Erythrocytapheresis for chronically transfused children with sickle cell disease: an effective method for maintaining a low hemoglobin S level and reducing iron overload

Fatty acid nitroalkenes - Multi-target agents for the treatment of sickle cell disease

Sickle cell disease (SCD) is a hereditary hematological disease with high morbidity and mortality rates worldwide. Despite being monogenic, SCD patients display a plethora of disease-associated complications including anemia, oxidative stress, sterile inflammation, vaso-occlusive crisis-related pain, and vasculopathy, all of which contribute to multiorgan dysfunction and failure. Over the past decade, numerous small molecule drugs, biologics, and gene-based interventions have been evaluated; however, only four disease-modifying drug therapies are presently FDA approved. Barriers regarding effectiveness, accessibility, affordability, tolerance, and compliance of the current polypharmacy-based disease-management approaches are challenging. As such, there is an unmet pharmacological need for safer, more efficacious, and logistically accessible treatment options for SCD patients. Herein, we evaluate the potential of small molecule nitroalkenes such as nitro-fatty acid (NO2-FA) as a therapy for SCD. These agents are electrophilic and exert anti-inflammatory and tissue repair effects through an ability to transiently post-translationally bind to and modify transcription factors, pro-inflammatory enzymes and cell signaling mediators. Preclinical and clinical studies affirm safety of the drug class and a murine model of SCD reveals protection against inflammation, fibrosis, and vascular dysfunction. Despite protective cardiac, renal, pulmonary, and central nervous system effects of nitroalkenes, they have not previously been considered as therapy for SCD. We highlight the pathways targeted by this drug class, which can potentially prevent the end-organ damage associated with SCD and contrast their prospective therapeutic benefits for SCD as opposed to current polypharmacy approaches.

Erythrocytapheresis in Children and Young Adults with Hemoglobinopathies and Iron Overload in Need of Iron Chelation Therapy

Limited data regarding erythrocytapheresis in children, adolescents, and young adults have been published. The aim of this study was to evaluate erythrocytapheresis, either as a standalone therapy or in combination with iron chelation therapy, in children and young adults with hemoglobinopathies in whom current iron chelation therapy is not sufficient in decreasing the iron overload during management. We retrospectively analysed erythrocytapheresis in 19 patients with hemoglobinopathies in need of iron chelation therapy diagnosed with sickle cell disease (SCD) or β-thalassemia major. Patients were divided into (1) a case cohort who received erythrocytapheresis alone or in combination with iron chelation therapy and (2) a control cohort who received oral iron chelation therapy alone. Serum ferritin and haemoglobin levels were compared at five different time points over a one-year period. In the erythrocytapheresis cohort, there was a significant decrease in serum ferritin (p < 0.001). In the iron chelation therapy alone cohort, there was no significant decrease in serum ferritin over time (p = 0.156). Comparing the evolution of median serum ferritin between therapy with erythrocytapheresis and iron chelation therapy showed a statistically significant difference (p = 0.008). Patients with β-thalassemia major receiving erythrocytapheresis showed a greater reduction in serum ferritin compared to patients without (p = 0.036). A difference could not be shown between the erythrocytapheresis and iron chelation single therapies (p = 0.100). This study showed an overall significant reduction in serum ferritin in patients with hemoglobinopathies treated with erythrocytapheresis in addition to iron chelation. A clinical, although not statistical, trend of higher haemoglobin levels was maintained. Erythrocytapheresis in paediatric patients with β-thalassemia major was as effective in decreasing ferritin levels as in previously reported studies with SCD. Erythrocytapheresis is a promising therapy for treating and preventing transfusion-related iron overload.

Red Blood Cell Exchange in a Patient With Extramedullary Hematopoiesis and Cor Pulmonale Secondary to Beta Thalassemia

Rationale: Beta thalassemia is a congenital defect in the production of the beta globin chain. Patients with beta thalassemia major will have higher levels of hemoglobin F (HbF), which is suboptimal in releasing oxygen to tissue. Herein, we describe the use of red blood cell (RBC) exchange transfusion, a therapy typically used in sickle cell patients, in the management of a patient with beta thalassemia with extensive extramedullary hematopoiesis and elevated levels of HbF.

Patient concerns: A 34-year-old male of mixed African American and Southeast Asian descent with a known history of beta thalassemia major presented with progressive dyspnea on exertion with marked fatigue.

Diagnoses: The patient was transferred to our facility for management of acute hypoxemic, hypercapnic respiratory failure associated with cor pulmonale.

Interventions: The patient was initially managed with non-invasive positive pressure support ventilation (NIPPV) and intravenous diuresis. Hydroxyurea and epoprostenol nebulization were added to his treatment regimen; however, he progressively became more unstable, necessitating inotropic support. With extramedullary hematopoiesis leading to mass-like effect on critical organs and very high HbF (96%) thought to contribute to his presentation, red blood cell exchange transfusion was initiated once the blood pressure stabilized.

