Caregivers and community perceptions of blood transfusion for children with severe anaemia in Uganda.

OBJECTIVE: To describe local perceptions of blood transfusion for children with severe anaemia in Uganda. BACKGROUND: Blood transfusion is a common emergency treatment for children with severe anaemia and saves millions of lives of African children. However, the perceptions of transfusion recipients have not been well studied. A better understanding of the perceived risk may improve transfusion care. METHODS: A qualitative study based on 16 in-depth interviews of caregivers of transfused children, and six focus group discussions with community members was conducted in three regions of Uganda between October and November 2017. RESULTS: Caregivers of children and community members held blood transfusion in high regard and valued it as life-saving. However, there were widespread perceived transfusion risks, including: Human immunodeficiency virus (HIV) transmission, too rapid blood infusion and blood incompatibility. Other concerns were: fatality, changes in behaviour, donor blood being 'too strong' and use of animal blood. In contrast, recent transfusion, older age, knowledge of HIV screening of blood for transfusion, faith in God and having a critically ill child were associated with less fear about transfusion. Respondents also emphasised challenges to transfusion services access including distance to hospitals, scarcity of blood and health workers' attitudes. CONCLUSION: Perceptions of the community and caregivers of transfused children in Uganda about blood transfusion were complex: transfusion is considered life-saving but there were strong perceived transfusion risks of HIV transmission and blood incompatibility. Addressing community perceptions and facilitating access to blood transfusion represent important strategies to improve paediatric transfusion care.

Reversal of oral factor Xa inhibitors by prothrombin complex concentrates: a re-appraisal.

Oral factor Xa inhibitors are an attractive class of anticoagulants expected to have broad application. Rapid and reliable reversal of the anticoagulant effect is important for patients with bleeding complications or those in need of urgent reversal for procedures. While no specific reversal agent is yet available, multiple published clinical guidelines suggest that four-factor prothrombin complex concentrates (PCC) should be considered when urgent reversal is desired. This presentation updates prior reviews on this topic (Crit Care, 17, 2013, 230; Thromb Haemost, 111, 2014, 189; J Thromb Thrombolysis, 2015, 39, 395); and summarizes more recent evidence in human studies indicating that four-factor PCCs available in North America do not reverse oral factor Xa-inhibitor anticoagulants. New agents on the horizon appear to be far more promising as therapies for reversal or oral factor Xa inhibitors.

Plasmodium falciparum malaria and the immunogenetics of ABO, HLA, and CD36 (platelet glycoprotein IV).

Plasmodium falciparum malaria has long been a killer of the young, and has selected for polymorphisms affecting not only erythrocytes, but the immunogenetics of three histocompatibility systems: ABO, human leukocyte antigen (HLA), and CD36. The ABO system is important because the original allele, encoding glycosylation with the A sugar, acts as an adhesion ligand with infected red blood cells (iRBC), thereby promoting vasoocclusion. The prevalence of blood group O, which reduces this cytoadhesion, has increased in endemic areas. Other adaptations which could mitigate A-mediated rosetting include weaker A expression and increased soluble A secretion. The role of the HLA system in malaria has been harder to verify. Although HLA-B53 and DRB1*04 may be associated with clinical outcome, HLA studies are challenged by numerous comparisons in this most polymorphic of systems, and confounded by increasingly heterogeneous populations. Certain HLA markers may also reflect linkage artefact with other malaria-relevant polymorphisms. HLA may be less important because the parasite predominantly invades a compartment which does not express HLA. Adhesion of iRBCs is also mediated by CD36, expressed on platelets, monocytes, and microvascular endothelium. CD36 on monocytes is involved in clearing iRBC, while CD36 on platelets and the endothelium may play a role in tissue sequestration. The genetics of CD36 expression are complex, and recent research is fraught with inconsistent results. The solution may lie in examining genotype-phenotype correlations, zygosity effects on differential tissue expression, or other mechanisms altering CD36 tissue expression. Carefully designed prospective studies should bridge the gap between in-vitro observations and clinical outcomes.

When monocytes and platelets compete: The effect of platelet count on the flow cytometric measurement of monocyte CD36.

