SYMPTOMS.—It is possible that a slight degree of pulmonary congestion may exist when the circulation is hurried without the occurrence of any other symptoms except moderate acceleration of the breathing. Under such circumstances, however, the existence of congestion cannot be proved. When it is brought about in greater degree, either by over-action of the heart or sudden recession of blood from other parts, the earliest and most prominent symptoms are a sense of oppression in the chest and quickened, laborious respiration, which may rapidly increase until the dyspnoea becomes most urgent and distressing. The heart's action grows more hurried, the pulsations in the carotid and temporal arteries are strongly felt, and the face is deeply flushed. Cough is always present, at first dry in character and afterward accompanied with expectoration of frothy mucus, which may be tinged with blood or may be even mingled with a considerable amount of bright-red blood.
The different appearances of the expectoration are probably due to the fact that in some cases the distended pulmonary capillaries allow the transudation of blood-corpuscles, and in others they are actually ruptured by the strain, so that pure blood escapes from them.
If the congestion is due to weakened action of the heart, with remora of the venous circulation, and is passive in character, the symptoms may be less acutely developed and less urgent than they are in the active form; indeed, in some cases in which very considerable portions of the lung are involved there may be no excessive dyspnoea while the patient is quiet, in consequence of the organism having become gradually accustomed to the imperfect respiration.
As the congestion increases, however, and the lungs become more affected, the signs of malaëration are more conspicuous. Dyspnoea is more oppressive, the face and surface generally, especially the lips and extremities, become cyanotic and cold, and the patient perishes from apnoea and from coma occasioned by oedema of the brain or medulla or stasis of blood in the cerebral veins, the respiratory centres being paralyzed. With the occurrence of somnolence the efforts to free the air-passages from fluid by coughing and expectoration grow less and less as the sensibility is obtunded.
When the congestion is not very extensive the amount of air in the lungs is not lessened sufficiently to materially affect the percussion note, which may remain resonant, though it may have a somewhat tympanitic quality. The vesicular murmur is still heard, but it is rather rough in character. When the general symptoms indicate a graver degree of congestion there will be corresponding changes in the physical signs; resonance will be lessened, or even replaced by dulness, in consequence of the filling of the alveoli with serum or blood; and the respiratory murmur will be completely masked by coarse and fine mucous râles. If the dulness is very marked, bronchial breathing and bronchophony may be observed. Elsewhere in parts not involved in the congestion exaggerated or puerile breathing may be heard from the supplementary action that takes place there.
The physical signs may vary as to their situation with the patient's position as the blood in the congested vessels and the serum in the alveoli and connective tissue gravitate from side to side. But when the change described as hypostatic pneumonia has taken place, and the affected portion of the lung has become condensed in texture, position has little or no influence on the physical signs, which will still remain even when the affected side is kept uppermost.
When oedema of the lungs is produced by serous effusion invading the air-cells, there is some degree of dulness on percussion, especially at the lower part of the chest. Respiratory murmur is feeble or suppressed, and fine moist râles are heard, with an intermixture at times of the true crepitant râle. These signs are generally heard on both sides, but when an area of oedema is due to pneumonia the signs may be present only on the affected side.
COURSE AND TERMINATIONS.—Acute congestion of the lungs depending on over-action of the heart or a sudden recession of blood may cause death in a short time, or may disappear, either spontaneously or under appropriate treatment, almost as suddenly as it has come on. The abatement of the symptoms is generally attended with profuse serous expectoration, and sometimes with hemorrhage, by which the congested vessels are relieved, so that they return to their natural state.
When acute oedema of the lungs is due to Bright's disease in the acute or one of the chronic forms, it is often quickly fatal, though if properly treated it may disappear. When a consequence of chronic renal disease it is apt sooner or later to return. Chronic passive hyperæmia and chronic oedema of the lungs admit of only temporary relief, because they are occasioned by such diseases of the heart or kidneys as are themselves generally incurable; and they are very sure to recur, even though they may be relieved for a time. It is not uncommon in cases of this sort to see the symptoms of chronic oedema suddenly aggravated by the occurrence of an acute attack, which is the immediate cause of death.
PATHOLOGY AND MORBID ANATOMY.—The pathological appearance of a congested lung varies according to the form of the congestion and the manner in which it has been occasioned. Acute congestion may occur very suddenly from some of the causes that have been mentioned, and may disappear with equal rapidity, leaving no traces behind. But sometimes, from the extent of the congestion, respiration is interrupted to such a degree that life is quickly destroyed. In such cases the affected portion of the lung is of a dark color from being engorged with blood, which flows from it if an incision is made. The part is heavier and crepitates less than normal lung-tissue. The bronchial mucous membrane is apt to be hyperæmic, as might be expected from the communication that exists between the pulmonary and bronchial vessels, and the tubes themselves are filled with mucus and sometimes with frothy and bloody serum.