Saline Washed Red Blood Cells |
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Saline-washed RBCs are units of whole blood or RBCs that have been washed with 1 to 2 liters of saline manually or in an automated cell washer. Washed units contain 10 to 20% less RBCs than the original units. Therefore, a greater number of washed units may be required to alleviate symptoms. These units have a hematocrit of 70% and have been depleted of 99% of the plasma proteins and 85% of the leukocytes. The residual potassium concentration is 0.2 mEq/L. Other RBC metabolites are almost entirely removed. Washing also removes cytokines that cause febrile reactions. Saline washed RBCs must be used within 24 h after washing since the original collection bag has been entered, which breaks the hermetic seal and increases the possibility of bacterial contamination. Removal of the anticoagulant-preservative solution also limits cell viability and function. Saline washed red blood cells have limited medical indications.
Indications for Saline Washed Blood Components
- Febrile transfusion reactions not prevented by leukocyte reduction.
- IgA deficiency with documented anti-IgA antibodies and IgA deficient donor not available.
- History of a previous anaphylactic transfusion reaction.
- Severe urticarial reactions not prevented by the pre-transfusion antihistamines.
- Potassium depletion of units irradiated more than 12 hours before that will be transfused to a neonate or fetus.
- Maternal single donor platelets collected for neonates affected by neonatal alloimmune thrombocytopenia.
Administration of IgA containing products to patients with anti-IgA results in anaphylaxis. Washing red cell and platelet components is one modality to prevent anaphylaxis, while transfusion of blood components from IgA deficient donors is another. Most regional blood centers maintain a registry of IgA deficiency donors.
Irradiated components have elevated levels of plasma potassium. Washing units with saline can decrease potassium levels. However, the best policy is to irradiate units immediately before transfusion.
Inappropriate use of saline washed whole blood or red blood cells includes:
- Emergent situations because they are not readily available
- Questionable transfusions because units outdate 24 hours after washing
- Non IgA deficient patients
- Febrile reactions that can be successfully treated with antipyretics and leukocyte depleted components
Administration of washed components is the same as those covered in their respective sections, except for the shortened shelf life of 24 hours. Platelets can also be washed. The major indication is transfusion of maternal apheresis platelets to an infant with neonatal alloimmune thrombocytopenia.
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