Transfusion
-
The DARC (Duffy blood group, chemokine receptor) gene encodes for a transmembrane glycoprotein that functions as a chemokine transporter, is a receptor for Plasmodium vivax and P. knowlesi, and expresses the Duffy blood group antigens (Fy). The Fy(a-b-) phenotype found in people of African descent is typically associated with a -67t>c mutation in the 5'-untranslated region (UTR), which prevents red blood cells being invaded by P. vivax and P. knowlesi. The aim of this study was to establish DARC allele frequencies in an African American blood donor cohort, determine a phylogenetic tree for DARC, and compare human and Neandertal DARC genes. ⋯ The nucleotide sequencing approach using one amplicon is a practical genotyping method for DARC and allows the determination of haplotypes even in heterozygous constellations. We developed a phylogenetic tree for DARC alleles and postulated a distinct FY*B allele as ancestral for the extant DARC alleles in humans.
-
Plasma utilization has increased over the past two decades, and there is a growing concern that many plasma transfusions are inappropriate. Plasma transfusion is not without risk, and certain complications are more likely with plasma than other blood components. Clinical and laboratory investigations of the patients suffering reactions after infusion of fresh-frozen plasma (FFP) define the etiology and pathogenesis of the panoply of adverse effects. ⋯ Other less common risks include 1) transmission of infections, 2) febrile nonhemolytic transfusion reactions, 3) red blood cell alloimmunization, and 4) hemolytic transfusion reactions. The effects of pathogen inactivation or reduction methods on these risks are also discussed. Fortunately, a majority of the adverse effects are not lethal and are adequately treated in clinical practice.
-
Review
Plasma transfusion for bedside, radiologically guided, and operating room invasive procedures.
Frozen plasma (FP) is commonly used in an attempt to correct coagulation defects before performing bedside, radiologically guided, or operating room procedures. Use of FP prophylactically is closely linked to results for standard coagulation tests in the laboratory, including prothrombin time, but there is a general lack of evidence supporting the predictive value of abnormalities of these tests for bleeding. Use of FP has little effect on correcting abnormal coagulation tests when mild and moderate results are recorded. ⋯ When the lack of clinical effectiveness is combined with the risks of FP transfusion, such as transfusion-related acute lung injury and transfusion-associated circulatory overload, the need to challenge continued preprocedure prophylactic use of FP becomes pressing. In clinical practice, abnormalities of standard coagulation tests should not be interpreted in isolation, but alongside review of clinical bleeding history and other hemostatic markers such as platelet count. A more appropriate transfusion strategy may be one that emphasizes the therapeutic use of FP.
-
Fingerstick blood samples are used to estimate donor venous hemoglobin (Hb). ⋯ Fingerstick is considered a useful estimator of venous Hb. However, in some donor groups, particularly female donors with AIS, fingerstick overestimates venous Hb at the donation cutoff. This significant limitation should be considered in setting donor fingerstick Hb or Hct requirements.