Transfusion Management in Sickle Cell Disease

Prevalence of Red Blood Cell Alloimmunization Among Pediatric Patients With Sickle Cell Disease in Saudi Arabia

OBJECTIVE

Sickle cell disease (SCD) is a common hereditary hemoglobin disorder worldwide. One of the main treatments for patients with SCD is the requirement for blood transfusions. Posttransfusion alloimmunization with red blood cell (RBC) antigens continues to be a major risk factor for SCD. The objective of this study was to determine the rate, nature, and risk factors of red cell alloimmunization among pediatric patients with SCD in our center and compare our results with published reports from Saudia Arabia SA, regional countries, and some international countries.

MATERIALS AND METHODS

A retrospective chart review of patients with SCD at King Abdulaziz Medical City-Jeddah, between 2008 and 2019 was performed. Demographic characteristics and transfusion histories were recorded. Blood samples were analyzed for alloimmunization using immunohematologic techniques.

RESULTS

In total, 121 patients were analyzed. Alloantibodies were detected in 21 patients (17.4%) and were mostly single in 15 patients (71.4%), anti-K (23.7%), anti-E (19.0%), and anti-S (9.5%). The other 6 patients (28.6%) had multiple alloantibodies, especially the combination of anti-C and anti-K (9.5%) and the combination of anti-C and anti-E (9.5%). Alloantibody levels were significantly higher in patients with frequent hospital admissions (>5 times annually), those who had an exchange blood transfusion, those younger than 3 years old, and those who received a larger number of blood units ( P ≤0.05).

CONCLUSION

The rate of RBC alloimmunization is determined and considered relatively low compared with that in other nations. Matching for extended RBC antigens to include ABO, RH (D, C, c, E, e), K, Fy a , Fy b , Jk a , and Jk b antigens in the screening panel for donors and recipients is highly recommended to ensure better transfusion practices and avoid transfusion-related complications.

Elective Laparoscopic Cholecystectomy Complicated by Hemorrhagic Crisis in a Patient With Sickle Cell Disease

Sickle cell disease (SCD) is a common genetic disorder associated with complications such as cholelithiasis. Cholecystectomy is often performed in SCD patients, but they have a higher risk of postoperative complications. Blood transfusion, while beneficial, can also have adverse effects. The optimal approach to perioperative transfusion in SCD patients is still debated. This case report presents a rare surgical presentation of gallbladder stones in an SCD patient complicated by a hemolysis crisis and bleeding after laparoscopic cholecystectomy. A 24-year-old SCD patient with symptomatic gallbladder stones underwent laparoscopic cholecystectomy. Preoperative exchange transfusions were done to optimize hemoglobin and hemoglobin S (HbS) levels. Postoperatively, the patient experienced abdominal pain, tachycardia, and hypotension, indicating a possible hemolysis versus hemorrhagic crisis. Supportive management started but patient was still not improving and persisted to be tachycardic and hypotensive and laboratory results showed a drop in hemoglobin level (4.7 g/dL) and low platelets. A massive transfusion was activated and the patient received four units of packed red blood cells, four units of platelet and four units of fresh frozen plasma, but bleeding persisted. Laparoscopic exploration was done and oozing from liver bed was controlled and shifted again to surgical intensive care unit. Unfortunately, the next day, patient again experienced rebleeding which mandating laparoscopic converted to open laparotomy, and multiple sites of ongoing bleeding were identified and controlled with liver packing. The patient required subsequent interventions, including additional transfusions and second look and abdominal closure. After several days of intensive care, the patient's condition improved, and he was discharged with follow-up arrangements. Optimal management of surgical cases in SCD patients necessitates a multidisciplinary approach and personalized perioperative care. Preoperative transfusion should be tailored based on risk factors and the procedure. Standardized protocols and guidelines are needed to enhance perioperative management and outcomes. Prioritizing perioperative care can help mitigate complications and improve results for SCD patients undergoing surgery. Further research is required in this area.

Hypoxic storage of donor red cells preserves deformability after exposure to plasma from adults with sickle cell disease

BACKGROUND

Red cell (RBC) transfusions are beneficial for patients with sickle cell disease (SCD), but ex vivo studies suggest that inflamed plasma from patients with SCD during crises may damage these RBCs, diminishing their potential efficacy. The hypoxic storage of RBCs may improve transfusion efficacy by minimizing the storage lesion. We tested the hypotheses that (1) The donor RBCs exposed to the plasma of patients in crisis would have lower deformability and higher hemolysis than those exposed to non-crisis plasma, and (2) hypoxic storage, compared to standard storage, of donor RBCs could preserve deformability and reduce hemolysis.

STUDY DESIGN AND METHODS

18 SCD plasma samples from patients who had severe acute-phase symptoms (A-plasma; n = 9) or were at a steady-state (S = plasma; n = 9) were incubated with 16 RBC samples from eight units that were stored either under conventional(CRBC) or hypoxic(HRBC) conditions. Hemolysis and microcapillary deformability assays of these RBCs were analyzed using linear mixed-effect models after each sample was incubated in patient plasma overnight at 37°C RESULTS: Relative deformability was 0.036 higher (p < 0.0001) in HRBC pairs compared to CRBC pairs regardless of plasma type. Mean donor RBC hemolysis was 0.33% higher after incubation with A-plasma compared to S-plasma either with HRBC or CRBC (p = 0.04). HRBCs incubated with steady-state patient plasma demonstrated the highest deformability and lowest hemolysis.