Outcomes: The patient clinically improved, and was discharged home within a week on supplemental oxygen by nasal cannula and long-term red blood cell exchange.

Lessons: We postulated that significantly elevated HbF contributed to the patient’s chronic hypoxia and subsequent respiratory complications. Based on the patient's clinical improvement following the intervention, we believe that RBC exchange transfusion could be considered in the management of beta thalassemia patients with significantly elevated levels of HbF.

Automated exchange compared to manual and simple blood transfusion attenuates rise in ferritin level after 1 year of regular blood transfusion therapy in chronically transfused children with sickle cell disease

BACKGROUND

Optimal strategies for regular blood transfusion therapy are not well defined in sickle cell disease (SCD). This analysis tested the hypothesis that in the first of year of regular transfusions, when chelation therapy use is minimal, automated exchange transfusion would be the superior method for attenuating the rise in ferritin levels compared to simple and manual exchange transfusions.

STUDY DESIGN AND METHODS

The Silent Cerebral Infarct Multi-Center Clinical Trial randomly allocated children with SCD and silent cerebral infarcts to receive standard care or regular transfusions with a target pre-transfusion HbS concentration ≤ 30% and minimum hemoglobin level > 9.0 g/dL. Participants with at least nine transfusions and sufficient ferritin testing in the first year of the trial were included in a planned secondary analysis. Ferritin levels by the end of the first study year were compared between participants receiving automatic exchange transfusion, manual exchange transfusion, and simple transfusion.

RESULTS

A total of 83 participants were analyzed. During the first year of the study, 75.9% of the participants had >80% of transfusions via one transfusion method. At baseline no significant differences in ferritin levels were observed in the three transfusion groups (p = 0.1). After 1 year of transfusions the median (interquartile range) ferritin levels in the simple transfusion (n = 40), manual exchange transfusion (n = 34) and automatic exchange transfusion (n = 9) groups were 1800 ng/mL (1426-2204 ng/mL), 1530 ng/mL (1205-1805 ng/mL), and 355 ng/mL (179-579 ng/mL), respectively (p < 0.001).

CONCLUSION

Automated exchange transfusion, when compared to other transfusion methods, is the optimal transfusion strategy for attenuating increase in ferritin levels in children with SCD.

Blood utilization and characteristics of patients treated with chronic transfusion therapy in a large cohort of Brazilian patients with sickle cell disease

BACKGROUND

Red blood cell (RBC) transfusions are used in sickle cell disease (SCD) to treat acute complications or as chronic transfusion therapy (CTT) to prevent severe manifestations. The objectives of this study were to describe blood utilization and adverse events (AEs) associated with RBCs in the Brazilian SCD population and compare characteristics of patients treated or not with CTT.

STUDY DESIGN AND METHODS

A SCD cohort was established at six Brazilian centers. Medical and blood bank records were abstracted for clinical and transfusion history. Two controls not treated with CTT matched on center, SCD genotype, sex, and age were selected for each CTT case within the cohort to compare characteristics between the two groups.

RESULTS

Most of the 2794-member cohort had received a transfusion (75.0% of children and 89.2% of adults) with 29.2% of patients receiving transfusion in the prior year. There were 170 (10.6%) children and 115 (9.2%) adults treated with CTT. Children not treated with CTT were more likely to have pain and acute chest hospitalizations in the prior year (25.3% vs. 11.9%, p = 0.0003; and 22.0% vs. 10.7%, p = 0.002, respectively). Both iron overload and alloimmunization were more common in CTT cases compared to controls (65.6% vs. 17.0% and 36.2% vs. 15.9%, respectively). A higher proportion of adults treated with CTT demonstrated oxygen saturation of greater than 95% compared to controls not treated (51.1% vs. 39.2%), while there was no difference in oxygenation between children treated or not. Of 4501 transfusion episodes, 28 (0.62%) AEs were reported. There was no difference in AEs associated with transfusions for acute indications versus CTT.

CONCLUSION

Red blood cell transfusion was common in Brazilian SCD patients, with utilization driven by CTT. Transfusion reactions were not common; however, alloimmunization and iron overload were frequent among those on CTT, highlighting the need for novel clinical strategies to mitigate these risks.

Transfusion service knowledge and immunohaematological practices related to sickle cell disease and thalassemia

Objectives

To assess current knowledge of National Heart, Lung and Blood Institutes (NHLBI) and Thalassemia International Federation (TIF) recommendations, blood banking practices and perceived challenges among transfusion services in the management of patients with haemoglobinopathies.

Background

Previous reports have demonstrated variations in transfusion practices for sickle cell disease (SCD) and thalassemia patients. Recently, NHLBI/TIF have provided transfusion recommendations for patients with haemoglobinopathies.

Methods

A cross‐sectional survey was conducted of transfusion services from the state of Georgia previously identified as having SCD/thalassemia populations. The survey assessed transfusion service practices in pre‐transfusion testing and blood product selection; awareness/implementation of NHLBI/TIF transfusion‐based recommendations and perceived challenges in transfusing haemoglobinopathy patients.

