Dr. Muhammad Ismail Physiotherapist ([email protected])
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THE CONSTANT DIRECT CURRENT
The constant direct current, which is sometimes known as constant galvanic
current, is unidirectional current of unvarying intensity.
PHYSIOLOGICAL EFFECTS
The tissues of body are conductors of electricity because the tissue fluids
contain ions and so are electrolytes. Consequently the current, which passes
through the body, is convection current, consisting of two-way migration of
ions. The conductivity of the different tissues varies according to the amount
of fluid that they contain, muscles with a good blood supply, being a good
conductor, while fat is poor conductor. The epidermis has a high resistance,
about 1000 ohms, as it contains little fluid and the superficial layers do not
readily absorb moisture. The resistance of the underlying tissues is much
less than that of the skin, so the current spreads considerably once it has
passed through the skin and the current density, and therefore the effects, are
much greater in the superficial than in the deep tissues. The physiological
effects of the constant D.C. are due to two-way migration of ions and may
be divided in to two groups, those obtained through the interpolar pathway
and those produced at the poles.
EFFECTS IN THE INTERPOLAR PATHWAY
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These effects are produced throughout the pathway of the current, but are
most marked in the superficial tissues where the density of the current is
greatest.
The movement of ions causes alteration in the concentration of substances in
the tissue fluids and this is thought to accelerate the interchange of materials
between the cells and the tissue fluids and to increase cell metabolism.
The erythema of the skin, which is observed when the pads are removed
after treatment, indicates that the current causes vasodilatation. This
undoubtedly takes place in the superficial tissues and has been assumed to
occur by the underlying ones as well, although there is no definite proof of
this is so. There are several theories as to the cause of vasodilatation.
It may be due to moving ions stimulating the sensory nerve endings and so
causing a reflex vasodilatation of blood vessels.
Irritation of these cells may cause the liberation of the “H” substance. This
produces the triple response of dilatation of the capillaries, by a direct effect,
dilatation of arterioles, by the axon reflex, and local edema, due to increase
permeability of the capillary walls.
The vasodilatation may the result of the mechanical action of the moving
ions bombarding the walls of the blood vessels.
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As a result of the vasodilatation there is an increased blood supply to the
tissues, an increased supply of the nutritive materials is made available and
the removal of the waste products is accelerated. The increased blood supply
also produces the sensation of warmth experienced during the treatment.
There is no direct production of heat in the tissues as the intensity of the
current that can be tolerated is not sufficient for this purpose.
POLAR EFFECTS
These are the effects, which are produced in the tissues immediately under
the electrodes and differ at the cathode and anode.
ELECTROTONUS
Electrotonus is the effect on the conductivity and excitability of nerves, and
can be demonstrated in the laboratory with the gastrocnemius muscle and
sciatic nerve of a frog. Electrical stimulation of the nerve produces a muscle
contraction, but if at the same time a constant D.C. is applied the strength of
contraction is modified. If the anode is applied the strength of contraction is
reduced. If the anode is applied (Fig. 119) the strength of the contraction is
reduced, as the anode has effect of decreasing the conductivity of the nerves.
The cathode has opposite effect of increasing the conductivity of the nerves,
and so the strength of the muscle contraction.
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Anelectrotonus is the decreased excitability and conductivity of the nerve in
the region of the anode, Catelectrotonus the increased excitability and
conductivity of the nerve in the region of the cathode. Both are due to the
development of a P.D. across the plasma membrane of the axon of the nerve
as the current passes. The P.D. developed under the anode argument the
normal resting P.D. and so makes it more difficult for any pulse to pass,
while that under the cathode reduces the resting P.D. and increases the
conductivity.
Fig. 119 Effect of D.C. on conductivity of nerve.
While these effects can be demonstrated in the laboratory it seems doubtful
whether they can occur in the living body, as increase in P.D. on one side of
the axon is accompanied by a reduction of that on the other side. At the same
time clinical evidence indicates that the effect is produced to some extent.
There is no explanation of the relief of pain that follows treatment with
galvanism, and further is provided by the greater erythema produced at the
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cathode than the anode. This probably occurs because the excitability of
nerves is increased at the cathode and reduced at the cathode, so that there is
a greater reflex vasodilatation at the former than at the later.
ELECTROPHORESIS:
When a current is passed through a non-living semi-solid electrolyte, such as
gelatin, there is an increase in fluid at the cathode and a decrease at the
anode. Various explanations of this effect have been given what it is thought
to be due to the movement of positively charged colloidal particles which
are present in the electrolytes and to which water molecules adhere. When
P.D. is applied the colloidal particles, which are considerably larger than
ions, migrate slowly away from the anode and towards the cathode, carrying
water molecules with them and bringing about the redistribution of fluid. In
the living tissues the continual circulation of fluid must to a large extent
counteract this effect, but there appears to some reduction in the fluid
present in the superficial tissues underlying the anode, and an increase at the
cathode.
INTRODUCTION OF IONS IN TO THE TISSUES
When the constant D.C. is passed through the body there are two-way
migrations of the ions in the tissues and also in the solution contained in the
pads. Consequently there is an interchange of the ions between the tissues
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and the pads. Positive ions are repelled by the anode and pass from the pad
to the tissues under this electrode, while at the cathode they are attracted
from the tissues to the pads.
