BLOOD DOWNSIDE 2

7.3.2 HEPATITIS

Hepatitis B and C can be transmitted through blood transfusion.
Screening technique once again can increase the rate of detection
and cut the risk of transmission of the virus.

7.3.3 TRANSMISSION OF TROPICAL DISEASES
Malaria can also occur as a result of transfusion in our country. Donor screening procedures and history taking can limit this mode of transmission

7.4 MASSIVE TRANSFUSION

Changes are expected if more than 10 unit of blood are
transfused in 24 hours.
These effects are because of changes that occur in the blood
stored at 1 to 6oC in the blood bank.
-Leakage of intracellular Potassium from the RBC results in high
potassium in the plasma of stored blood.
-Decrease in pH and decrease in intracellular ATP also occur in stored blood.
-Affinity of RBC for oxygen (slow release of O2) and degeneration of white cells and platelets is observed in stored blood.
-There are also changes in clotting factor V and VIII leading to bleeding disorders.
-Blood stored for several days is devoid of functioning platelets. Therefore, there is dilutional thrombocytopenia

7.4.1 THERMAL LOAD

When large quantity of blood is transfused and blood is not
warmed there is excessive heat loss resulting in hypothermia.
Patient’s core temperature may fall below 34oc and the blood does
not clot normal.
Hypothermia slows citrate metabolism and reduces oxygen release by the hemoglobin

This effect can be counteracted if blood is warmed before
Transfusion.

7.4.2 ACID BASE CHANGES

There is usually alkalosis after massive transfusion.
Sodium citrate, (the anti-coagulant in the stored blood) is converted
into Sodium Bicarbonate in the liver.
The post transfusion pH may range from 7.48 to 7.50 and there is increased excretion of Potassium.

7.4.3 OTHER CHANGES DUE TO CITRATE

The citrate received with massive transfusion can also lead to
decreased level of calcium because the citrate binds ionized
calcium lowering the plasma calcium levels, this effects the
blood pressure (hypotension), narrowing pulse pressure, increase
central venous pressure.
The EGG shows a prolonged QT interval.

7.4.4 CHANGES IN POTASSIUM

This occurs because of leakage of potassium from the RBC into the
plasma.
This high potassium may cause rise in T waves in ECG.
In *association with hypocalcaemia this may alter cardiac
function.

7.4.5 HOMEOSTASIS
Massive transfusion leads to a decrease in a number of viable
platelets, since the stored blood has a very few platelets.
The platelet count may fall in cases of massive transfusion.
The PT and aPTT provides a reliable indicator for deciding whether FFP
is needed for the treatment of this effect.
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