The reduction of blood loss during or after surgical procedures where suturing or ligature is either impractical or impossible can often be accomplished by the use of sterile, absorbable haemostats.
The reduction of blood loss
during or after
surgical procedures where
suturing or ligature
is either impractical or impossible can often be accomplished by the use of
sterile, absorbable haemostats. These consist of a soft pad
of solid material
packed around and over the wound
that can be left in situ and
absorbed by body tissues
over a period of time, usually up to 6 weeks. The principal mechanism of action of these is their ability
to encourage platelet fracture
because of their fibrous or rough
surfaces, and to act as a matrix
for complete blood clotting. Four products commonly used are
oxidized cellulose, absorbable gelatin
sponge, human fibrin
foam and calcium alginate.
A) Oxidized Cellulose
This consists
of cellulose material
that has been partially
oxidized. White gauze
is the most common form, although lint is also used.
It can be absorbed by the body in
2–7 weeks, depending on the size.
Its action is based
principally on a mechanical effect
and it is used in the
dry state.
As it inactivates thrombin, its activity cannot be
enhanced by thrombin incorporation.
B)
Absorbable Gelatin Foam
This insoluble foam is produced
by whisking warm gelatin solution to form a uniform foam, which is then
dried. It can be cut into suitable
shapes, packed in metal
or paper containers and sterilized by dry heat
(150 °C for 1 hour). Moist
heat destroys the physical properties of the material. Immediately before use, it can be moistened with normal saline containing thrombin. It behaves
as a mechanical haemostat,
providing the framework on which blood
clotting can occur.
C) Human Fibrin Foam
This is a dry sponge of
human fibrin prepared by clotting a foam of human fibrinogen solution with human thrombin. It is then
freeze-dried, cut into
shapes and sterilized by dry heat at 130 °C for 3 hours.
Before use it is saturated with thrombin solution. Blood coagulation occurs
in contact with the thrombin
in the interstices of the foam.
D) Calcium Alginate
This is composed of the sodium
and calcium salts
of alginic acid
formed into a powder of fibrous material
and sterilized by autoclaving. It aids clotting by forming a sodium–calcium alginate complex in contact with
tissue fluids, acting principally as a mechanical haemostat. It is relatively
slowly absorbed and some residues may occasionally remain in the tissues.
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