Safety and benefits of automated red cell depletion-exchange compared to standard exchange in patients with sickle cell disease undergoing chronic transfusion.

BACKGROUND: The Spectra Optia allows automated performance of red blood cell reduction and isovolemic hemodilution (IHD) prior to standard red cell exchange (RCE), and is primarily intended for patients with sickle cell disease (SCD) undergoing chronic RCE. Data on the safety of inducing transient further anemia and the benefits of IHD-RCE is limited and occasionally contradictory. STUDY DESIGN AND METHODS: In this retrospective crossover analysis of six patients with SCD who underwent chronic exchange with standard RCE (Cobe Spectra) followed by IHD-RCE (Spectra Optia), we compared safety and benefit outcomes with IHD-RCE vs standard RCE. RESULTS: There were statistically but not clinically significant drops in blood pressure in the post-IHD phase. With IHD-RCE, there were significant reductions in red blood cell (RBC) usage and/or lower fraction of cells and significant increases in postprocedure hematocrit (Hct) associated with increased preprocedure Hct. There were no differences achieved in the time interval between procedures or in the net RBC gain with IHD-RCE. Overall, there were also no significant differences in pre- and postprocedure percentage of hemoglobin S, reticulocyte count, interval daily hemoglobin A decrement, or postprocedure white blood cell, neutrophil, or platelet counts. CONCLUSIONS: Our study supports that IHD-RCE can be safely used in patients with stroke risk and compared to standard RCE, results in benefits of lower RBC usage and/or fraction of cells remaining and higher postprocedure Hct associated with higher preprocedure Hct. These findings support wider use of IHD-RCE, especially in the current environment with reduced availability of minority units.

Case series supporting heme detoxification via therapeutic plasma exchange in acute multiorgan failure syndrome resistant to red blood cell exchange in sickle cell disease.

BACKGROUND: Depletion of haptoglobin (Hp) and hemopexin (Hx) with increase in free hemoglobin and heme are important etiologies of vaso-occlusive complications in sickle cell disease (SCD). This study is the first to show an association between clinical improvement in SCD and repletion of Hp and Hx by therapeutic plasma exchange (TPE) using plasma replacement. STUDY DESIGN AND METHODS: Thirteen fresh-frozen plasma (FFP) units derived from consecutive whole blood donations were thawed at 37°C after 10 months of storage; Hp and Hx concentrations immediately postthaw and after 5 days of refrigerated storage were analyzed by enzyme-linked immunosorbent assay (ELISA). All SCD patients presenting to a single institution over a 2-year period with acute multiorgan failure syndrome resistant to red blood cell exchange (RCE) were treated with TPE with FFP replacement; concentrations of Hp, Hx, and heme were evaluated before and after TPE by ELISA. RESULTS: Plasma concentrations of Hp and Hx decreased approximately 20% (p ≤ 0.002) after 5 days of refrigerated storage. Significant mean fold increases after TPE of 10 for Hp (p < 0.005) and seven for Hx (p < 0.003) and a 30% mean decrease in heme concentrations (p = 0.07) were noted in association with clinical improvement (three patients), whereas minimal increases in Hp and Hx were associated with continued clinical deterioration in one patient. CONCLUSION: Fresh-frozen plasma rather than thawed plasma is optimal for Hp and Hx replacement. Patient data are consistent with Hp and Hx increases via TPE limiting clinical toxicity of worsened hemolysis associated with severe vaso-occlusive complications refractory to RCE in SCD.