Note: Descriptions are shown in the official language in which they were submitted.
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IONTOPHORETIC BURN-PROTECTION METHOD AND APPARATUS
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TECHNICAL FIELD
This invention pertains to plural electrodes for
application to living subJect having skin, to accomplish
effects related to the passage of electric current.
BACKGROUND OF THE PRIOR ART
Around the turn of the ~entury the art disclosed
a plethora of electrode ty~es for applylng "electric
treatments" to the human body. The elctrodes were
normally placed upon the body in relation to the position
of an organ to be treated.
These l'electric treatments" encompassed a wide
range of appllcations. ~or example, galvanic (direct
current) treatments have been popular in the past for
their polar effects on ionized molecules, causlng the
lonized molecules to be driven through the skin, usually
superficially This phenomenon is known as iontophore-
sis or ion transfer, and it has been employed for the
introduction of medicants3 or even simply moistur~, into
the skin of a patient.
More specifically, some ions of zinc and copper
can be employed in the treatment of some skin infectionsg
and chlorine ions have been employed for the loosening
of superficial scars. FurtherJ vasodilating drugs can
be used in rheumatic and peripheral vascular affections,
and skin anesthesia can be produced by iontophoresis
o~ local anesthetlc drugs. It has been suggested that
application of direct current to carefully selected
areas of a living anlmal can produce anesthetic ef~ects.
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(see Limoge, An Introduction to Electroanesthesiag 1975,
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University Park Press).
In generalg the electrodes were disclosed
merely as structures and were not related to any unde-
sirable side-effects the electric current might have
upon the skin. An example is the U S. Patenk No.
562g7655 issued in 18953 to Hortong Jr. The usual ob~ec-
tive was merely to decrease the contact resistance to
the skin.
F. Levitt ln "Archives of Dermatology"g Vol. 98
No. 5, November 1968, reports on pps. 505-7 the produc-
tion of long-term anhidrosis by electric treatment of
the feetg or hands. However, he disclosed only the use
Or "a two inch square of sheet lead" as an electrode.
This is "placed ln a shallow pan containing enough water
to ~us-t cover the palm or soles'ig there being one elec-
~rode and one pan f`or each palm or sole. IIls test
results indicate that the treatment inhibits perspira-
tion (sweat) where the electric current is provided.
Although the above-melltioned iontophoretic
treatments have been ~ound to be effective, using known
electrodes in these direct current applications fre-
quently results in iontophoretic burns to the patient,
generally at the negative electrode. These burns are
not caused by elevated temperature but by a spontaneous
ef~ect o~ the electrlc current on the skin. These burns
require a relatively long time to healg and can result
in formation of unsightly and highly undesirable scar
tissue.
A paper by Leeming and Howland in the "~ournal
o~ the American Medical Association"g Vol. 214g NoO 9g
Nov. 30, 1970g recites instances of burns but does not
present means for preventing such trauma. This unde-
sirable effect of iontophoretic treatment has resulted
in a less than enthusiastic reception of iontophoretic
techniques by the medical community in spite o~ the
great and varied advantages to be realized through
their use and development.
Accordinglyg there has existed a need for a
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8~52
convenient and e~fective method and apparatus for pre
venting iontopheric burns during the application o~
electrical energy to the skin of a human body. As will
become apparent from the following~ the present inven-
tion satisfies that need.
BRIEF SUMMARY OF THE INVENTION
A method and apparatus ~or applying electricalenergy topically to the skin of the human body is pro-
vided by which undeslred side-effects are greatly mini-
mized and may be eliminated.
The electrode configuration o~ the inventionincludes two conductive areas to which opposite polariky
of electric current is supplied and wh~ch may be rela-
tively adjacent. When the electrodes are ad~acent the
15 electric current does not pass through or near electro~
sensitive organsJ such as the heart.
Although the present method and apparatus for
preventing iontophoretic burns will be described as
used in connection with an ele~trical treatment for
lnhibiting perspiration, it will be understood that this
method and apparatus is equally well suited for use with
other electrical treatments, such as the examples de-
scribed above.
