Transfusion practice for patients with sickle cell disease

The haemoglobinopathy survey: The reality of transfusion practice in sickle cell disease and thalassaemia in England

OBJECTIVES

To establish, in an unselected population of London haemoglobinopathy patients, transfusion requirements, blood antigens/alloantibodies, transfusion modalities, burden of transfusion reactions and donor exposure.

BACKGROUND

Haemoglobinopathy patients are among the most highly transfused patient populations, and the overall population and number of patients on long-term transfusion programmes are increasing. To provide a safe and efficacious transfusion service for patients, it is important to understand current practice, morbidity associated with transfusion, efficacy of different transfusion modalities and geno-/phenotype requirements.

METHODS

Data on 4451 transfusion episodes in 760 patients from 12 London hospitals were collected retrospectively over a 6-month period in 2011.

RESULTS

Alloimmunisation prevalence was 17% for sickle cell disease (SCD) and 22% for thalassaemia, most commonly anti-Rh/Kell/Kp_a /C_w . Rh phenotypes differed between SCD (R_o r 59.8%/R₁ r 15.9%/R₂ r 15.6%) and thalassaemia (R₁ R₁ 29.6%/R₁ r 28.4%/R₁ R₂ 15.4%). Recording of pheno-/genotypes fell below recommendations. A 2-weekly manual exchange and 3-weekly automated exchange came closest to achieving presumptive targets. In adults with thalassaemia, the mean blood requirement was 36 units per year; for SCD, erythrocytapheresis was carried out every 7 weeks with 66 units; for manual exchange, it was 38 units every 4 weeks; and for simple transfusion, it was 30 units p.a. every 4 weeks.

CONCLUSION

Transfusion modality choice was influenced by the resources available-children mostly received simple transfusions, and adults received erythrocytapheresis; the relationships between frequency of exchanges/transfusion modality/target HbA% were not simple, possibly reflecting the difference in recipient erythropoiesis and consequent transfusion modality selection bias; adherence to existing and current guidelines regarding geno-/phenotyping was limited; and alloimmunisation had a low incidence and high prevalence in both disorders.

Pathologic angiogenesis in the bone marrow of humanized sickle cell mice is reversed by blood transfusion

Sickle cell disease (SCD) is a monogenic red blood cell (RBC) disorder with high morbidity and mortality. Here, we report, for the first time, the impact of SCD on the bone marrow (BM) vascular niche, which is critical for hematopoiesis. In SCD mice, we find a disorganized and structurally abnormal BM vascular network of increased numbers of highly tortuous arterioles occupying the majority of the BM cavity, as well as fragmented sinusoidal vessels filled with aggregates of erythroid and myeloid cells. By in vivo imaging, sickle and control RBCs have significantly slow intravascular flow speeds in sickle cell BM but not in control BM. In sickle cell BM, we find increased reactive oxygen species production in expanded erythroblast populations and elevated levels of HIF-1α. The SCD BM exudate exhibits increased levels of proangiogenic growth factors and soluble vascular cell adhesion molecule-1. Transplantation of SCD mouse BM cells into wild-type mice recapitulates the SCD vascular phenotype. Our data provide a model of SCD BM, in which slow RBC flow and vaso-occlusions further diminish local oxygen availability in the physiologic hypoxic BM cavity. These events trigger a milieu that is conducive to aberrant vessel growth. The distorted neovascular network is completely reversed by a 6-week blood transfusion regimen targeting hemoglobin S to <30%, highlighting the plasticity of the vascular niche. A better insight into the BM microenvironments in SCD might provide opportunities to optimize approaches toward efficient and long-term hematopoietic engraftment in the context of curative therapies.

Patients with sickle cell anemia on simple chronic transfusion protocol show sex differences for hemodynamic and hematologic responses to transfusion

BACKGROUND

Chronic transfusion therapy (CTT) is a mainstay for stroke prophylaxis in sickle cell anemia, but its effects on hemodynamics are poorly characterized. Transfusion improves oxygen-carrying capacity, reducing demands for high cardiac output, while decreasing hemoglobin (Hb)S%, reticulocyte count, and hemolysis. We hypothesized that transfusion would improve oxygen-carrying capacity, but that would be counteracted by a decrease in cardiac output due to increased hematocrit (Hct) and vascular resistance, leaving oxygen delivery unchanged.

STUDY DESIGN AND METHODS

To test this hypothesis, we examined patients on CTT immediately before transfusion and again 12 to 120 hours after transfusion, using echocardiography and near infrared spectroscopy.