CONCLUSION

Hypoxic storage significantly influenced RBC deformability. Patient condition significantly influenced post-incubation hemolysis. Together, HRBCs in steady-state plasma maximized donor red cell ex vivo function and survival.

Frequency, pattern, and associations of renal iron accumulation in sickle/β-thalassemia patients

We evaluated frequency, pattern, and associations of renal iron accumulation in sickle/β-thalassemia. Thirty-three sickle/β-thalassemia patients (36.5 ± 14.7 years; 13 females), 14 homozygous sickle cell disease (SCD) patients, and 71 thalassemia major (TM) patients, enrolled in the E-MIOT Network, underwent magnetic resonance imaging. Iron overload (IO) was quantified by the T2* technique. Sickle/β-thalassemia patients had a significantly lower frequency of renal IO (T2* < 31 ms) than homozygous SCD patients (9.1% vs. 57.1%; P = 0.001), besides having similar hepatic, cardiac and pancreatic IO. Kidney T2* values were comparable between regularly transfused sickle/β-thalassemia and TM patients but were significantly lower in regularly transfused homozygous SCD patients than in the other two groups. In sickle/β-thalassemia patients, global renal T2* values were not associated with age, gender, splenectomy, and presence of regular transfusions or chelation. No correlation was detected between renal T2* values and serum ferritin levels or iron load in the other organs. Global renal T2* values were not associated with serum creatinine levels but showed a significant inverse correlation with serum lactate dehydrogenase (R =  - 0.709; P < 0.0001) and indirect bilirubin (R =  - 0.462; P = 0.012). Renal IO is not common in sickle/β-thalassemia patients, with a prevalence significantly lower compared to that of homozygous SCD patients, but with a similar underlying mechanism due to the chronic hemolysis.

Retinopathy in Egyptian patients with sickle cell disease: A cross-sectional study

Sickle cell disease (SCD) is a disorder that causes red blood cells to become sticky and rigid. Sickle cells can block blood flow in small blood vessels depriving the eye of oxygen and cause damage. This is called sickle retinopathy that can progress to severe proliferative sickle cell retinopathy, bleeding into the eye, detachment of the retina or even loss of vision.To assess ocular manifestations and detect frequency of retinopathy in patients with SCD.Cross-sectional study was conducted on 32 patients with SCD. They were 22 males and 10 females with mean age of 12 years. Routine investigations as well as ophthalmological examination including visual acuity, fluorescein angiography and optical coherence tomography were done.We found that 8 patients (25%) suffered from proliferative retinopathy, 10 patients (31%) showed tortuous retinal veins, while 14 patients (44%) were normal. All patients showed macular thinning on optical coherence tomography examination.We concluded that frequency of retinopathy in patients with SCD is more than expected and it was higher in patients who started transfusion at a later age. More attention should be paid for this problem and close observations and follow up is strongly needed.

Ex Vivo Activation of Red Blood Cell Senescence by Plasma from Sickle-Cell Disease Patients: Correlation between Markers and Adhesion Consequences during Acute Disease Events

BACKGROUND: Blood transfusion remains a key treatment for managing occlusive episodes and painful crises in sickle-cell disease (SCD). In that clinical context, red blood cells (RBCs) from donors and transfused to patients, may be affected by plasma components in the recipients’ blood. Senescence lesion markers appear on the red cells after transfusion, shortening the RBC lifespan in circulation. In the specific context of SCD, senescence signals can also trigger the occlusive painful events, typical of the disease. This work follows through our previous data that described a RBC senescence process, rapidly detected after challenge with SCD pathological plasmas. In this clinical context, we wanted here to further explore the characteristics and physiologic consequences of AA RBC lesions associated with senescence, as lesions caused by RBCs after transfusion may have adverse consequences for SCD patients. METHODS: Plasma samples from SCD patients, with acute symptoms (n = 20) or steady-state disease (n = 34) were co-incubated with donor AA RBCs from blood units for 24 to 48 h. Specific markers signing RBC senescence were quantified after the incubation with SCD plasma samples. The physiologic in-flow adhesion was investigated on senescent RBCs, an in vitro technic into biochips that mimic adherence of RBCs during the occlusive events of SCD. RESULTS: Senescence markers on AA RBCs, together with their in-flow adhesion to the plasma-bridging protein thrombospondin, were associated with the clinical status of the SCD patients from whom plasma was obtained. In these experiments, the highest values were obtained for SCD acute plasma samples. Adhesion of senescent RBCs into biochips, which is not reversed by a pre-treatment with recombinant Annexin V, can be reproduced with the use of chemical agents acting on RBC membrane channels that regulate either Ca²⁺ entry or modulating RBC hydration. CONCLUSION: We found that markers on red cells are correlated, and that the senescence induced by SCD plasma provokes the adhesion of RBCs to the vessel wall protein thrombospondin. In-flow adhesion of senescent red cells after plasma co-incubations can be reproduced with the use of modulators of RBC membrane channels; activating the Piezo1 Ca²⁺ mechanosensitive channel provokes RBC adhesion of normal (non-senescent) RBCs, while blocking the Ca²⁺-dependent K⁺ Gardos channel, can reverse it. Clinically modulating the RBC adhesion to vascular wall proteins might be a promising avenue for the treatment of painful occlusive events in SCD.

