+INFLAMMATION+
+Definition.+ Inflammation may be defined as the local reaction against
injurious influences. An aseptic wound heals without any of the
clinical signs of inflammation and without reaction. It is only by a
study of the minute changes about such a wound that the resemblance,
between the processes of wound repair and those of slight
inflammation, become evident.
+Etiology.+ The cause of inflammation is any injury to the tissues by
mechanical, thermal, or chemical means; by the effect of electricity,
or by the growth of bacteria.
+Pathology.+ Inflammation occurs through changes in the circulation.
When one of the causes mentioned above acts upon the tissues, the
first alteration seen is an increasing blood supply to the part, the
arterial circulation being increased both by the greater rapidity and
force of the current through the vessels, and by the dilatation of all
the small branches and capillaries.
When the inflammation grows more intense, the circulation in the
capillaries becomes slower and the corpuscles collect, until they clog
the vessels. The normal current of blood in small vessels, as seen
under the microscope, shows a thick central stream of corpuscles with
a transparent border of lymph (containing only a few white corpuscles)
between it and the vessel wall.
As the stream diminishes in rapidity, the number of white cells in the
clear space increases, the blood plaques appear also, and finally,
when the current is reduced to stagnation, the clear space disappears,
being filled entirely with cells, chiefly leucocytes, although red
cells find their way into it.
This tendency of the white cells to separate from the others, even
when the current is rapid, is partly due to their viscosity and power
of ameboid movement, but in the main is a purely mechanical effect of
the slower current.
It has been proven that when particles of different density are
suspended in a liquid which is circulating through a system of narrow
tubes with a very rapid current, there is a clear space next to the
wall of the tube where the friction necessarily reduces the speed of
the fluid which is free from particles, and, as the current is slowed
down, some of the particles of least density, begin to appear in this
clear space, their number increasing as the current becomes slower,
until even the heavy particles also collect here when it is very slow.
It is known that among the cellular elements of the blood, the
leucocytes have the least specific gravity or density, and the blood
plaques rank next, while the red blood disks are the heaviest, and
these bodies appear in the clear serum near the vessel wall in that
order, according to the law just cited. The slow current is associated
with an increased intravascular blood pressure, which, in part, is the
cause of the phenomena of exudation, emigration and diapedesis.
+Exudation.+ Serum of the blood passes out of the vessels, and collects
in the lymphatic spaces in the cellular tissue, and elsewhere, and
also exudes from the surface of the mucous membranes or forms vesicles
or blisters in the skin by detaching the superficial epithelial
layers. Complete stasis, or stoppage of the circulation is seen only
when the inflammation is exceedingly intense, and would cause the
death of the part if continued long.
Usually the current merely becomes slower than normal. This retarded
circulation is followed by the phenomena of emigration.
+Emigration.+ Emigration of the white blood corpuscles consists in the
passage of the cells directly through the vessel walls. It is most
frequently seen in the capillaries, although it also takes place in
the small veins. The white corpuscles, or leucocytes, have the
property of ameboid movement, stretching out at will in any direction,
long, narrow processes of their protoplasm, called pseudopodia, which
may be attached to any object, and having secured such an anchorage,
the rest of the protoplasmic body is drawn towards it.
In this way, the leucocytes are able to pass through the interstices
between cells, or along narrow channels in the tissues. When the blood
current becomes sufficiently slow to enable them to cling to the walls
of the vessels, it is then that ameboid movement begins. Sometimes the
cells loose their hold and are swept on again, but in other cases a
minute bud of protoplasm will appear on the other side of the wall of
the vessel, opposite to the spot where the leucocyte is clinging, and
as this grows larger, a narrow neck of protoplasm can be traced
through the wall directly to the leucocyte, and presently the mass of
the leucocyte becomes proportionately smaller as the external bud of
protoplasm grows larger. The conditions are gradually reversed, the
nuclei of the cells appear outside and only a small mass of protoplasm
remains within the vessel until finally the entire leucocyte is in the
tissue outside of the vessel and is free to wander in any direction.
The mechanical part of this process is not yet understood. It is
claimed by some that small openings exist in the walls of the vessels,
between the endothelial cells which line them, to which is given the
name of _stomata_. These openings ordinarily are invisible, but they
are said to enlarge under the effect of the dilation of the vessels,
and of the alterations in their walls, produced by the inflammatory
reaction, and that the leucocytes escape through those openings.