Results

Responses were received from 35 of 49 (71%) institutions. Only institutions indicating transfusing SCD or thalassemia patients (32) were included in analysis. Seventy‐one percent of non‐sickle cell treatment centres (SCTCs) and 20% of non‐thalassemia treatment centres follow NHLBI and TIF recommendations to perform a red blood cell phenotype beyond ABO/Rh(D) and provide Rh and Kell prophylactically matched units for SCD and thalassemia patients, respectively. Forty percent of institutions (33% of non‐SCTCs) employ RBC genotyping to evaluate the red cell phenotype for SCD patients. Over 77% of institutions do not utilise a reliable method to identify SCD patients prior to transfusion, such as a required question/answer field on type/screen or crossmatch orders.

Conclusion

Many healthcare systems' transfusion practices for haemoglobinopathy patients are discordant with NHLBI/TIF recommendations. Efforts are needed to increase awareness and implementation of current recommendations among all transfusion services seeing these patients.

Comparative efficacy in red blood cell exchange transfusions with different apheresis machines in patients with sickle cell disease

The purpose of this study is to compare the efficacy and side effects of two red blood cell exchange (RBCX) transfusion systems in sickle cell disease (SCD). The data is collected retrospectively from the January 2010 to March 2015. 447 RBCX transfusions were performed to 165 patients. Side effects, clinical and technical efficacy were compared in between procedures with Cobe Spectra (CS) and Spectra Optia (SO) systems. Furthermore a subgroup analyses was performed for 40 patients who had RBCX transfusions with both system at least two times. Vasoocclusive crises, preoperative period and foot ulcers (49.6, 13, and 15.2% respectively) were the common indications of RBCX transfusion. While the levels of post-RBCX HbS and the actual fraction of cells remaining (FCRa) were found significantly higher in the SO compared to CS system (p = 0.018 and p = 0.016 respectively), the rate of targeted hemoglobin S (HbS) levels (< 30%) were same in both. The length of procedure and replacement volume were significantly lower in SO compared to CS system (p = 0.025 and 0.044 respectively). Subgroup analyses of 40 patients did not reveal any statistically significant differences regarding post-procedure HbS levels, FCRa levels, replacement volume and procedure duration. The inter-rater correlation coefficient for FCRa was calculated to be 0.82. Serious adverse reactions were not observed from either system. Both systems are efficiently achieved the targeted post-procedure HbS level. The recently introduced SO apheresis system is as effective and safe as the CS system, which has been used for all indications of SCD for years.

Automated RBC exchange compared to manual exchange transfusion for children with sickle cell disease is cost-effective and reduces iron overload

BACKGROUND

Chronic transfusion in sickle cell disease (SCD) remains the gold standard therapy for stroke prevention and for patients with severe disease despite adequate hydroxyurea treatment. The aim of our study was to assess the safety and efficacy of automated red blood cell exchange (aRBX) in patients with SCD previously treated with manual exchange transfusion (MET). Costs related to transfusion and chelation overtime were evaluated.

STUDY DESIGN AND METHODS

Beginning in January 2012, children with SCD who weighed 30 kg or more on MET could switch to aRBX. Clinical, biological, and procedures' data, including costs, were recorded for the last 6 months on MET and compared to those after the first and the second year on aRBX.

RESULTS

Ten patients switched from MET to aRBX at a median age of 11.8 years. After the switch, median hemoglobin S (HbS) increased significantly (33.5% on MET compared to 45% on aRBX; p < 0.001) but remained in the target values for all patients. Median ferritin decreased significantly (663.3 µg/L on MET compared to 126.8 µg/L on aRBX; p < 0.001) and intervals between procedures were significantly longer. The requirements of red blood cells (RBCs)/kg/year were not different on MET (0.88 unit/kg/year) than during the second year on aRBX (1.07 unit/kg/year; p = NS). MET costs were similar compared to aRBX since chelation was stopped in previously treated patients.

CONCLUSION

Erythrocytapheresis reduces iron overload and allows a longer interval between procedures without a higher RBC requirement from the second year on aRBX. The cost did not increase as estimated in our Belgian Health Care System.