Laparoscopic splenectomy in children with sickle cell disease younger than 5 years old

Background

The purpose of this paper is to evaluate the feasibility, safety, efficacy, benefits, and outcome of elective laparoscopic splenectomy for children younger than 5 years with sickle cell disease (SCD) who needed splenectomy. We conducted a retrospective review for a prospective data on patients younger than 5 years with SCD requiring splenectomy from January 2007 to June 2019. Patients were evaluated with regard to patient demographics, operative time, presence of accessory spleens, blood loss, length of hospital stay, morbidity, mortality, and clinical outcome.

Results

A total of 71 patients younger than 5 years with SCD underwent laparoscopic splenectomy (LS) at our institution from January 2007 to June 2019. There were 28 boys and 43 girls. The age at LS is from 2 years to less than 5 years (mean 3.2 years). The mean operating time was 65 min. There was no conversion to open surgery; all the cases were successfully performed laparoscopically. Twelve patients (17%) underwent a concomitant cholecystectomy. The hospital stay ranged from 2 to 6 days (median, 3 days). The mean follow-up was 86 months (range, 17 to 161 months). Postoperative follow-up revealed no cases of overwhelming postsplenectomy sepsis infection (OPSI).

Conclusion

Laparoscopic splenectomy in young children less than 5 years of age with sickle cell disease is a safe and effective treatment. When patients are given preoperative vaccination and penicillin prophylaxis, OPSI rarely occurs.

Outcomes of a preoperative risk-based transfusion assignment protocol in sickle cell disease patients: a single-center retrospective study from Saudi Arabia

Many patients with sickle cell disease (SCD) need surgical management during their lifetime. The best approach for preoperative transfusion in SCD is still to be determined. In this single-center retrospective study, we included HBSS/HBS-Beta⁰-thalassemia patients younger than 16 years of age who underwent surgery between January 2008 and July 2019. Preoperative transfusion assignment (PTA) was based on SCD severity and surgical risk. Patients were assigned to no transfusion, simple transfusion, or exchange transfusion. A total of 284 patients were identified and 66 (23%) underwent 78 procedures. Mean age at the time of procedure was 8 (5-11) years, mean baseline hemoglobin was 8.5 (7.8-9.3) g/dl, and mean hemoglobin F was 18.4 ± 8.2%. SCD severity was low-risk in 57 (73%) and high-risk in 21 (27%) patients. Surgical risk was low-risk in 20 (25.6%) and medium-risk in 58 (74.4%) procedures. PTA was no transfusion in 17 (22%), simple transfusion in 40 (51%), and exchange transfusion in 21 (27%) procedures. Postoperative complications occurred in five (6.4%) of procedures only in the simple transfusion group (three acute chest syndrome, one hemolytic anemia, one pain crisis) undergoing medium-risk surgery. Preoperative risk-based transfusion assignment is feasible. Despite a high baseline hemoglobin level in the no transfusion group, none of the patients developed postoperative complications. It is possible that the high baseline hemoglobin F phenotype was protective and indicates the need to study the risk/benefit of interventions used in this phenotype.

Cytokine changes in sickle-cell disease patients as markers predictive of the onset of delayed hemolytic transfusion reactions

BACKGROUND

Changes in cytokine production are known to contribute to the pathogenesis of sickle-cell disease (SCD), particularly in painful acute complications (crises) and episodes of post-transfusion hemolysis. Little is known about cytokine profiles in patients with these complications.

STUDY DESIGN AND METHODS

We investigated possible associations between cytokine profile and the onset of delayed hemolytic transfusion reactions (DHTRs), particularly during acute-phase episodes, to improve characterization of the biological parameters predictive of such events. We included SCD patients with severe acute symptoms (n = 36) or steady-state disease (n = 31), both possibly leading to a DHTR (n = 18) event. Luminex® technology was used to determine the plasma concentrations of 23 cytokines.

RESULTS

Regardless of clinical context, the concentrations of interleukin (IL)-6, IL-10, inducible protein-10, and macrophage inflammatory protein-1β were higher in plasma samples from SCD patients than in those from healthy controls. IL-6 and IL-10 concentrations were even higher in acute-phase plasma samples from SCD patients. In addition, IL-27 and TNFα levels were higher, and IL-6 and RANTES levels were lower in acute-phase SCD patients just before the onset of DHTR than in patients experiencing painful occlusive episodes.

CONCLUSION

In addition to reporting the plasma cytokine profiles of SCD patients in various clinical phases of the disease, we provide the first evidence of a significant association between low plasma TNFα concentration, high plasma IP-10 concentration and the onset of DHTR in SCD patients.

Perioperative Endocarditis Management in a Patient with Homozygous Sickle Cell Disease

Background  Homozygous sickle cell disease (SCD) compounded with bacterial endocarditis makes open-heart surgery a multidisciplinary challenge.

