U.S. patent number 3,848,600 [Application Number 05/328,120] was granted by the patent office on 1974-11-19 for indifferent electrode in electrosurgical procedures and method of use.
This patent grant is currently assigned to NDM Corporation. Invention is credited to Charles L. Milligan, Charles T. Patrick, Jr..
United States Patent |
3,848,600 |
Patrick, Jr. , et
al. |
November 19, 1974 |
**Please see images for:
( Reexamination Certificate ) ** |
INDIFFERENT ELECTRODE IN ELECTROSURGICAL PROCEDURES AND METHOD OF
USE
Abstract
A disposable indifferent electrode easily contoured to body
surfaces including an electrode electrolyte assembly in which the
electrode is relatively small in size yet provides very effective
electrical contact between it and the body surface by virtue of an
interposed electrolyte composition of predetermined
characteristics; and, in surgical diathermy, a method of conducting
high frequency radio waves to ground.
Inventors: |
Patrick, Jr.; Charles T.
(Centerville, OH), Milligan; Charles L. (Centerville,
OH) |
Assignee: |
NDM Corporation (Dayton,
OH)
|
Family
ID: |
26917452 |
Appl.
No.: |
05/328,120 |
Filed: |
January 30, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
223107 |
Feb 3, 1972 |
|
|
|
|
Current U.S.
Class: |
606/32;
607/153 |
Current CPC
Class: |
A61N
1/04 (20130101); A61B 18/16 (20130101); A61B
2562/125 (20130101) |
Current International
Class: |
A61B
18/16 (20060101); A61B 18/16 (20060101); A61B
18/14 (20060101); A61B 18/14 (20060101); A61N
1/04 (20060101); A61N 1/04 (20060101); A61n
003/02 () |
Field of
Search: |
;128/2.6E,2.1E,303.13,303.14,303.17,303.18,404,411,413,416,417,418,422,DIG.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Irons & Sears
Parent Case Text
This application is a continuation-in-part of pending U.S.
application Ser. No. 223,107, filed Feb. 3, 1972 and now abandoned
by Charles T. Patrick, Jr. and Charles L. Milligan and entitled
INDIFFERENT ELECTRODE IN ELECTROSURGICAL PROCEDURES.
Claims
What is claimed is:
1. An indifferent electrode for use in electrosurgical procedures
and easily contoured to body surfaces which comprises an
electrode-electrolyte assembly including an electrode and an
electrolyte composition in which the electrode is an electrically
conductive means having at least 0.038 square inch surface thereof
in essentially complete contact with said electrolyte composition
having at least 2.0 square inches of its conductive surface
adaptable to be applied in essentially complete conductive contact
with the skin of a patient and having a thickness of at least 10
mils to thus space any part of said conductive means from the skin,
said thickness being at least about 165 mils when the conductive
element surface area is between about 0.038 and 0.10 square inch,
said electrically conductive means, in turn, having a means for
electrically connecting said electrode.
2. The indifferent electrode of claim 1 wherein the electrically
conductive means is a disc.
3. The indifferent electrode of claim 1 wherein the electrically
conductive means is a wire.
4. The indifferent electrode of claim 1 wherein the electrically
conductive means is a flexible sheet of stainless steel and the
electrolyte is an alkali metal sulfate.
5. The indifferent electrode of claim 4 wherein the electrolyte is
an aqueous composition containing, by weight, from about 0.5
percent to about an aqueous saturated solution of alkali metal
sulfate.
6. The indifferent electrode of claim 5 wherein the electrolyte is
an aqueous composition containing, by weight, from about 5 percent
to about 20% alkali metal sulfate.
7. The indifferent electrode of claim 6 wherein the alkali metal
sulfate is sodium sulfate.
8. The indifferent electrode of claim 4 having means defining a low
profile cup shaped non-conductive cavity which opens to the body
surface and having said flexible sheet of conductive metal
electrode at the base of the cavity and coplanar to said base, said
electrolyte composition being contained in said cavity and
completely overlying and in contact with the surface of the
electrode away from said base.
9. The indifferent electrode of claim 8 wherein the electrolyte
comprising an alkali metal sulfate and a sponge-like cellular
matrix is an aqueous highly viscous semisolid composition
comprising, by weight, from about 3 percent to about an aqueous
saturated solution of alkali metal sulfate, and a small but
effective amount of a water-soluble, water-swellable mucilage, said
sponge-like cellular matrix containing said sulfate-mucilage blend
uniformly distributed throughout its interstices.
10. The indifferent electrode of claim 9 wherein the mucilage is a
neutralized, water-soluble water-swellable carboxypolymethylene
present in the concentration of about 0.2 percent to about 5.0
percent, based upon the total weight of the electrolyte
composition.
11. The indifferent electrode of claim 8 wherein the electrode is a
flexible sheet of stainless steel which is in electrical contact
with a conductive means passing through the base of the cup-shaped
member and to a ground external to the cup.
12. The indifferent electrode of claim 11, wherein the aqueous
highly viscous semisolid electrolyte composition substantially
fills the interior of said cup member and has a thickness at least
as great as the depth of said cup member.
13. The indifferent electrode of claim 12 wherein the thickness of
said aqueous highly viscous semisolid electrolyte composition
exceeds the depth of said cup member.
14. The indifferent electrode of claim 13 wherein a removable
protective covering overlies the open end of the cup member, said
covering being a sheet material having a raised portion overlying
the semisolid electrolyte protruding from the cup member.
15. The indifferent electrode of claim 14 having an apertured
flexible and resilient sheet carrying said cup member, the surface
of said flexible and resilient sheet in coplanar relationship to
the outer surface of the base of the cup member being substantially
greater than that of the outer surface of the base member and
having a pressure sensitive adhesive coating thereon for adhering
to a body surface.
16. The indifferent electrode of claim 15 having conductive
securing means projecting through the aperture in said flexible and
resilient sheet, through the base of said cup member, and securely
attached to the flexible sheet of conductive metal.
17. The indifferent electrode of claim 16 wherein the conductive
securing means is securely attached to the flexible sheet of
conductive metal by projecting through said thin flexible sheet,
and the said securing means is a conductive metal snap
fastener.
18. The indifferrent electrode of claim 17 wherein the stud portion
of said snap fastener passes sequentially through the flexible
sheet of conductive metal, the cup member and the flexible,
resilient adhesive-bearing sheet and terminates in locking
engagement with the mating socket of said snap fastener.
19. The indifferent electrode of claim 18 wherein the aqueous
highly viscous semisolid composition has an aperture therein
through which a non-conductive rivet passes and terminates in
locking engagement in the hollow neck portion of said stud of said
snap fastener, thus mounting the semi-solid composition on the
flexible sheet of conductive metal and in immediate contact
therewith.
20. The indifferent electrode of claim 15 further including a cover
sheet releasably secured to said adhesive coating and means
securing said protective covering to said cover sheet.
21. The indifferent electrode of claim 1, wherein the electrolyte
composition has on its skin an electrical capacitor insulator
capable of capacitively coupling under electrosurgical
conditions.
22. The indifferent electrode of claim 21, wherein said insulator
is at the interface of the electrically conductive means and the
electrolyte composition.
23. The indifferent electrode of claim 21, wherein, in addition, a
similar insulator is at the interface of the electrolyte
composition and the electrically conductive means.
24. The indifferent electrode of claim 23, wherein the insulator is
a thin polymer film.
25. The indifferent electrode of claim 24, wherein the insulator is
a saran film.
26. The indifferent electrode of claim 1, wherein the electrolyte
composition is an electrolyte-containing fabric.
27. The indifferent electrode of claim 26, wherein the fabric is
unwoven cotton fabric.