RESULTS

Comparable increases in Hb and Hct and decreases in reticulocyte count and HbS with transfusion were observed in all patients, but males had a larger rebound of HbS%, reticulocyte count, and free Hb levels between transfusions. In males, transfusion decreased heart rate by 12%, stroke volume by 15%, and cardiac index by 24% while estimates for pulmonary and systemic vascular resistance increased, culminating in 6% decrease in oxygen delivery. In contrast, stroke volume and cardiac index and systemic and pulmonary vascular resistance did not change in women after transfusion, such that oxygen delivery improved 17%.

CONCLUSION

In our sample population, males exhibit a paradoxical reduction in oxygen delivery in response to transfusion because the increase in vascular resistance is larger than the increase in oxygen capacity. This may result from an inability to adequately suppress their HbS% between transfusion cycles.

Unusual causes of abdominal pain: sickle cell anemia

Sickle cell disease is characterized by chronic hemolytic anemia and vaso-occlusive painful crises. The vascular occlusion in sickle cell disease is a complex process and accounts for the majority of the clinical manifestation of the disease. Abdominal pain is an important component of vaso-occlusive painful crises. It often represents a substantial diagnostic challenge in this population of patients. These episodes are often attributed to micro-vessel occlusion and infarcts of mesentery and abdominal viscera. Abdominal pain due to sickle cell vaso-occlusive crisis is often indistinguishable from an acute intra-abdominal disease process such as acute cholecystitis, acute pancreatitis, hepatic infarction, ischemic colitis and acute appendicitis. In the majority of cases, however, no specific cause is identified and spontaneous resolution occurs. This chapter will focus on etiologies, pathophysiology and management of abdominal pain in patients with sickle cell disease.

Sickle cell disease: health promotion and maintenance and the role of primary care nurse practitioners

PURPOSE

To discuss the role of nurse practitioners (NPs) with regard to early identification of affected individuals, effective monitoring and screening, effective pain management and prophylaxis, and health education for patients with sickle cell disease (SCD).

DATA SOURCES

Electronic database searches were performed using Medline, Cinahl, and PsycINFO. Data were obtained from medical textbooks, research, and review articles.

CONCLUSIONS

SCD is a chronic inherited disease belonging to a group of conditions called hemoglobinopathies. Individuals with SCD often require close medical care from specialists. Nonetheless, NPs are in ideal positions to facilitate the health promotion and health maintenance necessary to decrease the high rate of morbidity and mortality associated with this disease.

IMPLICATIONS FOR PRACTICE

NPs must understand the importance of early identification of affected individuals, effective monitoring and screening, effective monitoring and screening, effective pain treatment, and prophylaxis. The unpredictable trajectory of SCD can lead to frustration, fear, helplessness, hopelessness, and emotional distress. Ineffective pain management is a major problem for people with SCD. NPs can overcome this problem by initiating effective and prompt pain management in a nonjudgmental manner.

Acute pancreatitis during sickle cell vaso-occlusive painful crisis

Sickle cell disease is characterized by chronic hemolytic anemia and vaso-occlusive painful crisis. The vascular occlusion in sickle cell disease is a complex process and accounts for the majority of the clinical manifestations of the disease. Abdominal pain is an important component of vaso-occlusive painful crisis and may mimic diseases such as acute appendicitis and cholecystitis. Acute pancreatitis is rarely included as a cause of abdominal pain in patients with sickle cell disease. When it occurs it may result form biliary obstruction, but in other instances it might be a consequence of microvessel occlusion causing ischemia. In this series we describe four cases of acute pancreatitis in patients with sickle cell disease apparently due to microvascular occlusion and ischemic injury to the pancreas. All patients responded to conservative management. Acute pancreatitis should be considered in the differential diagnosis of abdominal pain in patients with sickle cell disease.

Secondary iron overload

Transfusion therapy for inherited anemias and acquired refractory anemias both improves the quality of life and prolongs survival. A consequence of chronic transfusion therapy is secondary iron overload, which adversely affects the function of the heart, the liver and other organs. This session will review the use of iron chelating agents in the management of transfusion-induced secondary iron overload. In Section I Dr. John Porter describes techniques for the administration of deferoxamine that exploit the pharmacokinetic properties of the drug and minimize potential toxic side effects. The experience with chelation therapy in patients with thalassemia and sickle cell disease will be reviewed and guidelines will be suggested for chelation therapy of chronically transfused adults with refractory anemias. In Section II Dr. Nancy Olivieri examines the clinical consequences of transfusion-induced secondary iron overload and suggests criteria useful in determining the optimal timing of the initiation of chelation therapy. Finally, Dr. Olivieri discusses the clinical trials evaluating orally administered iron chelators.