BACKGROUND: Flow cytometric measurement of monocyte surface CD36 is relevant to several conditions including diabetes, cardiovascular disease, lipid disorders, platelet isoimmunization, and susceptibility to P falciparum malaria. CD36 is also strongly expressed on platelets where it is also known as platelet glycoprotein IV. METHODS: Whole blood samples, containing identical monocyte concentrations, were adjusted to contain platelets ranging from 20,000/uL to 600,000/uL, were stained with fluorescent-labeled anti-CD36, and analyzed by flow cytometry. RESULTS: CD36 median fluorescent intensity (MFI) observed on monocytes decreased as the platelet concentration in the sample increased with more than a 50% decline in monocyte MFI over the normal range of platelet values. The effect was not abolished by using larger volumes of monoclonal antibody and was observed with different clones of reagent anti-CD36. The findings were most consistent with competition by platelets for the CD36 reagent. Similar findings were observed with antibody to class I HLA. Under defined assay conditions, monocyte CD36 MFI declined with rising platelet concentration in a predictable fashion following an inverse linear relationship. CONCLUSIONS: Measurement of CD36 expression on monocytes by flow cytometry in whole blood samples is affected by the sample platelet count. When comparing the monocyte CD36 expression among different individuals, our approach can be used to adjust measured monocyte CD36 expression for the effect of the platelet concentration in the sample. Competition by platelets for monoclonal reagents may occur in other settings when whole blood assays are used and when the target antigen is strongly expressed on both platelets and leukocytes.

The James Blundell Award Lecture 2006: transfusion and the treatment of haemorrhage: past, present and future.

In the early years of the 19th century, James Blundell reported in the Lancet the first clinical application of blood transfusion for the treatment of haemorrhage. Although these initial experiments may appear to us to have burst upon the medical world, Blundell had in fact done a decade of pre clinical research using animal models to establish principles to be brought to the clinic. His pivotal pre clinical experiments and the insights he gained are described in detail. Today, blood transfusion remains the cornerstone of treatment for serious bleeding - not only to restore oxygen carrying capacity but also to improve haemostasis, arrest and prevent bleeding. However, the indications for the use of blood components to treat bleeding remain ill-defined. In particular, despite the enormous volumes of fresh frozen plasma (FFP) transfused worldwide, the evidence that commonly used coagulation tests are reliable guides to transfusion with FFP is scant. Recent laboratory and clinical studies provide insight into the weaknesses of current coagulation tests as a guide to blood management. In the future, the application of genomics to haemostasis will uncover genetic polymorphisms leading to improved diagnostics and more tailored medical therapeutics. Examples of the emerging use of clinical genomics are presented. Ultimately, the application of widescale genomics testing will refresh our understanding of human physiology and will reassert the importance of the individual in patient care.

Current performance of patient sample collection in the UK.

Collection of the patient sample for pretransfusion testing begins a complex chain of events in the transfusion process. Hospitals in England and North Wales were surveyed to compare local policies against recommendations of the British Committee for Standards in Haematology (BCSH). Hospitals also measured the frequency of rejected and miscollected samples [designated as wrong blood in tube (WBIT)]. 185 of 360 (51.4%) hospitals returned questionnaires and 182 of 185 (98%) hospitals reported that a policy for sample collection existed. Apart from frequent omission of the gender of the patient, there was 96% compliance with all mandatory identifiers of the BCSH guidelines. Practice allowing additions or changes to labelling on sample tubes and request forms varied. 3.2% (14 114/445 726) of samples submitted were rejected for various reasons, the most frequent being incomplete or missing information (49.5% of the total rejected samples). The corrected mean frequency for WBIT in the 27 hospitals with one or more observed WBIT was 1 in 1501 samples (95% CI: < or =1129.09 to < or =1872.91), and the median corrected frequency for WBIT was 1 in 1303 samples. This study has identified great variation in the policy and practice for sample collection for pretransfusion testing. Regular tracking of the rates of sample rejection and WBIT could be used to identify poor performance in individual hospitals requiring investigation and action.

An international study of the performance of sample collection from patients.