Case description  A 45-year-old African male patient with homozygous SCD presented with right heart decompensation, tricuspid regurgitation, and endocarditis of the aortic valve. Blood coulters were positive for coagulase-negative staphylococci. An emergent double valve replacement was successfully performed involving a multidisciplinary team.

Conclusion  Homozygous SCD is associated with an increased risk of preoperative vaso-occlusive complications. Surgery with cardiopulmonary bypass can be performed, if hypothermia, hypoxia, acidosis, or low-flows are being avoided. Due to the lack of data, the adequate approach is still intuitive and requires standardization.

Frequency of Red Blood Cell Alloimmunization in Patients with Sickle Cell Disease in Palestine

Background

Transfusion of red blood cells (RBC) is an essential therapeutic tool in sickle cell disease (SCD). Repeated RBC transfusions can cause alloimmunization which causes difficulty in cross-matching and finding compatible blood for transfusions. This study aimed to investigate the frequency of RBC alloimmunization and related risk factors among Palestinian SCD patients.

Materials and Methods

A multicenter cross-sectional study on 116 previously transfused SCD patients from three centers in West Bank, Palestine. Demographic, medical data and history of transfusion were recorded. Blood samples were collected from transfused consenting SCD patients. Gel card method was used for antibody screening and identification. In all patients, autocontrol and direct antiglobulin (DAT) test were performed using polyspecific (anti-IgG + C3d) anti-human globulin (AHG) gel cards for the detection of autoantibodies.

Results

Of the SCD patients, 62 (53.4%) patients were HbSS and 54 (46.6%) patients were sickle β-thalassemia (S/β-thal). There were 53 (45.7%) females and 63 (54.3%) males. Mean age was 18.8 years (range 3-53 years). The frequency of RBC alloimmunization among SCD patients was 7.76%, with anti-K showing the highest frequency (33.3%) followed by anti-E (22.2%), anti-D (11.1%), anti-C (11.1%), and anti-c (11.1%). All reported IgG alloantibodies were directed against antigens in the Rh (66.7%) and Kell (33.3%) systems. Older ages of patients, increased number of blood units transfused, and splenectomy were the commonest risk factors for alloimmunization in our study.

Conclusions

RBC alloimmunization rate among Palestinian SCD patients is low compared to neighboring countries and countries all over the world but still warrants more attention. Phenotyping of donors/recipients' RBC for Rh antigens and K₁ (partial phenotype matching) before their first transfusion may reduce the incidence of alloimmunization.

Simple chronic transfusion therapy, a crucial therapeutic option for sickle cell disease, improves but does not normalize blood rheology: What should be our goals for transfusion therapy?

Sickle cell anemia is characterized by a mutation resulting in the formation of an abnormal beta-hemoglobin called hemoglobin S. Hemoglobin S polymerizes upon deoxygenation, causing impaired red blood cell deformability and increased blood viscosity at equivalent hematocrits. Thus, sickle cell disease is a hemorheologic disease that results in various pathologic processes involving multiple organ systems including the lungs, heart, kidneys and brain. Red blood cell mechanics and the perturbations on blood flow-endothelial interaction underlie much of the pathology found in sickle cell disease. Transfusion therapy is one of the few therapeutic options available to patients, acting as both primary and secondary prevention of stroke. Transfusion therapy, both simple and exchange, is also used for unremitting and frequent pain crises and pulmonary hypertension. Therefore, understanding basic rheologic changes following transfusion inform other therapeutic options that aim to mitigate this diffuse pathologic process. This review will aim to highlight transfusion effects on blood rheology.

Anti-Toxoplasma gondii antibodies in patients with beta-hemoglobinopathies: the first report in the Americas

Background

In Brazil, there have been no previous studies of Toxoplasma gondii infection in sickle cell anemia patients and carriers of severe forms of beta-thalassemia. This study evaluated T. gondii infection in patients with beta-hemoglobinopathies.

Methods

A total of 158 samples, 77 (48.7%) men and 81 (51.3%) women, were evaluated. Three groups were formed: G1 (85 patients with sickle cell disease); G2 (11 patients with homozygous beta-thalassemia; G3 (62 patients with heterozygous beta-thalassemia). ELISA was employed to identify anti-T. gondii IgM and IgG antibodies, and molecular analysis was performed to determine beta-hemoglobin mutations. Fisher’s exact test was used to compare frequencies of anti-T. gondii IgM and IgG antibodies in respect to gender and age.

Results

Anti-T. gondii IgG antibodies were found in 43.5% of individuals in G1, 18.1% in G2 and 50% in G3. All samples from G1 and G2 were seronegative for anti-T. gondii IgM antibodies, but 3.2% from G3 were seropositive. Considering anti-T. gondii IgG antibodies, no statistical significant differences were found between these groups nor in seroprevalence between genders within each group. Despite this, comparisons of the mean ages between G1, G2 and G3 were statistically significant (G2 vs. G1: p value = 0.0001; G3 vs. G1: p-value <0.0001; G3 vs. G2: p-value = 0.0001).

Conclusion

A comparison by age of patients with sickle cell anemia showed a trend of lower risk of infection among younger individuals. Therefore, this study demonstrates that T. gondii infection occurs in patients with beta-thalassemia and sickle cell anemia in Brazil as seen by the presence of anti-T. gondii IgM and IgG antibodies.

