Eberhart's Manual of High Frequency
Noble M. Eberhart
Physiological Action of High Frequency Currents; Burns; Offsetting
Tendency to X-Ray Burns.
The physiological action of high frequency varies with
the form employed.
In the construction of the apparatus the coarse coil or
solenoid of the D’Arsonval machine is used as the primary coil of the Oudin
resonator, and the current from the secondary of the Tesla coil is essentially
the same as that from the secondary of the resonator.
If a vacuum tube is excited by attaching to one pole of
the Tesla secondary it gives the same effect as if coming from the top
of the Oudin resonator.
With the hyper-static transformer the primary yields a
D’Arsonval current and the secondary one similar to that of the resonator
or Tesla secondary.
When vacuum tubes are applied locally there is soon produced
redness and hyperemia, with all of the resultant benefits on nutrition.
In short, the fundamental value of high frequency currents
is their beneficial effect on all nutritive processes. Incidental
to this we have increased oxygenation of blood and tissues, increased leucocytosis
(and Phagocytosis); and increased elimination.
There is no painful sensation produced by the vacuum tube
when held firmly in the hand, thus establishing complete electrical contact.
Ordinarily there is a sensation of heat and in some instances perceptible
vibration. Removing the tube produces a spark which increases in
sharpness as the tube is drawn away, up to the full length spark it is
capable of emitting. The longest spark which may be drawn from the
tube has been my method of roughly calculating the strength of the current
and the regulation of the dosage. See Chapter VI.
General Action of Vacuum Electrode. In a
general way the action of the current when applied by means of the glass
vacuum electrode is as follows: A mild current with tube in contact
is sedative. As the current is increased, or the electrode removed
from the surface, allowing a spark to pass, it becomes first mildly stimulating,
then strongly stimulating and finally caustic or destructive. The
whole gradation of effect from sedation to cauterization being essentially
a question of current intensity and length or sharpness of spark.
With this is the effect of hyperemia and the germicidal
action of the spark and the ozone which it liberates.
Summary of Vacuum Tube Effects, from Oudin resonator or
1. Increase blood-supply to a given area.. (Hyperemia.)
2. Increase oxidization and local nutrition.
3. Increase intake of oxygen.
5. Increase output of carbon dioxide.
6. Increase secretions.
7. Increase elimination of waste products.
8. Liberate ozone, with the resultant benefit of more or less
of this ozone being inhaled by the patient, and also probably carried directly
into the tissues.
9. Increase bodily heat, without a corresponding rise in temperature.
10. Locally germicidal.
11. Mild and medium sparks stimulate or soothe according to length
and character of application.
12. Strong sparks are caustic.
13. Sparks to spine increase arterial tension.
14. Promote absorption of plastic exudates or adhesions.
These effects of vacuum tube applications, while essentially
local, are not absolutely so. The current traverses the body in all
directions from the point of entry, but is, of course, most intense and
pronounced at the latter point. Prolonged applications of vacuum
tubes will give systemic effects, but these are obtained more easily by
Constitutional Effects. These are derived
through auto-condensation and auto-conduction. These currents
increase bodily heat, almost always showing a rise of from one-half to
one and a half degrees in temperature during a ten-minute application.
Some attribute the effect of these currents to the heat
they develop in the tissues. In my opinion their principal effects
are due to “cellular massage.” They have, therefore, a great effect
The effect of auto-condensation in producing cellular
massage is appreciated when we realize that the charge in the patients’s
body must return back into the circuit and then alternate with one of opposite
polarity; thus, first a positive and then a negative charge is carried
into the body and back again. This produces a to-and-fro wave
that acts upon every cell in the organism. No sensation is usually
perceptible if perfect electrical contact with the patient exists in the
Synopsis of Constitutional Effects:
1. Increase general metabolism.
2. Increase glandular activity.
3. Increase temperature and bodily heat.
4. Increase oxidization and hemoglobin.
5. Increase secretions.
6. Increase elimination.
7. Lower blood-pressure when hypertension exists.
8. Soothing to the nervous system.
High Frequency Burns. This is a subject which
has not been touched upon in the literature on high frequency. There
is a prevalent idea among many operators that these currents do not and
cannot produce a burn. True, they do not cause a dermatitis, comparable
to that produced by the X-ray, but they are still capable of causing annoying
It will be noted by the physician who is accustomed to
handling the excited tube with his hands that after a time the skin, especially
about the finger tips, feels as if he had been handling a hot dish, that
had seared the outer skin. Also in giving vaginal treatments, prolonged
application may result in shreds of the mucous membrane adhering to the
tube when it is withdrawn.
Fig. 28 - Formalin Sterilizer.
To avoid this, I make it a rule never to leave a vacuum tube
in contact with a mucous membrane for more than seven minutes at a time.
Occasionally the urgency of a case is such that I am willing to give longer
treatments and take the chance of a possible burn.
Fig. 28a - Portable Outfit.
High frequency currents seem to have no cumulative effect
in so far as burning is concerned, and treatment may be repeated frequently
without any apparent danger; thus, three seven-minute treatments may be
given in one day with intervals of three to six hours between, without
any serious consequence when one twenty-minute treatment may be disastrous.
High frequency burns appear immediately; there is no interval
as with the X-ray. Another use of the high frequency in which burns
may result is in the application of the spark to a mucous membrane, as
for instance, to the lip, where care and judgment must be used.
I have seen a fairly sharp application to a “cold sore”
result in the formation of a large vesicle which ruptured and poured forth
an incredible amount of serum and was three weeks in healing.
As a sharp spark has a cauterizing effect and is used
for that purpose, it is readily inferred that the reaction just referred
to is of this nature, as even a comparatively mild spark will influence
a mucous membrane.
Another condition in which these currents must be used
with care is about the neck or scalp, where there is a fine, fuzzy growth
of hair, as with some forms of apparatus having considerable amperage,
enough current comes through to produce a spark capable of setting fire
to any inflammable substance.
This property of the high frequency spark may be easily
demonstrated by lighting a gas jet with it. I have been told of one
or two instances where severe burns occurred from the spreading of the
tiny flame to the hair on the head.
I wish to specially caution against the danger of using
the high frequency spark on the scalp in connection with lotions containing
a high per cent of alcohol or other readily inflammable material.
Where such lotions are employed, the high frequency spark must be used
first and the lotion applied thereafter, or a serious accident may happen.
The same point must be kept in mind when using the cataphoric
Offsetting Tendency to X-Ray Burns. While
I am touching on the subject of burns I wish to call attention to a use
which I have made of the high frequency current, regarding which I have
seen no reference elsewhere. This is the use of this current to offset
some of the effects of the X-ray, and by its use in conjunction with the
latter, to enable a larger dose of the X-ray to be administered without
a corresponding degree of danger. A stimulating application is used
to the point of producing some reddening of the skin.
The ultimate action of the application of the X-ray is
to cause a decreased amount of blood in the part treated through the action
of the ray in increasing the cellular lining of the arterioles and thereby
producing a diminution in their caliber. It is well known that in
deep X-ray burns we have a condition of starvation and death of tissues,
resulting from insufficient nourishment. Now, as far as the action
of the high frequency current on the vessels is concerned it is diametrically
opposite. It increases the blood-supply to the part treated, and
to this extent it tends to offset the anemia produced by the X-ray.
Otherwise the two methods usually act in harmony with one another in a
large number of diseases, particularly those affecting the skin, and by
combining the two, a greater amount of X-ray may be safely used, while
its action is hastened by the complementary effect of the high frequency
This must not confound the reader with the action of strong
sparks, which, as in fulguration, destroy arterioles, or produce an endarteritis
similar to that caused by the X-ray.