Packed Red Blood Cells

Packed Red Blood Cells (PRBCs) are the most commonly used blood component. 

PRBCs are prepared from whole blood by centrifuge or by apheresis collection. 

Typically, one unit of PRBC is approximately 350 mL in volume, of which RBC volume is 200–250 ml. The remaining volume is due to plasma (typically <50 ml), White Blood Cells (WBCs), platelets and anticoagulants. 

The most commonly used anticoagulant is CPDA-1 (citrate, phosphate, dextrose and adenine), which allows for 35 days storage at 2–6°C. 

The hematocrit of such units is less than 80% (range, 70–80%).

Each unit of PRBC is expected to increase the hematocrit by 3% and the hemoglobin level by 1 g/dL. This effect can be measured 15 min after transfusion. 

In a bleeding patient, it must be remembered that transfusion of multiple units of PRBC will aggravate the coagulopathic state of the patient. 

The unit of PRBC that is being transfused must be compatible with the recipient’s plasma ABO antibodies. 

Thus, if the recipient is blood group A, he or she has anti-B antibodies and cannot be transfused with B or AB units. 

If the recipient is B, he or she has anti-A antibodies and cannot be transfused with A or AB units. 

Both A and B patients can receive O units. 

If the recipient is AB, he or she has no anti-A or anti-B antibodies and can therefore receive A, B, AB or O units. 

If the recipient is O, he or she has anti-A and anti-B antibodies and can receive only O units.