Fig. 120 Interchange of ions between tissues and pads.
Similarly negative ions move from the pad to the tissues under the cathode
and from the tissues to the pad under the anode. Thus ions contained in the
pads are repelled into the tissues under the electrode bearing the same charge
as the ions, and the current can be used to introduce ions into the tissues, the
treatment being known as Medical Ionization.
CHEMICAL EFFECTS
When a direct current is passed through an electrolyte, chemical changes
take place at the electrodes. If the current is applied to the body with anodal
electrode in direct contact with the tissues, the tissues are involved in the
chemical actions and are destroyed. There is coagulation of the tissues at the
anode, while at the cathode they tend to liquefy. When pads are used the
chemicals are formed between the pads and electrode but should the pad be
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of insufficient thickness the Acid formed at the anode and the Alkali formed
at the cathode soak through to the skin and cause destruction of the tissues.
The chemical effects are used in the tissues known as Surgical Ionization,
but are also responsible for the burns, which are liable to occur with direct
current treatments.
THERAPEUTIC EFFECTS, USES AND METHODS OF
APPLICATION
The constant D.C. is most often applied with pads on opposite aspects of the
parts to be treated, so that the current is directed through the deep tissues.
THERAPEUTIC EFFECTS AND USES:
The increased blood supply makes more oxygen and foodstuffs available to
the tissues and removal of waste products is accelerated. These effects help
to bring about the resolution of chronic inflammation and are utilized in such
conditions as Osteoarthritis, Chronic Rheumatoid Arthritis, Stiff Joint
following injuries, Tennis Elbow and Tenosynovitis.
The anode and cathode lie fairly close together, so the effects, which are
different under the two poles, tend to counteract each other. The increase in
blood supply is however, more marked under the cathode than under the
anode, and there is a counterirritant effect at the cathode. The moving ions
irritate the superficial sensory nerve endings, which have been rendered
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more excitable by Electrotonus and the marked stimulation of these nerves
appear to reduce the impulses reaching the brain from the underlying
structure. Pain due to the lesion of the deeper structures is relieved and the
method is found to be particularly effective in the treatment of chronic
lesions, so when the constant D.C. is applied for the condition mentioned
above the cathode is usually placed over the more painful aspect of the part.
The effect of the constant D.C. are purely on the superficial tissues so the
treatment is of most value for lesions of superficial structures such as the
both knee and ankle joints, being much less effective for deep structures
such as the hip joints. The constant D.C. alone is rarely an adequate
treatment, but is used in conjunction with other forms of Physiotherapy,
most usually being a preliminary to active exercises.
METHOD OF APPLICATION
The pads are placed on the opposite aspects of the structure to be treated, the
most suitable surface being chosen. For instance, when treating the knee
joint, the pads are usually placed on the medial and lateral aspects, avoiding
the irregular anterior and posterior surfaces.
The effects of constant D.C. are most marked in the tissues immediately
under the pads, so to obtain maximum effect the pads should be as large as
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possible. Care however be taken that the pads do not approach too close to
each other, or the current may concentrate between them.
When the structure being treated is equidistant from the surface to which the
pads are applied, both pads should be of the same size. When the structure is
nearer to one surface than to the other the active electrode, which is as large
as is practicable, is placed on the near surface, with a large directing
electrode opposite. The intensity of current passing through both pads is the
same, so the current density and therefore the sensory stimulation, is less
under the large pad than under the small one. Thus undue sensory
stimulation under the directing electrode, which might limit the total current
tolerated, is avoided.
A current density of 2 milliamperes per square inch of pads is desirable and
the treatment usually lasts for 20 to 30 minutes. Both the intensity and the
duration of the treatment must, however, be determined by the tolerance of
the patient’s skin, which varies considerably in different individuals.
Treatment is usually applied on the alternate days, as the skin tends to
become sore with more frequent applications.
CAHTODAL GALVANISM
When the cathodal effects are particularly required, the cathode is applied over the
affected structure and a circuit completed with a much larger anode elsewhere on
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the body. The active pad may be large, covering as much area of the affected
structure as possible or when the lesion is localized, a small pad is used.
THERAPEUTIC EFFECTS AND USES
The cathodal effects are primarily a marked increase in blood supply to the
superficial tissues and relief of pain by counter irritation. Cathodal
galvanism may be used for chronic inflammatory and posttraumatic
conditions, being particularly effective when the lesion is localized and a
small active pad is used. Theoretically a large pad should be of value
because of the widespread effects but it often proves a less effective method
than the direct current through the lesion, possibly because the patient tend
to tolerate the high current density with the latter method. The increase in
blood supply may also be of value when the circulation is defective, as in
chilblains, lower motor neuron lesions, etc.
It has been claimed that the catophoretic effect is of value in softening the
scar tissue, and cahtodal galvanism my be used in conjunction with active
exercise when scare tissue is limiting movement and muscle action.