Spectra Optia® for Automated Red Blood Cell Exchange in Patients with Sickle Cell Disease: A NICE Medical Technology Guidance

The Spectra Optia® automated apheresis system, indicated for red blood cell exchange in people with sickle cell disease, underwent evaluation by the National Institute for Health and Care Excellence, which uses its Medical Technologies Advisory Committee to make recommendations. The company (Terumo Medical Corporation) produced a submission making a case for adoption of its technology, which was critiqued by the Newcastle and York external assessment centre. Thirty retrospective observational studies were identified in their clinical submission. The external assessment centre considered these were of low methodological and reporting quality. Most were single-armed studies, with only six studies providing comparative data. The available data showed that, compared with manual red blood cell exchange, Spectra Optia reduces the frequency of exchange procedures as well as their duration, but increases the requirement for donor blood. However, other clinical and patient benefits were equivocal because of an absence of robust clinical evidence. The company provided a de novo model to support the economic proposition of the technology, and reported that in most scenarios Spectra Optia was cost saving, primarily through reduced requirement of chelation therapy to manage iron overload. The external assessment centre considered that although the cost-saving potential of Spectra Optia was plausible, the model and its clinical inputs were not sufficiently robust to demonstrate this. However, taking the evidence together with expert and patient advice, the Medical Technologies Advisory Committee considered Spectra Optia was likely to save costs, provide important patient benefits, and reduce inequality, and gave the technology a positive recommendation in Medical Technology Guidance 28.

Sickle Cell Disease: A Brief Update

Sickle cell disease (SCD) is an inherited monogenic disease characterized by misshapen red blood cells that causes vaso-occlusive disease, vasculopathy, and systemic inflammation. Approximately 300,000 infants are born per year with SCD globally. Acute, chronic, and acute-on-chronic complications contribute to end-organ damage and adversely affect quantity and quality of life. Hematopoietic stem cell transplantation is the only cure available today, but is not feasible for the vast majority of people suffering from SCD. Fortunately, new therapies are in late clinical trials and more are in the pipeline, offering hope for this unfortunate disease, which has increasing global burden.

Effectiveness of red blood cell exchange, partial manual exchange, and simple transfusion concurrently with iron chelation therapy in reducing iron overload in chronically transfused sickle cell anemia patients

BACKGROUND

Chronic transfusion therapy (CTT) is indicated for stroke prevention in children with sickle cell anemia (SCA) and is complicated by iron overload and alloimmunization. CTT is performed by simple transfusion (ST), partial manual exchange (PME), or erythrocytapheresis (RCE). Although small case series have demonstrated RCE in combination with iron chelation therapy stabilizes and/or decreases ferritin, there are no reports comparing the effect of ST, PME, and RCE on liver iron concentration (LIC). CTT modality effect on serum ferritin and LIC were compared in SCA patients on iron chelation, with hemoglobin (Hb)S goal of 30%.

STUDY DESIGN AND METHODS

Medical records of SCA patients on CTT and deferasirox (≥25 mg/kg/day) were retrospectively reviewed. Mean HbS%, change in ferritin and LIC, and alloimmunization rate were determined for each CTT group.

RESULTS

Twenty-eight patients were included; six crossed over (one from ST to PME, one from ST to PME then to RCE, three from ST to RCE, and one from PME to RCE) to include 36 transfusion modality intervals. Median pretransfusion HbS% levels were 32.7% (ST), 36.2% (PME), and 34.7% (RCE; p = 0.732). Median ferritin changes were +15 (-17 to +45), +38 (+24 to +105), and -91 (-141 to -48) ng/mL/month (p = 0.003), and median LIC changes (available in 22 patient transfusion modality intervals) were +1.3 (-1.6 to +4.3), +2.3 (-6.5 to +8.9), and -5.7 (-10.7 to -0.5) mg/g/year (p = 0.024) in ST, PME, and RCE, respectively. There was no significant difference in alloimmunization rate between ST/PME and RCE groups.

CONCLUSION

We recommend RCE plus chelation as an effective method for reducing iron overload, while maintaining HbS at 30% to 35%.

Transfusional iron overload and iron chelation therapy in thalassemia major and sickle cell disease

Iron overload is an inevitable consequence of blood transfusions and is often accompanied by increased iron absorption from the gut. Chelation therapy is necessary to prevent the consequences of hemosiderosis. Three chelators, deferoxamine, deferiprone, and deferasirox, are presently available and a fourth is undergoing clinical trials. The efficacy of all 3 available chelators has been demonstrated. Also, many studies have shown the efficacy of the combination of deferoxamine plus deferiprone as an intensive treatment of severe iron overload. Alternating chelators can reduce adverse effects and improve compliance. Adherence to therapy is crucial for good results.

Red cell exchange: special focus on sickle cell disease

The primary function of red blood cells (RBCs) is to deliver oxygen from the lungs to tissues. Tissue hypoxia occurs when the oxygen-carrying capacity of RBCs is compromised due primarily to 3 causes: (1) a reduction in circulating RBC mass, (2) an increase in circulating RBC mass, or (3) abnormal hemoglobin (Hb) that either does not sufficiently release oxygen to tissues (high-oxygen-affinity hemoglobin) or occludes the microvasculature due to deformed RBCs (sickled RBCs). To improve oxygenation in patients with reduced or increased RBC mass, RBC administration (simple transfusion) or RBC removal (RBC depletion) is performed, respectively. However, for patients with abnormal Hb, RBCs containing abnormal Hb are removed and replaced by healthy volunteer donor RBCs by red cell exchange (RCE). RCE can be performed by manual exchange or by automated exchange using a blood cell separator (erythrocytapheresis). In this review, indications for RCE in sickle cell disease using the evidence-based American Society for Apheresis categories(1) are presented and the rationale for RCE in each disorder are discussed. Simple transfusion versus RCE and manual RCE versus automated RCE are compared. Finally, this review briefly presents some of the challenges of performing erythrocytapheresis in small children and discusses various choices for central venous access during RCE.(2.)

