Wednesday, December 8, 2010

massive blood transfusion

We recently had a 35 yo guy with a massive upper GI bleed not amenable to banding of varices.He had a Sengstaken- Blakemore tube....and his TIPSS next day was not possible due to thrombosis of splenic & portal vein. He finally had a spleno-renal shunt. He was transfused 11 units of PRBCs, 12 units of FFP, and 8 units platelets before being stabilised. This can be categorized under "massive blood transfusion". There are a few complications associated with this amount of transfusion....and its important these are addressed so that our good work at resuscitation is not lost because of  these problems. Lets look at those complications.....

 Massive blood transfusion is usually defined as the need to transfuse from one to two times the patient's normal blood volume. In a "normal" adult, this is the equivalent of 10-20 units.

Coagulopathy - The most common cause of bleeding following a large volume transfusion is dilutional thrombocytopenia. This should be suspected and treated first before moving on to factor deficiencies as the cause of coagulopathy.

Citrate toxicity - results as citrate in the transfused blood can bind calcium in the patient's body. Clinically significant hypocalcemia does not usually occur unless the rate of transfusion exceeds one unit every five minutes . This is more of a risk in patients with hepatic citrate is metabolised in liver. Treatment is with intravenous calcium administration. So check Calcium levels every 4 hours. Hypomagnesemia can co exist with hypocalcemia...but does not affect mortality.(Transfusion 2010)

Hypothermia -  should not occur on a regular basis. Massive transfusion is an absolute indication for the warming of all blood and fluid to body temperature as it is being given.
Acid-Base balance - can be seen after massive transfusion. The most common abnormality is a metabolic alkalosis. Patients may initially be acidotic because the blood load itself is acidic and there may be a prevailing lactic acidosis from hypoperfusion. However, once normal perfusion is restored, any metabolic acidosis resolves and the citrate and lactate are then converted to bicarbonate in the liver.

Hyperkalemia - The potassium concentration in stored blood increases steadily with time. The amount of potassium is typically less than 4 milliequivalents per unit - So it needs a lot of units to raise the potassium.
Watch out for your next worse GI bleeder!!!