The oxygen saturation of red blood cell concentrates: The basis for a novel index of red cell oxidative stress.

BACKGROUND: Oxidative stress is a major driving force in the development of storage lesions in red cell concentrates (RCCs). Unlike manufactured pharmaceuticals, differences in component preparation methods and genetic/physiological status of donors result in nonuniform biochemical characteristics of RCCs. Various characteristics of donated blood on oxygen saturation (SO2 ) distribution were investigated, and a model to estimate potential oxidative stress burden of stored RCC at transfusion is proposed. STUDY DESIGN AND METHODS: The oxygen content of freshly prepared RCCs (770) was quantified noninvasively as fractional hemoglobin saturation (SO2 ) with visible reflectance spectrometry. Using separate RCCs and mimicking typical handling of RCCs during routine storage, evolution of SO2 was followed for construction of an empirical model. Based on this model, the oxygen exposure index (OEI) was formulated to estimate the accumulated oxygen exposure burden of RCC at the time of transfusion. RESULTS: The SO2 of RCCs varied widely at donation (mean 43% ± 1.3%; range 20%-93%). Multivariate regression model showed that sex and processing method had small effects on SO2 (R2  = 0.12), indicating that variability was mainly attributed to other individual donor characteristics. Storage simulation model indicated that median SO2 increased gradually over 6 weeks (approx. 1.3 fold), while OEI increased at a faster rate (approx. eight-fold). CONCLUSION: In addition to storage age, the OEI provides a potential new metric to assess the quality of RCCs at the time of transfusion in terms of their oxidative stress. In future studies, a single noninvasive measurement during storage could link OEI to clinical outcomes in transfusion recipients.

Changes in blood center red blood cell distributions in the era of patient blood management: the trends for collection (TFC) study.

BACKGROUND: As patient blood management becomes more widespread, fewer red blood cell (RBC) units have been transfused. This multinational study evaluated changes in blood center RBC distributions. STUDY DESIGN AND METHODS: Data on number and ABO and D groups of RBC distributions were obtained from several large American blood centers and national or provincial blood services (NPBS) from fiscal year (FY) 2010 through FY2014. Due to relatively larger numbers of distributions and differences in ABO and D groups between the Japanese Red Cross and the other NPBS, Japanese data were not included in distributions calculations. RESULTS: Data from seven American blood centers and eight NPBS were obtained. Overall, at both the American and the seven NPBS that were analyzed, there were declines in the number of RBC distributions between FY2010 and FY2014, 16.9 and 8.0%, respectively. The number of O- RBC distributions decreased by 9.0% at American blood centers but the proportion of RBC distributions that were O- increased by 9.3% during this time. The NPBS had 1.6% increase in O- RBC distributions and 10.5% increase in the proportion of O- distributions. The proportion of O+ distributions increased slightly over time at American centers (2.9%) while decreasing slightly (1.1%) at NPBS despite reductions in the absolute numbers of O+ distributions. Overall there was 2.6% decrease in the proportion of B+ and AB+ RBCs distributed and 13.6% absolute reduction in the number of these units distributed. CONCLUSION: Although overall RBC distributions have decreased over time, the proportion of O units has increased substantially.

Factors affecting red blood cell storage age at the time of transfusion.

BACKGROUND: Clinical trials are investigating the potential benefit resulting from a reduced maximum storage interval for red blood cells (RBCs). The key drivers that determine RBC age at the time of issue vary among individual hospitals. Although progressive reduction in the maximum storage period of RBCs would be expected to result in smaller hospital inventories and reduced blood availability, the magnitude of the effect is unknown. STUDY DESIGN AND METHODS: Data on current hospital blood inventories were collected from 11 hospitals and three blood centers in five nations. A general predictive model for the age of RBCs at the time of issue was developed based on considerations of demand for RBCs in the hospital. RESULTS: Age of RBCs at issue is sensitive to the following factors: ABO group, storage age at the time of receipt by the hospital, the restock interval, inventory reserve, mean demand, and variation in demand. CONCLUSIONS: A simple model, based on hospital demand, may serve as the basis for examining factors affecting the storage age of RBCs in hospital inventories. The model suggests that the age of RBCs at the time of their issue to the patient depends on factors external to the hospital transfusion service. Any substantial change in the expiration date of stored RBCs will need to address the broad variation in demand for RBCs while attempting to balance considerations of availability and blood wastage.