METHOD OF APPLLICATION
The cathodal plate is placed over the site of lesion or in suitable cases; a
cathodal bath may be used. The indifferent pad should be appreciably larger
than the active, so that the current density under this is low, otherwise the
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sensory stimulation in this area may limit the total current that can be
applied. A high current density is desirable and when the active pad is small
2 milliamperes per square inch or more may be tolerated, although if a large
active pad is used it is not as a rule possible to apply so high a current
density. The duration of treatment is usually 20 to 30 minutes, both this and
intensity of the current is must be determined by the patient’s tolerance. The
treatment is usually applied on the alternate days.
ANODAL GALVANISM
When the anodal effects are particularly required, the anode is applied over
the area to be treated and the circuit completed with a larger cathode on the
body.
THERAPEUTIC EFFECTS AND USED
As a result of the reduced excitability and conductivity of the nerve there is
relief of pain and muscle spasm. This effect is utilized in the treatment of
recent injuries, such as sprained ankle, and in more acute stages of
inflammation, as Rheumatoid Arthritis and Tenosynovitis. For these
conditions the anode is more effective for relieving pain than the counter
irritation produced by the cathode. Anodal galvanism may also be used in
palliative treatment of, for example, sciatic pain in prolapsed vertebral disc.
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The anaphoretic effect may be utilized to assist in the reduction of recently
accumulated fluids due to injury or inflammation in, for example, synovitis
and Bells palsy. The method is not, however, of valued for more than 7 to 10
days following the exudation, as after this time the organization of the fluid
has commenced.
The slight increase in the blood supply, which occurs at the anode, is of
value in the above condition, to improve the supply of nutritive materials to
the tissues and to accelerate the removal of the waste products. The increase
in blood supply is not, however, sufficient to cause increased pain from site
of lesion in the area.
In all the conditions mentioned above anodal galvanism is an accessory to
the other physical measures, which are commonly employed.
METHODS OF APPLICATION
A large anodal pad is applied to cover the as much of the swollen or painful
area as possible, or an anodal bath, may be used. The indifferent pad is
applied to the suitable area, at some distance from the anode in order that it
shall not interfere with the anodal effect. It should be larger than the anode
so that the patient is not unduly conscious of it, though as a low current
density is used, it is not likely to limit the intensity of current that can be
appl8ied. The treatment is found to be most effective if a low current
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density, ¼ to ½ a milliampere of per square inch of pad, is applied for 45 to
60 minutes. As the current density is low and the treatment effective only for
a limited period, the skin usually tolerates daily applications.
TECHNIQUE OF TREATMENT
PREPARATION OF APPARATUS
The source of current is either a cell battery or apparatus which uses the
main supply, the former being advisable for any part of the head.
The apparatus must be tested before applying the current to the patient.
Leads are attached to the terminals and held with the free ends not touching
each other, in a bowl of tape water. The current is turned up and the needles
of the milliamperemeter watched to ensure that the regulation of the current
is even. The control should be turned up as for as will be required for the
treatment, or faults, for instance in the potential divider may pass
undetected. Tap water is used because it has a fairly high resistance and so
the control can be turned well up without passing excess current through the
milliamperemeter. The polarity can be checked by observing the bubbles
from the cathode. The polarity is rarely incorrectly marked but is easily
checked in the course of the other test. The operator may then test the
current on herself as for the faradism, and if she is not familiar with the
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apparatus, it is advisable to test the shunts to ensure that the circuit is not
broken when the switch is moved from one position to another.
Pads similar those used for faradism are required, but they must be at least
half an inch in thickness for a treatment of the average intensity and duration
in order that the chemicals formed at the electrodes shall not soak through to
the skin. Sixteen thicknesses of lint or eight of turkish toweling, evenly
folded with no creases or raw edges, are suitable. The pads are soaked in
warm 1 percent saline, care being taken that the salt is fully dissolved as
otherwise it may cause concentration of current. The electrodes are half an
inch smaller all round than the pads, with rounded corners.
PREPARATION OF THE PATIENT
The skin is washed and abrasions protected as for faradism, but in addition
skin sensations must be tested at the first attendance to ensure that the
patient will be able to detect any concentration of current. The test may be
made with a blunt object and cotton wool.
APPLICATION OF PADS AND ELECTRODES
The skin moistened with saline and the pads and electrodes are applied. Care
must be taken that no metal comes in contact with the skin. The electrodes
are covered by the half an inch larger all around than the pads and are firmly
held in position with the bandages. The whole of the both the pads must be
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covered by bandage and it is advisable to bandage the leads away from the
skin. If the surface is irregular, hollows may be padded with the wool soaked
in saline, or brown wool may be placed over the hollows, on top of the pad
and electrode, in order to exert extra pressure in these areas and maintain
even contact between the pad and the skin.