Cardiac iron overload in sickle-cell disease

Chronically transfused sickle cell disease (SCD) patients have lower risk of myocardial iron overload (MIO) than comparably transfused thalassemia major (TM) patients. However, cardioprotection is incomplete. We present the clinical characteristics of six patients who have prospectively developed MIO, to identify potential risk factors for cardiac iron accumulation. From 2002 to 2011, cardiac, hepatic, and pancreatic iron overload were assessed by R2 and R2 * magnetic resonance imaging techniques in 201 chronic transfused SCD patients as part of their clinical care. At the time, they developed MIO, five of six patients had been on chronic transfusion for more than 11 years; only one was on exchange transfusion. The time to MIO was correlated with reticulocyte and hemoglobin S percentages. All patients had qualitatively poor chelation compliance (<50%). All patients had serum ferritin levels >4600 ng/ml and liver iron concentration >22 mg/g. Pancreatic R2 * was >100 Hz in every patient studied (5/6). Cardiac iron rose proportionally to pancreas R2 *, with all patients having pancreas R2 *>100 Hz when cardiac iron was present. MIO had a threshold relationship with liver iron that was higher than observed in TM patients. In conclusion, MIO occurs in a small percentage of chronically transfused SCD patients and is only associated with exceptionally poor control of total body iron stores. Duration of chronic transfusion is clearly important but other factors, such as levels of effective erythropoiesis, appear to contribute to cardiac risk. Pancreas R2 * can serve as a valuable screening tool for cardiac iron in SCD patients.

Partial manual exchange reduces iron accumulation during chronic red cell transfusions for sickle cell disease

Iron overload is an inevitable consequence of chronic red cell transfusions without erythrocytapheresis or chelation therapy. The effectiveness of partial manual exchange, a technique used to slow iron loading, has not been evaluated. We evaluated all children with sickle cell disease (SCD) receiving chronic transfusion to identify chelation-naive subjects who had quantitative liver iron concentration (LIC) studies. Seventeen chelation-naive children with SCD received a median of 29 transfusions before first LIC determination. Serum ferritin concentrations were assessed before each transfusion. The mean volume of blood phlebotomized before each transfusion was 5.1±1.8 mL/kg, which cumulatively resulted in a calculated median of 35.0 mg/kg iron removal. Using linear regression, pretransfusion phlebotomy resulted in a statistically significant reduction in ferritin (-8.8 ng/mL of ferritin for each mg/kg of iron phlebotomized, P=0.02). A reduction in LIC from pretransfusion phlebotomy could not be established (P=0.4). Partial manual exchanges appear to be an effective strategy for slowing the pace of iron loading in the setting of chronic transfusion for SCD.

Transfusion medicine problems and solutions for the pediatric hematologist/oncologist

Blood component transfusion is an integral part of the care of children with oncologic and hematologic conditions. The complexity of transfusion medicine may however lead to challenges for pediatric hematologists/oncologists. In this review, three commonly encountered areas of transfusion medicine are explored. The approach to the investigation and management of suspected platelet refractoriness is reviewed. The unique transfusion related challenges encountered by children undergoing stem cell transplantation are also discussed. Finally, issues arising out of the care of children with hemoglobinopathies are explored, with an emphasis on the incidence of allo- and autoimmunization.

Red cell exchange does not appear to increase the rate of allo- and auto-immunization in chronically transfused children with sickle cell disease

BACKGROUND

Allo- and auto-antibody development is a well recognized complication of chronic red cell transfusion (RCT) in sickle cell disease (SCD). Limited matching of Rh (C, c, D, E, e) and K red cell antigens reduces the incidence of immunization.

PROCEDURE

We reviewed our experience with red cell allo- and auto-immunization in pediatric SCD patients receiving chronic and/or exchange transfusions, to evaluate the rate of immunization after limited red cell antigen matching and specifically during red cell exchange (RCE) transfusion. A retrospective chart review of the patients with SCD followed at our center between 2002 and 2006, who were started on chronic RCT before or during that time period, was conducted.

RESULTS

Of the 93 patients who met study criteria, 23 (24%) developed antibodies during chronic red cell transfusions. Thirty-four antibodies (15 auto-antibodies, 18 allo-antibodies) developed after the institution of limited red cell antigen matching. The rate of allo- and auto-immunization per unit of red cell exposure after limited phenotyping was 1.5%, comparable to other published data. Fifteen patients underwent RCE, utilizing a total of 2,289 packed red cell units. None developed antibodies during RCE.