One side-effect that is substantially elimin-
25 ated by the electrode structure o~ thls inventlon is
the iontophoretic burn. This is because of the inter-
position o~ relatlvely thick porous and pre~erably
moistened material between the negative electrode and
the skin.
Another side-effect that is reduced is pain or
tingling due to the passage of current. This is brought
about by increasing the area of the positive electrode.
An alternate embodiment utili~es intermingled
nagative and positive electrodes of small size, all
35 having porous material.
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1~ 35'~
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In accordance with one broad aspect, the
invention relates to an electrode structure for apply-
ing an essentially unidirectional electric current
through the skin of a living bodyr comprising: a first
electricall~ conductive electrode having a porous
material with a thickness of at least thxee millimeters
upon one side thereof adapted to be interposed between
said electrode and said skin' a second electrically
conductive electrode adapted to contact said skin at a
location thereon spaced from said first electrodeS a
controlled source of unidirectional electric current having
a positive pole and a negative pole~ and means for connect-
ing said first electrode to said negative pole and said
second electrode to said positive pole, whereby ionto-
phoretic burn is minimized.
BRIEF `PESCRIPTION OF THE PR~WINGS
FIGURE 1 is a sectional elevation, at 1-1 in
F~G. 2, of a conductive electrode, the porous intervenor,
and the skin to be treated.
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FIG. 2 is an lllustrative plan view o~ a pair
o~ electrodes and of the remainder o~ the system.
FIG 3 is an alternate embodlment in which one
electrode is larger than the other.
FIG. 4 is another alternate embodiment in which
positive and negative electrodes o~ small size are
spatially intermingled.
FIG. 5 is another alternate embodiment in
which positive and negative electrodes o~ small size
are sp~tially intermingled, with the positive electrodes
larger than the negative electrodes.
DEl'AILED DESCRIPTION OF THE INVENTION
In FIG. 1 numeral 1 indicates a conductive
electrode. This may be ~lexible or rigid and is typi-
cal~y ~abrlcated of metal, of which stalnless steel and
alu~inum are examples.
The skin is represented by epidermis 2. This
h~s been simply shown. The physiolo~ical detail o~ the
epidermis is shown in a drawing on page 8~o~ Vol. 16,
15th Editionj c~pyright 1974J of the "Encyclopedia
Britannica".
Porous intervenor mate;rial 4 is typically in
loose electrical contact to the underside of electrode
1 so that it can be changed and discarded a~ter each
use.
A suitable material ~ is a type of felt thatcan b~ obtained commercially. While the thickness
stipulated as principal in this invention is not com-
monly available, it can be obtained in special order. A
3 quallty control speci~ication for this material is that
it be ~ree of tramp metal.
A thickness greater than 3 millimeters may be
chosen if a greater value of the current times the
time-of-treatment factor is desired.
Flexible electrical conductor 5 is conductively
connected to electrode 1. Electrode`l may take the
form of a snap ~astener as well as a metallic plate or a
conductive plastic such as silicone. Two examples o~
electrode arrangements are illustrated in ~IGS. 2 and 3.
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~n the view of FIG. 2 the negative electrode 1 is seen.
Porous material ~ is underneath the same.
Second electrode 5 is shown adjacent to elec-
trode 1, with a separation between the tl~o of the
order of a fraction of one to a few centimeters9 typi-
cally. Positive electrode 6g connected by conductor 7
to a source 8 of electric current, may be a simple
metallic electrode, with or without the thick porous
intervenor 4.
Source 8 may be merely a source of di~ect cur-
rent9 such as a batteryO The current normally required
is within the range of from a fraction of a milliampere
to twenty milliamperesO A known adjustable resistor
may be included within source ~ to allow the user to
obtain the proper current for any process.
For inhibiting perspiration a current density
on the positive electrode of from 1/20 to perhaps 1/2
milliampere per square cent-lmeter is desired. Natural-
1~, the actual current density and treatment duration
employed in any of the above-mentioned applications o~
this inven~ion should be chosen to accommodate the
particular case at hand. Accordingly, the actual values
mentioned herein are offered as an example of one of the
treatments whlch can employ the method and apparatus
of this invention.