APPLICATION OF CURRENT
The patient is warned that she will experience a pricking sensation as the
current is increased, which will gradually pass off and be replaced by a
feeling of warmth, also that she must report any discomfort or concentration
of current. The currant is turned up slowly, taking about 5 minutes to reach
the maximum, inorder to allow time to skin resistance to fall. It will be
noticed that during this period the pointer of the milliamperemeter continues
to move up when the control is stationary, due to fall in resistance as the ions
enter the skin. When the current is first applied the ions mainly enter through
the hair follicles and ducts of the sweat glands where the resistance is less
than that of the intervening epidermis. The pricking sensations experienced
at this stage are thought to be due to stimulation of sensory nerve endings at
the basis of hair follicles. Due to the continuous passage of current, ions
enter the epidermis and reduce its resistance, so that the distribution of
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current becomes more even. The pricking passes off and the sensation of
warmth is due to increased blood supply.
Throughout the treatment the operator should be with the call of the patient
and should inspect the meter at frequent intervals. If the needle goes up after
it has stabilized, the situation must be investigated. It may be due to the
bandage becoming damper and forming a short circuit between the pads, or
the skin may be breaking down with the development of a burn. It the patient
reports discomfort, especially at one spot, the current must be turned down
and the area examined.
At the conclusion of the treatment the current is reduced slowly and turned
off. The skin is washed to remove any chemicals that may have soaked
through the pads, dried and powdered or a soothing cream such as a glycol
jelly may be applied. The skin should be evenly red under the cathode, while
the erythema at the anode is usually less marked and may be even.
The intensity of the current and duration and frequency of treatment have
been considered with the therapeutic effects. At the first attendance it is
usual to apply rather less current, and for a shorter time, than on the
subsequent occasions, in order to ensure that there is no adverse reaction of
the skin. A record should be kept of the size and position of the pads, the
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intensity of the current, the duration of the treatment and the skin reaction at
each attendance.
TREATMENT IN BATHS
The advantages and disadvantages of applying the current in baths and the
methods of arranging the treatment have been considered in the chapters of
faradic and sinusoidal currents. The same principles apply with the galvanic
baths but a few additional precautions are necessary.
PRECAUTIONS
When the treatment is applied in bath the danger of burn is rather less than
when the treatment is applied with pads and electrodes are used, as any
chemical which may be formed dissolve in the water and so are diluted.
Burns could occur however if metal were in contact with the tissues, so
rings, etc, must be removed and the patient warned not to touch any
electrode. Breaks in the skin are protected by petroleum jelly, as they would
cause discomfort due to concentration of ions.
The danger of shock is greater than with the pads and electrodes. The reason
for this and the necessary precautions are given in chapter 11.
In addition the patient should be warned not to take the limb out of the bath
during treatment, as this would break the circuit and cause a shock.
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The control is turned up and down very slowly as, owing to the low skin
resistance. Slight variation in the EMF causes an appreciable variation in the
intensity of current. The patient’s sensation is the main guide to the intensity
of current that should be applied.
USES OF THE BATH TREATMETN
Treatment in the baths is satisfactory where a widespread effect is but the
method is not suitable for the localized application. It is of most value for
increasing the blood supply to a limb and for the application of the current to
an irregular area such as the hand or the foot, but as the limb must be
dependent it is not suitable for the treatment of the swollen areas. In some
cases a monopolar bath may conveniently be used as an indifferent
electrode.
DANGER AND PRECAUTIONS
ELECTRIC SHOCK
Electric shock is one of the dangers associated with the application of the
constant D.C. The ways in which shocks may occur are considered in
chapter 11, also the treatment of the shock and the precautions that should be
taken.
ELECTROLYTIC BURNS
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Burns produced by the constant D.C. are electrolyte or chemical burns.
Tissue is destroyed and the burn appears, as a grey spot surrounded by the
reddened area. As tissue is destroyed, healing is by second intention and is
liable to slow. The area should be kept dry and care must be taken that it
does not become infected. The burn is usually protected by dry sterile gauze
and healing can be hastened by the application of infrared and ultraviolet
rays. If a burn should occur it must be reported to the medical officer.
Burns are most liable to occur if the current is applied with metal in contact
with the tissues, as the tissues are then directly involved in the chemical
actions. This may occur if the electrode, clip, or end of the lead projects over
the edge of the pad, if there are small pieces of metal on the pad, which
might have been dropped when trimming a lead or electrode, if there are
metal objects, such as ring in contact with the tissues, or if there is metal
embedded in the tissues, e.g. a plated fracture.
Concentration of current may also cause burn as more chemicals are formed
in the area of concentration than elsewhere. This may be due to a break in
the skin to the presence of undissolved slats on the pad, to pads of uneven
thickness or with creases or with raw edges of pads that are unevenly damp.
It may be due to an electrode being bent, cracked or much smaller than the
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pad, to he pads being too close together so that current concentrates between
them.
If the pads are too thin for the intensity and duration of the treatment,
chemicals may soak through skin, or if the pads have been properly washed
after a previous treatment and still contain some chemicals, the same thing
may occur. If the patient has not received adequate warning of the sensations
she will experience, she may tolerate too much current or concentration may
pass undetected. Application of liniment may render the skin more
susceptible to damage, and so it is wiser not to apply the current to areas on
which liniment has recently been used.
GALVANIC RASH
A rash may be produced on the skin as a result of the passage of the constant
D.C., individuals with sensitive skins being particularly liable to show this
reaction. The type of rash varies in different cases; it may be red, like nettle
rash, or small white spots or minute blisters may appear. The skin should be
washed and soothing cream applied. This is better than powder, as the skin
tends to become dry and chapped with repeated application of the current.
