Delirium is not an uncommon symptom when the inflammation of the lung is intense in persons of powerful constitutions, particularly during the exacerbation of fever in the night. It yields with the other symptoms when relief is obtained. When, however, it comes on at a later period of the complaint, or when the accompanying fever is not purely inflammatory, or in persons weakened by exhaustion and privation, it is usually a fatal symptom if continued. When mild, it often occurs after repeated and efficient bleedings, which have subdued, but not entirely removed the disease; and yields to opiates and gentle stimulants, by which the pain is removed, although it sometimes remains in a milder degree than before.
The ear discovers, soon after the commencement of the disease, that the natural murmur cannot be distinctly heard, it having been at first partly obscured, and after a time entirely superseded by a peculiar noise, called a crepitating or crepitous rattle or rhonchus. In its purest state it has been likened to the sound of a lock of hair rubbed close to the ear, or to that made by rumpling a fine piece of parchment; or again, to that which is produced by what under ordinary circumstances is called the crepitation of salt, when scattered in small quantities on red-hot coals. This crepitating rhonchus is heard at first in a small part of the lung, generally at the lower rather than at the upper part; it marks the first stage of the disease. It is not of long continuance; the vesicular murmur is either restored, or the crepitating rhonchus ceases to be heard, in consequence of the second stage to this, or that of hepatization, having commenced; the small air-vesicles are no longer pervious; the sound of the breathing, which is now heard, is that of the air more forcibly driven into the larger bronchial tubes causing bronchial respiration, which is no longer a vesicular or crepitating, but a whiffing sound, like that caused by blowing forcibly through a quill, or as if little gusts of air were blown in or blown out. The voice betrays to the ear of the auscultator another sign; it descends into the pervious bronchi, and being conveyed to the ear through the solid lung, gives rise to that peculiarity of voice called bronchophony, a correct knowledge of which can only be acquired by repeated observation.
When the inflammation of the lung is confined to a small and deeply-seated spot, auscultation may not at first reveal the evil; or it may possibly be overlooked, through the sound part of the lung becoming more active, and giving forth in consequence a stronger and more puerile breathing, which may mislead the listener.
When the vesicular murmur cannot be heard, when the rhonchus or crepitating râle or sound is not present, and bronchial respiration and bronchophony only can be distinguished, the case is one of great anxiety and danger. The second stage of hepatization is passing into the third, or purulent infiltration, of which auscultation shows no further signs, although the matter secreted may be expectorated, in proof of what has taken place. Pus is thus formed, which it is steadily maintained by some pathologists is not deposited in the form of abscess, but is infiltrated throughout the parenchymatous substance of the lung, finding its way into larger bronchial tubes, or being poured out from some parts of their secreting surface; the accuracy of this statement, however, as a rule, may be doubted, from some dissections having proved the reverse.
302. The effects of inflammation of the pleura are well marked; the first is to diminish, if not to annul, the secretion of the exhalation, or halitus, by which it is lubricated; so that its surfaces can no longer glide without noise upon each other. The patient is often made aware of the difference by some uneasy internal sensation; the auscultator, by a rubbing or creaking sound emitted as the inflamed pleuræ, no longer smooth and polished, rub against each other, and become covered by a thick, effused matter, although not actually separated by a liquid. It is a sound which cannot exist after separation has taken place by the intervention of a fluid, or after adhesions have formed; it is, therefore, an early and transitory sign, is frequently interrupted, and returns, as if by jerks, three or four times repeated in succession. The pleura when inspected, after being attacked by inflammation, shows at first but little sign of derangement on its serous surface. It quickly, however, exhibits numberless small vessels, carrying red blood, which are principally seated in the sub-serous cellular tissue, reddening the membrane more deeply in one part than another. These soon begin to take on a new action, leading to the deposition of coagulable lymph or fibrin, which adheres to the inflamed surfaces. These deposits soon assume the determinate form of very thin layers, constituting what are called false membranes; while a serous or sero-purulent effusion takes place, even to filling the cavity of the chest, and which may or may not be ultimately absorbed. When coagulable lymph is first deposited, and about to form a false membrane, it is soft, of a grayish-white color, and does not possess any appearances of organization. Red points are, after a time, perceived in it, which soon become red lines or streaks, on the surface. This organization of the lymph does not depend on the period which has elapsed from the commencement of the complaint. It is seen in the first day of the disease in some cases; it is altogether absent in others, and depends much on the state and habit of the patient. The lymph is sometimes deposited in small drops or spots; in others, in patches of a greater or less size, varying according to the extent of the inflammation which has produced them. When a false membrane is once fully formed, it becomes itself a secreting surface, and may go on augmenting its thickness to so great a degree as materially to diminish the cavity of the chest. I have seen the pleura with a solid deposit of this kind much more than an inch in thickness. In general, it is found in distinct layers, superimposed one upon the other. Whatever may be their thickness, they commonly admit of being separated from each other. The false membranes thus formed, resembling areolar tissue in their properties, may ultimately become cartilaginous, and even bony. When simple adhesions form between the pleuræ, they become lengthened with time; and, although they impede the motion of the lung at first, and may give rise to some uneasy sensations, they gradually become elongated, and give no further inconvenience. The fluid thrown out is serous; is often mingled with flocculi or lymph, which are seen floating in it; it is therefore more or less turbid, resembling whey. It is often nearly colorless and transparent; when the consequence of injury, it is often tinged with blood, forced out from the capillary vessels of the pleura, or of the false membrane, if not caused by the deposition of the fluid coagulated in the first instance after the receipt of the injury.