There can be no doubt that the emigration is due to the ameboid motion
of the cell, and the discovery of the phenomenon, to which is given
the name chemotaxis, affords a sufficient explanation.
This is the influence possessed by certain substances to attract or
repulse ameboid cells. In some cases this attraction appears purely to
be mechanical, but it is probably a chemical effect of some kind in
most, if not in all, instances.
The process of inflammation produces some chemical compound which
similarly causes the cells to leave the vessels, and when there is any
inflammatory action in their neighborhood, to find their way by the
shortest route to the seat of the inflammation.
The leucocytes direct their course through the tissues to the chief
points of inflammation by reason of chemotaxis, and surround the dead
tissues, or any point of bacterial growth, or any foreign body which
may be the cause.
The wandering leucocytes form the pus cells, and if they are very
numerous, they constitute a purulent or suppurative inflammation. The
wandering cells, however, are almost entirely made up of leucocytes,
of which three forms are known, varying in size and in the size and
number of their nuclei. The leucocytes surround any foreign body, and
if the particles are small enough, they incorporate them within
themselves, in fact, they may be said to swallow them. This taking up
of particles by the wandering cells is called _phagocytosis_.
+Diapedesis.+ When the circulation becomes very low and the pressure
very high, there is a tendency of the red corpuscles to leave the
vessel.
This is a purely passive process, and is observed only when the
changes in the vessel wall are extreme. Both varieties of these cells
die and are destroyed in the exudate, the former furnishing the fibrin
which is so abundant in some forms of inflammation. This escape of red
corpuscles is known as _diapedesis_, and is sometimes so extensive as
to amount to capillary hemorrhage.
+Symptoms.+ From antiquity the local symptoms of inflammations have been
enumerated, as heat, redness, pain and swelling and to these has been
added, impaired function.
The _redness_ is due to congestion. The _pain_ is due to the pressure
exerted on the sensory nerves by the surrounding swelling, as is well
shown by the intensification of the distress, as every beat of the
heart forces more blood into the space already filled. In some cases,
however, it may be caused by the direct action of the inflammatory
agent upon the nerves. The _heat_ is caused by the increased supply of
warm arterial blood, for it has been abundantly proven that the
temperature never rises above the heat of the blood, although
naturally in a patient with fever, it will be above the normal
temperature of that fluid. The _swelling_ is due to the dilated
vessels, and to the escape of serum and blood cells from the vessels
into the tissues. The _impaired function_ is chiefly caused by the
pain which is often increased by any attempt to use the part, and by
the swelling which prevents free movement, though the loss of function
may also be dependent upon the direct action of inflammation upon the
nerves.
The constitutional symptoms of inflammation are an elevation of
temperature with or without a chill. There are also other
disturbances, such as nausea, vomiting, diarrhea, sweating and
polyuria. These are due to efforts on the part of the general economy
to eliminate toxic substances.
The inflammatory products may poison the system in two ways: (1) by
the diffusion of their chemical substances, (toxins and ptomains), or
(2) by the passage of bacteria themselves into the blood.
+Termination.+ Inflammation may result in resolution, suppuration,
necrosis or sloughing, or in the establishment of a chronic state.
+Resolution.+ Resolution is the termination of an inflammation by the
gradual cessation of all the changes which have occurred. The pain
subsides, the circulation becomes more normal, and the exudate is
absorbed, or makes its way to the free surface of the body, where
drainage occurs either spontaneously or by incision.
If there has been any loss of substance caused by the inflammation, it
is restored by processes exactly similar in character to those in the
repair of wounds.
+Suppuration.+ Pus consists of a serum containing little or no fibrin
and large numbers of leucocytes. There are also many cells, either
dead or dying, which represent the waste thrown off from the tissues
as a result of the inflammatory reaction. A purulent inflammation or
suppurative inflammation, is one in which there is pus formation.
When suppuration occurs, the pus may make its way to a free surface,
such as a mucous membrane, or may form an abscess, or may cause
sloughing of the skin over the seat of inflammation, and so escape
from the cellular spaces in the tissues.
Pus may be thrown off by a mucous membrane, without any actual breach
of continuity. Diffuse infiltration of the tissues is the most
dangerous form of suppuration.
In this variety of inflammation the exudate is brought into contact
with the greatest possible extent of absorbent vessels, for as a
surface of a sponge is greater than that of a bag, which would contain
it, so the surface of these intercellular spaces is much greater than
that of an abscess cavity filled by the same amount of pus. In this
form the bands of cellular tissue, lying between and forming the
boundaries of these spaces, remain intact, and the exudate is either
absorbed into the circulation, or seeks escape through many punctate
openings in the skin.