The presence of the rash should be reported to the medical officer as, though
it will often disappear before the next treatment, the patient’s skin is unlikely
to tolerate a long course of treatment.
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GIDDINESS
This is liable to occur if the current is passed through the region of the
semicircular canals, particularly when the intensity is being varied e.g. in
treatment of the ear or mandibualr joint. When applying current to these
areas the patient must be fully supported, the current increased and
decreased very slowly, and the operator at hand throughout the treatment.
CONTRAINDICATIONS
For reasons already explained, the current must not be applied to anesthetic
areas of the skin or where there is metal embedded in the tissues. Also there
are many breaks in the skin, it is impossible to give a satisfactory treatment.
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Chapter 17
IONIZATION
THEORY OF MEDICAL IONIZATION
Medical ionization is the introduction of therapeutic ions in to the tissues by
the action of the constant direct current. One pad is soaked in a solution
containing the ions to be introduced, and placed under the electrode bearing
the same charge as the ions. The circuit is completed by a second pad and
electrode, and when the current is passes there is an interchange of ions
between the pads and the tissues. The required ions are repelled in to the
tissues by the like charge on the active electrode.
PROOF THAT IONS ENTER THE TISSUES
An experiment to prove the entry of the ions into the tissues under the
influence of the current was performed by Leduc.
Fig. 121 Leduc’s Experiment
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Two rabbits were connected in series with each other to a source of D.C.
One pad on each rabbit was soaked in a solution of a salt of strychnine, the
other in a harmless solution. On one rabbit the cathode was placed over the
pad containing the strychnine ions, on the other the anode (Fig. 121). The
strychnine bear a positive charge and, when current was passed, the rabbit
with the pad containing the strychnine ions under the anode A died, while
the other rabbit B, was unaffected. Thus the entry of the ions was due to
repelling effect of the anode, not to absorption through the skin.
There is other evidence that the current causes the ions to enter to the tissues.
A visible reaction of the superficial tissues can be observed following certain
ionizations, such as histamine, and zinc when applied to wounds, but this
reaction is not produced unless the electrode bears the same charge as the
ions. Also following ionization with some substances as lithium, the ions
may be detected in the urine, although they are not normally present and
could not have come from any other source.
VALUE OF THE METHOD
It is not possible to achieve any great depth of penetration of the ions. Their
speed of movement is slow, and the current intensity and duration of
treatment are limited by the patient tolerance. There are many ions already
present in the tissues, and frequently these move more readily than those
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introduced. Also as soon as the ions reach the blood vessels they are carried
away from the area in the blood stream.
As the ions do not penetrate beyond the superficial tissues, no direct effect
of the ions can be obtained on the deep structures. Where, however, the
effects are required on the skin, mucus membrane or surface of wounds, the
method is of value. It has the advantage that the treatment cab be accurately
localized and that dosage can be exactly controlled. Some ions such as the
iodine, mentioned below, may be introduced to enhance the effect of the
constant direct current, and when medical ionization is used the effect of the
constant D.C., are obtained in addition to those of the ions which are
introduced.
A considerable variety of the ions have been used for medical ionization in
the past, and new ones are introduced from time to time, but only in a few
cases do their effects warrant extensive use. A few examples are given
below to illustrate the principles of treatment, and it should be possible to
apply those principles to other ionization which may be required.
EFFECTS OF VARIOUS IONS
The following ions bear a negative charge and so are introduced under the
cathode.
IODINE IONS
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These are obtained from the solution of potassium iodide and have an
irritating effect on the superficial sensory nerve endings. Consequently the
iodine ions increase the vasodilatation and relief of pain by counter irritation
which is normally obtained at the cathode. They are used in the treatment of
chronic inflammatory lesions. Iodine ionization is also sometimes used for
softening superficial scars, but the effect is probably due to the increases
blood supply and fluid contents of the tissues, rather than to any specific
effect of the iodine ions.
CHLORINE IONS
These are obtained from solution of sodium chloride and have been said to
cause softening of scar tissues, but the effects are probably due entirely to
the action of the cathode.
SALICYLATE IONS
These are obtained from a solution of the sodium salicylate and are
sometimes used in the treatment of rheumatic conditions. It is unlikely that
the salicylate ions reach the site of the lesions, and the main effect is
probably relief of pain from the analgesic effect of the salicylate ions on the
superficial sensory nerve endings.
ALBUCID (Sulphacetamide ions)
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These are obtained from the solution of Sulphacetamide. They destroy
certain bacteria and are sometimes used in the treatment of infection of the
eye.
The following ions bear a positive charge and so are introduced under the
anode.
ZINC IONS
These are obtained from a solution of zinc sulaphate or zinc chloride and are
often used in the treatment of infected superficial wounds, sinuses ands
mucus membranes, also for destroying exuberant granulations on wounds,
for some infections of the ear, hay fever and certain eye conditions. When
the zinc ions pass in to the superficial tissues, they react with the tissue
proteins forming zinc albuminate, which appears as pearly grey film over the
surface and is adherent to the underlying tissues. Thus effects are most
apparent when ionization is applied to the surface of the wounds, in which
case the superficial cells are destroyed by their reaction with the zinc ions.