Evidence of benefits from using fresh and cryopreserved blood to transfuse patients with acute sickle cell disease

BACKGROUND

The transfusion of red blood cell (RBC) concentrates is the main treatment for acute vaso-occlusive symptoms in sickle cell disease (SCD). Units of packed RBCs (pRBCs) must retain optimal characteristics for transfusion throughout the storage period. Transfused RBCs interact with the plasma and the endothelium that lines blood vessels and may be the target of immune-hematologic conflict if the patient produces antibodies against RBCs. Questions remain concerning the benefit-risk balance of RBC transfusions, in particular about the shelf-life of the units.

STUDY DESIGN AND METHODS

Plasma samples from 33 hemoglobin SS patients with SCD who had severe acute-phase symptoms or were in steady-state were put in contact with 10 fresh-stored and older stored samples from the same 10 RBC units. The factors affecting RBC survival (phosphatidylserine exposure, cytosolic calcium influx, cell size reduction) were analyzed.

RESULTS

We show that the effects of plasma samples from patients with SCD on pRBCs depend on the clinical condition of the patients and the duration of red cell storage. Signs of RBC senescence were correlated with the clinical status of the patient from whom the plasma sample was obtained. A decrease in RBC size and an increase in phosphatidylserine exposure were correlated with the duration of RBC storage. The behavior of cryopreserved pRBCs was similar to that of fresh refrigerated RBCs when challenged with patient plasma samples.

CONCLUSION

The key points of this study are that the clinical condition of patients with SCD can negatively affect the integrity of pRBCs for transfusion, and those effects increase with longer storage. Also, cryopreserved pRBCs behave similarly to fresh RBCs when challenged with plasma samples from patients with SCD in acute phase. Our data provide the first evidence that fresh RBCs stored for short periods may be of greater benefit to patients with SCD than RBCs that have been refrigerated for longer periods, particularly for those who have acute symptoms of SCD.

Surgical management of osteonecrosis of the femoral head in patients with sickle cell disease

Sickle cell disease is a known risk factor for osteonecrosis of the hip. Necrosis within the femoral head may cause severe pain, functional limitations, and compromise quality of life in this patient population. Early stages of avascular necrosis of the hip may be managed surgically with core decompression with or without autologous bone grafting. Total hip arthroplasty is the mainstay of treatment of advanced stages of the disease in patients who have intractable pain and are medically fit to undergo the procedure. The management of hip pathology in sickle cell disease presents numerous medical and surgical challenges, and the careful perioperative management of patients is mandatory. Although there is an increased risk of medical and surgical complications in patients with sickle cell disease, total hip arthroplasty can provide substantial relief of pain and improvement of function in the appropriately selected patient.

Pattern and prevelence of alloimmunization in multiply transfused patients with sickle cell disease in Nigeria

BACKGROUND AND STUDY OBJECTIVES

Blood transfusion is central in the prevention and treatment of certain chronic complications of sickle cell disease. It is indispensible in correcting anaemias as well as in the practice of exchange blood transfusion. These gains are largely limited by formation of allo-antibodies. Several studies demonstrated varying frequencies of allo-immunization in various patient groups. The effect of the racial differences between the donor and recipient pool, which has been subsumed in this study, has continuously created a confounding effect on the results of previous studies.

AIM

This study was aimed at determining the pattern and frequency of allo-immunization in multiply transfused sickle cell patients, in a racially matched donor and recipient population.

PATIENTS AND METHODS

This was a cross-sectional case-controlled study involving 80 Nigerian sickle cell disease patients who had received three or more units of packed red cells in the within 4 weeks of the study and 40 controls (who were SCD that had not been transfused in their life time). Antibody screening and identification was done using the Diamed microtyping system.

RESULTS

Frequency of allo-immunization was determined to be 18.7 % (15/80) among the previously transfused and 5 % (15/120) in all sickle cell disease patients. Auto-antibodies were detected in 1.25 % of the study group and 2.5 % of the control, and all reacted with the Kell and Lutheran blood group antigens. The pattern of allo-antibodies found showed; 46.7 % Rhesus, 40 % Kell, while Lutheran and Duffy 13.3 %, each.

CONCLUSION

Sickle cell disease patients are particularly susceptible to development of allo-antibodies despite racial similarities between the donor and recipient population. The most common allo-antibodies are Rhesus, Kell and Lutheran and Duffy respectively in order of decreasing frequency. Development of auto-antibodies seems to be independent of blood transfusion in sickle cell disease with possibly different pathogenetic mechanism. Policy on extended red cell phenotyping for common antigens will reduce allo-immunization among multiply transfused patients.