28. The indifferent electrode of claim 1, wherein the electrolyte
composition contains an inert filler.
29. The indifferent electrode of claim 28, wherein the inert filler
is powdered talc.
30. In surgical diathermy, a method of conducting high frequency
radio waves to ground which comprises placing against and coplanar
to the body surface a flexible sheet of conductive metal electrode,
said sheet surface opposite and nearer said body surface having an
area in the range of about 0.5 square inch to about 10 square
inches, and interposing in direct and essentially complete contact
with said opposed surfaces of electrode and body an electrolyte
composition of substantially uniform thickness, said thickness
being in the range of about 62 mils to about 500 mils.
31. The method of claim 30 wherein the said sheet surface opposite
and nearer said body surface has an area in the range of about 2
square inches to about 5 square inches.
32. The method of claim 30 wherein the flexible sheet of conductive
metal is stainless steel and the electrolyte is an alkali metal
sulfate.
33. The method of claim 32 wherein the alkali metal sulfate is
sodium sulfate.
34. The method of claim 33 wherein the electrolyte is an aqueous
composition containing, by weight, from about 0.5 percent to about
an aqueous saturated solution of alkali metal sulfate.
35. The method of claim 34 wherein the electrolyte is an aqueous
composition containing, by weight, from about 5 percent to about 20
percent alkali metal sulfate.
36. The method of claim 26 wherein the alkali metal sulfate is
sodium sulfate.
Description
BACKGROUND
As far back as 1919, Iredell and Turner were primarily responsible
for surgical diathermy as we know it today, wherein current used to
sever tissue is conducted to ground by the use of an indifferent
electrode, also called a patient ground plate. While a great many
innovations have been made in electrosurgical procedures since
Iredell and Turner demonstrated the effectiveness of a 72 square
inch (6 .times. 12 inches) ground plate, surprisingly enough the
field of surgical diathermy has zealously retained and promoted the
concept that a relatively large area of body surface should be in
contact with an equally large patient ground plate to avoid
burns.
Present day literature is replete with allusions to the necessity
for ground plates measuring 6 .times. 5 inches, 6 .times. 8 inches,
etc., a rule of thumb being about 9 square inches of plate surface
per 100 watts of power generated by the electrosurgical apparatus.
As is well known, in surgical diathermy such apparatus generates
high frequency electric current which is fed to an active electrode
used to cut tissue and coagulate blood vessels, a large patient
ground plate being used to provide a low current density path to
complete the electrosurgical circuit and minimize tissue heating at
the plate/skin interface. To lower skin resistance at the
interface, electrolytes are generally used, e.g., conductive
pastes, jellies or saline solutions. Caution is generally given,
however, that during extended electrosurgery the electrolytes will
dry up and it is therefore very important, to avoid burns and other
complications, to maintain a large skin contact area with the
ground plate.
Obviously, the large ground plates in common use have their
drawbacks: they are not easily contoured to the body and, of
course, relatively few body surface areas can accommodate them;
when placed under a patient, for instance, it is difficult to know
whether substantial plate/body contact is being maintained,
particularly when the patient moves or is moved; depending upon
area contacted and method of applying the ground plate, circulation
can readily be affected, thus increasing the possibility of burns;
the general stiffness of plates and the inflexible and, at times,
sharp edges thereof can cause substantial discomfort to the
patient, especially in the case of a prolonged operation; of
course, a large patient ground plate inherently increases the
possibility of accidental contact with surgical instruments or
other metal objects that can result in a burn to the patient;
etc.
It is therefore the purpose of the present invention to provide an
indifferent electrode and method of use which overcomes the
drawbacks of the conventional patient ground plates. Other objects
of the present invention are to provide an indifferent electrode
which is: relatively small in size; easily contoured to various
body surfaces, thus allowing many sites for application;
disposable; readily and securely attached to the body without
restricing circulation; capable of maintaining good and stable
electrode/electrolyte/skin contact for long periods of time with
minimum electrolyte evaporation and impedance increase; capable of
being pre-wet, pre-sterilized and/or pre-packaged, if desired; etc.
These and other objects and advantages will be apparent from the
more detailed description infra.
Of interest are the following references:
U.s. pat. Nos. 3,601,126, 3,590,322, 3,568,662, 3,543,760, and
3,518,984;
Canadian Pat. No. 675,494;
French Pat. Nos. 1,255,797 and 915,335;
Mitchell, J. P., Lumb, G. N.: The Principles of Surgical Diathermy
and Its Limitations, Brit. J. Surg. 50 pp. 314-320 (Nov) 1962;
Mitchell, J. P., Lumb, G. N.: A Handbook of Surgical Diathermy,
Bristol, John Wright and Sons Ltd. 1966, pp. 34-38;
Nicholson, Morris J., Anesthesia and Analgesia -- Current
Researches, Vol. 49, No. 8, (May-June) 1970;
Dobbie, A. K., The Electrical Aspects of Surgical Diathermy, Bio
Medical Engineering, 1969 pp. 206-216;
Battig, Charles G., Electrosurgical Burn Injuries and Their
Prevention, JAMA June 17, 1968, Vol. 204, No. 12, pp. 91-95;
and
Wald, Alvin, S., Mazzia, Valentino D. B., Spencer, Frank C.,
Accidental Burns, JAMA Aug. 16, 1971, Vol. 217, No. 7, pp.
916-921.
The later (1966) Mitchell and Lumb reference above teaches that the
conventional size patient ground plate (usually lead) is 6 .times.
5 inches, i.e., 30 square inches. It points out: "In practice,
however, it is found that the size can be reduced to a total of 12
square inches, and will still carry the maximum output without
heating, provided adequate contact is made over the whole of its
surface."
The A. K. Dobbie reference, supra, in rejecting the impression that
ECG monitoring causes diathermy burns has this to say on p. 214,
column 3:
"This is virtually impossible when the patient plate electrode (or
electrodes) is correctly fitted to the patient and the surgeon is
not using heavy diathermy currents within a few inches of an
earthed monitoring electrode, since only a small current will take
the alternative ECG path back to the diathermy set earth terminal
owing to the presence of the much lower impedance presented by the
plate electrode with its short return path. An ECG electrode 5 cm
.times. 3 cm has a contact impedance of around 15 ohms at diathermy
frequencies and is capable of carrying a current of 600 mA
continuously for 120 seconds without undue heat being produced if
the electrode is placed directly over a muscle; if it is fixed over
fat the maximum current is around 500 mA."
The article goes on to say: "A properly fixed ECG electrode is
capable of carrying the currents used in pediatric surgery with an
output setting of 2 or 3."
U.S. Pat. No. 3,601,126 in FIGS. 2 through 6 of its drawing teaches
an indifferent electrode having a metallized sheet electrode on
which is superimposed a spongy sheet containing viscous
electrolyte.
Canadian Pat. No. 675,494 discloses an electrode made of a foil
sandwiched between a plastic sheet (having a pressuresensitive
adhesive on its inner surface) and an absorbent felt or fabric
material "...adapted to be wetted with an electrical conducting
agent." The peripheral edge of the plastic sheet lamina extends
considerably beyond the peripheral edges of each of the other two
laminae. A snap fastener terminal is carried by the plastic sheet
and the foil through opposed apertures in these laminae.
As will be seen from the detailed description to follow, the above
references and selected excerpts therefrom are readily
distinguishable.
U.S. Pat. No. 3,701,346 hereby incorporated herein by reference
describes in detail electrolyte compositions of the type
contemplated herein and a pre-filled body suitable for sensing the
bioelectrical potentials of a living animal body.
THE INVENTION
The present invention concerns an indifferent electrode for
electrosurgical procedures utilizing high frequency radio waves.