BACKGROUND AND OBJECTIVES: Collection of a blood sample from the correct patient is the first step in the process of safe transfusion. The aim of this international collaborative study was to assess the frequency of mislabelled and miscollected samples drawn for blood grouping. MATERIALS AND METHODS: Hospitals in 10 countries provided data on sample error rates during a period of at least 3 months, including the last quarter of 2001. Mislabelled samples were defined as those not meeting local criteria for acceptance by the laboratory. Miscollected samples [wrong-blood-in-tube (WBIT)] were defined as samples in which the blood group result differed from the result on file from prior testing. WBIT rates were corrected for the proportion of repeat samples and for undetectable errors occurring as a result of chance collection of blood from the wrong patient with the same ABO group. Participants also completed a questionnaire on current policies regarding sample collection. RESULTS: A total of 71 hospitals completed surveys describing policies related to sample collection. Sixty-two hospitals provided usable data on the frequency of mislabelled and miscollected samples. Mislabelled and miscollected samples were common. Based on results from over 690,000 samples, the median hospital performance resulted in a rate for mislabelling of 1 in every 165 samples (6.1 per 1000; interquartile range 1.2-17 per 1000). The presence of national patient identification systems in Sweden and Finland was associated with rates of miscollected samples that were too low to estimate. Outside these nations, miscollected samples demonstrating WBIT occurred at a median rate of 1 in every 1986 samples (0.5 per 1000; interquartile range <0.3-0.9 per 1000). There was great variation worldwide in the reported frequency of mislabelled samples, probably resulting from variation in policies for sample acceptance. Miscollected samples occurred at a more constant rate. CONCLUSIONS: The rate of mislabelled samples and miscollected samples is 1000-10,000-fold more frequent than the risk of viral infection. Rates of mislabelled samples and WBIT can be tracked as key indicators of performance of an important step in the clinical transfusion process. WBIT episodes represent important 'near-miss' errors. By providing baseline performance data for the collection of patient blood samples, this study may be useful in formulating future national standards of performance for sample collection from patients.

A prospective, randomized clinical trial of universal WBC reduction.

BACKGROUND: Recipient exposure to allogeneic donor WBCs results in transfusion complications for selected populations of recipients. Whether or not WBC reduction should be universally applied is highly controversial. STUDY DESIGN AND METHODS: In a general hospital, a randomized, controlled clinical trial of conversion to universal WBC reduction was conducted. Patients (11%) with established medical indications for WBC-reduced blood were not eligible. All other patients who required transfusion were assigned at random to receive either unmodified blood components or stored WBC-reduced RBCs and platelets. Analysis for each patient was restricted to the first hospitalization. RESULTS: All eligible patients (n = 2780) were enrolled. Three specified primary outcome measures were not different between the two groups: 1) in-hospital mortality (8.5% control; 9.0% WBC-reduced; OR, 0.94 [95% CI, 0.72-1.22]; p = 0.64); 2) hospital length of stay (LOS) after transfusion (median number of days, 6.4 for control and 6.3 for WBC-reduced; p = 0.21); and 3) total hospital costs (median, $19,500 for control and $19,200 for WBC-reduced, p = 0.24). Secondary outcomes (intensive care LOS, postoperative LOS, antibiotic usage, and readmission rate) were not different between the two groups. Subgroup analysis based on patient age, sex, amount of blood transfused, or category of surgical procedure showed no effect of WBC reduction. Patients who received WBC-reduced blood had a lower incidence of febrile reactions (p = 0.06). CONCLUSION: A beneficial effect of conversion from selective to universal WBC reduction was not demonstrated.

Leukocyte counting during process control of leukoreduced blood components.

BACKGROUND AND OBJECTIVES: To describe the characteristics of counting assays used for process control of leukoreduction. MATERIALS AND METHODS: Literature review. RESULTS: Counting assays with good performance characteristics are an essential element of the process control of leukoreduction. A recent multicenter study by a Working Party of the ISBT has evaluated three widely used methods for counting low numbers of leukocytes in leukoreduced blood. CONCLUSION: Automated methods provide greater accuracy and better inter-laboratory precision than Nageotte hematocytometry. However, deterioration of performance as a result of prolonged sample shipment remains an obstacle to centralized testing services. Although several mathematical approaches have been used to model the distribution of residual leukocytes in leukoreduced blood, no single model has been shown to be clearly superior.