A rapid paper-based test for quantifying sickle hemoglobin in blood samples from patients with sickle cell disease

Quantification of sickle hemoglobin (HbS) in patients with sickle cell disease (SCD) undergoing hydroxyurea or chronic transfusion therapy is essential to monitoring the effectiveness of these therapies. The clinical monitoring of %HbS using conventional laboratory methods is limited by high per-test costs and long turnaround times usually associated with these methods. Here we demonstrate a simple, rapid, inexpensive paper-based assay capable of quantifying %HbS in blood samples from patients with SCD. A 20 μL droplet of whole blood and hemoglobin solubility buffer was deposited on chromatography paper. The relative color intensities of regions of the resulting blood stain, determined by automated image analysis, are used to estimate %HbS. We compared the paper-based assay with hemoglobin electrophoresis (comparison method) using blood samples from 88 subjects. The test shows high correlation (R(2)  = 0.86) and strong agreement (standard deviation of difference = 7%HbS) with conventional Hb electrophoresis measurement of %HbS, and closely approximates clinically predicted change in %HbS with transfusion therapy (mean difference 2.6%HbS, n = 5). The paper-based assay can be completed in less than 35 min and has a per-test cost less than $0.25. The assay is accurate across a wide range of HbS levels (10-97%) and hemoglobin concentrations (5.6-12.9 g/dL) and is unaffected by high levels of HbF (up to 80.6%). This study demonstrates the feasibility of the paper-based %HbS assay. The paper-based test could improve clinical care for SCD, particularly in resource-limited settings, by enabling more rapid and less expensive %HbS monitoring.

Computerized physician order entry improves compliance with a manual exchange transfusion protocol in the pediatric intensive care unit

AIM

To evaluate the use of a computerized physician order entry (CPOE) protocol on manual red blood cell (RBC) exchange transfusion in critically ill children with sickle cell disease.

METHODS

We conducted a retrospective study of children with sickle cell disease who received a manual RBC exchange transfusion before (2001 to 2008, n=22) and after (2008 to 2009, n=11) implementation of a CPOE protocol. Outcomes included compliance with protocol, percentage reduction in sickle hemoglobin, and peak hemoglobin during exchange.

RESULTS

Compliance with the manual exchange protocol improved after introduction of CPOE (pre-CPOE: 20 protocol violations vs. post-CPOE: 3 violations, P=0.02). Percentage reduction in sickle hemoglobin also improved (pre-CPOE: 55% vs. post-CPOE: 70%, P=0.04), whereas peak hemoglobin during RBC exchange was similar (pre-CPOE: 12.0 g/dL vs. post-CPOE: 11.5 g/dL, P=0.25). However, hemoglobin levels after the mean of 7 hours of exchange were significantly higher pre-CPOE (pre-CPOE: 11.5 g/dL vs. post-CPOE: 10.5 g/dL, P=0.006).

CONCLUSIONS

Use of CPOE for manual RBC exchange transfusion in children is associated with improved protocol compliance, improved reduction of sickle hemoglobin, and better maintenance of hemoglobin levels in a goal range during prolonged exchanges.

Genomic analyses of RH alleles to improve transfusion therapy in patients with sickle cell disease

BACKGROUND

Red cell (RBC) blood group alloimmunization remains a major problem in transfusion medicine. Patients with sickle cell disease (SCD) are at particularly high risk for developing alloantibodies to RBC antigens compared to other multiply transfused patient populations. Hemagglutination is the classical method used to test for blood group antigens, but depending on the typing methods and reagents used may result in discrepancies that preclude interpretation based on serologic reactivity alone. Molecular methods, including customized DNA microarrays, are increasingly used to complement serologic methods in predicting blood type. The purpose of this study was to determine the diversity and frequency of RH alleles in African Americans and to assess the performance of a DNA microarray for RH allele determination.

MATERIAL AND METHODS

Two sets of samples were tested: (i) individuals with known variant Rh types and (ii) randomly selected African American donors and patients with SCD. Standard hemagglutination tests were used to establish the Rh phenotype, and cDNA- and gDNA-based analyses (sequencing, PCR-RFLP, and customized RHD and RHCE microarrays were used to predict the genotype).

RESULTS

In a total of 829 samples (1658 alleles), 72 different alleles (40 RHD and 32 RHCE) were identified, 22 of which are novel. DNA microarrays detected all nucleotides probed, allowing for characterization of over 900 alleles.

CONCLUSIONS

High-throughput DNA testing platforms provide a means to test a relatively large number of donors and potentially prevent immunization by changing the way antigen-negative blood is provided to patients. Because of the high RH allelic diversity found in the African American population, determination of an accurate Rh phenotype often requires DNA testing, in conjunction with serologic testing. Allele-specific microarrays offer a means to perform high-throughput donor Rh typing and serve as a valuable adjunct to serologic methods to predict Rh type. Because DNA microarrays test for only a fixed panel of allelic polymorphisms and cannot determine haplotype phase, alternative methods such as Next Generation Sequencing hold the greatest potential to accurately characterize blood group phenotypes and ameliorate the clinical course of multiply-transfused patients with sickle cell disease.

Beyond the definitions of the phenotypic complications of sickle cell disease: an update on management

The sickle hemoglobin is an abnormal hemoglobin due to point mutation (GAG → GTG) in exon 1 of the β globin gene resulting in the substitution of glutamic acid by valine at position 6 of the β globin polypeptide chain. Although the molecular lesion is a single-point mutation, the sickle gene is pleiotropic in nature causing multiple phenotypic expressions that constitute the various complications of sickle cell disease in general and sickle cell anemia in particular. The disease itself is chronic in nature but many of its complications are acute such as the recurrent acute painful crises (its hallmark), acute chest syndrome, and priapism. These complications vary considerably among patients, in the same patient with time, among countries and with age and sex. To date, there is no well-established consensus among providers on the management of the complications of sickle cell disease due in part to lack of evidence and in part to differences in the experience of providers. It is the aim of this paper to review available current approaches to manage the major complications of sickle cell disease. We hope that this will establish another preliminary forum among providers that may eventually lead the way to better outcomes.

