CONGESTION may be defined to be "excess of blood in the vessels of a part, with diminished motion of that blood." The chief causes of congestion may be classed under the two heads of (1) congestion from venous obstruction, and (2) congestion from want of tone in the vessels.
1. Congestion from venous obstruction is easily illustrated by tying up the arm, as is done before opening a vein, when the veins are compressed more than the arteries. If the ligature is kept on for a sufficient time, the veins swell, the fingers become red, and then livid, and the whole limb is swollen. Cold applied to the surface of the body acts similarly on it, and contracts the veins more rapidly than the arteries, which lie deeper; and the purple color of the hands and face after exposure to cold shows the con gested state of the capillaries. " Congestions," says Dr. C. J. B. Williams, " are caused in external organs by an obstruction of the veins leading from them. Thus, congestion of the brain may be produced by a tight cravat or by a tumor pressing on the jugular veins. Efforts of straining, coughing,, holding the breath, and asthmatic paroxysms which impede the flow of blood through the lungs. cause congestion in vari ous parts Tubercles in the lungs cause congestion of that organ. Obstruction to the transit of blood through the liver causes congestion in the abdomen, hemorrhoids, etc." —Principles of _Medicine, 2d ed., p. 140.
2. Congestion from want of tone in the vessels includes a numerous class of eases. In stony of the vessels generally, as in extreme debility, certain fevers, etc., there is gen eral congestion of the parenchymatous organs—the lungs, liver, etc.—and the blood gravitates to the lowest parts, giving rise to what is termed hypostatic congestion of the posterior parts of the lungs, the skin of the back, etc. In other cases, the weakness is local, as when the feet swell after long standing, in consequence of over-distention of the veins. Similarly, a continued stooping posture may occasion headache, giddiness, and the other symptoms of congestion of the brain. Congestive affections of this kind
are often mistaken for inflammation, and instead of being treated by tonics, are treated by depletion, which, although affording temporary relief, increases the evil.
Another cause of congestion is over-excitement of the vessels, and this often occurs at an early stage of inflammation, or as a result of that process.
We must pass over the symptoms and effects of congestion, because they vary very much according to the organ affected, and shall conclude with a few words on the gen eral remedies for congestion. First in order, we must notice such as remove the cause, as the loosening of a ligature, or the removal of a tumor compressing veins, elevation of the head in affected brain, and the recumbent position in congestion of the hemor rhoidal or uterine vessels. Pressure, by supporting the weak vessels, and friction, by increasing the onward movement of (lie blood in the veins, are often of great use. Astrin gents, such as solutions of alma, sulphate of zinc, tannin, oak•bark, etc., may he applied with advantage locally to certain parts, as the eye. throat, rectum, etc. ; and stimulants may be similarly used, as a capsicum gargle to a relaxed sore-throat. Medicines of these classes may also be given internally. Thus, the principal action of bark, quinine, and arsenic in the cure of ague is supposed to lie in their reducing the great visceral conges tion that is always present. A glass of strong hot brandy and water will often remove a congestive headache, and a stimulant draught will often relieve the pulmonary con gestion which follows a fit of asthma. Various remedies are supposed to have a special power of removing the congestion'of certain organs: thus, mereurials are recommended for congestion of the liver; digitalis and cantharides for congestion of the kidneys; and squills, benzoin, and the balsams for bronchial congestion.—For further details, the reader is referred to the excellent work of Dr. Williams, from which we have quoted.