Transfusion therapy: a coming-of-age treatment for patients with sickle cell disease

Use of Cellular and Plasma Apheresis in the Critically Ill Patient: Part II: Clinical Indications and Applications

Apheresis is the process of separating the blood and removing or manipulating a cellular or plasma component for therapeutic benefit. Such procedures may be indicated in the critical care setting as primary or adjunctive therapy for certain hematologic, neurologic, renal, and autoimmune/rheumatologic disorders. In part I of this series, the technical aspects of apheresis were described and the physiologic rationale and clinical considerations were discussed. This review highlights the pathophysiologic basis, specific clinical indications, and treatment parameters for disorders that more commonly require management in the intensive care unit. The choice of plasma or cellular apheresis in these cases is guided by wellaccepted, evidence-based clinical treatment guidelines. For some disorders, such as liver failure, severe sepsis, and multiple-organ dysfunction syndrome, apheresis treatment approaches remain experimental. Ongoing studies are investigating the potential utility of conventional plasma exchange, ex vivo plasma manipulation, and newer technologies for these and other disorders in severely ill patients.

Red cell storage age policy for patients with sickle cell disease: A survey of transfusion service directors in the United States

In patients with sickle cell disease (SCD), the effects of the red cell storage lesion are not well defined. The objective of this study was to determine the prevalence of transfusion services that limit red cell units by storage age for patients with SCD. We developed a 22 question survey of transfusion service director opinions and their corresponding blood bank policies. Target subjects were systematically identified on the AABB website. Responses were recorded in SurveyMonkey and summarized using standard statistical techniques. Ninety transfusion service directors responded to the survey. Response rate was 22%. Only 23% of respondents had storage age policies in place for patients with SCD, even though 36% of respondents consider older units to be potentially harmful in this patient population. Of those with a policy, a less-than 15 day storage age requirement was most often used (75%), but practices varied, and most respondents (65%) agreed that evidence-based guidelines regarding storage age are needed for patients with SCD. Policies, practices and opinions about the risks of older units for patients with SCD vary. As patients with SCD may have unique susceptibilities to features of the red cell storage lesion, prospective studies in this population are needed to determine best practice.

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.

Antibody development in pediatric sickle cell patients undergoing erythrocytapheresis

BACKGROUND

Erythrocytapheresis, or red blood cell exchange transfusion (RBCX), with donor red blood cell (RBC) units is now increasingly used in the treatment of acute and chronic complications of sickle cell disease (SCD). As in all transfusions, RCBX carries a risk of immunization against foreign antigen on transfused cells. However, by selecting donor units with RBC phenotypes similar to the patient, the risk of allo- and autoimmunization can be reduced.

PROCEDURE

The formation of RBC alloantibodies and/or autoantibodies in 32 multitransfused pediatric SCD patients undergoing monthly RBCX over a 11-year period (12/1998 to 12/2009) was evaluated utilizing a retrospective patient chart review at Kosair Children's Hospital, Louisville, Kentucky.

RESULTS

After starting C, E, K antigen-matched RBCX, the rate of clinically significant allo-immunization decreased from 0.189/100 to 0.053/100 U, with a relative risk of 27.9%. Likewise, the rate of autoimmunization decreased from 0.063/100 to 0.035/100 U, with a relative risk of 55.9%.

CONCLUSION

After controlling for clinically insignificant antibodies, our auto- and alloimmunization rate was much less than previously reported values. In addition, the incidence of clinically significant allo- and autoimmunization decreased in our patient population after starting minor antigen-matched RBCX. These results suggest that by matching selected RBC phenotypes, there may be an association in the risk of allo- and autoimmunization of multi-transfused SCD patients.

Blood bank management of sickle cell patients at comprehensive sickle cell centers

BACKGROUND

Transfusion therapy has been integral to decreasing morbidity and mortality in sickle cell disease (SCD). Several studies however, have demonstrated variation in the blood bank (BB) practices for these patients. The purpose of this study was to examine BB practices for SCD patients at NIH Comprehensive Sickle Cell Centers (CSCCs) and to determine whether consensus in BB management exists.

STUDY DESIGN AND METHODS

A cross-sectional survey of BB medical directors and laboratory supervisors at CSCCs was conducted between October 2004 and March 2005. The survey assessed respondent, hospital, and BB characteristics; pretransfusion procedures; blood product selection; and agreement with statements about consensus in management. Physician respondents were also asked to select their preferred management strategy in four hypothetical transfusion-related cases.