The entire skin of the part is frequently detached from the fascia by
the sloughing of the subcutaneous tissues, before it gives way, and
even when it finally yields to the necrotic process, the openings
formed will be altogether too small in proportion to the extent of the
disease beneath, so that healing is still further delayed.
+Sloughing.+ Inflammation may be accompanied by sloughing or death of
tissues. Gangrene, mortification or necrosis is a death of the tissue
from any cause. The part which has died is designated as a _slough_.
When inflammation has subsided, granulation tissue forms on the living
tissue, exerting pressure upon the slough, thus hastening its
absorption or separation.
+Chronic Inflammation.+ An interruption at some stage of resolution or
suppuration and the continuance of mild symptoms constitutes a chronic
state.
By chronic inflammation, we understand a long continuance of some or
all of the changes seen in acute inflammation, but less in intensity,
and an abnormal tendency to the production of new tissue.
+Treatment.+ The general indications to be observed in the treatment of
inflammation are: (1) to combat the congestion of the parts; (2) to
relieve tension; (3) to give free issue to the products of
inflammation; (4) to produce early separation of sloughs.
Very hot or very cold applications exert a beneficial and soothing
effect upon inflamed areas.
Cold has the tendency to reduce tension by constricting the blood
vessels thus diminishing the amount of blood supplied. In an infected
area the reproduction and development of bacteria are checked, and
suppuration is frequently aborted.
Heat has the effect of dilating the blood vessels and hastens repair
in bruised, strained, or torn tissues. This is a variety of hyperemia
treatment which is especially useful in the absence of bacteria. In
infected areas the growth of bacteria, and increased pus formation,
would be encouraged and heat is contraindicated.
We are yet without an antiseptic material which can be used in
sufficient strength to affect the growth of germs and yet not injure
the patient. Injury of the part treated, and absorption into the
circulation are both to be avoided. The application of dressings, wet
with corrosive sublimate, or other chemical solutions to the unbroken
skin over inflamed areas, is a fallacy. Any benefit which has been
observed to follow their use, has undoubtedly been due to the effect
of the moisture and warmth or cold, according to the temperature of
the dressing, thus obtained, while local sloughing and general
constitutional poisoning are a common result of such applications. A
light gauze dressing, applied cold, and kept constantly wet with any
evaporating solution, will greatly relieve the congestion and so
assist the inflamed tissues in their contest with any irritating
materials.
A thick wet dressing made with a hot solution, and well protected
against evaporation so that it will retain its heat, will produce the
same effect as a poultice, although less powerful. When there are
discharging wounds or raw surfaces, unprotected wet gauze should be
employed, for poultices are then inadmissible, and the weak antiseptic
solution will inactivate and wash away bacteria.
Astringent solutions have an excellent effect upon inflammatory
processes and the most generally useful of these is the 50 per cent.
solution of acetate of aluminium.
The following is a modified Burow’s solution:
Alum 24 gms., or 6 drachms
Lead acetate 38 ” ” 9-1/2 ”
Water 1000 ” ” 2 pints
Filter after mixture has been allowed to stand for 24 hours.
Ointments are employed by many in the treatment of small areas of
inflammation; they are useful, though not as efficient as hot or cold
wet dressings. Over the unbroken skin, they can only act like a
poultice and should not be employed where infection exists. On clean
wounds they are unnecessary, but upon ulcers or wounds which show no
tendency to heal, such ointments as Peruvian balsam, 5 per cent., or
scarlet red, 4 per cent., are extremely valuable.
+THE PROCESS OF REPAIR+
+Regeneration of Tissues.+ The reparative powers of the tissues of the
human body are considerable, although not comparable with those of the
lower animals, in the lowest orders of which the reproduction of an
entire limb, or even one-half of the body, may take place. In order to
understand the regeneration of tissue, we must first consider briefly
the life history of the cells.
A cell consists of a mass of protoplasm, generally enclosed in a cell
membrane, and containing a nucleus and nucleolus. The nucleus
represents the most vital part of the cell protoplasm, and has a more
granular appearance than the latter. The nucleolus is a minute solid
spot in a nucleus, appearing to be more highly refractive.
