Absorbable Haemostats

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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.


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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