More particularly, the instant discovery concerns a novel
electrode/electrolyte assembly easily contoured to body surfaces
and useful in surgical diathermy for conducting harmlessly to
ground the current used to sever tissue.
Still more particularly, the instant discovery relates to an
electrode/electrolyte assembly in which the electrode is an
electrically conductive means having a predetermined area of its
conductive surface adaptable to be applied in essentially complete
conductive contact with the skin of a patient through an interposed
electrolyte means which, in turn, has sufficient thickness to
properly space any part of said conductive means from the skin.
Preferably, according to the present invention, the
electrode/electrolyte assembly comprises an electrically conductive
electrode element, such as a disc or wire, usually made of metal or
other like conductive material, having at least about 0.038 square
inch conductive surface thereof in essentially complete contact
with an electrolyte composition having at least about 2.0 square
inches of its conductive surface adaptable to be applied in
essentially complete conductive contact with the skin of a patient
and having a thickness of at least about 10 mils to thus space any
part of said conductive element a distance of at least about 10
mils from the skin of a patient. The thickness of the interposed
electrolyte composition should be greater than 10 mils, generally
at least about 165 mils, when the conductive element surface area
is less than about 0.10 square inch, i.e., between about 0.038 and
0.10 square inch, thus spacing any part of said conductive element
a distance of at least about 165 mils from the skin surface of a
patient.
For example, when a wire is used and, say, embedded in an
electrolyte composition, the surface of the wire is preferably
spaced from the skin of a patient by at least about 190 mils, the
electrolyte composition generally being interposed and thus
providing efficient current transfer from the skin to the
wire-shaped electrode.
Quite surprisingly, it has been found that a wide variety of
electrode shapes and configurations may be employed having at least
the minimum conductive surface area hereinbefore described. The
wire shape, for instance, may be that of a loop, a straight line, a
convolution, a square, an ellipse, etc., provided, of course, the
minimum conductive element surface area and electrolyte thickness
are maintained. Other electrode shapes within the purview of the
present invention include snap-fasteners, foils, discs, wire mesh,
and so on. Preferably, while always maintaining the conductive
electrode surface properly spaced from the skin, the interposed
electrolyte essentially covers the total skin-side surface of the
electrode.
Illustrative of an electrolyte/electrode assembly of the type
wherein the electrolyte composition does not totally cover the
skin-side surface of the electrode is one made up of a disc of
non-conductive plastic material containing multiple apertures
therethrough resembling, for example, the hexagonal cells of a
honeycomb and laminated to one surface of the honeycomb disc,
closing off the apertures, is an electrode disc which thus forms
individual honeycomb-shaped cups. While all of these cups may be
filled with an electrolyte composition, such as a gel or a paste,
it is only necessary, pursuant to the present invention, to fill
sufficient of these cups to establish conductive contact, as
described hereinbefore, with at least about 0.038 square inch of
the electrode disc and, of course, provide at least about 2.0
square inches of the conductive surface of the electrolyte
composition adaptable to be applied in essentially complete
conductive contact with the skin of a patient. The honeycomb disc
must, of course, be thick and rigid enough, in the case of a thin
disc, to space the skin side of the electrode disc at least about
10 mils from the skin of the patient.
Obviously, many other shapes of electrode means and electrolyte
means are within the purview of the present invention and will
become readily apparent from the general and specific descriptions
herein contained.
One of the preferred embodiments comprises an electrode/electrolyte
assembly wherein the electrode is a relatively small thin flexible
sheet of conductive metal having one side thereof essentially
completely covered by and in essentially complete contact with a
viscous electrolyte composition having a substantially uniform
thickness, the surface area of said covered side of the electrode
being in the range of about 0.5 square inch to about 10 square
inches, generally about 2 square inches to about 5 square inches,
and the thickness of the electrolyte composition being in the range
of about 62 mils to about 500 mils.
The thin flexible sheet or foil of conductive metal in this
embodiment is preferably of stainless steel and the electrolyte is
an alkali metal sulfate, e.g., sodium sulfate, the electrolyte
comprising an aqueous highly viscous semisolid composition
containing, by weight, from about 0.5 percent to about 20 percent
alkali metal sulfate.
While the alkali metal sulfates, such as sodium, potassium and
lithium sulfates, are very effective for use herein as
electrolytes, other water-soluble, ionizable, inorganic and organic
salt electrolytes are contemplated herein, including alkali metal
halides and nitrates, e.g., sodium chloride, potassium bromide,
potassium nitrate, and the like; ammonium halides, nitrate and
sulfate; magnesium halides, nitrate and sulfate; and other like
ionizable alkaline earth metal salts; ionizable organic salts or
organic acid salts of citric, tartaric, salicylic, benzoic, lactic
or other like acids with metals, such as alkali and alkaline earth
metals, including sodium, potassium, magnesium, and the like.
Preferably a small but effective amount of a water-soluble, water
swellable mucilage is present in the electrolyte composition, such
as the aqueous alkali metal sulfate solution, to provide a viscous
electrolyte mixture which, according to a still further embodiment,
is absorbed or uniformly distributed throughout the interstices of
a sponge-like cellular matrix (e.g., polyurethane foam or other
like absorbent material) to provide a highly viscous semisolid
electrolyte composition.
Among the water-soluble, water-swellable mucilages (also known as
gelling acids and water-soluble resins) useful herein are
carboxymethylcellulose, polyvinyl alcohols, cellulosic gums,
polymethylene oxide, sodium alginate, gum tragacanth, polyacrylic
acids, such as those hydrophilic, high viscosity, polyacrylic acids
having a molecular weight of about 1 million to about 6 million and
useful in cosmetic and pharmaceutical preparations, e.g., the
Carbopol water-soluble resins. (Carbopol is a trademark used by B.
F. Goodrich Chemical Co.)
Best results are achieved with the polyacrylic acids by
neutralizing same with any of a number of neutralizing agents, such
as the fairly strong organic and inorganic bases, including but not
limited to NaOH, KOH, NH.sub.4 OH, alkyl amines(mono-, di-, and
tri-), alkanol amines(mono-, di-, and tri-), such as
triethanolamine, triamylamine, dodecylamine, di(2-ethylhexyl)
amine, and the like.
The resulting neutralized mucilage is usually present in the
concentration of about 0.2 percent to about 8.0 percent, preferably
from about 0.85 percent to about 5.0 percent, by weight, based upon
the total weight of the electrolyte composition.
If desired, conventional additives, such as mold inhibitors and the
like, may be present in small quantities, usually less than about 1
percent. For example, very desirable results are achieved with
chlorinated aromatic hydrocarbons, including
2-chloro-meta-5-xylenol, salts of organic acids, such as sodium
benzoate, etc.
While the blending sequence of the electrolyte components of these
preferred embodiments admits of numerous variations, it is
desirable and preferred to make the aqueous alkali metal sulfate
solution separately and add thereto, with adequate stirring, the
mucilage component which may then be neutralized in situ. The mold
inhibitor or the like, if any, is preferably introduced with the
neutralizing agent for more effective disbursement.
Generally, the electrolyte components are blended at ambient
temperature and atmospheric pressure. If desired, however, elevated
temperatures and pressure conditions, for instance, could be used
very satisfactorily.
If desired, the electrolyte may comprise a column or multiple
columns (e.g., the honeycomb disc hereinbefore discussed) of
electrolyte paste, gels, or the like. Also, the electrolyte may
comprise a paste or gel having therein interspersed finely-divided
particulate materials, usually inert, such as powdered talc,
regenerated cellulose, sand, fumed silica (SiO.sub.2), silica gel,
or other similar fillers. Generally, from about 5 to 60 percent by
weight filler is present, based upon the total weight of the
electrolyte (e.g., gel or paste) and filler composition, preferably
about 20 to about 50 percent.
