Blood Transfusions With CAD, AIHAs Require Special Care: Study

Communication among clinicians, lab workers key ahead of transfusion

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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Special considerations should be taken when preparing a blood transfusion for someone with cold agglutinin disease (CAD), a recent study indicates.

The study, “Evaluating patients with autoimmune hemolytic anemia in the transfusion service and immunohematology reference laboratory: pretransfusion testing challenges and best transfusion-management strategies,” was published in Hematology.

Blood transfusions are an important medical tool, but care is needed to ensure patient safety. A transfusion involves collecting blood cells from one person and inserting them into another person. There’s always a risk of a problematic immune response, but efforts can be made to minimize risk, such as blood type testing to ensure compatibility.

CAD is a type of autoimmune hemolytic anemia (AIHA), a group of disorders wherein the immune system mistakenly launches an attack against its own red blood cells, resulting in their destruction. This attack is driven by the production of self-reactive antibodies.

In CAD, these disease-driving antibodies are most active at low temperatures. In other forms of AIHA, self-reactive antibodies are active at warm temperatures, or across a range of temperatures.

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When a person is preparing to have a blood transfusion, testing is done to look for alloantibodies, which will react to the blood being administered. Alloantibodies are generally rare, but are somewhat more common in people who’ve carried a pregnancy.

In AIHA, the self-targeting antibodies that drive the disease can complicate alloantibody testing. Since antibodies are already targeting the patient’s own red blood cells, it can be hard to tell if there are additional alloantibodies that would react to other blood cells. This is particularly true with warm AIHA.

Testing for alloantibodies in this situation commonly involves an adsorption strategy, the idea being to use the patient’s red blood cells to “filter out” disease-driving antibodies and then test the remaining sample for alloantibodies.

This detailed testing can be technically challenging and time-consuming, and in many situations, the patient may require a blood transfusion before lab tests can be completed. While bed rest and oxygen support can help keep patients stable while they’re waiting for a transfusion, investigators emphasized that transfusions shouldn’t be withheld in an emergency even when testing is incomplete.

“When transfusion is medically necessary, the patient’s physician should be assured that [blood transfusion is] unlikely to cause an acute hemolytic transfusion reaction,” the researchers wrote, noting that studies have reported a complication rate of under 2% for AIHA patients receiving a blood transfusion.

The researchers said all clinicians and lab personnel involved in a patient’s care should communicate with each other, given the complexities of administering a blood transfusion to someone with CAD or another form of AIHA.

“Early and frequent communication is essential for the exchange of information to effectively guide the best approach for immediate and future transfusions. This extra effort provides assurance for the clinical and laboratory teams that units released for transfusion … have a high likelihood of being safe and efficacious for the patient,” they wrote.