[Study of 206 transfused sickle cell disease patients: immunization, transfusion safety and red blood cell supply]

BACKGROUND

Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion.

METHODS AND RESULTS

Immunohematological data of 206 chronically transfused patients have been collected as well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally, this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens.

CONCLUSION

To insure optimal transfusion safety for sickle cell disease patients, three points have to be improved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system.

Iron overload following red blood cell transfusion and its impact on disease severity

Transfusion of red blood cells can be a life-saving therapy both for patients with chronic anemias and for those who are critically ill with acute blood loss. However, transfusion has been associated with significant morbidity. Chronic transfusion results in accumulation of excess iron that surpasses the binding capacity of the major iron transport protein, transferrin. The resulting non-transferrin bound iron (NTBI) can catalyze the production of highly reactive oxygen species (ROS) leading to significant and wide spread injury to the liver, heart, and endocrine organs as well as increases in infection. Acute transfusion of red blood cells in critically ill patients likewise has significant effects including increased mortality, prolonged hospital stays, and elevated risk of nosocomial infection. These effects appear to be more profound with increasing age of stored blood. The progressive release of free iron associated with storage time suggests that morbidity following acute transfusion, like that seen in chronic transfusion, may be due in part to elevated levels of NTBI. It is clear that transfusion is necessary in many instances; however, its risks and benefits must be carefully balanced before proceeding to avoid unnecessary iron toxicity.

Splenectomy reduces packed red cell transfusion requirement in children with sickle cell disease

PURPOSE

The purpose of the study was to measure the effect of splenectomy on packed-cell transfusion requirement in children with sickle cell disease.

METHODS

Thirty-seven sickle cell children who underwent splenectomies between January 2000 and May 2006 at a children's hospital were reviewed. Data were collected 6 months preoperatively to 12 months postsplenectomy. Paired t test, analysis of variance, and multivariable regression analyses were performed.

RESULTS

Of 37 children with median age 11 years (range, 2-18 years), 34 (21 males) had data that allowed analyses. Twenty-six had Hgb-SS, 5 had Hgb-SC, and 3 had Hgb S-Thal. Laparoscopic splenectomy was attempted in 36 and completed successfully in 34 (94% success). The number of units transfused decreased by 38% for 0 to 6 months and by 45% for 6 to 12 months postsplenectomy. Postoperatively, hematocrit levels increased and reticulocytes concurrently decreased with a reduction in transfusion clinic visits. The decrease in transfusion was not influenced by spleen weight, age, or hemoglobin type. Two children had acute chest syndrome (6%), and 1 had severe pneumonia (3%).

CONCLUSION

Laparoscopic splenectomy can be successfully completed in sickle cell children. Splenectomy significantly reduces the packed red cell transfusion requirement and frequency of clinic visits, in sickle cell children for at least 12 months postoperatively.

Advances in clinical research in sickle cell disease

Sickle cell disease continues to cause significant morbidity and mortality despite increases in life expectancy. This review looks at recent translational research in sickle cell disease, covering the red cell membrane, the vascular endothelium, local and systemic inflammation and the potentially pivotal role of nitric oxide as a key regulator of sickle cell complications. Clinical research reviewed includes pulmonary hypertension, which is emerging as a particularly deadly scourge of adults with any haemolytic anaemia, and newer insights into older, more established complications and treatments, such as red cell transfusions, the need for and use of iron chelation and avascular necrosis. Finally, recent studies about those factors that affect the day-to-day lives of persons with sickle cell disease, pain and neuropsychiatric functioning, are discussed.

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.

Platelet P-selectin expression in patients with sickle cell disease who undergo apheresis

Activated platelets have been identified in patients with sickle cell disease. However, the association of platelet P-selectin expression and automated red cell exchange procedures in these patients is not well known. We hypothesized that altered whole platelet P-selectin expression is associated with automated red cell exchange. Flow cytometric quantification of platelet P-selectin expression was carried out in 23 patients with sickle cell disease before and after automated red cell exchange. P-selectin expression was quantified as a binding index for platelet P-selectin (the percentage of positive platelets multiplied by the mean fluorescence of positive platelets). The patients were divided into two groups: individuals with painful vaso-occlusive crises (four women and five men; group 1) and those in a steady state (six women and eight men; group 2). The 33 exchange procedures were evaluated prospectively and used acid-citrate-dextrose A solution (whole blood to anticoagulant ratio = 14:1). Platelet P-selectin expression did not significantly change after automated red cell exchange. Clinical factors such as the volume of replacement fluid and the citrate infusion rate did not correlate with postapheresis platelet P-selectin expression. In addition, the association of platelet P-selectin expression and automated red cell exchange was independent of other laboratory factors (hematocrit level, hemoglobin S level, platelet count, and nitric oxide level). Finally, the difference between the study groups regarding platelet P-selectin expression before and after apheresis was insignificant. In conclusion, automated red cell exchange procedures do not induce platelet P-selectin expression in patients with sickle cell disease in the steady state or in vaso-occlusive crisis.

