Faculty of Allied Medical ScienceBlood Banking (MLBB 201)

Changes that occur in Stored Blood

Prof. Dr. Nadia Aly SadekProf. in Haematology and

Director of Blood Bank Centre,Medical Research Inst, University of Alexandria

OutcomesBy the end of this lecture, the students will

be able to:Know the changes that occur in blood bags

with storageKnow what is blood filtration and its types.

Storage Lesion Long storage times of blood bags may

influence the quality of blood that is transfused. During storage, the red cells undergo a number of physical and chemical changes including:

Increased membrane rigidityLoss of organic phosphatesRelease of pro-inflammatory cytokinesSome changes take place slowly and some take

place rapidly.

Consequences of transfusing older blood1- Increased in-hospital mortality2- Increased rates of sepsis2- Delayed healing of wounds3- Tumour recurrence.

Immediately after blood donation, the red cells are subjected to an acidic, hypotonic, anticoagulant solution which damages a small proportion of them irreversibly.

Cells that survive the first 24 hours will remain viable for the end of their life span.

At least 70% of them remain viable in the recipient’s circulation 24 hours after transfusion.

Granulocytes become non-functional after 24 hours, but still they can cause febrile transfusion reactions.

Some lymphocytes may remain viable for several weeks.

Platelet function declines to zero after 24 hours of storage.

Biochemical changes1- Oxygen affinity Stored blood has depleted levels of 2,3

Diphosphoglycerate (DPG) which causes the oxygen dissociation curve to shift to the left, so increasing the oxygen affinity of hemoglobin = less release of oxygen to the tissues.

2- ATPThere is a time-dependent reduction in

intracellular RBC ATP which is essential for:- membrane stability - glucose transport- oxidative stress defense mechanisms- membrane phospholipid distribution

The biochemical changes that occur in the stored bags lead to alteration in corpuscle shape, decreased deformability, increased aggregability and intracellular viscosity as well as changes in osmotic fragility.

Immunologic changesRBcs transfusion produces a state of

immunosuppression in the recipients which predisposes them to acquire infections or develop transfusion-related acute lung injury.

Electrolytes1- Potassium: During storage, there is constant leak of

potassium out of the cells and levels may sometimes exceed 30mmol/L. After transfusion, potassium rapidly enters the red cells as they begin active metabolism.

But it may become a problem with rapid transfusion of large amounts of stored blood especially in severe renal failure or in neonatal exchange transfusion.

2- CalciumEach unit of blood contains 3g. Citrate which

binds ionized calcium. The liver is able to metabolize 3g of citrate every 5 minutes.

In patients with impaired liver function, there is a risk of citrate toxicity and hypocalcemia. It does not affect coagulation but patients may have transient tetany and hypotension.

Acid-Base balanceDuring storage, there is gradual

accumulation of lactic acid with a resultant fall in pH, but it is rapidly metabolized and the citrate by the recipient to bicarbonate which may then produce metabolic alkalosis.

CoagulationLabile coagulation factors i.e. FV and FVIII

have a 50% decrease in activity within the first 72 hours of storage, but the other coagulation factors remain normal.

Blood filtration= Leucoreduction of blood components which

is a process by which leucocytes are removed from blood by specific WBC reduction filters. There are two types:

1- Pre-storage filtration2- Bedside filtration.

Pre-storage filtrationEach unit of whole blood is filtered before

storage. Pre-storage filtration has many advantages:-

1- Diminished accumulation of leucocyte-derived cytokines during storage.

2- Removal of cells infected with cytomegalovirus (CMV) and Epstein-Bar virus (EBV) and HTLV-1 virus.

3- It decreases recurrent transfusion febrile reactions.

4- Improves RBCs potency5- Reduces HLA alloimmunizationDisadvantage:-It may activate the complement system.

Bedside filtrationIt is carried at the beside of the patient with a

different type of filter.Although it removes the remaining leucocytes

yet it does not remove the cytokines already secreted from the leucocytes and which are responsible for the transfusion reactions.

Study questionsState true or false:a- Bedside filtration is better than prestorage

filtrationb- Tetany is a sign of hypocalcemiac- Potassium decreases in blood bags by

prolonged storaged- RC membrane rigidity decreases by storage.

AssignmentsStem cell transplantation

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