The ions also have a bactericidal effect. Thus if wound is treated with zinc
ionization, the infected or indolent superficial layers of tissues are destroyed,
the wound is sterilized and the layer of zinc albuminate seals the surface,
preventing the entry of the bacteria. The bactericidal effect is utilized in
infections of the eye and ear, while in the treatment of hay fever the
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ionization serves to reduce the sensitivity of the nasal mucus membrane. The
technique required for these conditions is described in the section on
techniques for special areas.
COPPER IONS
These are obtained from a solution of copper sulaphate, and have similar
effects to zinc ions, except that instead of zinc albuminate a bluish green
film of copper albuminate is formed. They are used in the treatment of some
skin conditions and fungus infections and may replace zinc ions in the
treatment of wounds. The technique is similar to that required for zinc
ionization,
IONS OF VASODILATOR DRUGS
Histamine is a vasodilator which in the past was widely used for ionization,
but in recent years has largely been replaced by Renotin. When histamine
ions are introduced in to the tissues the triple response is produced. This is,
dilatation of the capillaries by the direct action of the histamine, dilatation of
the arterioles by the axon reflex and exudation of the fluid and local edema,
as a result of the increased permeability of the capillary walls. A white
raised wheal is formed, surrounded by reddened area, or flare. The wheal is
due to local edema and the flare to dilatation of the arterioles. If an
appreciable quantity of the histamine is carried round the body in the blood
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stream it causes wide spread vasodilatation, fall in peripheral resistance and
fall in blood pressure. The first sign of this general effect is usually flushing
of the face and neck, and there may be giddiness, a prickling feeling in the
eyes and an increase in the pulse rate. Headache is liable to follow. Renotin
produces a similar local reaction, but only on very rare occasions a general
effect, so is commonly used in preference to histamine.
The local effects of anodal galvanism are similar to, but more marked than
those produce by cathodal galvanism. The local hyperemia and counter
irritations are of value in the treatment of chronic rheumatic and post
traumatic conditions such as osteoarthritis, rheumatic arthritis, fibrositis and
tennis elbow, particularly if the lesion is localized. The vasodilatation is
beneficial in some circulatory effects, such as Raynaud’s disease and the
increase in blood supply and the exudation of fluid into the tissues may help
to soften superficial scar tissues.
Special techniques are required for ionization with the vasodilators and are
described below.
TECHNIQUES OF MEDICAL IONIZATION
Ionizations which require special techniques are considered separately, but
for the remainder the technique is similar to that for a constant D.C.
treatment. A directing electrode may be placed opposite to that from which
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the ions are introduced, so that they penetrate as deeply as possible, or an
indifferent electrode may be applied to some convenient area. The pad
under the active electrode is soaked in a 1 or 2 percent solution of a salt of
the substance to be introduced and placed under the electrode bearing the
same charge as the ions. The number of the ions introduced into the tissues
depends on the intensity of the current and the duration of the treatment i.e.
on the quantity of the electricity passes. Therefore as high a current density
as the skin can tolerate is usually applied for 30 minutes, the treatment being
given on alternate days.
SOLUTION FOR IONIZATION
The pad is commonly soaked in a 1 or 2 percent solution of the selected salt.
Use of the stronger solution does not increase the number of the ions
introduced, because this depends on the current intensity, which is limited by
the patient’s tolerance. The 1 or 2 percent solution contains an adequate
number of ions, so stronger solutions are a waste of the salt and may irritate
the skin.
One ounce of salt dissolved in 100 ounces of water makes a 1 percent
solution and produces 100 fluid ounces of the solution, as the salt does not
increases the volume of the liquid. To make one pint of the solution ½
ounces of the salt is dissolved in 1 pint of water or 20 fluid ounces (1 pint =
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20 fluid ounces). Stronger solutions are often stored in the departments and
are diluted as required. To prepare 1 percent of solution from a stronger
solution, one part of the solution is added to 19 parts of the water, while a 2
percent solution requires a 2 parts of the solution to 18 parts of the water.
TECHNIQUES OF IONIZATION WITH VASODILATOR DRUGS
HISTAMINE IONIZATION
The treatment must produce general effects so the patient should receive the
ionization reclining on a couch and fully supported, and the pulse is taken
before commencing treatment. The indifferent electrode attached to the
negative terminal of the source of D.C., is applied to some convenient area
or a directing electrode may be used. The skin of the area to which the active
electrode is applied is cleansed with ether soap and outlined with a skin
pencil. It should not exceed 24 square inches. The histamine can be applied
on the area by means of a piece of lint soaked in 1 in 5000 solutions of
histamine acid phosphate in distilled water or more usually in the form of 1
or 2 percent jelly. The jelly is spread evenly on the marked area. The patient
is warned to report any discomfort, and throughout the treatment the
operator must watch for any sign of general reaction, which are an indication
to stop the ionization. There are various methods for assessing the dose of
the histamine ionization, but ¼ to ½ milliampere per square inch of the
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active pad for three minutes is suitable for the first treatment. Provided there
are no ill effects, this is increased at subsequent treatments until a complete
wheal is obtained, but the dose should not exceed 120 milliamperes a
minutes. At the end of the treatment pads and electrodes are removed and
the skin swabbed with methylated ether to remove all traces of the
histamine. The patient should rest then for three quarters of an hour to allow
the pulse rate and blood pressure to return to normal, and she should be
warned to take no strenuous exercise for some hours. Notes are kept of the
size of the area treated, the current intensity, duration of treatment, the local
reaction and any general effect. The single piece of lint used for the
histamine ionization must be destroyed and the pad washed and reserved for
these cases. Histamine is a poison and must be replaced in the drug cupboard
immediately after use. All equipments that have been in contact with the
histamine must either be destroyed or cleaned with spirit, and the
physiotherapist must take care that she does not get the histamine on her
hands.
