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Faculty of Allied Medical Science. Blood Banking (MLBB 201). Changes that occur in Stored Blood. Prof. Dr. Nadia Aly Sadek Prof. in Haematology and Director of Blood Bank Centre, Medical Research Inst, University of Alexandria. Outcomes.

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faculty of allied medical science

Faculty of Allied Medical Science

Blood Banking (MLBB 201)

changes that occur in stored blood
Changes that occur in Stored Blood

Prof. Dr. Nadia AlySadek

Prof. in Haematology and

Director of Blood Bank Centre,

Medical Research Inst, University of Alexandria

outcomes
Outcomes
  • By the end of this lecture, the students will be able to:
  • Know the changes that occur in blood bags with storage
  • Know what is blood filtration and its types.
storage lesion
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:
slide5

Increased membrane rigidity

Loss of organic phosphates

Release of pro-inflammatory cytokines

Some changes take place slowly and some take place rapidly.

consequences of transfusing older blood
Consequences of transfusing older blood

1- Increased in-hospital mortality

2- Increased rates of sepsis

2- Delayed healing of wounds

3- Tumour recurrence.

slide7

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.

slide8

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.
slide9

Some lymphocytes may remain viable for several weeks.

Platelet function declines to zero after 24 hours of storage.

biochemical changes
Biochemical changes

1- 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 atp
2- ATP

There is a time-dependent reduction in intracellular RBC ATP which is essential for:

- membrane stability

- glucose transport

- oxidative stress defense mechanisms

- membrane phospholipid distribution

slide12

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 changes
Immunologic changes

RBcs transfusion produces a state of immunosuppression in the recipients which predisposes them to acquire infections or develop transfusion-related acute lung injury.

electrolytes
Electrolytes

1- 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.
slide15

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 calcium
2- Calcium
  • Each 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 balance
Acid-Base balance
  • During 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.
coagulation
Coagulation

Labile 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
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 filtration

2- Bedside filtration.

pre storage filtration
Pre-storage filtration

Each 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.

slide21

3- It decreases recurrent transfusion febrile reactions.

4- Improves RBCs potency

5- Reduces HLA alloimmunization

Disadvantage:-

It may activate the complement system.

bedside filtration
Bedside filtration

It 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 questions
Study questions
  • State true or false:

a- Bedside filtration is better than prestorage filtration

b- Tetany is a sign of hypocalcemia

c- Potassium decreases in blood bags by prolonged storage

d- RC membrane rigidity decreases by storage.

assignments
Assignments
  • Stem cell transplantation

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