STERILIZATION
In the practice of medicine and its allied branches, it is recognized
that no unsterilized object is clean; it is therefore necessary for
every such object to be sterilized before being brought in contact
with, or near to a wounded surface, or to a surface about to be wounded.
Previous to the time of Lister, who was the first one to practise and
to advocate asepsis and antisepsis, it was considered normal for a
wound to suppurate and the consequent appalling results were accepted
as being in order. Today, however, asepsis and antisepsis have been
proven to be absolute essentials to intelligent treatment, and it is
accordingly necessary that every practitioner treating the human body,
should exercise the greatest care so as to prevent the invasion of
hostile bacteria.
Sterilization may be defined as the act of rendering an object sterile
(clean), by the destruction of microorganisms, preferably by means of
heat. To perform any operative work, so that there is perfect asepsis,
or freedom from bacteria, depends entirely upon the care exercised in
practising such asepsis. The instruments, the dressings, the field of
operation and the hands of the operator are all media for contamination
and the infection of wounds, and the sterilization of all these is
necessary, as infection might come from lack of care in the preparation
of any one of these details before an operation.
=Instruments.= The most efficient way of rendering instruments sterile,
is by immersing them in boiling water for fifteen minutes. To each
quart of water used in the sterilizer, is added one-half an ounce of
sodium carbonate (washing soda). This prevents rusting and also acts
as a solvent for any fatty substance that may be on the instruments.
Superheated steam is used for sterilizing instruments, but this
requires especially large and expensive apparatus which is not at the
command of most practitioners. Dry heat will destroy bacteria, but it
is not as effective as moist heat (steam). To procure absolute results
requires a high temperature, which effects the temper of the steel in
the instruments.
Instruments with sharp cutting edges, such as are used in the removal
of helomata, are blunted by boiling. They are therefore best sterilized
by immersing them in pure carbolic acid for a few minutes, followed by
dipping in grain alcohol, the instruments being handled with a pair of
forceps.
=Dressings.= Dressings such as gauze, bandages, absorbent cotton and
other cloth materials are best sterilized by steam which is allowed to
circulate through the material for fifteen minutes, and they may then
be placed in dry heat for a short time, thus allowing the moisture to
evaporate. If a steam sterilizer is not available, the dressings may be
boiled, or they may be baked for ten minutes in a temperature not lower
than that of the boiling point of water. Care should be taken that the
heat is not great enough to scorch or burn the materials.
Sterilized dressings of all kinds may be purchased in convenient,
hermetically sealed packages, and may be safely used without
preparation. Once such a package has been opened and used, the contents
do not remain sterile; the materials left over from an operation should
not be used at another operation unless they have been again thoroughly
sterilized.
=Field of Operation.= The skin of the foot is much thicker than that
on the other parts of the body and in addition it usually does not
receive the same hygienic care as does the rest of the skin surface. It
is therefore highly essential that additional precautions be taken in
preparing the foot for operation.
The entire foot should be scrubbed with soap and warm water so as to
remove as much of the exfoliated skin and dirt as possible. It is then
immersed in a solution of bichloride of mercury (¹⁄₂₀₀₀) and wrapped
in a sterile towel until ready for operation. The foot may also be
prepared by first scrubbing with soap and water, washing with alcohol,
60%, and finally painting the part to be operated upon with tincture of
iodine. Iodine has proven to be the best antiseptic in use today, but
very often it interferes with chiropodical operations due to the stain
it produces. This may be overcome to a certain extent by washing the
part with alcohol after the iodine has been applied.
Alcohol in a sixty per cent. solution is a very efficient antiseptic
and wherever iodine cannot be used, it may be substituted. A piece of
absorbent cotton, dipped into the alcohol, is placed in contact with
the part to be treated and is allowed to remain for a few minutes. Like
iodine, alcohol penetrates the layers of the epidermis and so destroys
the bacteria that lurk between the outer layers.
=Hands of the Operator.= There are several ways of cleaning the
operator’s hands, but each such procedure is preceded by thoroughly
scrubbing them with green soap and a nail brush for at least ten
minutes, in warm water. Alcohol or ether should then be rubbed over the
hands to dissolve fats, and they should then be dipped in a solution
of bichloride of mercury (¹⁄₂₀₀₀) for a few minutes. A most efficient
way of sterilizing the hands consists of the following: after scrubbing
the hands as before described, take equal parts of chloride of lime and
carbonate of soda (about one-half teaspoonful of each) and add enough
water to make a paste. This is thoroughly rubbed into the hands and
when the sensation of warmth has disappeared they are rinsed in sterile
water.