RENOTIN IONIZATION
The technique of application may be similar to that described for histamine
ionization except that the precautions necessitated by the possible fall in
blood pressure need not to be taken. Alternatively a much large area may be
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treated, in which case a current of 2 to 6 milliamperes is applied for not
more than four minutes, irrespective of the size of the area. When this
method is employed the Renotin is spread on the skin and covered with a
piece of damp lint as before, but instead of using a pad and electrode, the lint
is impregnated with aluminum. The felt mould to the area more readily than
does a large electrode and a small electrode is placed in contact with the
aluminized surface provides the connection to the source of the current.
Although no general reaction is anticipated, it is advisable to warn the
patient not to take strenuous exercise for 3 to 4 hours after the treatment.
TECHNIQUES FOR SPECIAL AREAS
A SEPTIC ULCER OR WOUND
Zinc ionization is described, but similar technique is used for the
introduction of other ions. An indifferent pad and electrode are applied to
some convenient area, which need not to be exactly opposite to the active
electrode as deep penetration of the ions is not essential. A high current
density employed for the wound so the indifferent pad must be of such a size
that the current required for the wound does not cause undue sensory
stimulation in this area. When applying the electrode to the wound, all
aseptic precautions are observed. The wound is cleansed with one percent
zinc sulaphate solution and any scabs are removed. The skin surrounding the
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wound is dried and a pad of sterile gauze is soaked in the zinc sulaphate
solution and fixed over the wound. Any crevices are filled with ribbon gauze
soaked in the zinc sulaphate solution before applying this pad. A piece of
cellophane, rather larger than the pad, is cleaned with methylated ether and
placed on top of the gauze. This prevents the entry of bacteria, and the pad
and the electrode on top of it need not to be sterile. A pad of lint is soaked in
tap water and applied over the cellophane, then the electrode connected to
the positive terminal of the source of the constant D.C. the pad may extend
beyond the edges of the wound, but as the resistance of the skin is
considerably higher than that of the wound surface, most of the current
passes through the latter. The dose measured in milliampere minutes per
square inch of the wound, 30 milliampere minutes per square inch being
suitable. Thus if the area of the wound is 2 square inches, and the patients
tolerates a current of 6 milliamperes, i.e. 3 milliamperes per square inch of
the wound, the treatment is given for 10 minutes, while if 12 milliamperes
are tolerated, only five minutes are required. At the end of this time the
current is reduced, the pad is removed and the wound examined. The gauze
under the cellophane should be adherent to the surface of the wound, and
must not be disturbed, or the covering of the zinc albuminate will be broken.
One corner of the gauze may be raised to inspect the wound and if the
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surface has turned grey, an adequate treatment has bee applied. If the
covering of the zinc albuminate has not formed, the current is applied for a
further period. An alternative method of assessing the dosage is to continue
the treatment until the intensity of the current falls, indicating that the layer
of zinc albuminate, which has a high resistance, has formed. After the
treatment a dressing of dry, sterile gauze is applied over the adherent layer
of gauze. The treatment is not repeated for at least a week, to allow any
sloughs to separate, and only two or three treatments are commonly
required.
A SINUS
A sinus is a track leading from the surface of the body to a deep area of
infection, and for permanent healing to occur, it is essential to sterile the
base of the sinus. Zinc ionization may be used for the treatment of a sinus
and is applied with a zinc rod in direct contact with the tissues. When a
current is passed through the ions of the sodium chloride using zinc
electrode, zinc ions from the electrode enter the solution at the anode.
Similarly, when the current is applied with the zinc anode in contact with the
tissues, zinc ions enter the tissues, zinc ions enter the tissues and producing
the same effects as when a pad soaked in a zinc sulaphate solution is used.
The upper part of the zinc rod may be encased in a fine rubber tube, so that
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entry of the ions is confined to the deeper parts of the sinus. When applying
the treatment large indifferent electrode is placed on some convenient area,
then the sinus cleansed with the zinc sulaphate solution. This can be done
most effectively with a syringe, and some of the solution is left in the sinus,
so that the zinc ions may reach the parts inaccessible to zinc rod. The rod
previously sterilized by boiling, is introduced into the sinus and the current
applied. The dose may be assessed in milliampere minutes per inch of rod,
30 milliamperes minutes per inch being suitable or the current applied until
the intensity falls. When the current turned down it is found that the zinc rod
is adherent to the walls of the sinus, but it cab be loosened by reversing the
polarity and applying a few milliamperes of the current for ½ to 1 minute.
