_Bier's Constricting Bandage._--To induce a _passive hyperæmia_ in a limb, an elastic bandage is applied some distance above the inflamed area sufficiently tightly to obstruct the venous return from the distal parts without arresting in any way the inflow of arterial blood (Fig. 6). If the constricting band is correctly applied, the parts beyond become swollen and œdematous, and assume a bluish-red hue, but they retain their normal temperature, the pulse is unchanged, and there is no pain. If the part becomes blue, cold, or painful, or if any existing pain is increased, the band has been applied too tightly. The hyperæmia is kept up from twenty to twenty-two hours out of the twenty-four, and in the intervals the limb is elevated to get rid of the œdema and to empty it of impure blood, and so make room for a fresh supply of healthy blood when the bandage is re-applied. As the inflammation subsides, the period during which the band is kept on each day is diminished; but the treatment should be continued for some days after all signs of inflammation have subsided. This method of treating acute inflammatory conditions necessitates close supervision until the correct degree of tightness of the band has been determined. [Illustration: FIG. 7.--Passive Hyperæmia of Finger induced by Klapp's Suction Bell.] _Klapp's Suction Bells._--In inflammatory conditions to which the constricting band cannot be applied, as for example an acute mastitis, a bubo in the groin, or a boil on the neck, the affected area may be rendered hyperæmic by an appropriately shaped glass bell applied over it and exhausted by means of a suction-pump, the rarefaction of the air in the bell determining a flow of blood into the tissues enclosed within it (Figs. 7 and 8). The edge of the bell is smeared with vaseline, and the suction applied for from five to ten minutes at a time, with a corresponding interval between the applications. Each sitting lasts for from half an hour to an hour, and the treatment may be carried out once or twice a day according to circumstances. This apparatus acts in the same way as the old-fashioned _dry cup_, and is more convenient and equally efficacious. [Illustration: FIG. 8.--Passive Hyperæmia induced by Klapp's Suction Bell for Inflammation of Inguinal Gland.] _Active hyperæmia_ is induced by the local application of heat, particularly by means of hot air. It has not proved so useful in acute inflammation as passive hyperæmia, but is of great value in hastening the absorption of inflammatory products and in overcoming adhesions and stiffness in tendons and joints.