While stainless steel is one of the preferred electrode elements,
the invention is not limited thereto. The electrode may be made out
of any conductive material, e.g., aluminum, copper, silver,
silver/silver chloride, brass, platinum, gold, and the like. The
conductive metal can, for instance, merely be present as a plating
on a substrate of, for example, another metal, plastic, or the
like. A flexible conductive metal sheet may, for instance, be
prepared from powdered metal which is sintered to the desired
shape; the pulverized metal may be shaped into a sheet by embedding
the metal particulates in a binder, such as a polymeric binder or
matrix. The expression "conductive metal" is intended to encompass,
also, other conductive materials including, for instance, a carbon
disc.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of a protective covering for an
electrode.
FIG. 1A is a schematic of the electrosurgical current source,
active electrode, patient and indifferent electrode.
FIG. 2 is a cross sectional view of the electrode and protective
covering taken along line 2--2 of FIG. 1.
FIG. 3 is partially exploded perspective view of the electrode with
the protective covering removed.
FIG. 4 is a partially exploded perspective view of the electrode
with the protective covering and the protective releasable cover
sheet removed.
FIG. 5 is a partially exploded perspective view of the electrode
with the protective covering, the protective releasable cover
sheet, the non-conductive cup member, the snap fastener, and the
flexible and resilient sheet removed, and the electrolyte-saturated
cellular matrix of FIG. 4 is substituted by a single non-woven
cotton fabric disc, likewise electrolyte-saturated.
FIG. 6 is the same as FIG. 5 with the exception that multiple
non-woven cotton fabric discs are stacked and, of course,
electrolyte-saturated.
FIG. 7 is a perspective view of a disc-shaped sponge-like cellular
electrolyte matrix having a wire electrode therein embedded.
FIG. 8 is a partially exploded perspective view of the electrode
with the protective covering, the protective releasable cover
sheet, the non-conductive cup member, the snap fastener, and the
flexible and resilient sheet removed, and the conductive metal
sheet is covered with a polymeric film partly broken away to show
the metal sheet.
FIG. 9 is a cross sectional view of the polymeric film covered
conductive metal sheet taken along line 9--9 of FIG. 8.
FIG. 10 is a partially exploded perspective view of the electrode
with the protective covering, the protective releasable cover
sheet, the non-conductive cup member, the snap fastener, and the
flexible and resilient sheet removed, and the disc-shaped
sponge-like cellular electrolyte matrix is covered with a polymeric
film partly broken away to show the electrolyte matrix.
FIG. 11 is a cross sectional view of the polymeric film covered
disc-shaped sponge-like cellular electrolyte matrix, the polymeric
film partly broken away to show the electrolyte matrix.
FIG. 12 is a partially exploded perspective view of the electrode
with the protective covering, the protective releasable cover
sheet, the non-conductive cup member, the snap fastener, and the
flexible and resilient sheet removed, and the conductive metal
sheet and disc-shaped sponge-like cellular electrolyte matrix are
each covered with a polymeric film partly broken away in each case
to show the metal sheet and electrolyte matrix, respectively.
FIG. 13 is a partially exploded perspective view of the electrode
with the protective covering, the protective releasable cover
sheet, the non-conductive cup member, the snap fastener, and the
flexible and resilient sheet removed, and the
electrolyte-containing member is a disc of non-conductive polymer
having honeycomb apertures therethrough, some filled with
electrolyte gel and some empty.
FIG. 14 is a partial central cross sectional view of the electrode
with the protective covering and the cellular electrolyte matrix
removed, the non-conductive cup member being shown filled with an
electrolyte gel.
DESCRIPTION OF A PREFERRED EMBODIMENT
The drawing illustrates an electrode, generally designated 10,
consisting of a substantially rectangular flexible and resilient
sheet 12 (as here shown) carrying a generally centrally located
non-conductive cup member 14, the surface of the flexible and
resilient sheet 12 in coplanar relationship to the outer surface of
the flat base 16 of the cup member 14. The latter, in turn, in its
cavity which opens to the body surface (not shown) carries coplanar
to and resting on the interior surface of its flat base 16 flexible
sheet (or foil) of conductive metal electrode 17. The diameter of
the cup member 14 is substantially greater than its height, thus
defining a low profile.
The flexible and resilient sheet 12, the cup member 14 and the
flexible sheet of conductive metal 17 are held together by a
metallic conductor formed from a male snap fastener member,
generally designated 18, and which includes a lower, circular plate
portion 20, from the center of which a hollow stud 22 projects
upwardly, and an upper plate portion 24 having an upwardly
protruding hollow socket portion 26 receiving the stud 22.
The parts are assembled and held together by centrally locating and
aligning the cup member 14 containing the likewise centrally
located and aligned flexible sheet of conductive metal 17 and the
upper plate portion 24 with its upwardly protruding hollow socket
portion 26 on opposite sides of sheet 12. The stud 22 is then
inserted through aligned apertures in the centers of flexible
conductive sheet 17, base 16 and resilient sheet 12 and into the
socket 26. The pressing together of the snap fastener portions
causes the upper end of the stud 22 to fold inwardly and its side
walls to collapse outwardly whereupon the snap fastener parts are
tightly wedged together.
The bottom surface of the sheet 12 has a commercially available,
medical grade acrylic pressure sensitive adhesive coating 28. Until
the electrode 10 is to be used, the adhesive coating 28 is covered
by a protective paper sheet 30 having a release coating on its face
which engages the adhesive coating 28. The outer surface of flat
base 16 of flexible cup member 14 is not only mounted on resilient
sheet 12 by means of the above-described snap fastener but the
outer surface of flat base 16 is adhered to the bottom surface of
resilient sheet 12 by means of the pressure adhesive coating 28 on
sheet 12. For this purpose protective paper sheet 30 has an opening
therein through which cup member 14 projects.
The sheet 12 is preferably formed of a foamed plastic, such as
polyurethane, polyvinyl chloride, or the like, which provides for
adequate aeration or ventilation of the skin. Such a sheet is quite
flexible, readily conforming to skin contours and permitting free
movement of the skin to which it is applied. The cup member 14 may
be vacuum formed from a non-conductive thermoplastic sheet material
which is flexible but sufficiently rigid to prevent its collapse. A
variety of plastic materials may be used to form the cup member 14,
examples being linear polyethylene, polyvinyl chloride, cellulose
acetate butyrate, or the like.
The electrolyte may be preassembled with the electrode 10 by
soaking a disc-shaped sponge-like cellular matrix 32 of
non-conductive, open-cell material with an electrode jelly. The
sponge-like matrix 32 preferably has a diameter substantially equal
to the diameter of the base 16 of the cup member 14 and a thickness
greater than the depth of the cup member 14. It is sufficiently
heavily laden with electrode jelly that, when the electrode 10 is
pressed on the skin, the jelly fills the entire volume of the
cavity between the skin and the conductive metal sheet 17 and plate
portion 20 whereupon good electrical contact between the skin and
the conductive metal sheet electrode 17 and conductive plate 20
through the jelly is assured.
The sponge-like matrix 32 may be manufactured from open-cell
polyurethane foam material although other cellular materials would
be suitable. The sponge-like matrix 32 may be soaked with the jelly
(e.g., sodium sulfate) by immersing it in a quantity of jelly,
squeezing it under pressure and then gradually releasing the
pressure before removing it from the jelly in the same manner that
one would load a sponge with water. Of course it could be soaked
with electrolyte by other methods.