+Cell Division.+ When the cell is quiescent, the protoplasm appears
evenly granular, but when it is stirred to active life, slender
twining threads can be traced in the nucleus, perhaps consisting of
one long thread twisted upon itself.
On account of their readiness to take up dyes used in staining, these
threads are called _chromatine threads_.
When the cells are about to divide, the chromatine threads are seen to
arrange themselves in a line across the center, called the _equator_
of the nucleus, forming a rosette or star shape, known as the _mother
star_. Some large granules then appear in the nucleus at points on
either side of this line, which are known as the _poles_ of the
nucleus. The loops of the thread are directed towards the poles.
Gradually these threads become arranged in radiating lines, converging
at the poles, and then break away from their former connections with
the equator, forming a _daughter star_ at each pole, a clear space
appearing at the equator. A constriction next appears in the now clear
equator, and the nucleus divides into two distinct nuclei.
Simultaneously with this division, or immediately following it, the
protoplasm of the cell body divides in the same place, and thus two
complete cells are produced. The chromatine threads lose their rosette
arrangement, and gradually become imperceptible as the new cell
returns to the quiescent state. This process of cell division is known
as _karyokinesis_ or _aryomitosis_.
In simple cells like the leucocytes, reproduction may take place by
simple fission, thus: a constriction appears in the nucleus and in the
body of the cell in the same line, and the two divide without any
visible protoplasmic changes. Such a simple mode of division does not
occur in the more highly specialized cells of various tissues. If the
karyokinetic action be not very vigorous, the nucleus may divide, but
the cell body remains intact, producing the cell with two or more
nuclei so commonly observed. Every cell reproduces its kind, spindle
cells producing connective tissue; epithelial cells epithelium; and
bone cells producing bone.
+Repair of Wounds and Healing by Apposition.+ When a wound occurs, the
cut edges immediately retract on account of the elasticity of the
tissues, and the gap fills with blood and serum. If no bacterial or
chemical irritant is introduced, there are no true inflammatory
changes. The divided blood vessels are soon plugged with coagulated
blood, which extends into the cut vessels to the nearest branch. The
capillaries around the seat of injury dilate slightly, the fixed cells
of the tissues become active, dividing by karyokinesis as already
described. The endothelial cells lining the divided blood vessels
multiply and take an active part in the process. In spite of the
congestion and the new cells produced, the reaction is much less than
that of inflammation. The new cells invade the blood clot, consuming
it and also any foreign matter, or any tissue which may have been
killed by the injury. From the loops of the occluded capillaries, at
the sides of the wound, spring buds of endothelial cells, becoming
thicker and then hollow as they extend, blood cells forming in them
and blood entering them also from behind. These advancing endothelial
tubes join with those on the opposite side of the wound, and thus the
new forming tissues are supplied with blood vessels.
It is said that new vessels are also formed by the pre-existing
lymph-spaces and by independent cells. Meantime the connective tissue
cells have been forming fibres across the clot and epithelial cells
over its surface, if skin or mucous membrane be involved in the
injury. The new vessels disappear, and the new connective tissue
forms the scar. This is the process of primary union in a wound in
which there is not a marked cavity or a loss of tissue on any of the
exposed surfaces of the body, and no matter how closely the edges of
such a wound may lie in contact, it can heal by no other method. Even
the closest apposition of the sides of a wound cannot prevent the
interposition of a thin layer of clot and the partial death and
absorption of a very thin layer on its surfaces. This is also known as
primary union.
+Healing by Granulation.+ When a wide gap has been produced by
retraction or by actual loss of tissue, healing takes place by
granulation, as it is called, a process which differs from that just
described merely in the fact that more tissue must be reproduced. The
outpouring of blood and serum, occlusion of the vessels, congestion,
multiplication of fixed cells, emigration of leucocytes, and
production of vascular loops and buds, goes on as before. As the
formative changes advance, small, round elevations of a rosy color
appear on the new surface, making it look like velvet. These rounded
elevations of the healing surface are called granulations.
They advance steadily on all sides, filling the gaping wound until the
level of the original surface is reached, the new tissue organizing
behind them, and contracting as it organizes, so that the space to be
filled is daily made smaller by this contraction as well as by the
production of new tissue. As the surface is reached, the epithelial
cells on the edges of the granulating area slowly spread over it, the
granulations generally projecting above the adjoining surface and the
epithelium growing over them as they contract again to their proper
level. The advancing line of epidermis is visible as a pink line,
gradually whitening with time.