The quantity of fluid thus thrown out varies from an ounce to several pints; it gravitates according to the position of the patient, unless, when from old adhesions between the pleuræ, it is confined to particular parts. When the cavity of the pleuræ is free, and the fluid is in quantity, it compresses the lung, and diminishes its size by pressing or squeezing the air out of it; it is thus pressed toward the vertebral column, and so greatly diminished in size and augmented in density as to be useless for the purposes of respiration. While the lung is undergoing this compression to its utmost, the mediastinum also yields, and bulges into the opposite side of the chest, carrying the heart more or less with it; so that when the left side of the thorax is thus affected, the heart is seen and heard to beat on the right. The diaphragm now yields in turn, more on the left than on the right side, from the obstacle to its descent afforded by the liver. The intercostal muscles and ribs resist the internal pressure for a considerable length of time, even for weeks; they at last, however, yield; the ribs may even turn a little outward, while the interspaces in thin persons are said to fill out, so as to render that side of the chest nearly smooth, the size of that side, when measured, being larger than the other, in some instances even by two inches, but this rarely occurs unless the fluid within is purulent, and the disease of long standing.
303. After a time, and particularly in wounds of the chest, the effused fluid becomes purulent, the lung, compressed to a small, flattened surface, adheres to the spine by what was its root, if no adventitious attachments have retained it in a different position; and the pleura has become a thick, yellowish-white, irregular, honey-combed sort of covering for it, as well as completely lining the chest. The serous as well as the purulent effusion are both free from any unpleasant odor; unless a kind of gangrene has taken place, when the latter becomes very offensive, and of a greenish-black color, as well as the substance of the false membranes extending to and sometimes beneath the pleura covering the condensed lung, into which openings have even thus been made.
In some cases the surface of the pleura is covered with small tubercles, some as large as a filbert; in others it appears to have a reticular or honey-combed appearance; and in particular cases, large irregularities or excavations may be observed in it when much thickened, being evidently spots of ulceration, which, if they had proceeded, would have ended by allowing passage to the matter outward, until it formed an external abscess, implicating in all probability one or more of the ribs; thus giving rise to an exfoliation which, by being separated internally, might in time be the cause of further mischief, if not previously covered by a thin layer of false membrane. When chronic pleurisy succeeds to a more acute attack, or they alternate with each other, particularly after penetrating wounds of the chest, several layers seem to be laid down one upon the other. This deposit is never so thick upon the pleura pulmonalis; nevertheless it is thick enough in most instances to prevent the lung from again dilating, the substance of it being generally quite permeable to, although so compressed as to be deprived of, air. It is then flattened, drawn upward toward its root against the mediastinum and spinal column, unless by some previous adhesion such a course has been prevented, and it adheres, as it has been often known to do, to the side of the chest. As that adhesion may occur in more than one spot, so may the effusions or deposits take place between them, constituting circumscribed sacs, and rendering the case more complicated.
304. The changes which take place in the structure of the lung in pneumonia are three in number: 1. Engorgement. 2. Hepatization. 3. Purulent infiltration. The formation of an abscess or vomica, and the occurrence of gangrene, may be omitted, as well as of chronic disorders, in the views about to be taken of the disease from injury.
In the first stage of inflammatory obstruction, or that of engorgement, the lung has assumed externally a livid-red or violet color. It is heavier and firmer than in its healthy state, and the natural feeling of crepitation, although greatly diminished, is not extinct. The lung retains the impression of the finger, and pits on pressure as if it contained a liquid, although air-bubbles can yet be distinguished in it, and its cellular or spongy texture is still to be observed. On cutting into it, a quantity of sanguineous or turbid fluid flows from it, mingled with numerous minute air-bubbles. In some places the color of the incised surface is darker and more compact, showing that some progress has been made toward the stage of hepatization. It nevertheless tears with greater facility than in a healthy state.