In view of being wetted by the viscous electrolyte, the soaked
sponge-like matrix 32 tends to adhere to conductive metal sheet
electrode 17, conductive plate portion 20 and the inner surfaces of
cup member 14. As shown, the sponge-like cellular matrix 32 is
fastened to the electrode assembly conductive plate portion 20 by
means of a plastic (e.g., nylon, polyacetate) non-conductive rivet
34 having a shaft 35 which passes upwardly through apertured
aqueous highly viscous semisolid electrolyte composition 32 into
and in locking engagement in the hollow neck portion 22 of said
stud 20.
Further in accordance with this invention, a protective cover 38 in
FIGS. 1, 2 and 3 is provided for the cup member 14 and the jelly
soaked sponge-like matrix 32 so that the electrode 10 may be stored
ready for immediate use. The cover 38 comprises an essentially flat
strip of non-conductive plastic sheet having flat ends 40 and a
raised center portion 42 formed as a cylinder, the inner diameter
of which is substantially the same as the outer diameter of the cup
member 14. The height of the cylindrical center portion 42 is at
least the combined height of the cup member 14 and the sponge-like
matrix 32. The protective cover 38 is lightly adhered to protective
sheet 30 such that removal of releasable sheet 30 carries with it
protective cover 38, yet cover 38 may be readily separated from
sheet 30 without disturbing the latter.
The cover 38 is assembled on the non-adhesive face of the
protective sheet 30 with the cylindrical center section 42 slipped
over the cup member 14. The protective cover 38 serves to prevent
soiling and evaporation of the aqueous semisolid matrix 32. As
suggested hereinbefore, when the electrode 10 is to be used, the
protective sheet 30 is merely peeled away from the sheet 12, taking
with it the protective cover 38.
Pursuant to another embodiment of the present invention, FIG. 5,
the sponge-like disc-shaped cellular electrolyte matrix 32 of FIG.
3 is replaced by a non-woven cotton fabric disc 50, which disc is
at least 10 mils thick, is saturated with an electrolyte jelly and
completely covers the lower or skin-side surface of the electrode
sheet 17, i.e., the diameter of the disc 50 being preferably
greater than that of the disc-shaped conductive metal sheet 17.
The embodiment shown in FIG. 6 resembles the structure of FIG. 5 in
every essential respect with the exception that the electrolyte
composition structure comprises multiple laminated non-woven cotton
fabric discs 60, also saturated or soaked with electrolyte
jelly.
The FIG. 7 embodiment comprises a disc-shaped sponge-like cellular
electrolyte matrix 70 having no central aperture yet having a thin
wire electrode 72 transversely embedded therein along its diametric
plane, one end of the wire terminating within the cellular
electrolyte matrix disc and the other end of the wire directed to
ground and away from the skin-surface of the cellular matrix disc,
as shown. When this wire provides a conductive surface in contact
with the electrolyte in the range of 0.038 and 0.10 square inch,
the electrolyte composition should be at least about 165 mils in
thickness, i.e., the conductive wire should be maintained (spaced)
a distance of at least about 165 mils from the skin.
A still further embodiment is shown in FIG. 8 wherein the
sponge-like cellular electrolyte matrix 32 of FIG. 3 (without a
central aperture) is spaced from conductive metal sheet disc 17 by
a polymer film 80, the edges and sides of conductive metal sheet 17
both being covered, as shown, with continuous polymeric film 80,
neither the matrix 32 nor film 80 being centrally apertured. FIG. 9
is a cross sectional view of the conductive metal sheet 17/polymer
film 80 of FIG. 8 when assembled.
The embodiment of FIG. 10 teaches the cellular matrix 32 of FIG. 3
(without a central aperture) covered on the skin and lateral sides
with a continuous polymeric film 80 of the type shown in FIGS. 8
and 9. FIG. 11 is merely a cross sectional view of the covered
cellular matrix of FIG. 10.
The embodiment shown in FIG. 12 comprises a structure in which the
sponge-like disc-shaped cellular matrix 32 and the conductive metal
sheet 17 are each covered on their skin-side and lateral surfaces
with continuous polymeric film 80.
In the FIG. 13 embodiment, the electrode/electrolyte assembly of
FIG. 3 in which the electrolyte-containing member 32 is substituted
with a disc 90 of non-conductive material, e.g., polymeric
material, having honeycomb hexagonal apertures 92 therethrough, or
the like, and certain of these apertures (as shown) are filled with
electrolyte gel while others are devoid of same.
In FIG. 14 a still further embodiment is shown in which
non-conductive cup member 14 is filled with an electrolyte gel or
paste 100 in lieu of the sponge-like matrix 32 of FIG. 3.
Referring to FIG. 13, electrolyte-containing polymer disc 90 may be
made of any number of polymeric, preferably non-conductive,
plastics usually rigid enough so that they do not collapse under
the conventional pressure of use. Typical polymers are polyamides,
polyethylene, polyvinyl chloride, polyurethane, oxymethylene
polymers, and the like. Of course, as suggested hereinbefore, the
apertures may be other than hexagonal, such as round, rectangular,
elliptical, or the like.
Referring to FIGS. 8 through 12, the polymeric sheet or film
material 80 may likewise be of a non-conductive nature and would
include such polymers as polyvinylidene chloride (saran), nylon,
polyethylene, polyester, polyacrylic, and the like.
Additional advantages accruing in the use of a polymeric film as
shown in FIGS. 8 through 12 are the fact that the skin surface of a
patient need not be in direct contact with electrolyte, such as
sodium chloride, thus providing greater comfort to the patient;
also, for storage purposes and to avoid corrosion, a caustic
electrolyte, such as sodium chloride, may be kept out of direct
contact with the metal electrode disc.
It is obvious that many other configurations are inherent in the
description herein with respect to the electrolyte/electrode
assembly, without losing the superior effectiveness thereof in
grounding current under electrosurgical conditions while at the
same time preventing burns and the other complications indigenous
to the large ground plates. As will be seen hereinafter, current is
very effectively dissipated through the assembly of the present and
the large ground plate hazards obviated.
It may be desirable under certain circumstances to use rectangular
or ribbon-type electrolyte bodies in conjunction with any of the
electrode configurations described or suggested herein to provide a
ground for extremities or difficultly accessible human body areas.
Since the present invention provides for such uniform current
density distribution across the surfaces of, and through the
electrolyte and electrode components, it will be apparent to the
person skilled in the art that a multitude of shapes and uses for
the assembly are suggested and contemplated.
EXAMPLES
The present invention will best be understood from the following
examples in which, unless otherwise indicated, percentages and
parts are by weight.
Example I
The following components are blended into an electrolyte
composition:
93.3 parts water
2.0 parts Carbopol* 940
1.6 parts triethanolamine
0.1 parts 2-chloro-m-xylenol
3.0 parts sodium sulfate (anhydrous) L6 *Trademark used by B. F.
Goodrich Chemical Co. for carboxypolymethylene (polyacrylic acid of
4-6 million molecular weight)
The anhydrous sodium sulfate is dissolved in water with mild
stirring and the polyacrylic acid is then slowly sifted into the
aqueous salt solution with rigorous stirring until the polyacrylic
acid is homogeneously dispersed and/or dissolved. A solution of the
triethanolamine and 2-chloro-m-xylenol, which is prepared by mild
heating and stirring of the two components, is rapidly added to the
mixture (with rigorous stirring and following the method used just
above for polyacrylic acid). Rigorous stirring is continued for
10-60 minutes until the proper viscosity is obtained.