Human plasma and tirilazad mesylate protect stored human erythrocytes against the oxidative damage of gamma-irradiation.

Transfusion-associated graft-versus-host disease (TA-GVHD) is a serious condition that under certain circumstances can be lethal in immunosuppressed patients. The risk of TA-GVHD can be reduced in this population by gamma irradiation (gammaRad) of blood components. gammaRad results in production of reactive oxygen species which can damage red blood cells (RBC). Tirilazad mesylate (TM) is a member of the 21-aminosteroids (Lazaroids) family and is a powerful antioxidant. We investigated the ability of TM and human plasma (which contain powerful antioxidants) to protect stored human RBC against the oxidative damage of gammaRad. Fresh intact packed RBC obtained from the normal donors, with and without autologous plasma or TM (0.05 mg mL-1 RBC), were exposed to gammaRad (50 Gy) and stored for 28 days at 4 degrees C. Oxidative damage was assessed by osmotic fragility at 65 mM NaCl concentration (expressed by percentage haemolysis in 65 mM NaCl solution) and lipid peroxidation (measured by thiobarbituric acid reactive substances, TBARS). Our results showed that storage and irradiation of untreated intact RBC increased the osmotic fragility at 65 mM NaCl concentration (65.8 +/- 1.3 vs. 51.20 +/- 0.87% haemolysis; irradiated vs. controls, respectively; P = 0.002) and lipid peroxidation (TBARS = 4.47 +/- 0. 12 vs. 3.45 +/- 0.09 microM L-1 RBC; irradiated vs. controls, respectively; P = 0.001). TM protected the intact RBC against radiation-induced haemolysis (35.8 +/- 5.0 vs. 65.8 +/- 1.3% haemolysis; treated vs. untreated irradiated RBC, respectively; P = 0.02) and lipid peroxidation (TBARS = 2.91 +/- 0.2 vs. 4.47 +/- 0.12 microM L-1 RBC; treated vs. untreated irradiated RBC, respectively; P = 0.005). Addition of autologous plasma to packed RBC significantly reduced the extent of radiation-induced haemolysis by more than six-fold (12.45 +/- 0.26 vs. 65.8 +/- 2.2% haemolysis; irradiated RBC with versus without plasma, respectively; P = 0.0001). In conclusion, these results show that irradiation and storage of blood damages RBC via oxidative processes and addition of autologous plasma and/or TM protects RBC against such damage and possibly enhances their storage and survival.

Detecting failed WBC-reduction processes: computer simulations of intermittent and continuous process failure.

BACKGROUND: By regulation, ongoing process control of WBC-reduced processes is performed on 1 percent of WBC-reduced components, typically four to five samples per month. However, prospective study of the power of this small sample has been difficult. Using computer-generated "residual WBC" distributions, sample size sensitivity to continuous or intermittent WBC-reduction failure was examined. STUDY DESIGN AND METHODS: Populations of log-normally distributed values (mean +/- SD, 4.5+/-0.5; n = 10(5)) were generated. Continuous failure (log-normality maintained) was simulated by incrementally increasing the population mean or its SD. Intermittent failure (bimodal distributions with discrete subpopulations of WBCs > the FDA cutoff) was simulated by admixing increasing percentages of secondary outlier populations. Sample sizes of 4 to 60 were examined (500 repetitions each) for their power to detect drift or failure by standard control criteria. RESULTS: Normally distributed low variance failure was easily detected by comparison of the mean of four samples to an upper control limit (95% confidence of detecting 2% failure). However, 40 samples were required to detect > 5 percent intermittent (bimodal) failure or high variance failure with 90-percent confidence, and only if individual WBC values were compared to cutoff. CONCLUSION: Sampling error limits the detection of high variance or bimodal distributions. While the mean of a small sample is highly sensitive to shifts in a low-variance normal distribution, the detection of a high-variance bimodal population requires a large number of individual values compared to cutoff. Therefore, the number of samples required for confident failure detection depends on both the nature of the underlying distribution and the interpretive criteria. Further research is necessary to determine the true distributions of WBC-reduction process failure, as well as clinically relevant quality limits.

