Whole blood storage

[Ref: PK1:p253-254; KB2:p184-185]

Collection

400-480mL of blood is taken, with 63mL of anticoagulant
* Citrate combines with calcium and anticoagulates the blood

Criteria

• Minimum acceptable survival rate is 70% survival of transfused RBC at 24 hours after transfusion
• CPDA1 blood has 70% survival when stored for 35 days at 4C
• Adsol blood has a shelf-life of 42 days

Methods of preservation

• Addition of preservative solution at the time of collection
• Storage condition (low temperature)
  * Blood is stored at 4-6C
  --> Minimise bacterial growth and decrease metabolic rate
• Aseptic technique to minimise risk of contamination

Types of anticoagulant/preservative solutions

Citrate-phosphate-dextrose (CPD)
* Sodium citrate 1.66g
* Anhydrous dextrose 1.46g
* Citric acid monohydrate 206mg
* Sodium acid phosphate 158g
* Water to 63mL

CPD-adenine
* Sodium citrate 1.66g
* Anhydrous dextrose 1.82g
* Citric acid monohydrate 206mg
* Sodium acid phosphate 158mg
* Adenine 17.3mg
* Water to 63mL

SAG-M
* Saline, adenine, glucose, and mannitol

Adsol
* Adenine, glucose, mannitol, and sodium chloride
* ??Same as SAG-M
* Shelf-life = 42days

Purpose of each ingredient

• Citrate
  --> Anticoagulates by binding to Ca2+ (reducing [Ca2+] to zero)
• Phosphate
  --> Buffers which also provides phosphate source for metabolism
• Dextrose
  --> Provides energy source for continued glycolysis and ATP production
• Adenine
  --> Provides substrate for ATP synthesis
  * Addition of adenine  to CPD prolongs shelf-life to 35 days

NB:

• Anticoagulant solution dilutes the plasma by about 20%
• CPD and CPDA1 have higher pH
  --> 2,3 DPG levels are maintained longer

Changes in whole blood during storage

RBC

• As storage time increase, some RBC becomes spherical due to metabolic changes
  * Associated increase in cell rigidity
• RBC transfused at maximum storage time
  --> 10-20% may be destoryed within 24 hours

WBC

• Granulocytes lose phagocytic and bactericidal properties within 4-6 hours
• Maintains their antigenic properties

Platelets

• Platelets becomes non-functional within 36-48 hours in blood stored at 4C

Factor 5 and 8

• Factors 5 and 8 are also called labile factors
  * Also inactivated by activated protein C
• Decreases with storage of whole blood

[KB2:p185]

• Factor 5 decreases to 50% at 14 days
• Factor 8 decreases to 50% by 24 hours and 6% after 21 days

[PK1:p254]

• Factor 5 decrease to 50% by 21 days
• Factor 8 decreases exponentially to 75% by 24 hours and to 30% after 21 days

NB:

• Normal haemostasis requires
  * Factor 5 at 5-20% of normal level
  * Factor 8 at 35% of normal level
• Following massive transfusion, coagulopathy due to dilutional thrombocytopaenia usually occurs before coagulopathy due to coagulation factor deficiency

ATP

• ATP falls slowly to 75% at 28 days

2,3-DPG

Also see 2,3-Diphosphoglycerate (2,3 DPG)

• In CPD-A blood, 2,3-DPG decreases to 50% at 14 days and 5% at 28 days
• Low pH increases rate of 2,3-DPG loss
• Decrease in 2,3-DPG is mainly due to reduction in glycolysis
  * [JN5:p270]
• Clinically, changes in p50 due to changes in 2,3-DPG do not usually exceed 3.8mmHg

Potassium level

• After the first 48 hours
  --> Progressive loss of K+ from RBC into plasma
  --> Plasma [K+] increase to about 12mmol/L at 7 days and 30mmol/L at 28 days

Other changes

• Rise in RBC [Na+]
• Fall in pH
• Loss of Ca2+
• Formation of microaggregates
• Small amount of haemolysis

 

Other notes

High [K+] does not normally cause problem because

• Restoration of RBC metabolic activity
  --> Reuptake of K+
• Elevated catecholamine in patient
  --> Increased cellular uptake of K+
• Dilutional effect
• Slow transfusion process

Changes in stored blood

[PK1:p254, Table 9.1]

Change	0	7	14	21	28
RBC survival (%)	100	98	85	80	75
2,3DPG (%)	100	99	50	15	5
pH	7.2	7	6.9	6.8	6.7
Na+ (mmol/L)	168	166	163	156	154
K+ (mmol/L)	3.9	11.9	17.2	21	28
Glucose (mmol/L)	19.2	17.3	15.6	12.8	12.2
Free Hb (microgram/L)	1.7	7.8	12.5	19	29