Example II
The following components are blended into an electrolyte
composition:
79.1 parts water
2.4 parts Carbopol 940
3.0 parts triethanolamine
0.5 part 2-chloro-m-xylenol
15.0 parts sodium sulfate (anhydrous)
Blending is carried out essentially as in Example I, above, with
the exception that 2-chloro-m-xylenol and triethanolamine are added
(after the polyacrylic acid) separately and sequentially with
vigorous stirring upon each addition.
Example III
The following components are blended into an electrolyte
composition essentially as taught in Example I, above:
74.3 parts water
2.4 parts Carbopol 940
3.1 parts triethanolamine
0.2 part 2-chloro-m-xylenol
20.0 parts sodium sulfate (anhydrous)
Example IV
The electrolyte composition of each of the above examples is used
to soak a sponge-like cellular flexible polyurethane matrix and the
resulting semisolid composition tested by placing same in an
electrode of the type shown in FIGS. 1 to 4 of the drawing and
having the following dimensions.
Sponge (polyurethane foam) matrix 32 has a diameter of about 2.25
.+-. inches, a thickness of 310 mils, and a density of 2 pounds per
cubic foot. Electrode stainless steel conductive sheet 17 has a
diameter of 1.80 .+-. inches, a thickness of 0.003 inch, and an
aperture diameter of 0.165 .+-. inch.
Polyvinyl chloride cup 14 has an outside diameter of 2.48 .+-.
inches, a shoulder (wall) radius of 0.063 .+-. inch, a base 16
thickness of 0.040 .+-. inch, and an aperture diameter of 0.070
.+-. inch.
Polyurethane soft resilient flexible sheet 12 has a length of 7.5
inches, a width of 3 inches, a thickness of three-sizteenths inch,
and a radius (each end) of 1.56 .+-. inches.
Protective cover 38 of polyvinyl chloride sheet (10 mil thickness
and semi-rigid) has a cylindrical portion 42 having a diameter
(inside) of 2.57 .+-. inches.
Male snap fastener 18 components 20, 22, 24 and 26 are made of
stainless steel; circular plate portion 20 of stud 22 has a
diameter of 0.42 .+-. inch and height of 0.205 inch, and a stud
outside diameter of 0.126 .+-. inch; circular plate portion 24 has
a diameter of 0.42 .+-. inch, a height of 0.135 .+-. inch, and a
socket (barrel) outside diameter of 0.155 .+-. inch, and an inside
diameter of 0.125 .+-. inch.
Polyacetal rivet (accordion) 34 has a tapered shaft 35 which is
0.380 .+-. inch in length and its widest diameter is 0.160 .+-.
inch.
This just described indifferent electrode is connected through snap
fastener 18 to a suitable conductive locking means and cable, the
latter leading to the ground receptacle of a conventional Model CSV
Bovie high frequency radio wave electrosurgical unit. The unit has
a variable output.
Test Procedure (Example IV-continued)
The just described electrode is applied (adhered) to the upper arm
(bicep) of an adult male (in his 30's, 180 lb., 6 ft.) for
experimental purposes, the electrolyte thereof having the sodium
sulfate composition and concentration of Example II, supra. The
electrode snap fastener 18 is attached to a conductive locking
device and cable leading to the ground receptacle of a Model CSV
Bovie electro-surgical unit. The patient holds a piece of fresh
beef liver (8 .times. 3 .times. 3/4 inches) placed in his hand, the
latter having been smeared with the electrolyte jelly of Example II
to reduce impedance between the patient's skin (hand) and the liver
he is gripping.
The unit (CSV) is activated and using a conventional active ball
(1/8 inch diameter) electrode surgery is performed on the liver
using the following bursts of current settings which are
substantially more severe than employed in conventional
surgery:
1. At cutting power control setting of 60 (cutting current selector
of 1) on the CSV unit dial for two continuous minutes.
2. Pause one minute.
3. Repeat (1) above only using setting of 70.
4. Pause one more minute.
5. Repeat (1) above only using setting of 80.
A temperature increase at the interface of the electrolyte sponge
32 and the patient's skin of less than 1.degree. F. is noted and
absolutely no heat sensations (and, of course, no burn) is
experienced by the patient.
Example V
Example IV is repeated in every essential respect only a
coagulating power control setting (cutting current selector of 4)
is used in lieu of the cutting setting. Again the results are the
same.
Example VI
In over 600 actual surgical procedures in over a dozen hospitals
throughout the U.S.A. during 1971, the disposable indifferent
electrodes of Example III were tested and the reports are that the
electrodes not only did not cause any burns or other harm but they
functioned excellently.
Example VII
The liver test of Example IV is repeated using the electrode of
Example III only the area of the sheet conductive metal electrode
17 (on its electrolyte surface) is only 0.5 square inch, the
diameter of the sponge matrix electrolyte 32 is only 0.8 inch and
rivet 34 is not used. The current bursts are as follows:
1. Cutting power control setting of 30 (cutting current selector of
1) for 0.5 continuous minute.
2. Pause 0.5 minute.
3. Cutting power control setting of 40 (cutting current selector of
1) for 1.0 continuous minute.
4. Pause 0.5 minute.
5. Cutting power control setting of 50 (cutting current selector of
1) for 0.5 continuous minute.
6. Pause 0.25 minute.
7. Cutting power control setting of 50 (cutting current selector of
1) for 0.5 minute.
8. Pause 0.5 minute.
9. Cutting power control setting of 60 (cutting current selector of
1) for 2.0 continuous minutes.
10. Pause 0.5 minute.
11. Cutting power control setting of 70 (cutting current selector
of 1) for 2.0 continuous minutes.
A temperature rise of less than 3.degree. F. is experienced and no
deleterious effects are experienced by the patient.
As is obvious from the above, the indifferent electrode of the
present invention quite surprisingly overcomes the drawbacks
discussed hereinabove and accomplishes the objectives hereinbefore
described.
Example viii
the advantages attending isolation of the metallic conductor of the
electrode/electrolyte assembly contemplated herein from the skin
are illustrated as follows:
1. Experimental Procedure
An active electrode which is described below is attached to the
underside of the forearm of an individual. This active electrode is
electrically connected to the active terminal of a commercial
electrosurgical unit of the type described in Example IV, above,
(CSV Bovie, manufactured by Liebel-Florsheim Company). This
electrical connection contains a thermocouple amp. meter. The
ground electrode under test is mounted on the outside of the upper
arm (same arm as used for the active electrode). The ground
electrode is electrically connected through a thermocouple RF amp.
meter to the ground terminal of the electrosurgical unit.
The electrosurgical unit is then activated. Current flow (amperes)
through the active and ground loops, and power settings of the unit
are recorded. The time of continuous activation (Time of
Activation) in which heat is developed under either the ground or
active electrode to the point where it is very uncomfortable (heat
sensation) is also recorded.
2. Experimental Data
a. Active electrode of Example IV is used, i.e., a 0.9 inch radius
stainless steel (316) disc (3 mil thick) which contains in its
center a stainless steel (316) crimped snap. The active electrode
also contains on top of the disc 310 mils thick .times. 2.25 inch
diameter polyurethane foam matrix -- medium density -- saturated
with 15 percent sodium sulfate gel (of Example II).
b. Ground Test Electrodes
1. Ground electrode A is of the same construction as the above
described active electrode.
2. Ground electrode B consists of a 0.9 inch radius stainless steel
(316) disc (3 mil thick) which contains in its center a stainless
steel (316) crimped snap. This disc is placed directly onto the
skin.
3. Ground electrode C consists of a 0.9 inch radius stainless steel
(316) disc (3 mil thick) which contains in its center a stainless
steel (316) crimped snap. The surface of this disc is lightly
smeared with 15 percent, by weight, sodium sulfate gel (of Example
II).