Source 8 may also be a known "constant current
source''g ~laving the same specifications as above and a
control to allow the user to select the desired constant
value of current. Another feature of a suggested unit
would limit the maximum current that is applled.
The source of current may also have other
forms, including unidirectional pulses or varying cur-
rent, but not alternating current of commonly used
frequencies, nor radio frequency current.
The arrangement of electrodes 1 and 6 may take
many formsg depending upon the area that is to be
treated and the choice of the designer. These elec-
trodes may be attached to a non-conductive frameg which
is shown dotted at 9 ln FIG. 2. This is convenient for
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inhiblting perspiration on a hand or a foot.
Alternativelyg positive electrode 6 may be
placed on the palm of a hand for inhibiting perspira-
tion there9 and the negative electrode may be placed on
the back of the hand, or on the wrist.
Conme~tive means 3 attach electrodes 1 and 6
to frame 9.
Of coursej the negative electrode may be placed
elsewhere~ such as in combination with the positive
electrode within gloves ~or a hand or hands. The posi-
tive electrode is positioned to inhibit perspiration
and the negatlve electrode is positioned ad~acently for
the current return. Similar arrangements are possible
in stockings ~or the feet. Nominal pressure between
the electrodes and the skin can thereby be maintained
in any position.
For inhibiting underarm perspiration the posi-
tive electrode~ at least, can be curved to fit under
the armpit. The negative electrode may be located
nearby, or the positive and ne~,ative electrodes can
each occupy one-half o~ the ax~.lla area, with an insu-
lati.ve separator between.
In FIG. 3, elements 5~ 7 and 8 are as before.
However, positive electrode 10 has a relatively large
2F) area and negative electrode 1' has a relatively small
area. The positive electrode is rectangular, rather
than square~ as before. The elec~rode may have almost
any shape when secondary consi~erat~ons so requlre.
The conflguration shown is useful for inhib~t-
3 ing persplration of the hand. Electrode 10 is placedupon the palm of the hand and electrode 1' is placed
upon the fingers ~ the same hand.
In the practice of perspiration i~hibition and
similar treatments it has been found that iontophoretlc
burn is associated with the means of the prior art at
the current densltles re~uired to produce the desired
result. Our investigation isolated ~he burn phenomenon
to the negatlve electrode. In accordance with the
present ~nvention, the metallic termlnal or plate of the
8~5;~
negative electrode is adequately covered with a thick
felt padg and lontophoretic burns are thereby av~ided
when a current time limitation is observed.
The nature o~ the thic~ ~elt electrode has been
described. It :Is moistened ~or use by employing tap
water. It has been found that distllled or deionlzed
water may also be used.
In an illustrative example the palm o~ a hand
was treated with a positive electrode having an area
of 90 s~uare centimeters. The negative electrode con-
tacted the ~ingers and had an area of 30 square centi-
meters. The thickness o~ the ~elt was 6 millimeters.
A current of 15 milliamperes was allowable for
a period of 10 minutes without an iontophoric burn
occurring. Alternately, at 7.5 ma. the allowable treat-
ment time was 20 minutes. At 3.7~ ma. the allowable
time was 40 minutes.
It has been determined that there i~ some
particle or substance that migrates from metallic elec-
trode 1 through intervenor 4 as current is caused topass into skin 2. This particle or substance must not
be allowed to fully migrate to the skin; ~or if it
does, a burn results. Thus, the thickness ~ the in-
tervenor acts as a transit barrier or delay to prevent
the burn-causln~ particles ~rom reaching the ~in within
the treatment period ~or a given current.
The intervenor cannot be conveniently reJu-
venated, so as ~ practical matter the intervenors for
the negative electrode are used as requlred for a treat-
ment and then are disposed o~.
The presently preferred type of intervenormaterial 4 is composed of metal-~ree natural fibers of
wool or cotton.
Other equivalent man-made ~iberous materials
may be used, such as a synthetic o~ the viscose nylon
or polyester type Alternatively, porous materials
such as foams or sponges may be usedg and all of the
reclted substances have been generally termed l'porous 1l .
