[=Notice=: _Condition of membrane_—inflamed; extent and position of;
thickened; transparent or opaque; rough or smooth. _Contents_—blood,
gas, serum, pus, amount and probable source of. _Adhesions_—general or
local; firmness of, etc.]
Like other serous membranes, the pleura is liable to _inflammation_,
both acute and chronic, with their results—_plastic_, _serous_, or
_purulent effusions_, _adhesions_, etc.
=Inflammation.= The first change which is observed in inflammation of
the pleura (pleurisy) is a loss of the shining, transparent appearance
of that membrane, it becoming dull and opaque. Red injected vessels, in
minute ramifications, sometimes radiating from single points, in others
more uniformly diffused, will be noticed. Often the surface will present
a red mottled appearance, with here and there small points of
extravasation. This condition having existed for from six to twenty-four
hours, certain results follow—at least in the acute form—which give rise
to what is known as
=Plastic Effusion.= Soon after the inflammatory process is fully
established, there will appear upon the surface a small quantity of
clear fluid, which, as it increases in quantity, undergoes coagulation,
and thus gradually covers the surface with a jelly-like layer of
variable thickness and honey-comb surface. A thin fluid of a straw
color, will be found oozing from the surface, which is increased as the
coagulated membrane is cut or torn. This condition may be extended over
the whole surface of both the costal and pulmonary pleura, or may be
confined to a limited portion.
=Adhesions.= The two layers of the pleura being in immediate contact,
the consequence of this effusion of coagulated lymph will be an early
adhesion of the applied surfaces. This is accomplished by a blending of
the layers of coagulated matter in contact, and a gradual organization
of the same by an extension of blood-vessels from the pleura into the
new formation. At the same time that these changes are progressing, the
watery part of the exudation trickles down to the most dependent portion
of the cavity, and there forms a serous or sero-purulent accumulation.
Adhesions are more frequent at the upper portion of the lungs, but may
be found at any point, as between the inner surface and the mediastinum,
or the lower surface and diaphragm; or, from repeated attacks of
pleuritis, involving different portions of the serous membrane, the
whole of the exterior of the lung may become united to the adjoining
surfaces.
The strength of the adhesions will be somewhat in proportion to their
age, those of long standing requiring considerable force to break them
up, and in many instances the lung tissues becoming lacerated before the
attachments can be torn away.
Unusual thickness of the pleura is often found at points where no
adhesions exist, this being unquestionably the result of the effusion of
plastic matter into the subserous tissue during an attack of
inflammation.
=Serous Effusion.= While in the majority of cases of pleuritic
inflammation, we shall find _plastic effusions_ followed by adhesions of
the inflamed with the adjoining surface, in some instances a serous or
watery fluid is rapidly poured out, and, accumulating in the pleural
sac, constitutes _hydrothorax_ or dropsy of the chest. The fluid in
these cases may present a variety of shades of color, from a pinkish or
light straw color, to a dark brownish shade. It may be transparent or
opaque, and generally will be more or less albuminous. The quantity may
vary from a few ounces to three, four, or five pints, or more. When in
large quantity, the lung will be found more or less collapsed, shrunken,
and pressed against the posterior walls of the chest and spinal column.
In the general dropsy attending diseases of the heart, kidneys or liver,
effusions may take place into the pleural cavities, to such an extent as
to give rise to great dyspnœa from compression of the lungs.
=Sero-Purulent or Puriform Effusions=, consist in the presence of a
quantity of granular particles with albuminous matter, which subside to
the bottom of the vessel when drawn off, and always contains floating
flakes of lymph. It may be found in cases of both acute and chronic
pleurisy, and, like serous effusions, may be found in large quantity.
=Purulent Fluid=, as found in the cavity of the chest, consists of a
white or cream-colored, opaque, and homogeneous fluid, combined with
more or less albuminous matter, in the form of shreds and flakes, yet
destitute of the granular matter of the sero-purulent fluids, and not
separating into a fluid and solid portion when at rest, as is the case
with the latter.
It is a fact well established, that genuine purulent matter may be
formed in the pleural cavity, as well as in other serous cavities,
without ulceration of any portion of the surface, or discharge of an
abscess into the same, it being the result of a more advanced stage of
the process which gives rise to the serous or plastic effusions. It may
be secreted directly from the capillaries of the inflamed surface, or,
in some instances, it would appear to be derived from the organized
false membranes, which have taken on a suppurative action.
=Pneumothorax.= Air may enter the pleural cavity, by perforation of the
walls of the chest from external injury, or, as is more common, by the
destruction of the pulmonary portion of the membrane, from the bursting
of a distended air-cell, or from softening of tubercular deposits, or
bursting of an abscess. If there are but few or no adhesions, the
accumulation of air in the cavity may be accompanied by a more or less
complete collapse of the lung, as in hydrothorax. This condition, during
life, is not readily distinguished from emphysema, both being
accompanied with similar oppression in breathing, distension of the
chest, and displacements of the heart, and with increased clearness on
percussion. Serous or sero-purulent effusions will frequently accompany
the presence of air in the cavity, and thus give rise to many of the
peculiar physical signs which may have been noticed during life, as
metallic tinkling, a splashing sound on shaking the chest, etc.