__________________________________________________________________________
GROUND CSV BOVIE ACTIVE GROUND TIME OF ELECTRODE SUBJECT SETTINGS
AMP. AMP. ACTIVATION
__________________________________________________________________________
A Male I #1 Cut/33 0.73 0.72 35.0 sec. B Male I #1 Cut/33 -- 0.70
7.5 sec. C Male I #1 Cut/33 0.72 0.72 9.5 sec. A Male II #1 Cut/33
0.74 0.76 110.0 sec. B Male II #1 Cut/33 0.72 0.73 12.5 sec. C Male
II #1 Cut/33 0.72 0.74 19.0 sec.
__________________________________________________________________________
Example ix
experiments demonstrating the height requirements for separation of
the metallic conductor from the skin are carried out as
follows:
1. Height of Separation: 10 mil
a. The active electrode of Example VIII(2a) is used.
b. Ground electrode A consists of a 0.9 inch radius stainless steel
(316) disc (3 mil thick) which contains in its center a stainless
steel (316) crimped snap. The disc is covered with a 2 inch .times.
2 inch section of porous paper* (lab paper 10 mils thick) which is
saturated with 15 percent sodium sulfate gel (of Example II).
c. Ground electrode B (see FIG. 5) is similar in construction to
ground electrode A except that the disc is covered by a 2.25 inch
diameter piece of non-woven cotton fabric (10 mils thick) saturated
with 15 percent sodium sulfate gel (of Example II).
__________________________________________________________________________
GROUND CSV BOVIE ACTIVE GROUND TIME OF ELECTRODE SUBJECT SETTINGS
AMP. AMP. ACTIVATION
__________________________________________________________________________
A Male IV #1 Cut/28 0.58 0.65 47.0 sec. B Male V #1 Cut/30 0.63
0.72 46.0 sec.
__________________________________________________________________________
2. One Inch Electrolyte Matrix
a. The active electrode of Example VII(2a) is used.
b. The ground electrode consists of 0.9 inch radius stainless steel
(316) disc (3 mils thick) which contains in its center a crimped
stainless steel (316) snap. A 1 inch thick .times. 2.25 inch
diameter polyurethane foam matrix-medium density-saturated with 15
percent sodium sulfate gel is placed on top of the stainless steel
disc, instead of the 310 mil thick .times. 2.25 inch diameter
polyurethane foam matrix of the active electrode (Example VII(2a)).
For gel see Ex. II.
______________________________________ CSV BOVIE ACTIVE GROUND TIME
OF SUBJECT SETTINGS AMP. AMP. ACTIVATION
______________________________________ Male III #1 Cut/33 0.73 0.76
58.0 sec. Male IV #1 Cut/34 0.74 0.79 >120.0 sec.
______________________________________
Example x
the following experiments demonstrate that a variety of inert
supports (fillers) can be used in the gel for improving the
performance of the electrolyte/electrode assembly (cautery pad) of
the present invention:
1. The construction of the active electrode is the same as that
previously described for Example VIII(2a).
2. Ground Test Electrodes
a. Ground electrode A consists of a 0.9 inch radius stainless steel
(316) disc (3 mils thick) which contains at its center a stainless
steel (316) crimped snap. The disc is lightly smeared with
electrolyte gel (Example II).
b. Ground electrode B consists of a 0.9 inch radius stainless steel
(316) disc (3 mils thick) containing in its center a stainless
steel (316) crimped snap. The electrode contains on top of the disc
a 125 mil high .times. 2.25 inch diameter column of electrolyte.
The electrolyte consists of a 50/50 by volume mixture of 15 percent
sodium sulfate gel (Example II) and washed sand (approx. 40-80
mesh). The electrolyte is retained in the cylindrical shape by
means of a vinyl plastisol cup which has internal dimensions of 125
mil high .times. 2.25 inch diameter.
c. Ground electrode C consists of a 0.9 inch radius stainless steel
(316) disc (3 mils thick) which contains on top of the disc a 125
mil thick .times. 2.25 inch diameter column of electrolyte, the
electrolyte consisting of a 50/50 by volume mixture of 15 percent
sodium sulfate gel (Example II) and regenerated cellulose (chemical
cotton). The electrolyte is retained in the cylindrical shape by
means of a vinyl plastisol cup (see FIG. 14) which has internal
dimensions of 125 mil high .times. 2.25 inch diameter. The disc, of
course, has at its center a stainless steel (316) crimped snap.
d. Ground electrode D consists of a 0.9 inch radius stainless steel
(316) disc (3 mils thick) which contains at its center a crimped
stainless steel (316) snap. The electrode contains on top of the
disc a 125 mil high .times. 2.25 inch diameter column of
electrolyte. The electrolyte consists of a 24.3 percent by weight
mixture of powdered talc in 15 percent sodium sulfate gel (Example
II). The electrolyte is retained in the cylindrical shape by means
of a vinyl plastisol cup (see FIG. 14) which has internal
dimensions of 125 mil high .times. 2.25 inch diameter.
e. Ground electrode E consists of a 0.9 inch radius stainless steel
(316) disc (3 mils thick) which contains at its center a crimped
stainless steel (316) snap. The electrode contains on top of the
disc 40 layers .times. 2.25 inch diameter (see FIG. 6) of a
non-woven cotton fabric (10 mils thick each layer) saturated with
15 percent sodium sulfate gel (Example II).
f. Ground electrode F consists of a 0.9 inch radius stainless steel
(316) disc (3 mils thick) which contains at its center a crimped
stainless steel (316) snap. The electrode contains on top of the
disc a 210 mil .times. 2.25 inch diameter polyether urethane foam
(density = 1.5 lb./ft..sup.3) matrix saturated with 15 percent
sodium sulfate gel (Example II).
g. Ground electrode G is the same as F except the polyether
urethane foam matrix 178 mils thick .times. 2.25 inch diameter and
a density of 4.8 lb./ft..sup.3.
__________________________________________________________________________
GROUND CSV BOVIE ACTIVE GROUND TIME OF ELECTRODE SUBJECT SETTINGS
AMP. AMP. ACTIVATION
__________________________________________________________________________
A Male IV #1 Cut/30 0.59 0.65 18.5 sec. B Male IV #1 Cut/33 0.68
0.70 55.0 sec. C Male IV #1 Cut/33 0.69 0.71 40.0 sec. E Male IV #1
Cut/33 0.72 0.76 59.0 sec. F Male IV #1 Cut/33 0.68 0.70 90.0 sec.
G Male IV #1 Cut/33 0.69 0.71 69.0 sec. D Male V #1 Cut/33 0.73
0.77 51.0 sec.
__________________________________________________________________________
Example xi
various surface areas for both electrolyte composition and metal
electrode conductors are illustrated in the following
experiments:
1. Construction of the active electrode is exactly the same as that
of Example VIII(2a).
2. Ground Test Electrodes
a. Ground electrode A consists of a 0.8 inch radius stainless steel
(316) conductor (2.0 sq. in., and 3 mils thick) containing in its
center a crimped stainless steel (316) snap. The conductor is
lightly smeared with 15 percent sodium sulfate gel (Example II)
prior to placing the electrode on the skin.
b. Ground electrode B consists of a 0.012 inch diameter .times. 1.0
inch long silver wire as the metal contact (surface area = 0.038
sq. in.) (see FIG. 7). This wire is embedded in a 0.8 inch radius
(surface area = 2.0 sq. in.) polyether-urethane foam matrix (188
mils thick) which is saturated with 15 percent sodium sulfate gel
(Example II); the wire is embedded in the upper surface of the foam
matrix at least over 175 mils from the skin surface thereof.
