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