The use of rubber gloves to protect the hands is of some advantage in
that they may be thoroughly boiled before they are used; but unless
the hands are sore or the skin is tender, they should not be employed,
as they decrease the sense of touch so necessary in chiropodial
procedures.
STERILIZING APPARATUS
There are many kinds of apparatus for each form of sterilization, and
the podiatrist, in selecting a sterilizer, must be guided by the size
of his purse as well as the amount of space he can afford for such an
apparatus.
The steam sterilizer is unquestionably the best for general purposes,
and the dual compartment arrangement is better than a single chamber
outfit. Steam sterilizers for office purposes vary in size from the
small single chamber, measuring four inches wide, eight inches long and
four inches deep, to the larger double chamber which measures twelve
inches wide, twenty-four inches long, the upper chamber twelve inches
deep and the lower chamber six inches deep. The latter sterilizers are
the best possible for the podiatrist’s work, in that they allow for the
sterilization of towels, dressings and instruments at the same time,
and there is no direct contact between the instruments and the boiling
water. The apparatus may be heated by gas or by electricity, gas being
the most desirable as it is more easily controlled and regulated. The
cost of the instrument equipped for gas heating is very much cheaper,
and the operating expense is less than when electricity is similarly
used.
As its name implies, the double compartment sterilizer is composed
of two distinct sections which are easily separated, and when put
together look as if they were one section. The lower compartment is
more shallow than the upper and contains the water which is boiled for
the manufacture of the steam to be utilized in the sterilization. The
upper compartment has an inner jacket which is so arranged that the
steam passing from below is collected in it, and is admitted into the
compartment proper through a small opening at one end. This causes
the steam to be forced in under a slight pressure, which increases the
heat and adds to its power as a germ destroying agent. The opening is
controlled by an inlet valve which may be adjusted so as to prevent the
steam from entering the compartment. The steam then circulates around
it in the jacket and in this way dry heat is generated in sufficient
quantity to allow for dry heat sterilization. If space permits, it is
advisable to have two such sterilizers, one for steam sterilization
and the other for dry heat sterilization. The instruments, towels and
dressings may thus be dried which prevents the rusting of the steel,
and makes the linen more easy to handle. These sterilizers are as well,
an ornament to any office.
[Illustration: ELECTRIC STERILIZER]
Where space is limited, the smaller electric sterilizers may be
substituted for the larger outfits. There are many styles and shapes
of this kind of instrument, but the principle is the same in all of
them. There must be ample space for the reception of the instruments,
and the cover must be closed when the water is boiling. The electric
current is passed into a metallic disc, situated beneath the bottom
of the water receptacle. As the current passes through this disc, it
becomes hot, and the water in the compartment is gradually heated until
the boiling point is reached. The current must never be left on when
the machine is not in use, for when the water has evaporated, the heat
will cause the solder holding the joints of the sterilizer to melt and
cause a separation of the seams. This molten solder might even drip
on something combustible and set it alight. There are some electric
sterilizers which are equipped with safety devices which prevent this
possible accident. The device provides so that when this heat is great
enough, it melts a small piece of an alloy with a very low melting
point. This metal is held in position by a clamp which is attached
to the current flow and when this melts, the current is cut off and
further heating is impossible. This is a very valuable attachment,
particularly when one is inclined to be careless.
Another form of smaller electric sterilizer consists of a glass
compartment into which is placed the heating apparatus. This latter
is composed of coils enclosed in a metal protector. The protector is
attached to a handle, through which pass the electric wires. This coil
and handle is placed into the glass bowl and is held fixed by a small
clamp. A cover is then placed over the bowl, which is so arranged as to
allow the wires to pass through it.
For sterilization with pure phenol and alcohol, it is necessary to
have two wide mouth, glass stoppered, two-ounce bottles. When the
instruments are being sterilized they may be left standing in either
bottle until ready for use. A piece of felt, cut to fit the inside
bottom of each of the bottles, should be placed in situ, so that when
sharp edged instruments are placed in the bottles, their points will
not be broken, by coming in contact with the hard glass.
[Illustration: FORMALDEHYDE STERILIZER]
Formaldehyde gas is an agent which has germicidal properties, and is
used to a great extent where steam sterilizers are not available.
Formalin, a concentrated solution of the formaldehyde gas, readily
gives up its gaseous constituent so that when the liquid is placed on
a flat tray, the gas will penetrate objects around it. Cabinets have
been constructed which are so arranged that the lower shelf contains
the solution, and the upper shelves may be used for instruments,
dressings, towels, etc. When the cabinets, which vary greatly in size,
are tightly closed, the gas will penetrate every object contained
therein, thus destroying any microorganisms which might be present.