Hematologic emergencies. Management of transfusion reactions and crises in sickle cell disease.

Two hematologic emergencies are reviewed in this article: transfusion reactions and crises in patients who have sickle cell disease. Transfusion reactions may be due to incompatibility, IgA deficiency, allergy or, rarely, bacterial contamination of the blood product. A major hemolytic reaction due to incompatibility may progress to hypotension and shock. To prevent this type of reaction, blood products should be given only when necessary and attention should be given to eliminating clerical errors, which are responsible for many hemolytic reactions. In patients with sickle cell disease, a painful crisis due to vascular occlusion is the most common emergency. Rehydration is essential, and narcotics may be needed to relieve pain. Aplastic crisis is managed by transfusion of packed red blood cells and supportive care. Sickle cell crisis may affect major organ systems. The acute chest syndrome can be complicated by pneumonia; rapid respiratory failure may occur if multiple lobes are involved. Splenic or hepatic sequestration requires aggressive rehydration and transfusion. In patients who have had stroke or subarachnoid hemorrhage, a long-term exchange transfusion program is needed to keep hemoglobin S levels below 30%.