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.

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.

Morbidity and mortality in chronically transfused subjects with thalassemia and sickle cell disease: A report from the multi-center study of iron overload

A natural history study was conducted in 142 Thalassemic (Thal), 199 transfused Sickle Cell Disease (Tx-SCD, n = 199), and 64 non-Tx-SCD subjects to describe the frequency of iron-related morbidity and mortality. Subjects recruited from 31 centers in the US, Canada or the UK were similar with respect to age (overall: 25 +/- 11 years, mean +/- SD) and gender (52% female). We found that Tx-SCD subjects were hospitalized more frequently compared with Thal or non-Tx-SCD (P < 0.001). Among those hospitalized, Tx-SCD adult subjects were more likely to be unemployed compared with Thal (RR = 1.6, 95% CI 1.0-2.5) or non-Tx-SCD (RR = 3.1, 95% CI 1.3-7.3). There was a positive relationship between the severity of iron overload, assessed by serum ferritin, and the frequency of hospitalizations (r= 0.20; P = 0.009). Twenty-three deaths were reported (6 Thal, 17 Tx-SCD) in 23.5 +/- 10 months of follow-up. Within the Tx-SCD group, those who died began transfusion (25.3 vs. 12.4 years, P < 0.001) and chelation therapy later (26.8 vs. 14.2 years, P = 0.01) compared with those who survived. The unadjusted death rate in Thal was lower (2.2/100 person years) compared with that in Tx-SCD (7.0/100 person years; RR = 0.38: 95% CI 0.12-0.99). However, no difference was observed when age at death was considered. Despite improvements in therapy, death rate in this contemporary sample of transfused adult subjects with Thal or SCD is 3 times greater than the general US population. Long term follow-up of this unique cohort of subjects will be helpful in further defining the relationship of chronic, heavy iron overload to morbidity and mortality.

A randomised comparison of deferasirox versus deferoxamine for the treatment of transfusional iron overload in sickle cell disease

Deferasirox is a once-daily, oral iron chelator developed for treating transfusional iron overload. Preclinical studies indicated that the kidney was a potential target organ of toxicity. As patients with sickle cell disease often have abnormal baseline renal function, the primary objective of this randomised, open-label, phase II trial was to evaluate the safety and tolerability of deferasirox in comparison with deferoxamine in this population. Assessment of efficacy, as measured by change in liver iron concentration (LIC) using biosusceptometry, was a secondary objective. A total of 195 adult and paediatric patients received deferasirox (n = 132) or deferoxamine (n = 63). Adverse events most commonly associated with deferasirox were mild, including transient nausea, vomiting, diarrhoea, abdominal pain and skin rash. Abnormal laboratory studies with deferasirox were occasionally associated with mild non-progressive increases in serum creatinine and reversible elevations in liver function tests. Discontinuation rates from deferasirox (11.4%) and deferoxamine (11.1%) were similar. Over 1 year, similar dose-dependent LIC reductions were observed with deferasirox and deferoxamine. Once-daily oral deferasirox has acceptable tolerability and appears to have similar efficacy to deferoxamine in reducing iron burden in transfused patients with sickle cell disease.

Rheologic behavior of sickle and normal red blood cell mixtures in sickle plasma: implications for transfusion therapy

BACKGROUND

Guidelines for transfusion in sickle cell disease usually define an upper hematocrit (Hct) limit of 0.30 to 0.35 to avoid blood hyperviscosity. In vitro viscosity studies of normal (AA) and sickle (SS) red blood cell (RBC) mixtures in buffer appear to confirm that this Hct limit is optimal for oxygen delivery to vascular beds as judged by the ratio of Hct to viscosity, with this ratio often termed "oxygen or RBC transport effectiveness." In the absence of plasma, however, effects due to RBC-RBC interactions mediated by plasma proteins cannot be assessed.

STUDY DESIGNS AND METHODS

To investigate the optimal Hct-to-viscosity ratio of RBCs in plasma, the rheologic effects of Hct (0.20-0.40), the proportion of SS RBCs (0-100%), and shear rate (1-1000/sec) for mixtures of oxygenated and deoxygenated SS and AA RBCs were evaluated in sickle plasma at 37 degrees C.

RESULTS

RBC suspension viscosity was shear-dependent (i.e., viscosity decreased with increasing shear rate) and increased with Hct and proportion of SS RBCs. An "optimal" Hct level (defined as a maximal of the Hct-to-viscosity ratio) was seen only at shear rates above 50/sec. At lower shear rates (e.g., 5/sec), where plasma-mediated RBC-RBC interactions predominate, any increment in Hct was offset by a proportionally greater increase in viscosity, thus leading to a lower Hct-to-viscosity ratio.

CONCLUSION

These results indicate the importance of plasma-mediated RBC interactions and suggest that the benefits of transfusion may vary depending on local flow rates (i.e., shear rates) and organ-specific hemodynamics.