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Anticoagulation and Preservation
2. Anticoagulation and PreservationVarious anticoagulant-preservative solutions have been formulated for better red cell preservation, which are listed below,
Optimal additive solutions
RED CELLS - FROZEN STATE
Citrate Based Anticoagulants
The importnat citrate based anticoagulant - preservative solutions used are ACD, CPD, CPDA (CPDA-1 and CPDA-2).
A. Acid citrate dextrose (ACD):
The most widely used ACD solution has the following formula :
Trisodium citrate 22.Og
Citric acid (monohydrate) 8.0 g
Dextrose (monohydrate) 24.6 g
Distilled water to make upto IL
For each 100 ml of blood, 15 ml of the ACD solution (pH 5.0) is sufficient (e.g. for 450 ml, 67.5 ml of ACD solution is required).
Mechanism of action
Citrate (Calcium chelator)
(> 70% transfused cells viable after 24 hours)
B. Citrate phosphate dextrose (CPD) :
C. Citrate Phosphate Dextrose Adenine (CPDA):
- helps maintain high ATP levels
Blood collected in CDPA
- well tolerated
- shelf-life = 35 days
Formula for CPD, CPDA-1 and CPDA-2
For both CPD and CPDA solutions, 14 ml (pH 5.6 to 5.8) of the solution is added for each 100 ml of blood.
* inhibits coagulation
* inactivates FXa, IXa, Xla, plasmin
* potentiates action of antithrombin Ill
The dose of heparin required for anticoagulation is 0.5-2 lU/mi, i.e. approximately 500 units for 500 ml of blood. Heparinized blood is rarely recommended for routine blood collection because it has no preservative property and its anticoagulant properties are neutralized by plasma. Heparinized blood should be transfused within 24 hours of collection.
Ethylene Diamino Tetra Acetic Acid (EDTA)
The sodium salts of ethylene diamino tetra acetic acid are powerful chelating agents and prevent coagulation by binding Ca.
It is not used in blood transfusion as it has no advantages over citrate. It is toxic and damages platelets. Thus it is used for preserving blood samples only. 1 mg of EDTA is used for 1 ml of blood for anticoagulation purposes only.
Optimal Additive Solution (OAS) for Preservation of Red Cells
Different types of additive systems are now in use. These solutions contain saline, adenine and glucose and are added to the red cells after separating them from plasma. The advantages of using optimal additive solution (OAS) to red cells are as follows:
Blood is collected into a multiple bag system including one plstic bag containing 100 ml of optimal additive solution.
After collection the whole blood is centrifuged and maximum amount of plasma along with the buffy coat is expressed into a transfer bag for further processing. Red cells are now suspended by running down the optimal additive solution (100 ml) to the main bag containing the red cells.
Advantages of Optimal Additive Solutions
1. Provide the red cells with adequate nutrients.
2. Better storage condition for red cell preparation and lowering of viscosity for ease of transfusion.
3. Increased yield of plasma for plasma fractionation.
4. Removal of unwanted buffy coat
5. Additional 7 day storage time for red cell preparation
6. Avoid unnecessary transfusion of plasma
Currently available additive solutions are
1) CPD-SAG 2) CPD-SAGMAN 3) CPD-ADSOL
CPD-SAG (Citrate phosphate dextrose - saline, adenine, glucose). In this besides CPD as the primary anticoagulant, a satellite bag contains the additive solution - 100 ml physiological saline with adenine and glucose. CPD-SAG causes undesirable amountof haemolysis.
CPD-SAGMAN In this the additive solution also has mannitol to prevent lysis of red cels. Theman 24 hr post transfusion survival is better with the additive.
CPD-ADSOL This additive solution is similar to CPD-SAGMAN but has greater quantities of glucose, adenine and mannitol. It has better red cell preservation and 24 hr post-transfusion survival. The shelf life with this solution can be increased to 42-49 days.
Composition of CPD-SAGMAN and CPD-ADSOL
Effect of mixing red cell during storage
Red cells stored in SAGMAN or ADSOL show less spontaneous lysis and show fewer microvesicles if the suspension is mixed, probably because of the dissipation of acid metabolites on mixing, which collect in the bottom layer of stored red cells.
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