__________________________________________________________________________
GROUND CSV BOVIE ACTIVE GROUND TIME OF ELECTRODE SUBJECT SETTINGS
AMP. AMP. ACTIVATION
__________________________________________________________________________
A Male III #1 Cut/33 0.64 0.74 11.0 sec. B Male III #1 Cut/33 0.64
0.72 22.0 sec.
__________________________________________________________________________
c. Ground electrode C consists of a 1.86 inch radius stainless
steel (3 mils thick) conductor (surface area = 10.8 sq. in.) which
contains in its center a crimped stainless steel snap. The
conductor is lightly smeared with 15 percent sodium sulfate gel
(Example II) prior to placing the electrode on the skin.
d. Ground electrode D consists of a 1.86 inch radius stainless
steel (316) disc (surface area = 10.8 sq. in.) which contains at
its center a crimped stainless steel (316) snap. A 1.86 inch radius
(surface area = 10.8 sq. in.) polyetherurethane foam matrix (188
mils thick) which is saturated with 15 percent sodium sulfate gel
(Example II) is placed on top of the metal conductor.
__________________________________________________________________________
GROUND CSV BOVIE ACTIVE GROUND TIME OF ELECTRODE SUBJECT SETTINGS
AMP. AMP. ACTIVATION
__________________________________________________________________________
C Male III #1 Cut/50 -- 1.30 17.0 sec. D Male III #1 Cut/50 -- 1.30
30.0 sec.
__________________________________________________________________________
Example xii
the following data demonstrate that a variety of geometrical
configurations of both electrolyte composition and metal conductor
can be used:
1. Elliptical Configuration
a. The construction of the active electrode is the same as that
described in Example VIII(2a).
b. The ground test electrode consists of an elliptical stainless
steel (316) conductor (major axis = 37/8 inch; minor axis = 2 3/16
inch) which contains at its center a crimped stainless steel (316)
snap. An elliptical (major axis =4 3/8 inch; minor axis = 21/2
inch) polyether-urethane foam matrix (188 mils thick) which is
saturated with 15 percent sodium sulfate gel (Example II) is placed
on the metal conductor.
______________________________________ CSV BOVIE ACTIVE GROUND TIME
OF SUBJECT SETTINGS AMP. AMP. ACTIVATION
______________________________________ Male IV #1 Cut/45 0.86 0.97
75.0 sec. Male V #1 Cut/45 0.86 0.98 >90.0 sec. Male VI #1
Cut/45 0.84 0.95 >90.0 sec.
______________________________________
c. The ground test electrode consists of a 1 inch .times. 1 inch
square stainless steel (3 mils thick) (316) conductor which
contains at its center a crimped stainless steel (316) snap. A 3
inch .times. 3 inch square polyether-urethane foam matrix (188 mils
thick) which is saturated with 15 percent sodium sulfate gel
(Example II) is placed on top of the metal conductor.
______________________________________ CSV BOVIE ACTIVE GROUND TIME
OF SUBJECT SETTINGS AMP. AMP. ACTIVATION
______________________________________ Male III #1 Cut/43 -- 1.18
34.0 sec.* Male IV #1 Cut/43 -- 1.20 26.0 sec.* Male V #1 Cut/43 --
1.20 47.0 sec.* Male II #1 Cut/43 -- 1.20 24.0 sec.*
______________________________________ * In all cases the active
electrode became much hotter than the ground electrode.
d. The ground test electrode connsists of a 1 inch .times. 1/2 inch
rectangular stainless (316) steel conductor (3 mils thick) which
contains at its center a crimped stainless steel (316) snap. A 4
inch .times. 1 inch polyether-urethane foam (188 mils thick) matrix
which is saturated with 15 percent sodium sulfate gel (Example II)
is placed on top of the metal conductor.
______________________________________ CSV BOVIE ACTIVE GROUND TIME
OF SUBJECT SETTINGS AMP. AMP. ACTIVATION
______________________________________ Male IV #1 Cut/42 0.80 0.92
73.0 sec. Male V #1 Cut/42 0.82 0.86 94.0 sec.
______________________________________
Example xiii
the following data demonstrate that a non-conductive material
(insulator) can be placed either between the conductor and
electrolyte, between the skin and electrolyte, or between both the
conductor-electrolyte interface and the skin-electrolyte
interface:
a. The active electrode is that of Example VIII(2a).
b. Ground test electrode A consists of a 2.25 inch diameter
stainless steel (316) disc (3 mils thick) which contains at its
center a crimped stainless steel (316) snap. The disc is completely
covered (FIGS. 8 and 9) with a 3 mil thick piece of saran
(polyvinylidene chloride) film. A 2.25 inch diameter (310 mils
thick) polyether-urethane matrix which is saturated with 15 percent
sodium sulfate gel (Example II) is placed on top of the
polyvinylidene chloride film.
c. Ground test electrode B consists of a 2.25 inch diameter
stainless steel (316) disc (3 mils thick) which contains a crimped
stainless steel (316) snap. A 2.25 inch diameter (310 mils thick)
polyether-urethane matrix which is saturated with 15 percent sodium
sulfate gel (Example II) is placed on top of the disc. A 3 mil
thick film of saran (polyvinylidene chloride) film (FIGS. 10 and
11) which completely covers the foam matrix is placed on top of
it.
d. Ground test electrode C consists of a 2.25 inch diameter
stainless steel (316) disc (3 mils thick) which contains at its
center a crimped stainless steel (316) snap. The disc is completely
covered with a 3 mil thick film of saran (polyvinylidene chloride)
film. A 2.25 inch diameter polyether-urethane matrix which is
saturated with 15 percent sodium sulfate gel (Example II) is placed
over this film of polyvinylidene chloride. A second 3 mil thick
film of saran (polyvinylidene chloride) is then placed over and
completely covers the foam matrix (see FIG. 12).
e. Ground test electrode D consists of a 2.25 inch diameter
stainless steel (316) disc (3 mils thick) which contains at its
center a crimped stainless steel (316) snap. A 10 mil thick piece
(2.25 inch diameter) of non-woven cotton fabric which is saturated
with 15 percent sodium sulfate gel (Example II) is placed over the
disc. A 3 mil thick film of polyvinylidene chloride is placed over
and completely covers the non-woven fabric.
______________________________________ GROUND CSV BOVIE GROUND TIME
OF ELECTRODE SUBJECT SETTINGS AMP. ACTIVATION
______________________________________ A Male III #1 Cut/27 0.75
>120.0 sec. B Male III #1 Cut/25 0.74 61.0 sec. C Male III #1
Cut/25 0.74 93.0 sec. D Male III #1 Cut/22 0.74 41.0 sec.
______________________________________
It should be noted that the insulator can be any material which is
commonly used as an insulator in electrical capacitors. However, it
must be of such a nature that at the alternating current
frequencies encountered in electrosurgery, the skin and
electrolyte, and also the electrolyte and metal conductor can be
capacitively coupled.
Of course, the experimental procedure of EXAMPLE VIII is followed
in each of EXAMPLES IX through XIII.
The following Table I gives the ages and weights of each of the
males (I - VI) referred to in the above experiments:
MALE AGE WEIGHT ______________________________________ I 38 195 II
35 170 III 28 183 IV 40 170 V 33 180 VI 36 133
______________________________________
As is evident from the above experiments, the small size electrodes
of the present invention and the unique electrolytes with which
they are assembled provide a very effective, disposable biomedical
instrument. This is a finding which flies in the teeth of the
suggestions and teachings of the art of patient ground plates, not
to mention the many, many advantages insuring its immediate
success.
Pursuant to statutory requirements, there are described above the
invention and what are now considered its best embodiments. It
should again be understood, however, that the invention can be
practiced otherwise than as specifically described, within the
scope of the appended claims.
* * * * *