When they bleed, why not just give them blood?
Blood is a cocktail of substances. Water, cells, salts and proteins.
Cells carry oxygen (red cells) , fight infection (white cells) and stop bleeding by forming clots (platelets).
Because capillaries are prone to leaking certain salts and proteins hold water inside the blood vessel (albumen). These large molecules of albumen can't fit through the small holes in the capillary walls, and attract water, so by staying in the vessel this holds volume.
Another role of albumen is as a carrier of chemicals bound to the protein. Many drugs, bilirubin and hormones are transported on blood bound or plasma proteins.
Other proteins help fight infection. These are called antibodies or Immunoglobulins, and they are created by white blood cells after an exposure to a wild pathogen or vaccine .
Finally a class of proteins called coagulation factors aid in the clotting process ( collectively these proteins are called factors. There are 13 of them). Ultimately these factors are activated by damage to a vessel wall, and result in the formation of insoluble strands of solid matter called fibrin, or a fibrin clot.
Once blood is donated at a blood bank (volume 500 ml) it is spun into it's separate parts.
The factors ( factor 1, 8 and 13) can be are separated off and frozen , this is called cryoprecipitate (Cryo for short), or Anti-haemophilic factor (AHF). Additionally factor 8 (VIII) can be further isolated.
The rest of the plasma is fresh frozen and hence called FFP.
Usually the FFP is thawed and given neat, but some people have allergic reactions to some of the Coagulation Factors , especially 1, 8 and 13, (cryo) so they cleave this off and deplete the FFP to make it safer for people likely to have a transfusion reaction. Some proteins are more allergenic.
This type of FFP is called cryodepleated FFP.
They harvest the red cells for people needing a haemoglobin transfusions, eg bleeding post op, or trauma, anaemic people. This blood product is called "packed cells".
White cells are binned (they would attack the person getting a transfusion) .
Platelets are kept in a separate bag alive (they die in 8 days).
No comments:
Post a Comment