Packed Red Blood Cells

Packed red blood cells are red cells concentrated from whole blood by removing most of the plasma, usually with an additive solution to prolong storage. They restore oxygen carrying capacity and contain very little plasma, platelets or clotting factors, so they do not correct coagulopathy.

Composition. A unit is usually about 250 to 350 mL with a haematocrit of about 50 to 70% depending on the additive solution, and contains at least about 40 g of haemoglobin. Leucocyte reduced units contain fewer than 1 x 10⁶ leucocytes in each unit. Units stored in citrate phosphate dextrose adenine without additive have a higher haematocrit (about 70 to 80%) and a smaller volume.

Source and preparation. Whole blood derived, separated by centrifugation, or collected by apheresis. Leucodepletion is by filtration before storage in many systems.

Storage and shelf life. 2 to 6 degrees Celsius in a monitored refrigerator. Shelf life is usually 35 to 42 days depending on the additive solution. Irradiation shortens the shelf life, and washing limits it to hours.

Storage lesion. Potassium leaks out, 2,3-diphosphoglycerate falls, and deformability decreases during storage. This is most relevant in neonates, massive transfusion and exchange transfusion, where fresher units may be preferred.

ABO and RhD. Red cells must be ABO compatible and ideally RhD compatible with the recipient. Group O is the universal red cell donor.

Special groups. Neonates and young infants often receive small aliquots from a dedicated unit to limit donor exposure. In East Africa, whole blood may be used instead of packed cells because of supply.

Indications. Symptomatic anaemia with inadequate oxygen delivery, haemorrhage with loss of red cell mass, chronic transfusion programmes and selected perioperative settings, at thresholds that depend on the clinical circumstances (about 7 g/dL in most stable hospitalised adults, with higher values in cardiac and orthopaedic settings, and an individualised decision in acute myocardial infarction).

Non-indications. Volume expansion, iron or vitamin deficiency without instability, and haemoglobin in a normal or near normal range.

Contraindications and cautions. Heart failure and renal failure (risk of overload), known antibodies (need antigen negative units), IgA deficiency with anti-IgA (washed products), and recent haemolytic reaction.

Special products. Irradiated for defined immunosuppression, intrauterine and neonatal exchange transfusion and some donor relationships; cytomegalovirus safe (leucocyte reduced or seronegative) for pregnancy, neonates and transplant candidates; washed for repeated severe allergic reactions; antigen negative for alloimmunised patients; sickle negative or extended phenotype matched in sickle cell disease.

Dose.

• Adult without ongoing bleeding: one unit, then reassess. One unit raises haemoglobin by about 1 g/dL in a 70 kg adult.

• Children: 10 to 15 mL/kg, which raises haemoglobin by about 2 to 3 g/dL. A usual estimate is that 4 mL/kg of red cells raises haemoglobin by 1 g/dL.

• Whole blood in children: about 6 mL/kg raises haemoglobin by 1 g/dL, and 20 mL/kg is a usual dose for severe anaemia.

• Neonates: 10 to 20 mL/kg depending on indication and gestation.

• Bleeding patients: dose follows blood loss and response, not a fixed number of units.

Compatibility and testing. ABO and RhD identical or compatible, with a crossmatch or electronic crossmatch after a negative antibody screen.

Rate and time limit.

• Start at about 1 to 2 mL/min for the first 15 minutes while observing the patient.

• Then run the unit over 2 to 4 hours. A unit must be completed within 4 hours of leaving controlled storage, and hospital practice sets how long a unit can be out of the refrigerator before it is returned or discarded (often 30 minutes).

• In patients at risk of overload, about 1 mL/kg/hour, with a diuretic only when there is evidence of volume overload.

• In children, about 5 mL/kg/hour, and in neonates about 2 to 5 mL/kg/hour, depending on stability.

• Rapid infusion is used in life-threatening bleeding.

Equipment. A blood giving set with a filter (about 170 to 200 micrometres), intravenous access of suitable gauge, a blood warmer for rapid infusion (adults over 50 mL/kg/hour), exchange transfusion, neonates and cold agglutinin disease.

Compatible fluids. Only 0.9% sodium chloride in the same line. Do not add drugs, dextrose solutions or calcium containing solutions to the line, since they can cause haemolysis, clumping or clotting.

Observations. Temperature, pulse, blood pressure, respiratory rate and oxygen saturation before the unit, at 15 minutes, hourly (or at intervals set by the hospital) and after completion.

Special groups.

• Cardiac failure, renal failure, older adults: single units, slow rate and close monitoring.

• Sickle cell disease: avoid raising haemoglobin over 10 g/dL.

• Pregnancy: use RhD and K negative units for women of childbearing potential where possible.

Expected effects. Rise in haemoglobin, improved symptoms and oxygen delivery.

Serious reactions. Acute haemolytic reaction, anaphylaxis, bacterial contamination, circulatory overload, lung injury, hyperkalaemia in infants and rapid transfusion, citrate toxicity in massive transfusion, hypothermia, and delayed haemolysis.

Immediate interruption criteria. Fever of 38 degrees Celsius or over with a rise of 1 degree or more, rigors, chest or back pain, dyspnoea, hypotension, urticaria with systemic signs, haemoglobinuria, or any unexpected deterioration. Stop the transfusion, assess the patient, keep intravenous access with 0.9% sodium chloride, recheck patient and unit identity, and inform the blood bank. Do not restart without authorised clinical evaluation.

Investigations after a reaction. Return the unit and giving set, take new samples for group, antibody screen, direct antiglobulin test, haemolysis tests, cultures if septic features exist, and chest imaging if respiratory.

Follow up. Haemoglobin about 1 hour after completion in a non-bleeding patient. Watch for delayed haemolysis 3 to 14 days later (new anaemia, jaundice, fever). Record the response.

Referral and escalation. Haematology and blood bank staff for reactions, unexpected response, new antibodies and long term programmes (monitor ferritin and consider iron chelation when iron overload develops).