Immediate vein graft thrombectomy for acute occlusion after coronary artery bypass grafting.

A 76-year-old man underwent coronary bypass grafting 3 days after exposure to heparin. Immediately after chest closure, he developed acute graft thrombosis and cardiac arrest in the setting of thrombocytopenia. Immediate graft thrombectomies were performed. Postoperative tests for heparin-induced thrombocytopenia and thrombosis (HITT) were positive. This case represents a dramatic example of HITT after coronary revascularization.

A sequence-specific polymerase chain reaction assay for mitochondrial DNA polymorphisms in human platelets and white cells.

BACKGROUND: Because mitochondria are abundant in white cells and are also present in platelets, polymorphic sequences in mitochondrial DNA (mtDNA) represent a unique target for polymerase chain reaction (PCR)-based detection of donor material. STUDY DESIGN AND METHODS: A PCR assay was developed that uses sequence-specific primers (SSP) focused on two continent-specific mtDNA polymorphisms. Results were validated by the use of informative restriction endonucleases. Three commercially available methods to extract mtDNA from white cell-reduced human platelets was compared. In preparation for in vivo studies, in vitro mixing studies designed to mimic transfusion were conducted to investigate the performance of the SSP-PCR assay. RESULTS: The gene sequences of two representative examples of amplicons obtained with the new SSP-PCR matched the sequence expected from the published genetic code. Fifteen individuals were classified as either positive (n = 6) or negative (n = 9) for the Asian polymorphism by the use of published primers known to flank the polymorphic site followed by digestion with appropriate restriction enzymes. Results with SSP-PCR were nearly perfectly concordant with those of restriction enzyme analysis. Although the use of three DNA extraction methods allowed the preparation of mtDNA that was suitable for PCR, large and consistent differences (ranging from 10- to 1000-fold) in endpoint sensitivity were found. In vitro mixing studies reproducibly documented that the SSP-PCR assay could detect as little as 1 percent of donor platelets mixed with recipient blood. CONCLUSION: PCR-SSP can be reliably used to identify human mtDNA polymorphisms. By optimization of the method of mtDNA extraction, the sensitivity of PCR-SSP assay was greatly increased. This assay should prove useful in investigations of allogeneic platelet transfusions without cell labeling. It may also be applied to studies of the donor cell microchimerism that follows transfusion or transplantation.

A general method for concentrating blood samples in preparation for counting very low numbers of white cells.

BACKGROUND: To count extremely low levels of white cells (WBCs) in WBC-reduced blood components, a larger volume of sample must be processed. The goal was to develop an all-purpose method for concentrating the samples obtained from WBC-reduced red cells or platelets. The method was designed to be compatible with a variety of counting techniques. STUDY DESIGN AND METHODS: Coded samples of red cell concentrates with an expected WBC concentration of 200, 100, 50, and 10 per mL and of the diluent (undetectable WBCs/mL) were sent to three sites on five occasions and counted by the use of the concentration method, crystal violet stain, and a Nageotte counting chamber. Additional samples were tested by flow cytometry, polymerase chain reaction, and volumetric capillary cytometry. RESULTS: The results from the three test sites showed good linearity, with an overall r2 = 0.9994. The lower limit of accurate detection of the assay was 10 WBCs per mL. The results were biased toward underestimation, particularly at one of the test sites (Site A). There were no significantly different results in Sites B and C. The intra-assay CV was acceptable. Precision (reproducibility) at the three test sites varied. CONCLUSION: This method allows reliable determination of WBC concentrations as low as 0.01 per microL in blood. Despite the use of technologists trained in Nageotte chamber counting, validation testing demonstrated that one test site's performance was significantly different from that of the other two sites, because of both underestimation bias and variation in count results. The sample concentration method, when used in conjunction with an automated assay for WBC identification, should permit larger volume analysis with a greater degree of precision and a lower limit of detection than is found in assays that do not concentrate the sample before counting.