عدد المساهمات : 6
تاريخ التسجيل : 31/03/2008
|موضوع: Blood Preservation and Storage الجمعة أبريل 11, 2008 2:04 pm|| |
Blood Preservation and Storage
Blood is collected as whole blood, as shown below:
Blood can be stored as whole blood (with all of the plasma present) or, much more commonly, as packed red blood cells (PRBC's) in which about 70% of the plasma has been removed. This is done by light centrifugation, as shown below:
The platelet rich plasma can then be expressed off, leaving packed red blood cells (PRBC's) as shown here:
Both whole blood and PRBC's can be stored for up to 42 days at 1 - 6 degrees C.
The plasma can be centrifuged heavily a second time to separate the platelet rich plasma, as shown below:
The supernatant plasma can be expressed into a third bag and stored as fresh frozen plasma (FFP). The remaining platelet rich plasma is utilized as a platelet pack, as shown below:
As can be seen in the above diagram, a single donation of whole blood has supplied three separate components (packed red blood cells, platelets, fresh frozen plasma) that can potentially benefit three different patients.
After the expiration date, rare or valuable blood units can be "rejuvenated" with a biochemical solution that restores much of the original biochemical environment of the RBC's. The "rejuvenated" units are "washed" with isotonic saline in an automated device and then can be transfused as a saline-red blood cell suspension within 2 to 4 hours, or these units can be stored glycerolized and frozen for up to 10 years.
Cryopreservation of RBC's is done to store special, rare RBC's for up to 10 years. The RBC's are first incubated in a 40% glycerol solution which acts as an "antifreeze" within the cells. The units are then placed in special sterile containers in a deep freezer at less than -60 degrees C.
Cryopreserved units are thawed and washed free of glycerol prior to use as saline suspended RBC's. These units must be used in 2 - 4 hours to prevent possible bacterial contamination. The washed units are depleted of plasma and leukocytes.
Cryopreserved blood can help to maintain stores of Rh negative blood, to provide units for persons with antibodies to high-incidence antigens or persons difficult to cross-match because of multiple alloantibodies and to provide plasma-free blood to persons with IgA deficiency.
Thus, the types of RBC products available are:
Packed red blood cells (PRBC's)
Leukocyte depleted RBC's: cryopreserved blood that is thawed and degylcerolized is depleted of leukocytes, but much better depletion can be obtained by filtering the blood through leukocyte-specific filters.
Frozen, deglycerolized RBC's
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عدد المساهمات : 103
تاريخ التسجيل : 24/03/2008
|موضوع: رد: Blood Preservation and Storage الأحد أبريل 13, 2008 2:01 pm|| |
عدد المساهمات : 55
تاريخ التسجيل : 28/02/2008
|موضوع: رد: Blood Preservation and Storage الأربعاء أبريل 16, 2008 12:56 pm|| |