CONCLUSION

We conclude that limited red cell antigen matching is an effective strategy for reducing the incidence of allo- and auto-immunization in chronically transfused children with SCD. RCE does not appear to increase the risk of allo- or auto-immunization, despite exposure to more red cell units.

Discontinuing prophylactic transfusions increases the risk of silent brain infarction in children with sickle cell disease: data from STOP II

In the STOP II trial, discontinuation of prophylactic transfusions in high risk children with sickle cell disease (SCD) resulted in a high rate of reversion to abnormal blood-flow velocities on transcranial Doppler (TCD) ultrasonography and strokes. We analyzed data from STOP II to determine the effect of discontinuing transfusions on the development or progression of silent brain infarcts on magnetic resonance imaging (MRI). At study entry, 21 of 79 (27%) patients had evidence of silent infarcts. There were no statistically significant differences in baseline characteristics between patients with normal brain MRI or silent infarcts at study entry. At study end, 3 of 37 (8.1%) patients in the continued-transfusion group developed new brain MRI lesions compared with 11 of 40 (27.5%) in the transfusion-halted group (P = .03). The total number of lesions remained essentially unchanged decreasing from 25 to 24 in the continued-transfusion group while increasing from 27 to 45 in transfusion-halted patients. Thus, discontinuation of transfusions in children with SCD and abnormal TCD who revert to low-risk increases the risk of silent brain infarction. Together with data from STOP, these findings demonstrate that transfusions prevent the development of silent infarcts in patients with SCD and abnormal TCD but normal MRA.

Iron in sickle-cell disease: what have we learned over the years?

Over the last four decades, monumental advances have been made in the understanding, assessment, and management of transfusion-dependent patients, which have translated into significant improvements in patient morbidity and mortality. Important lessons have been learned from extensive clinical experience of iron management in the thalassemias, but greater knowledge of key differences in the sickle-cell disease (SCD) population may impact on our approach to patient assessment and management. The unique pathophysiology of SCD is reflected in a distinct pattern of iron loading with minimal organ-specific injury. An appreciation and understanding of these differences should allow us to develop tailored management approaches that optimize patient outcomes.

Iron overload cardiomyopathy: better understanding of an increasing disorder

The prevalence of iron overload cardiomyopathy (IOC) is increasing. The spectrum of symptoms of IOC is varied. Early in the disease process, patients may be asymptomatic, whereas severely overloaded patients can have terminal heart failure complaints that are refractory to treatment. It has been shown that early recognition and intervention may alter outcomes. Biochemical markers and tissue biopsy, which have traditionally been used to diagnose and guide therapy, are not sensitive enough to detect early cardiac iron deposition. Newer diagnostic modalities such as magnetic resonance imaging are noninvasive and can assess quantitative cardiac iron load. Phlebotomy and chelating drugs are suboptimal means of treating IOC; hence, the roles of gene therapy, hepcidin, and calcium channel blockers are being actively investigated. There is a need for the development of clinical guidelines in order to improve the management of this emerging complex disease.

Current issues in blood transfusion for sickle cell disease

PURPOSE OF REVIEW

Although blood transfusion has been felt to be a beneficial therapy for sickle cell disease (SCD) since the 1950s, associated complications initially limited this therapy for these patients. With advances now reducing the side effects of transfusion and several landmark studies over the last decade clearly defining the efficacy for decreasing sickle cell morbidity, the indications for transfusion have increased. This review will discuss the indications, methods and goals of transfusion as well as complications and recent changes in transfusion therapy for SCD.

RECENT FINDINGS

Recently studies have established the efficacy of transfusion for prevention of stroke, treatment of acute chest syndrome and perioperative transfusion management of SCD. Pulmonary hypertension is increasingly recognized as a significant source of morbidity and mortality and is an evolving indication for transfusion therapy. Phenotypically matching transfused blood has been shown to decrease alloimmunization, and genotyping for antigen matching may help match donors to patients in the future.

SUMMARY

The increased use of transfusions may ultimately be balanced by hydroxyurea and other newer therapies developed as the complex pathophysiology of SCD is better understood; however, red cell transfusion is currently the most studied and accepted therapy for most acute and many chronic complications of SCD. Physicians caring for patients with sickle cell disease should be aware of the unique complications and transfusion requirements in this population.

