Passive Hyperemia.

Synonym.—Chronic or Passive Congestion.

Definition.—A chronic engorgement of the renal vessels, which is usually secondary to congestion of the other viscera.

Etiology.—The most frequent causes giving rise to renal congestion are chronic cardiac diseases, especially the advanced stage of valvular lesion after compensation gives way, and chronic pulmonary lesions, such as emphysema, adhesive pleuritis, fibroid phthisis, etc.; also chronic disease of the liver, such as chronic hepatitis and the various degenerations. It may arise from pressure upon the renal veins, from a gravid uterus, ascitic fluid, or tumors.

Pathology.—There is enlargement of the kidneys, which are dark-red in color, and firm and resisting to the touch. The capsule is but feebly attached or non-adherent. On making a section, the medullary substance is seen to be darker in color than the cortex, has a coarse, fibrous appearance, and bleeds freely; the Malpighian bodies appear as dark-red points, and are more prominent than under normal conditions. The most constant and characteristic lesion is the thickening of the walls of the capillaries both glomerular and medullary. Where the congestion continues for a long time, the appearance of the kidneys change; the enlarged organ, owing to disturbed nutrition, atrophies, and we have the "contracted kidney of congestion."

Symptoms,—"The urine is diminished in quantity, the color is darker than normal, the reaction is strongly acid, and the specific gravity rises to 1,025 to 1,030, because the watery portion diminishes more than the other urinary constituents. Owing to the diminution of the percentage of water, the urates show a tendency to precipitate as the specimen cools, and form the well-known brickdust sediment (sedimentum lateritius), which is readily dissolved by heating to body temperature, by neutralizing or rendering the urine alkaline, and appears under the microscope as amorphous, golden-yellow granules, which occur either isolated or collected into cylindrical irregular masses. In addition to the pigment, which gives the sediment its brick-red or pink color (uro-erythrin, urinary pink), the urine may, on account of the accompanying hepatic congestion, contain bile pigment, especially urobilin, less frequently bilirubin." (Senator.)

There is weight in the loins, and the patient complains of backache. Gastric disturbance is common, and in long standing cases edema of the extremities follow. Accompanying these symptoms are those of the primary lesion, which may be cardiac, respiratory, or hepatic.

Diagnosis.—The scanty, highly colored urine, with but little albumin and few casts, enables us to recognize it from nephritis, the only disease with which it could be confounded.

Prognosis.—The prognosis will depend altogether upon the primary lesion and our ability to remove it. Chronic congestion may terminate in chronic nephritis.

Treatment.—An infusion of apocynum will be a good heart-tonic as well as diuretic, and is an agent that can hardly be dispensed with in the treatment of chronic congestion with cardiac complications. An infusion of digitalis is also a good remedy with the same conditions present. Cactus and crataegus will also be found useful. Should the liver be involved such remedies as leptandra, chionanthus, chelidonium, carduus marianus, polymnia, and agents of like character, may be used as indicated.

The bowels should be kept soluble, but we should avoid depleting cathartics. The diet should be nourishing, easily digested, and contain meat at least once per day. Fruits should be eaten freely.

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.