#General Principles of Treatment.#—­The capacity of the inflammatory reaction for dealing with bacterial infections being limited, it often becomes necessary for the surgeon to aid the natural defensive processes, as well as to counteract the local and general effects of the reaction, and to relieve symptoms.

The ideal means of helping the tissues is by removing the focus of infection, and when this can be done, as for example in a carbuncle or an anthrax pustule, the infected area may be completely excised.  When the focus is not sufficiently limited to admit of this, the infected tissue may be scraped away with the sharp spoon, or destroyed by caustics or by the actual cautery.  If this is inadvisable, the organisms may be attacked by strong antiseptics, such as pure carbolic acid.

Moist dressings favour the removal of bacteria by promoting the escape of the inflammatory exudate, in which they are washed out.

#Artificial Hyperaemia.#—­When such direct means as the above are impracticable, much can be done to aid the tissues in their struggle by improving the condition of the circulation in the inflamed area, so as to ensure that a plentiful supply of fresh arterial blood reaches it.  The beneficial effects of hot fomentations and poultices depend on their causing a dilatation of the vessels, and so inducing a hyperaemia in the affected area.  It has been shown experimentally that repeated, short applications of moist heat (not exceeding 106 F.) are more efficacious than continuous application.  It is now believed that the so-called counter-irritants—­mustard, iodine, cantharides, actual cautery—­act in the same way; and the method of treating erysipelas by applying a strong solution of iodine around the affected area is based on the same principle.

[Illustration:  FIG. 6.—­Passive Hyperaemia of Hand and Forearm induced by Bier’s Bandage.]

While these and similar methods have long been employed in the treatment of inflammatory conditions, it is only within comparatively recent years that their mode of action has been properly understood, and to August Bier belongs the credit of having put the treatment of inflammation on a scientific and rational basis.  Recognising the “beneficent intention” of the inflammatory reaction, and the protective action of the leucocytosis which accompanies the hyperaemic stages of the process, Bier was led to study the effects of increasing the hyperaemia by artificial means.  As a result of his observations, he has formulated a method of treatment which consists in inducing an artificial hyperaemia in the inflamed area, either by obstructing the venous return from the part (passive hyperaemia), or by stimulating the arterial flow through it (active hyperaemia).