Management of sickle cell disease: challenges and risks of transfusion

Abstract

Homozygous sickle cell (SS) disease is associated with rapid red cell destruction and a tendency to block flow in blood vessels. The bone marrow expansion needed to compensate for the rapid red cell destruction increases metabolic demands and folate requirements but also renders the bone marrow prone to suppression by renal impairment and infections especially those with human parvovirus B19. The abnormal red cells also tend to block blood vessels impairing flow in the bone marrow (dactylitis, bone pain crisis, hip necrosis), the spleen (acute splenic sequestration, chronic hypersplenism, loss of the normal filtering system rendering patients prone to overwhelming septicemia), the lungs (pulmonary embolism, acute chest syndrome), and the brain (ischemic stroke, hemorrhage). Transfusion plays a role in addressing all of these pathologies. During the acute lowering of hemoglobin due to acute splenic sequestration and aplastic crisis and the persistent lowering of hemoglobin due to chronic hypersplenism and chronic renal failure, top-up transfusions may help in maintaining oxygen delivery and symptomatic relief. Addressing vaso-occlusion is more complex but best documented in preventing recurrent stroke and primary stroke following detection of cerebral vessel stenosis by transcranial Doppler. Although top-up transfusions have minimal side effects, potentially serious complications arise from chronic transfusion, and there are many unanswered questions on the duration of such therapy and the natural history of the underlying complications. These issues are addressed with the knowledge currently available.