EDEMA (Nen-Lat., from Gk. oidnnn, swelling, from nidci V, oidein, to swell. from oidos. swelling). The term applied ill medicine to the swelling occasioned by the etTusion or infiltration of serum into cellular or areolar structures. The subcutaneous cellular tissue is the most common, but is not the only seat of this affection. It is occasionally observed in the submueous and subserous cellular tissue, and in the cellular tissue of the parenchymatous viscera; and in some of these eases it gives rise to symptoms which admit of easy recognition during life. Thus (edema of the glottis (see LARYNX. Diseases of I and (edema of the lungs constitute well-marked and serious forms of dis ease; while I Hie= of the brain. though not easily recognized during life, is not uneommonly met with in the post-mortem examination of in sane patients. A general is called a 11USUrca.
(Edema may be either passive or active, the former being by far the most common. Passive (edema arises from impeded venous circulation as from obstruction or obliteration of one or more veins; from varicose veins; from standing continuously for long periods, till the force of the circulation is partly overcome by the physical action of gravitation; from deficiency in the action of the adjacent muscles, which in health materially aids the venous circulation, etc.) ; from too weak action of the heart (as in dilata tion or certain forms of valvular diseases of that organ) ; o• from an impoverished or toxic state of the blood (as in chlorosis, scurvy, Bright's dis ease, etc.). By means of the knowledge derived
from pathological anatomy, we can often infer the cause from the seat of the swelling; for ex ample. cedema of the face, usually commencing with the eyelids, is commonly caused by obstruc tion to the circulation through the left side of the heart, or by the diseased state of the blood in Bright's disease; and oedema of the lower ex tremities most commonly arises from obstruction in the right side of the heart, unless it can be traced to the pressure of the gravid uterus, o• of accumulated ffeces in the colon. o• to some other local cause.
Active crdema is associated with an inflam matory action of the cellular tissue, and is most marked in certain forms of erysipelas. It is firmer to the touch, and pressure with the finger produces less pitting than in the passive form.
Angio-neurotic a•dema is an affection of neu rotic origin characterized by transient, circum scribed swellings in different parts of the body, which come and go suddenly. They may appear on the face and involve a single eyelid or the nose. The larynx may become swollen and cause death.
Malignant wdelna is due to a specific infection, the bacillus of which is found in earth. It is rapidly fatal. See ANTHRAX.
From the preceding remarks, it will be seen that is not a disease, but a symptom, and often a symptom indicating great danger to life. The means of removing it must be directed to the morbid condition o• cause of which it is the symptom. See DROPSY.