While the lnhibition o~ persplration is
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electrically inducedg the inhibition does not occur
immediately a~ter treatment9 but after an interval o~
about two weeksg after which time one or two further
treatments will inaugurate another six week period~ and
so on.
The area of skin that is effectively treated
also includes a leaching or spreading e~fect that
e~tends beyond khe lmmediate area that is directly con-
tacted by the electrodes.
By empirical means it has been determined that
the spreading of the electric current per se is very
small in relation tothe spreading of the inhibition of
perspiration. It thererore appears that the inhibition
is the result o~ a chemical effect that creates a
keratin plug in each sweat duct.
Because of the spreading er~ect o~ the treat-
ment to a limited area beyond the skin that ls contacted
by the electrodesg the latter may be flat, without
regard to undulation of the skin, as upon the palms of
- 20 the hand or the soles of the feet. In prior electrode
art it is believed that this spreading effect was not
observed, or was not appreciate~, since all of the art
that has been examined has not commented upon it.
The spacing between the pairs o~ electrodes in
FIGS. 2 and 3 may be relatively close, so long as the
current is prevented from going from one electrode to
the other without passing through the skin; hence not
accomplishing the method of thls invention.
To maximize safety and convenience to the user,
3 batterie~ ~ay be used for current source 8. The voltage
required varies according to the total resistance o~
the load circuit. h voltage ~ 45 volts is typical.
A small battery having this total voltage is commer-
cially available and is suitable, since the battery need
only supply a current o~ a few milliamperes.
An advantage of the close-spaced electrodes in
FIGS. 2 and 3 lles in the fact that the treatment
current may be rapidly increased at the start of a
kreatment without an undesired sensat~on to the user.
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It is desirable that the current be increased
from zero or a low value at the start. Wlth close-
spaced electrodes the current may be increased to treat-
ment amplitude in a fraction o~ a second.
With a distally removed electrode having a
spacing of many centimeters and perhaps attachment to
another member o~ the body, the current must be increased
slowly. A certain procedure is for a careful operator
or the user to turn a current-controlling potentiometer
very slowly and steadily so that pain and shock will be
avoided. However, the distally removed electrode mode
of treatment is equally effective in burn protection.
Unless close electrode spacing is employed the
current must be slowly decreased at the end of the treat-
ment.
Although inhibition of perspiration was con-
sidered primarily accomplished at the positive electrode~
inhibition to a lesser degree ls accomplished at the
negative electrode.
A basic period of treatment for anhidrosis,
the inhibition o~ perspiration" is ~orty minutes.
InitiallyJ six treatments are ~riven, preferably one
every other day.
Extensive preparation of the s}cin before the
electric treatments is not required. However, in order
to assure conslstent results i~, is desirable to s~ab
the ~kin where the electrodes are to be applied with
rubbing alcohol.
An opposite alternate skructure to the distal
arrangement of electrodes is that shown in FIG. 4.
Here, small positive electrodes 14 and negative elec-
trodes 15 are intermlngled, being typically about one
square centimeter in size and separated ~y a few milli-
meters one from the other. All are provided with a
~elt-like layer between the electrode proper and the
skin. A system of conductors 16 for the-positive and
17 for the negative electrodes which do not touch the
skin connects all electrodes to current source 8.
- Also, this type o~ intermingled structure may
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have the positive electrode 18 of larger area than that
of the negative electrode 19, as shown in FIG. 5. The
other aspects are the same as in FI~
~hen the posit~ve electrode is made larger in
area than that of the negatlve electrode in any of the
embodimentsg there -ls a ~mit to the difference in areas
allowable in practice. This is about three-to-oneg as
evidenced by the 90 sq. cm. positive area and the 30
sq. cm. negative area electrodes in the embodiment of
FIG. 3.
For simultaneous anti-perspiration treatment
of two hands or two feetg two sets of electrodes accord-
ing to FTG. 3 may be connected to a constant current
source 8. ~Ioweverg we elect to use independent con-
stant current sources9 each powered by its own battery.This allows greater current ~or one hand than the other
to compensate for possible dif~erent sensitlvities of
each hand.