Clinical effects of different types of red cell concentrates in patients with thalassemia and sickle cell disease

The treatment of thalassemia is still essentially based on continuous transfusion supporting using red cell concentrates (RCC) prepared in different ways. For patients with sickle-cell disorders, either urgent or chronic red blood cell transfusion therapy, is widely used in the management of sickle cell disease (SCD) because it reduces HbS level and generally prevents recurrent vaso-occlusive disease (VOD). Recently, the introduction of pre-storage filtration to remove leukocytes and the use of techniques for multicomponent donation have increased the types of blood components available for transfusion purposes. The clinical effects of different types of blood components in thalassaemic and sickle-cell patients have not been extensively studied so far. We evaluated the impact of the various different blood components currently available on transfusion needs, transfusion intervals and adverse reactions in order to determine which is the most advantageous for transfusion-dependent thalassaemic and sickle-cell patients followed in our centre. We believe that the optimal characteristics of the RCC are aged less than 10 days from time of collection; Hb content greater than 56 g per unit; Hct: 55-60%; volume (including additive) 300 mL+/-20%; leucodepleted to less than 200,000 leukocytes per unit; low cytokine content (achievable by pre-storage filtration carried out between two and 24 hours after the collection); lack of microaggregates (achievable by pre-storage filtration or filtration in the laboratory) and protein content less than 0.5 g per unit for patients allergic to plasma proteins (achievable with manual or automated washing). It is still recommended that the blood transfused should be as fresh as possible, compatible with the centre's product availability and the centre's organisation should be continuously adapted to this aim. We always transfuse blood within 10 days of its collection, respecting Rh and Kell system phenotypes. Pre-storage filtration is strongly recommended, both in order to prevent adverse reactions through the marked leucodepletion (less than 200,000 leukocytes per unit) and for a better standardisation of the final product, including the certainty that the product does not contain clots, an assurance that bed-side filtration cannot give. The RCC should be produced using a method causing as little as possible stress to the red cell membrane. The use of RCC with a high content of Hb (less than 56 g per unit) is strongly recommended, because our study clearly shows that this reduces the number of exposures to donors and the number of accesses to hospital, thus improving the patient's quality of life.

Assessment of corrected QT interval in sickle-cell disease patients who undergo erythroapheresis

Extension of the QT interval is characterized by syncope and cardiac arrest and often occurs in association with medical therapies and procedures. Whether erythroapheresis (EPH) could influence the QT interval duration in patients with sickle cell disease (SCD) is not known. We aimed to investigate the effects of EPH on the heart rate-corrected QT (QTc) interval. The study included 25 patients with SCD who underwent 34 EPH procedures. Two independent observers measured QTc interval duration from electrocardiograms performed continuously for 3 min at three different points during the EPH procedures (prior to EPH, after completion of 50% EPH and 15 min after EPH). Multiple regression analysis was used to determine if the ionized plasma calcium, the level of plasma magnesium, citrate infusion rate and painful crisis significantly contributed to the QTc interval. There was a non-significant trend (P = 0.184) towards increased QTc in sickle cell patients during EPH compared with pre-EPH values. QTc prolongation (>440 ms) occurred in 72% of the procedures. Fifty percent QTc values returned to baseline after the procedure. The independent variables were not significantly associated with QTc interval. Exchange procedures can induce QTc prolongation in patients with SCD.

Pinch-off syndrome in patients with sickle cell disease receiving erythrocytapheresis

A 6-year-old female with homozygous sickle cell disease had a central venous access device (CVAD) placed to facilitate chronic erythrocytapheresis. Erythrocytapheresis was ineffective due to the rare pinch-off syndrome causing communication between the dual lumen tubing. Awareness of and monitoring for the pinch-off syndrome is indicated in people with sickle cell disease and a CVAD for chronic erythrocytapheresis.

Evidence based therapeutic apheresis in autoimmune and other hemolytic anemias

PURPOSE OF REVIEW

This article reviews recent publications that bear on the evidential basis for therapeutic apheresis in diseases in which hemolytic anemia is a prominent feature.

RECENT FINDINGS

Therapeutic plasma exchange continues to be reported sporadically in severe autoimmune hemolytic anemia, with inconsistent results. Autoimmune deficiency of ADAMTS13 has provided a compelling rationale for therapeutic plasma exchange in some patients with thrombotic thrombocytopenic purpura; conversely such deficiency is consistently absent in certain clinically similar syndromes for which therapeutic plasma exchange is not or may not be beneficial. Refinements in assays for ADAMTS13 should further clarify its role in idiopathic thrombotic thrombocytopenic purpura. Oral iron chelators have shown promise in recent trials in chronically transfused patients with sickle cell disease and may provide an alternative to red cell exchange to prevent iron overload.

SUMMARY

The proper role of therapeutic plasma exchange in the treatment of autoimmune hemolytic anemia remains uncertain. Therapeutic plasma exchange continues to be indicated for idiopathic thrombotic thrombocytopenic purpura regardless of ADAMTS13 levels, but more accessible and physiological ADAMTS13 assays may raise questions about the rationale for and value of plasma exchange in ADAMTS13 nondeficient patients. Oral iron chelation may obviate the need for red cell exchange as a means to prevent iron overload in chronically transfused patients with sickle cell disease.

