Is there a place for epoetin alfa in managing anemia during critical illness?

Tangential flow filtration of hemoglobin

Bovine and human hemoglobin (bHb and hHb, respectively) was purified from bovine and human red blood cells via tangential flow filtration (TFF) in four successive stages. TFF is a fast and simple method to purify Hb from RBCs using filtration through hollow fiber (HF) membranes. Most of the Hb was retained in stage III (100 kDa HF membrane) and displayed methemoglobin levels less than 1%, yielding final concentrations of 318 and 300 mg/mL for bHb and hHb, respectively. Purified Hb exhibited much lower endotoxin levels than their respective RBCs. The purity of Hb was initially assessed via SDS-PAGE, and showed tiny impurity bands for the stage III retentate. The oxygen affinity (P(50)) and cooperativity coefficient (n) were regressed from the measured oxygen-RBC/Hb equilibrium curves of RBCs and purified Hb. These results suggest that TFF yielded oxygen affinities of bHb and hHb that are comparable to values in the literature. LC-MS was used to measure the molecular weight of the alpha (alpha) and beta (beta) globin chains of purified Hb. No impurity peaks were present in the HPLC chromatograms of purified Hb. The mass of the molecular ions corresponding to the alpha and beta globin chains agreed well with the calculated theoretical mass of the alpha- and beta- globin chains. Taken together, our results demonstrate that HPLC-grade Hb can be generated via TFF. In general, this method can be more broadly applied to purify Hb from any source of RBCs. This work is significant, since it outlines a simple method for generating Hb for synthesis and/or formulation of Hb-based oxygen carriers.

A meta-analysis of randomized controlled trials in critically ill patients to evaluate the dose-response effect of erythropoietin

The use of erythropoietin in critically ill patients has been investigated in multiple randomized clinical trials and its role in decreasing the number of units of blood transfused has been demonstrated in some trials. A meta-analysis was conducted to determine the pooled estimate of the decrease in number of units of blood transfused with the use of erythropoietin and investigated its dose-response effect. A systematic search was performed of the MEDLINE, EMBASE, and the Current Controlled Trials Register to identify randomized clinical trials investigating the role of erythropoietin in critically ill patients. Of 664 studies identified in the search, 5 randomized clinical trials met the inclusion criteria. The pooled estimate of the decrease of number of units of blood transfused was -1.64 (95% CI -2.6 to -0.67). Sensitivity analysis to establish the influence of temporal bias, quality of the study and comorbidities such as age and Acute Physiology and Chronic Health Evaluation (APACHE) II score were undertaken and did not reveal a significant difference. The inclusion of studies with higher doses of erythropoietin revealed a greater decrease in the number of units of blood transfused (-2.15; 95% CI -3.06 to -1.24). Despite the limitations of a meta-analysis we believe that the use of erythropoietin significantly decreases the number of units of blood transfused per patient. Our study also reveals the possibility of a dose-response effect of erythropoietin in decreasing the number of units of blood transfused.

Blood management: a primer for clinicians

Blood transfusions are common in the hospital setting. Despite the large commitment of resources to the delivery of blood components, many clinicians have only a vague understanding of the complexities associated with blood management and transfusion therapy. The purpose of this primer is to broaden the awareness of health care practitioners in terms of the risks versus benefits of blood transfusions, their economics, and alternative treatments. By developing and implementing comprehensive blood management programs, hospitals can promote safe and clinically effective blood utilization practices. The cornerstones of blood management programs are the implementation of evidence-based transfusion guidelines to reduce variability in transfusion practice, and the employment of multidisciplinary teams to study, implement, and monitor local blood management strategies. Pharmacists can play a key role in blood management programs by providing technical expertise as well as oversight and monitoring of pharmaceutical agents used to reduce the need for allogeneic blood.