Which factor is most likely responsible for a reaction when a B negative patient receives packed red cells?

In the context of a B negative patient receiving packed red cells, the most likely reaction to consider is indeed a volume overload reaction. This type of reaction can occur when a patient receives a transfusion and their body experiences difficulty managing the increased volume of blood being introduced, particularly in patients who may have underlying cardiac or renal issues.

Volume overload is a concern because it can lead to symptoms such as hypertension, pulmonary congestion, or heart failure due to the excess fluid. This is particularly significant in patients who have a history of cardiovascular problems or are particularly vulnerable due to their overall medical condition.

While febrile nonhemolytic reactions, acute hemolytic reactions, and anaphylactic reactions do significantly impact transfusion safety, they typically involve different mechanisms. For example, febrile nonhemolytic reactions are generally caused by recipient antibodies reacting to donor white blood cells or cytokines, and acute hemolytic reactions directly involve the destruction of red blood cells as a result of ABO incompatibility. Anaphylactic reactions, on the other hand, are due to severe allergic responses usually related to specific antibodies against components in the transfusion, such as IgA in patients with anti-IgA antibodies.

In contrast, volume overload reactions specifically relate to