surgical instrument pad has been provided, the parts of which are constructed and arranged so that the pad is capable of an extremely long life as compared to prior art pads despite frequent rolling or folding of the pad. The new pad is also incapable of maintaining a static electrical charge when connected to a grounded support thereby eliminating the possibility of explosion of anesthetic gas in an operating room as a result of an electrical discharge from the pad.
What is claimed is:
1. An instrument pad comprising:
(a) a flexible mat;
(b) a plurality of plate-like magnets embedded in said mat;
(c) a sheath of flexible material disposed about said mat and said magnets, said sheath defining major surfaces -upon which instruments are supported and maintained in position by magnetic attraction; and
(d) said sheath comprising a reinforcing fabric surrounded by a eXible plastic material, said material defining an interior face of said sheath adjacent said magnets and preventing said magnets from directly engaging said fabric when the pad is rolled or folded.
2. The pad claimed in claim 1 wherein said magnets define major surfaces devoid of relatively short edges and corners.
3. The pad claimed in claim 2 wherein said major surfaces of said magnets are circular.
4. The pad claimed in claim 1 wherein said magnets are disposed in rows extending diagonally of said pad.
5. The pad defined in claim 1 wherein said sheath is electrically conductive to prevent accumulation of a static electrical charge on the pad when electrically grounded.
6. The pad defined in claim 5 wherein said material of said s heath is impregnated with electrically conductive particles.
7. The pad dened n claim 1 wherein said sheath is defined by at least a pair of sheets extending along opposite surfaces of said mat and magnets, said sheets attached at sides of the mat.
8. An instrument pad comprising:
(a) a flexible plastic pad structure defining major surfaces and adapted to support instruments on one of said surfaces;
(b) a plurality of magnets disposed at spaced locations within said pad and providing magnetic forces for maintaining instruments in position on said one surface; and i (c) said flexible pad structure surrounding said magnets and said major surfaces defining electrically conductive paths for dissipating static electricity when said pad is electrically grounded.
9. The instrument pad claimed in claim 8 wherein said pad is defined by a ileXible mat supporting said magnets and said surfacesaredened by atleast a sheet of plastic material overlying said mat and magnet, 10. The instrument pad claimed in claim 8 wherein said electrically conductive paths are dened by electrical-V ly conductive particles disposed in'said major surfaces.
` vReferences Cited v UNITED STATES PATENTS 3,483,494 12/1969 croma ass-303 GEORGE HARRIS, Primary Examiner y U.s. c1. XR.
ghggo UNlTED STATES PATENT OFFICE CERTIFICATE QF n CRRECTION Patent N0- 8. 546L643 Batam It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shovm below:
Column 2, line 51, after "rnagnetsf'I insert `when the pad was folded. Thirdly, beoause the, sheath of material i covering the A'major surfaces ofv the magnets;
-Column 5, line 46, "part" should be -apart.
Signed and sealed this 20th day of Aprilv 1971 (SEAL) Attest:
EDWAREM. FLETCHERJR. .MLLTAM E. SCHUYLER, JR ,Atttrng vOfficer l I Cenmsscmer-4 of Patents
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|International Classification||H01F7/02, A61B19/00, A61B19/02|
|Cooperative Classification||H01F7/0215, A61B19/0256, A61B2019/0257|
|European Classification||A61B19/02H, H01F7/02A1A|