Automated Red Cell Exchange in the Management of Sickle Cell Disease.

Red cell transfusion represents one of the cornerstones of the chronic management of sickle cell disease, as well as its acute complications. Automated red cell exchange can rapidly lower the number of circulating sickle erythrocytes, without causing iron overload. Here, we describe our experience, having offered this intervention since 2011. A transient reduction in the platelet count by 61% was observed after the procedure. This was not associated with any haemorrhagic complications. Despite exposure to large volumes of blood, the alloimmunisation rate was only 0.027/100 units of red cells. The absence of any iron loading was confirmed by serial Ferriscans, performed over a number of years. However, patients with advanced chronic kidney disease showed evidence of iron loading due to reduced innate haemopoiesis and were subsequently switched to simple transfusions. A total of 59% of patients were on regular automated red cell exchange with a history of recurrent painful crises. A total of 77% responded clinically, as evidenced by at least a 25% reduction in their emergency hospital attendance for pain management. The clinical response was gradual and increased the longer patients stayed on the program. The earliest sign of clinical response was a reduction in the length of stay when these patients were hospitalised, indicating that a reduction in the severity of crises precedes the reduction in their frequency. Automated red cell exchange also appeared to be beneficial for patients with recurrent leg ulcers and severe, drug resistant stuttering priapism, while patients with pulmonary hypertension showed a dramatic improvement in their symptoms as well as echocardiographic parameters.

Distinct patterns of response to transfusion therapy for different chronic complications of sickle cell disease: A useful insight.

Two main sub-phenotypes have been described in sickle cell disease: one with higher baseline haemoglobin and a higher rate of painful crises and one with lower baseline haemoglobin, increased markers of haemolysis and a higher incidence of pulmonary hypertension, priapism and leg ulcers. We compared the patterns of response to regular automated red cell exchange transfusion over a five-year period of 21 patients with recurrent painful crises from the first group and 3 patients with pulmonary hypertension and 5 with recurrent severe stuttering priapism form the second and found them to be distinctly different. Response for pain is slow and increases gradually over years. The most pronounced clinical benefit and the one that appears first is a reduction in the severity rather than the frequency of painful crises. In contrast to the slow and gradual response we see for pain, response of patients with pulmonary hypertension and priapism is immediate with significant clinical improvement even after the first transfusion. The response appears to be directly correlated to the HbS level as the symptoms of both conditions invariably recur rapidly when transfusions are delayed or discontinued but resolve again once they are re-instituted.

A 5-year cost analysis of automated red cell exchange transfusion for the management of recurrent painful crises in adult patients with sickle cell disease.

The painful vaso-occlusive crisis is the most common acute manifestation of sickle cell disease resulting in poor quality of life and high utilisation of hospital facilities. The main disease modifying strategy is treatment with hydroxycarbamide. For patients intolerant or who fail hydroxycarbamide, chronic transfusions are an alternative. Automated red cell exchange transfusion (ARCET) are more effective in lowering rapidly the HbS level while avoiding iron overload. As they require specialised equipment and specially trained staff while utilising higher volumes of blood, there have been concerns regarding the costs involved. We retrospectively analysed data on 23 patients who have been on a regular programme for 1-5 years and found that their utilisation of hospital services reduced by 20%, 48%, 58%, 71%, and 79% after 1, 2, 3, 4 and 5 years respectively. The overall mean annual cost of care per patient was £9702 and £2378 higher than baseline after the 1st and 2nd years of ARCET respectively and then reduced by £5486, £8317, and £14,664 after the 3rd, 4th and 5th year of ARCET respectively indicating that ARCET leads to cost savings to health services in the medium to long term due to reduction in hospital attendance of these patients.

Successful outcome of three patients with sickle-cell disease and fat embolism syndrome treated with intensive exchange transfusion.

Fat embolism syndrome (FES) is a rare complication of sickle-cell disease (SCD) associated with extremely high mortality rates. It affects predominantly non-SS patients and those with previously mild disease. Rapid institution of exchange transfusion with an aim to reduce HbS to very low levels as soon as FES is suspected can be life-saving.

Safety, tolerability, and outcomes of regular automated red cell exchange transfusion in the management of sickle cell disease.

