Manual Chronic Partial Exchange In Children and Adolescents with Sickle Cell Disease: Impact on Clinical Outcome and Iron Overload

Red cell exchange transfusion is frequently used in the management of patients with sickle cell disease either electively or therapeutically to maintain an hemoglobin S (Hb S) level < 30–50%. This target is often difficult to maintain. In order to assess the effects of chronic partial exchange transfusion (CPET) a) on level of Hb and Hb S, b) on iron overload c) the need for chelation, d) on risk of long term adverse events and e) clinical outcome, we analyzed the data of sickle cell disease patients treated by long term CPET in our center.

In the cohort of 163 SCD patients followed at University Children's Hospital at Brussels (Belgium), 10 benefit from CPET. Main reasons for CPET were neurologic disease (4), frequent ACS (3), previous severe hepatic cholestasis (2), leg ulcer (1) and pulmonary hypertension (1). The median age at start of treatment was 13 years (range 4 –19). These patients (6 males and 4 females) account for 248 exchanges during a median follow-up of 20 months (range 6– 36). These exchanges are until now performed manually and the volume exchanged is calculated taking into account the Hb level and the last HbS percentage. It is usually between 30 and 40 ml/kg BW. Except if severe anemia occurs, the goal of these exchanges is to keep a constant hematocrit level. All patients had a full red cell phenotype performed and received blood matched for ABO, Rhesus, Kell and Duffy antigens systems. The estimation of iron balance (iron intake- iron removed) was calculated yearly.

The pre-exchange Hb value was 9.5 g/dl (median; range: 7.7–10.9 g/dl) and the mean post value was 9.4/dl (range: 8.4– 11.1 g/dl). These values are not statistically different (p> 0.05). The majority of patients (9/10) are reached an HbS < 50% when measured 3–5 weeks after PET (just before the next procedure) with a median HbS value of 40% (range: 30–54). At start of CPET program, the median ferritin level was 439 ng/ml (range: 80 – 1704). Five patients had already a ferritin > 500 ng/mL due to numerous previous transfusions. At last evaluation, the median ferritin did not change significantly and was 531 ng/ml (range 84– 3840). The two patients with ferritin higher than 1000 ng/ml start chelation with good result for one. One The mean annual net RBC load were 1.72 ml RBC/kg/yr provided approximately 1.85 mg of iron/kg/yr. Individual data are given in table 1. CPET-treated patients exchanged showed clinical improvement with disappearance of SCD crisis and related complications. The procedure was well tolerated by most patients, and adverse effects were limited to mild hypotension (3/10). No autoimmune hemolysis or allo-immunisation was documented in this cohort. All children remained negative for HIV and hepatitis C virus infections. Conclusion: Manual CPET seems to be safe to prevent middle-term iron overload and the need of elation therapy in most of patients. CPET can therefore be recommended for SCD patients who required decreased in Hb S levels either prophylactically or therapeutically. Manual are safe, effective and easy to use when mechanized exchanges are not possible for technical reasons.

No relevant conflicts of interest to declare.