RESULTS

Responses were received from 36 of 49 (73.5%) institutions. Pretransfusion procedures and blood product selection were nearly uniform among CSCCs. Of the respondents, 69 percent disagreed with the statement that clear consensus exists on the use of phenotypically matched red blood cells for SCD patients; 55 percent disagreed that clear consensus exists on the use of chronic transfusion programs for SCD patients. Although there was consensus on the use of transfusion therapy for life- or organ-threatening situations, optimal management of preoperative transfusion therapy and severe delayed transfusion reactions appears controversial.

CONCLUSION

This study provides the first overview of BB management of patients with SCD at CSCCs and identifies areas where there is perceived and actual lack of consensus. These results suggest that opportunities remain to standardize transfusion practices for SCD patients across all hospital settings.

The prevention and management of stroke in sickle cell anaemia

Perhaps the most important clinical complication of sickle cell anaemia is stroke, an event that occurs in approximately 5-10% of children who inherit this disorder. To prevent recurrent or progressive CNS damage, the institution of regular red blood cell (RBC) transfusions is the standard of care. In addition, children at high risk of developing stroke, as screened by transcranial Doppler, also benefit from regular RBC transfusions for stroke prevention. In this review, standard and novel techniques of RBC transfusion, and also alternative therapies to treat children with or at risk for stroke are considered. In addition, haematopoietic cell transplantation, the only curative option for sickle cell anaemia, is considered, and speculation about its present and future application in this clinical setting is discussed.

Risk factors and prediction of outcomes in children and adolescents who have sickle cell anemia

This article discusses risk factors and prediction in children and adolescents who have sickle cell anemia.

Haematopoietic cell transplantation in the treatment of sickle cell disease

Allogeneic haematopoietic cell transplantation (HCT) is presently the only treatment which offers the possibility of a cure for patients with sickle cell disease (SCD). While approximately 84% of patients survive disease-free after human leukocyte antigen (HLA)-identical sibling donor HCT, this therapy has traditionally been reserved for patients who have suffered serious complications due to the risk of transplant-related morbidity and mortality. Typically, these sickle-related complications have included recurrent episodes of acute chest syndrome, recurrent vaso-occlusive episodes and stroke. The future of HCT for haemoglobinopathies undoubtedly will evolve as transplant-related complications are reduced and as the process of selecting patients for HCT is refined.

Genetic basis of blood group diversity

In the last 18 years the genes that encode all but one of the 29 blood group systems present on red blood cells (RBCs) have been identified. This body of knowledge has permitted the application of molecular techniques to characterize the common blood group antigens and to elucidate the background for some of the variant phenotypes. Just as the RBC was used as a model for the biochemical characterization of cell membranes, so the genes encoding blood groups provide a readily accessible model for the study of gene expression and diversity. The application of genotyping techniques to identify fetuses at risk of haemolytic disease of the newborn is now the standard of care, and the expansion of nucleic acid testing platforms to include both disease testing and blood typing in the blood centre is on the horizon. This review summarizes the molecular basis of blood groups and illustrates the mechanisms that generate diversity through specific examples.

Survival of children with sickle cell disease

Contemporary survival data are not available for children with sickle cell disease (SCD). The few previous childhood SCD cohort studies do not reflect the benefits of modern therapy. We defined an inception cohort of newborns with sickle cell anemia (SS), sickle-beta degrees -thalassemia (S beta degrees ), sickle-hemoglobin C disease (SC), or sickle-beta(+)-thalassemia (Sbeta(+)) who were identified by newborn screening and followed for up to 18 years. The incidence of death and stroke were calculated. Overall survival, SCD-related survival (considering only SCD-related deaths), and strokefree survival were determined. The 711 subjects provided 5648 patient-years of observation. Twenty-five subjects died; mean age at death was 5.6 years. Five patients died from infection. Thirty had at least one stroke. Among SS and Sbeta degrees subjects (n = 448), the overall rates of death and stroke were 0.59 and 0.85/100 patient-years. Survival analysis of SS and Sbeta degrees subjects predicted the cumulative overall, SCD-related, and stroke-free survival to be 85.6%, 93.6%, and 88.5% by 18 years of age. No SCD-related deaths or strokes occurred in SC or Sbeta(+) subjects (n = 263). Childhood mortality from SCD is decreasing, the mean age at death is increasing, and a smaller proportion of deaths are from infection.

Sickle cell and the brain

Sickle cell disease affects many organ systems, but one of the major morbidities is brain disease, especially stroke. In this paper, the etiology, diagnosis, treatment, and prevention of clinical stroke, as well as so-called "silent stroke," are examined. Risk factors, diagnostic tools, and data from prevention and treatment studies as well as issues pertaining to neuropsychological function, especially in younger patients, are discussed and current best options for treatment considered.