We report here our experience with regular automated red cell exchange transfusion for the management of chronic complications of sickle cell disease in 50 patients in our institution from June 2011 to December 2014. The mean sickle hemoglobin level was 44% and 8.5% pre- and post-transfusion, respectively. Platelets were reduced by a mean 70% during the procedure with a count of less than 50 × 109 /l in 6% of cases. The alloimmunization rate was 0.065/100 units of red cells with no hemolytic reactions. Patients with no iron overload at baseline showed no evidence of iron accumulation with a mean liver iron concentration of 1.6 mg/g dry tissue and 1.9 mg/g dry tissue at baseline and 36 months, respectively. All six patients with pre-existing iron overload and on chelation therapy, showed a gradual reduction of their liver iron concentration and two patients could discontinue chelation during the follow-up period. Seventy percentage of patients who were on the programme for recurrent painful crises showed a sustained reduction in the number of emergency hospital attendances; the mean number of days in hospital for emergency treatment was 103 in the year prior to commencing ARCET and reduced to 62 (40%) after the first 12 months, 51 (50%) after 24 months, and 35 days (66%) after 36 months. J. Clin. Apheresis 31:545-550, 2016. © 2015 Wiley Periodicals, Inc.

Bone marrow necrosis and fat embolism syndrome in sickle cell disease: increased susceptibility of patients with non-SS genotypes and a possible association with human parvovirus B19 infection.

Fat embolism syndrome (FES) due to extensive bone marrow necrosis (BMN) in sickle cell disease (SCD) is a potentially under-diagnosed complication associated with severe morbidity and mortality. We identified 58 cases reported in the world literature to date. Typically, patients presented with a seemingly uncomplicated vaso-occlusive crisis (VOC) and subsequently deteriorated rapidly with a drop in their haemoglobin and platelets, development of respiratory failure, encephalopathy and varying degrees of involvement of other systems. Overall mortality in the reported cases was 64% but differed according to the use of transfusion and was 29%, 61% and 91% for patients receiving exchange, top-up or no transfusion respectively. Patients most at risk appear to be those with a "milder" form of SCD as 81% of patients had a genotype other than HbSS and the majority had no history of significant sickle-related complications. Human parvovirus B19 (HPV B19) infection was documented in 24% of cases.

Comparison of serial serum ferritin measurements and liver iron concentration assessed by MRI in adult transfused patients with sickle cell disease.

AIMS: Transfused patients with sickle cell disease (SCD) are at risk of iron overload and identifying such patients is important to prevent associated complications. Our aim was to assess the efficacy of serial serum ferritin (SF) measurements in identifying patients with hepatic iron overload as assessed by liver MRI and its usefulness in guiding decision making regarding chelation therapy. PATIENTS/METHODS: We retrospectively compared the results of 49 liver MRI scans (LS) with the median serum ferritin (MSF) values for 28 patients in our institution. RESULTS: We found a nonlinear increment of MSF with increasing liver iron concentration (LIC). 18.4% and 47.4% of abnormal LSs corresponded to MSF <1000 mcg/L and <2000 mcg/L, respectively. 30.4% of patients with LIC of 7 mg/g dry weight or higher had a MSF <2000 mcg/L. In 38.5% of patients receiving chelation, MSF offered little information regarding the efficacy of treatment and was sometimes misleading. CONCLUSION: Serial serum ferritin measurements in adult transfused patients with sickle cell disease have a low sensitivity for identifying patients with iron overload and are of limited value in guiding decision making regarding initiation or monitoring of chelation therapy. The iron status of such high risk patients should be assessed by more definitive ways such as MRI.

Hb Bart's in cord blood: an accurate indicator of alpha-thalassemia.

We quantified Hb Bart's (gamma4) levels by high performance liquid chromatography (HPLC) in 103 fresh cord blood samples from Homerton Hospital, East London, UK. The alpha-globin gene arrangement was determined by Southern blot hybridization and genomic sequence analysis of the alpha-globin genes. The cord blood Hb Bart's levels ranged from 0.5 to 11.9% of total hemoglobin (Hb) and were arranged into three categories: i) levels below 1.5%; ii) levels between 1.5 and 5.7%; iii) levels above 6.1%. These corresponded to a normal alpha-globin genotype, a single deleted/inactivated alpha-globin gene and two deleted/inactivated alpha-globin genes, respectively. The study identified the 3.7 kb and 20.5 kb alpha-thalassemia (thal) deletions, three non deletional alpha-thal mutations and a novel alpha-globin gene rearrangement. Hb Bart's screening of fresh umbilical cord blood is an effective method to evaluate globin chain imbalance. This strategy could be utilized to screen populations for the incidence of alpha-thal and also to identify rare or new molecular lesions that reduce alpha-globin gene expression.