A system of practical medicine. By American authors. Vol. 3

by Unknown

Where the tonicity of the pulmonary vessels has been impaired by sickness, age, or other debilitating influences, passive congestion of the lungs is very likely to ensue if the heart become weakened; and as the effect of gravity will aid in determining the stasis of the blood, the resulting congestion is in life most marked in the lower and posterior regions of the lungs, where the changes are chiefly found after death. As gravity may thus determine the congestion to one part of the lungs, so a change in the patient's position may cause it to disappear from where it was first manifest and to appear in another part which has become most dependent. The condition thus brought about is known as hypostatic congestion. One of the consequences of passive hyperæmia thus induced is a transudation of the serum of the blood into the air-cells and connective tissue of the lungs; and this is one way in which pulmonary oedema may be occasioned. When hypostatic congestion has lasted for some time, it may no longer be affected by changing the patient's position; and when this is the case it may be accompanied by exudation of fibrin into the air-cells and by proliferation of epithelium, thus producing the condition termed hypostatic pneumonia.

All three of these states may be present in one lung at the same time, one portion being passively congested, another oedematous, while the most dependent part may be the seat of hypostatic pneumonia.

The congested parts of the lungs are very dark in color, in some cases almost black; blood flows freely from a section through them, and serum exudes from the alveoli and interstitial tissue when oedema exists. If the altered condition of the lung has lasted for some time, the texture of the affected part may be so firm as to resemble that of the spleen; whence this change is sometimes termed splenization. In this condition dark-red points consisting of extravasated blood may be seen scattered about. If the state already described as hypostatic pneumonia exists, the affected part is still more firm and dense in texture, and presents a granular appearance on section from the exudation of fibrin which has probably taken place, so that it resembles a portion of a lung that has been the seat of an inflammatory process from the first.

DIAGNOSIS.—The diagnosis of pulmonary congestion in its different forms, and of pulmonary oedema, is in general not difficult if the symptoms of the causative diseases are carefully observed. Acute pulmonary congestion coming on suddenly, and not preceded by any other affection, needs to be distinguished from the early congestive stage of pneumonia, which it somewhat resembles from the slightly impaired resonance on percussion and the dyspnoea that may occur in both diseases. The chief points of distinction between the two affections are the absence in congestion of initial chill, of pain in the side, and of rise of temperature; all of which are in general present in pneumonia. As the case advances the divergence between the two affections will be wider.

The diagnosis of acute oedema and of chronic congestion and oedema is based upon the physical signs belonging to them, taken in connection with the symptoms of cardiac and renal disease with which they are associated.

Capillary bronchitis bears some resemblance to pulmonary oedema, since in both affections there are moist subcrepitant râles; but in capillary bronchitis there is no such loss of percussion resonance as occurs in pulmonary oedema, and, moreover, fever is not present in oedema, as it is in the inflammatory affection. The character of the expectoration is also different in the two diseases, being thicker and more tenacious in bronchitis and serous or watery in oedema. From hydrothorax, oedema is distinguishable by the shifting line of dulness and by the absence of râles in hydrothorax.

PROGNOSIS.—Acute congestion of the lungs is always a serious affection, and, as already stated, terminates fatally in some cases in a short time. In the majority of instances, however, it disappears spontaneously or under suitable treatment, and the lungs are in general restored to their integrity. It may result in pulmonary hemorrhage, from which recovery may take place, or which may give rise to hemorrhagic infarction, the blood being drawn into the alveoli.

Passive congestion being a secondary affection, its prognosis depends upon the diseases which occasion it.

In pulmonary oedema the prognosis is always very grave. When occurring suddenly as a consequence of acute congestive nephritis, it may wholly disappear under proper treatment, and if the kidney affection is likewise cured there will be no further return of the pulmonary complication. When it comes on in the course of chronic renal disease, it may disappear and recur from time to time, but it is apparently not often the direct cause of death by itself. Sometimes, however, it is associated with cerebral oedema and other conditions which together occasion a fatal termination. When due to pneumonia, oedema adds very much to the gravity of the affection, and may be the immediate cause of death.

TREATMENT.—The treatment of acute pulmonary congestion consists in the use of means to check the undue flow of blood into the engorged lungs. Of these the best, if the patient be seen promptly and the strength of the pulse admit of it, is general bloodletting, by which the mass of the blood is lessened and the action of the heart and pressure within the blood-vessels are lowered, so that both the amount of blood in the hyperæmic vessels and the force with which it reaches them will be diminished.