The moistening effect of the cathode frees the rod so that it can easily be
removed from sinus.
SCARS
Ionization can be used in the treatment of contracted and adherent scars, in
an attempt to soften the scar tissues so that it can be stretched and freed from
the surrounding structures. The aims of the ionization are to increase the
blood supply and exudates of fluid in to the tissues and the ions used may be
Histamine, Renotin, Iodine or chlorine. When using histamine or Renotin the
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technique and dosage are the same as those described in the section on
ionization with vasodilator drugs.
When iodine or chlorine ionization is used the effects are those of the
cathodal galvanism rather than those of the ions introduced. Consequently,
in order to ensure that the current passes through the scars, the surrounding
skin is protected with petroleum jelly and brown wool, or with jaconet. The
skin has lower resistance than the scars and if it were not protected, very
little current would pass through the scar itself. As the scar is anesthetic, the
dosage must be progressed with considerable caution. At the first treatment
not more than 1 milliampere of current per square inch of scar is applied for
10 to 20 minutes and the effects are carefully observed, progression being
made at subsequent treatments only if there is no severe reaction.
THE EAR
Inflammation of the middle ear behind the tympanic membrane may result in
the formation of an abscess, the condition being known as otitis media. The
membrane becomes inflamed and more perforate, pus escaping into the
external auditory meatus. Zinc ionization is being employed to clear up the
inflammation in the middle ear, when there is chronic discharge of pus
through the perforation of the membrane. The ear is cleansed and syringed
with warm solution of zinc sulaphate, which can be made up as follows; zinc
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sulaphate 20 grains, glycerin ½ ounce and water to a pint. At the conclusions
sodium must be left in the middle ear and external auditory meatus and it is
important that the air bubbles are removed, otherwise the zinc sulaphate
solution does not reach the middle ear and the ionization is valueless. An
indifferent electrode is applied to some convenient area, then a vulcanite
speculum, which contains a zinc wire electrode, is placed in the ear and the
solution is added until the speculum is half filled. The active electrode is
connected to the anode and a current of 2 or 3 milliamperes passed for 10
minutes. The ionization is repeated at weekly intervals, two or three
commonly being required.
THE NOSE
Hay fever is an acute inflammation of the mucus membrane to the nose,
which occurs in persons who are hypersensitive to pollen. Zinc ionization to
the mucus membrane of the nose before the hay season commences will
often prevent the attack during summer. An indifferent electrode is applied
to some convenient area, then the mucus membrane of the nose anesthetized
by spraying with cocaine and adrenaline. The nose is packed with layers of
the ribbon gauze, soaked in a zinc sulaphate solution similar to that used for
the ear and as the packing is an expert work and it should not be under taken
without special training. A zinc rod connected to anode, makes contact with
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the gauze in each nostril and care must be taken that the rod does not come
in contact with the nasal mucus membrane. A current of 5 milliamperes is
applied for ten minutes and a course of six treatments is usually adequate.
THE EYE
Corneal ulcer can be treated with zinc ionization, and iodine ionization may
prove beneficial for the corneal opacities which sometimes follow corneal
ulcers. Zinc or iodine ionization may be used for keratitis, a chronic
inflammation of the cornea, and the Sulphacetamide (Albucid) ionization for
intensive conjunctivitis. Similar technique is required for all these
ionizations. The patient is treated in lying position and the indifferent
electrode is applied to some suitable area, e.g. the forearm. The eyelids are
inspected and any abrasions protected by petroleum jelly. A ½ percent
solution of potassium iodide, zinc sulaphate or Sulphacetamide is used and a
drop put in to the medial corner of the eye. The patient blinks; so that the
solution runs over the eye then the lid is closed and damped with the
solution. A pad of white wool soaked in the solution is placed over the
closed lid, extra padding in the hollow in the medial corner of the eye is
often being necessary. The electrode is usually applied on top of this and
should be as light as possible. A special copper gauze electrode may be used
and the lead should be twisted in to the electrode to avoid the weight of a
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clip. Brown wool is spread over the electrode to bring the padding up to the
level of the forehead and the application is secured with the small sterilized
bandage. Alternatively if the condition of the eyelid is poor, an eyebath
electrode may be used. This is a rubber eye bath with metal electrode with
the metal base connected to terminal outside. The bath is filled with the
solution and the *site* round the eye moistened. The patient puts the eye in
the bath, and then lies down, the electrode being maintained in position by
the suction of the rubber on the damp skin. For zinc ionization the active
electrode is connected to the anode, fro iodine and Albucid to the cathode.
For the treatment of the conjunctivitis the active electrode may be made
positive and negative an alternative treatments. When it bears the same ****
(The notes are not complete as the old material was a little lost and only few
lines are missing.)
Compiled By: Dr. Muhammad Ismail Physiotherapist E-mail: [email protected] Comments: Feel free to pass.