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Posted: April 14, 2003

Addenda: April 15, 2003


Manual methods for washing small aliquots of red cells from a single unit dedicated for transfusion to hyperkalemic neonates

A transfusion medicine laboratory manager in North Dakota reports that in certain situations their neonatal physicians have requested washed red blood cells for low birth weight (< 2 pounds) infants who have very high potassium levels (> 6.0 mmol/L) due to renal insufficiency. They have been asked to wash small aliquots from a single RBC unit that is used over several days, to allow them to maintain a limited exposure plan of one unit for each baby. Presently, they routinely employ a "one unit per baby protocol" to minimize donor exposure risk, but since they do not have a procedure for washing a small RBC aliquot for these infants, they are being forced to wash an entire unit of RBCs, aliquoting off what is needed (usually ~10-50 cc) and then discarding the remainder of the unused unit within 24 hours. The inquiring colleague is concerned that employing a manual washing method for RBC aliquots might increase the risk of bacterial contamination and/or compromise the final hematocrit of the aliquots. The inquiring colleague was wondering if anyone else employs a manual method for washing of small red cell aliquots, and if so, what do they do to reduce the risk of contamination, and how do they ensure that the aliquot's hematocrit will be around 80%. She wonders if any colleagues would be willing to share their protocol with the network?

Editor's NOTE: Colleagues may wish to review a related discussion on this forum a few years ago.

ADDENDA April 15, 2003

The following response was received.

  1. A colleague in Oregon reports that they faced the same problem, and ultimately addressed neonatal potassium concerns by issuing fresh blood. Here is what he has to report (verbatim) "Our neonatologists were worried about potassium safety after a neonate developed an arrythmia with hyperkalemia while being transfused with RBC from a 14-day old unit. We formed a city-wide group of neonatologists and transfusionists to address their concerns. Our task force tried to design a "Cadillac" RBC product, one that would be safe for any infant, and that would address the following concerns:
    • Minimize risk of potassium toxicity
    • Minimize risk of CMV
    • Minimize risk of TA GVHD
    • Minimize donor exposures
    At the end of the process we agreed that under most circumstances, neonates would receive only two types of red cells:
    • 'RC5' - leukoreduced, irradiated O-neg RBC 5 days or less in age. (This is our "potassium safe" RBC product)
    • 'RCN' - leukoreduced, irradiated O neg RBC 28 days or less in age
    RC5 are reserved for children <4 mo old who require:
    • large volume transfusions (>60 cc)
    • rapid infusion, or
    • have significant hyperkalemia
    RCN are used for all other transfusions in infants until they are 4 months old. Washed products are still available, but require special approval. All aliqots are removed using sterile docking devices. Hospitals irradiate on release from the transfusion service if they have an irradiator. If they don't, they get their products irradiated at the blood center.

    This practice has been in use in the city for over 12 years. It has proven safe, with no significant complications or complaints. After we implemented this program at the University, we reduced the number of washed units by about 80 percent. Creation of two standardized neonatal products also reduced the number of blood bank errors involved in processing and labelling. Blood brought in as an RC5 but not used is migrated into the RCN pool to minimize wastage and allow continued dosing from the assigned unit. Each hospital places a standing order for fresh O-neg units with the blood center, allowing them to plan ahead. Our local ARC has been happy with this arrangement and has consistently met the city's need for fresh O neg blood.

    This doesn't really address how to wash a 30 mL aliquot, but I hope it helps."

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