2 Warming Techniques Useful When Transfusing CAD Blood: Study

No difference in viable blood cell count was seen between the two methods

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Either a hot water bath or a blood warmer attached to an infusion pump may be used to warm up blood donated from patients with cold agglutinin disease (CAD) in order to minimize the risk of agglutination, or blood cell clumping, in a subsequent stem cell transplant, a study reports.

There was no difference between the two methods in terms of how many viable blood cells could be obtained, suggesting that centers can use whichever method is most convenient.

“Transplant centers should be assured that whatever warming modality is available will ensure product quality prior to infusion,” the researchers wrote.

The study, “How do I warm HPC(A) products to maximize cell viability in the setting of cold agglutinin disease?,” was published in Transfusion.

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CAD is caused by self-targeting antibodies called cold agglutinins that destroy red blood cells at low temperatures. This happens because these cells tend to clump together, or agglutinate, in the presence of these antibodies, leading to their premature destruction.

Because CAD is a rare disease, many institutions do not routinely screen donated blood that’s meant to be used in a subsequent stem cell transplant for cold agglutinins, which may potentially “jeopardize the quality of [blood products].”

For this reason, “the presentation of CAD and product complications may arise spontaneously, necessitating real-time decision making,” the researchers wrote.

In cases where donors are known to have CAD, or blood products show signs of agglutination — suggesting that high levels of cold agglutinins are present — “additional guidance is needed to ensure proper product handling and management.”

“These additional guidances are aimed at keeping the product warmer than the temperature of spontaneous agglutination, which may be lower than room temperature,” the researchers wrote, adding that “there remains a lack of data around the impact of various warming techniques on the recovery of total and viable [blood cell progenitors].”

Scientists at Mayo Clinic compared two different strategies for warming up blood in preparation for a transplant. Their goal was to provide guidance and aid transplant centers that might deal with CAD products.

In one strategy, frozen blood samples were put in a hot water bath to the point of becoming “just slushy” and left there for an hour. In the other strategy, samples were thawed until slushy, then put through an infusion machine with a blood warmer (an attached device that warms the blood as it moves through the infusion tubes). Experiments where blood was put through the infusion machine without a warmer were also done for comparison.

Researchers used each of these techniques to process blood samples that’d been stored frozen for between one and 14 years from deceased individuals who ranged in age from about 40 to nearly 70 at the time it was collected. After processing, researchers counted the number of total and viable cells obtained from each sample.

“The broad ranges of selected [blood] product and patient ages benefitted the study by adding variability into our sample group, allowing conclusions to be applicable across a range of products collected recently and years before,” the researchers wrote.

The results showed no difference in viable cell recovery between the two techniques.

“The presented studies demonstrate that all methods of product warming would permit high recovery of viable cells across cell types prior to patient administration,” the researchers wrote. “Depending on the resources of the infusion center, either method would be appropriate. Individual infusion centers are encouraged to validate their chosen process.”

The researchers also encouraged centers to use their findings to proactively create standardized protocols for dealing with transfusions in the context of CAD.

“We know that most CAD cases and agglutinated products are managed in real time, with little literature to draw upon quickly,” they wrote. “Centers are encouraged to use this information to guide proactive measures to establish an SOP [standard operating procedure] to address complications arising in real time surrounding CAD cases.”