Massive blood transfusion

[Ref: PK1:p256]

Massive blood transfusion
= Transfusion of a volume of stored blood greater than the recipient's blood volume in less than 24 hours

Complications

Citrate toxicity and hypocalcaemia

See Calcium

Hyperkalaemia

Usually K+ diffuses into RBC after transfusion
--> Usually does not pose a problem

May be a problem if patient is hyperkalaemic or acidotic and hypotensive

Acidosis

Due to low pH of stored blood

However, as citrate is metabolised to bicarbonate in the liver
--> ?? Correction of acidosis

Hypothermia

Rapid transfusion of cold blood may cause hypothermia

Can lead to

• Ventricular arrhythmia
• Cardiac arrest
• Reduction in O2 delivery due to effect on ODC
• Aggravation of citrate toxicity

2,3-DPG deficiency

Transfused blood regenerates 2,3 DPG within 24 hours of infusion

Dilutional coagulopathy

• Stored blood has low levels of factor 5,8, 11
• Platelets in stored blood are reduced in number and are dysfunctional

--> Both contribute to coagulopathy
* Thrombocytopenia has greater effect on coagulopathy

Microaggregates

• Microaggregates consists of clumps of fibrin, platelets and leukocytes
• Microaggregates are trapped in pulmonary vessels and may release lysosomes
  --> Contribute to adult respiratory distress syndrome