Plasma exchange in critically ill patients with sickle cell disease

Red cell exchange transfusion is the recommended therapy for patients with sickle cell disease who have complicated vaso-occlusive episodes. However, the role of the therapeutic plasma exchange in the management of the potentially life-threatening complications in patients with sickle cell disease is not well known. To determine whether plasma exchange had a cumulative effect on the red cell exchange in patients with sickle cell disease who developed multi-organ failure during the post red cell exchange period, we performed plasma exchange in the nine episodes of multi-organ failure of 7 patients with sickle cell anemia. The median age of those patients was 21 years (range, 9-50 years). The criterion of the multi-organ failure was defined as organ failure of two or more organs i.e. lung, liver, or renal, established according to Acute Physiological and Chronic Health Evaluation-II (APACHE-II) criteria. The average total plasma exchange volume was 1.0 times the patient's plasma volume. The patients had a good outcome, with a survival rate at 86% after one year of follow-up. Plasma exchange may have cumulative benefits in the treatment of severe illness in patients with sickle cell disease who underwent automatic red cell exchange therapy.

Optimal management strategies for chronic iron overload

Iron overload is characterised by excessive iron deposition and consequent injury and dysfunction of target organs, especially the heart, liver, anterior pituitary, pancreas and joints. Iron overload disorders are common worldwide and occur in most major race/ethnicity groups. Physiological mechanisms to excrete iron are very limited. Thus, all patients with iron overload need safe and effective treatment that is compatible with their co-existing medical conditions. Treatments for iron overload include phlebotomy and erythrocytapheresis that remove iron predominantly as haemoglobin, and chelation therapy with drugs that bind excess iron selectively and increase its excretion. The most important potential benefits of therapy are preventing deaths due to cardiac siderosis and hepatic cirrhosis. Preventing iron-related injury to endocrine organs is critical in children. Successful treatment or prevention of iron overload increases quality of life and survival in many patients. This article characterises the major categories of iron overload disorders, tabulates methods to evaluate and treat iron overload, and describes treatment options for iron overload disorders. Research needed to advance knowledge about treatment of iron overload is proposed.

Automated red cell exchange procedures in patients with sickle cell disease

In automated red cell exchange, about 60% of the patient's red blood cells are exchanged via apheresis for those of the donor. We report the outcome of 83 patients with sickle cell anemia (48 women and 35 men; age range, 17-49 years) who underwent a total of 196 apheresis procedures between December 2003 and October 2006 at our institution. We found that automated red cell exchange involving a reduced citrate infusion rate may provide benefit in the prevention or treatment of vaso-occlusive complications in patients with sickle cell disease and may be associated with protean effects on biochemical dynamics.

Red cell exchange in sickle cell disease

Red cell exchange transfusions remain an effective but possibly underutilized therapy in the acute and chronic treatment of sickle cell disease. In sickle cell disease, increased blood viscosity can cause complications when the hemoglobin exceeds 10 g/dL even if this is due to simple transfusion. Red cell exchange can provide needed oxygen carrying capacity while reducing the overall viscosity of blood. Acute red cell exchange is useful in acute infarctive stroke, in acute chest and the multi-organ failure syndromes, the right upper quadrant syndrome, and possibly priapism. Neither simple or exchange transfusions are likely to hasten resolution of an acute pain episode.

Chronic blood transfusion therapy practices to treat strokes in children with sickle cell disease

PURPOSE

To identify variations in practices used by nurses for pediatric patients with sickle cell disease (SCD) receiving chronic blood transfusion therapy for strokes.

DATA SOURCES

Descriptive study of a convenience sample of 11 nurses who care for children with SCD from nine institutions completed a closed-ended questionnaire consisting of 37 items. Responses reflected practice experience with a total of 189 transfused patients with SCD.

CONCLUSIONS

A wide range of nursing practices exists for blood transfusion therapy for children with SCD and strokes. Manual partial exchange transfusion (66%) was the most commonly used method for blood transfusion in children with strokes reported among the nurses surveyed. Simple transfusions and erythrocytapheresis account for 21% and 13% of the practices reported. Opportunities exist to establish evidence-based nursing care guidelines to improve the care of children with strokes receiving blood transfusion therapy.

IMPLICATIONS FOR PRACTICE

A wide range of local standard care guidelines for blood transfusion therapy exists. The results of this survey indicate that partial manual exchange transfusion is the most commonly used method of chronic blood transfusion therapy in children with SCD and stroke despite the fact that the magnitude of benefit in comparison with simple transfusion has not been established. Factors such as peripheral venous access, compliance with current chelation regimen, and the presence of antibodies are important considerations in the choice of method.

Chronic red blood cell exchange to prevent clinical complications in sickle cell disease

We tracked the results of 394 manual or automatic red blood cell exchanges done with a cell separator in 20 sickle cell patients at high risk for recurrent complications. Over an average of 6 years, none of the patients developed complications related to the procedure or to the increased blood use. It was safe and effective in preventing complications of sickle cell disease, and if done automatically, reduced iron overload. Ferritin levels also decreased in patients treated with automatic red blood cell exchange. Furthermore, using Single Donor Red Blood Cell units (SDRC) we reduced the potential exposure to transfusion transmitted infectious diseases (TTI).