Errors in patient specimen collection: application of statistical process control.

BACKGROUND: Errors in the collection and labeling of blood samples for pretransfusion testing increase the risk of transfusion-associated patient morbidity and mortality. Statistical process control (SPC) is a recognized method to monitor the performance of a critical process. An easy-to-use SPC method was tested to determine its feasibility as a tool for monitoring quality in transfusion medicine. STUDY DESIGN AND METHODS: SPC control charts were adapted to a spreadsheet presentation. Data tabulating the frequency of mislabeled and miscollected blood samples from 10 hospitals in five countries from 2004 to 2006 were used to demonstrate the method. Control charts were produced to monitor process stability. RESULTS: The participating hospitals found the SPC spreadsheet very suitable to monitor the performance of the sample labeling and collection and applied SPC charts to suit their specific needs. One hospital monitored subcategories of sample error in detail. A large hospital monitored the number of wrong-blood-in-tube (WBIT) events. Four smaller-sized facilities, each following the same policy for sample collection, combined their data on WBIT samples into a single control chart. One hospital used the control chart to monitor the effect of an educational intervention. CONCLUSION: A simple SPC method is described that can monitor the process of sample collection and labeling in any hospital. SPC could be applied to other critical steps in the transfusion processes as a tool for biovigilance and could be used to develop regional or national performance standards for pretransfusion sample collection. A link is provided to download the spreadsheet for free.

Review of the quality monitoring methods used by countries using or implementing universal leukoreduction.

Several countries are implementing or have implemented universal leukoreduction (ULR). Specifications, leukocyte counting, and monitoring methods were essential elements in achieving process confidence and conformance. A review of these protocols is presented. A questionnaire was prepared, agreed, and circulated, and responses were collated. Different specifications have been adopted as well as disparate approaches to leukocyte counting and residual leukocyte monitoring. Parametric, nonparametric, and pass-rate methods of analysis were used. Despite these differences, users were satisfied that the methodologies were providing assurance of component quality.

Value of central analysis of leucocyte depletion quality control data within the National Blood Service, England.

BACKGROUND AND OBJECTIVES: The results of quality monitoring leucocyte counts were analysed nationally for the first 2 years of universal leucocyte depletion (LD), spanning the time-period before and after standardization of the counting and LD methods. The objectives were twofold: first to determine whether the implementation strategy was effective in achieving the LD specification (< 5 x 10(6) leucocytes in 99% of components with 95% statistical confidence); and second, whether quality monitoring was able to detect potential non-conformance. MATERIALS AND METHODS: Residual leucocytes were counted using Beckman Coulter or Becton Dickinson (BD) flow cytometers and reagents. Data were collected into standardized analysis software (NWA Quality Analyst) for local trend analysis and checks for conformance to process specification, and collated centrally. Analysis was performed for six time-periods between January 1999 and March 2001. Specification failures were analysed to determine the likelihood of extreme failure. Statistical process monitoring was adjusted to suit LD processes. RESULTS: Data from red cells in optimal additive solution (OAS), filtered either as whole blood or red cell concentrates, and platelet pools improved significantly over the 2-year period with specification failures falling from 0.35%, 0.48% and 0.56%, respectively, in January-June 1999 to 0.06%, 0.01% and 0.04% in January-March 2001. Specification failures in red cells in OAS LD for the period January-December 2000 showed only 0.02% with a leucocyte count of > 30 x 10(6)/unit. Extreme failures are now very rare. Monitoring methods have been effective in detecting process change and drift. CONCLUSION: LD performance varies between different LD systems, but monitoring has proved sufficiently robust to detect processes that perform poorly. The chosen specification has been both achievable and appropriate to the systems in use. Standardization of the counting method is central to the ability to monitor and analyse results effectively across the whole service.