An association of ABO non-identical platelet and cryoprecipitate transfusions with altered red cell transfusion needs in surgical patients

Reduction of anti-A and anti-B isoagglutinin titers of group O whole blood units employing an ABO antibody immune adsorption column

BACKGROUND

Massive hemorrhage is a leading cause of death from trauma. There is growing interest in group O whole blood transfusions to mitigate coagulopathy and hemorrhagic shock. Insufficient availability of low-titer group O whole blood is a barrier to routine use. We tested the efficacy of the Glycosorb® ABO immunoadsorption column to reduce anti-A/B titers in group O whole blood.

METHODS

Six group O whole blood units were collected from healthy volunteers, and centrifuged to separate platelet poor plasma. Platelet-poor plasma was filtered through a Glycosorb® ABO antibody immunoabsorption column, then reconstituted to prepare post-filtration whole blood. Anti-A/B titers, CBC, free hemoglobin, and thromboelastography (TEG) assays were performed on pre-and post-filtration whole blood.

RESULTS

Mean( ± SEM) anti-A (224 ± 65 pre vs 13 ± 4 post) and anti-B (138 ± 38 pre vs 11 ± 4 post) titers were significantly reduced (p = 0.004) in post-filtration whole blood. No significant changes were detected in CBC, free hemoglobin, and TEG parameters on day 0. Free hemoglobin increased throughout storage (48 mg/dl ± 24 Day 0 vs 73 ± 35 Day 7 vs 96 ± 44 Day 14; p = 0.14).

CONCLUSIONS

The Glycosorb® ABO column can significantly reduce anti-A/B isoagglutinin titers of group O whole blood units. Glycosorb® ABO could be employed to provide whole blood with lower risk of hemolysis and other consequences of infusing ABO incompatible plasma. Preparation of group O whole blood with substantially reduced anti-A/B would also increase the supply of low-titer group O whole blood for transfusion.

How do we forecast tomorrow's transfusion? - Next generation transfusion practices to improve recipient safety

Recipient safety measures play a key role in overall transfusion efficacy. The key advances in safety over the first century of transfusion medicine have been the development of techniques to prevent hemolytic transfusion reactions, hemolytic disease of the newborn and transmission of viral pathogens. While these risks remain important, they affect many fewer patients than previously. We propose that some of the most important current safety issues relate to toxicities broadly encompassed by the immunomodulatory effects of allogeneic transfusion. These include (1) universal leukoreduction to mitigate nosocomial infections, inflammation and organ injury, (2) removal of stored supernatant and its attendant toxic contents that cause dysfunctional immunity and organ injury, (3) avoiding infusing ABO incompatible antigen and antibody that can lead to bleeding, platelet refractoriness and inflammation, (3) minimizing prophylactic transfusions (particularly of plasma and platelets) except where benefit is proven, and (4) avoiding use of normal saline which is linked to renal failure and possibly hemolysis. Accompanying these safety measures will be the continued growth of one of the most important safety measures, patient blood management, which has as one benefit the avoidance of unnecessary and harmful transfusions. Reducing the toxicity of transfusions will enhance the improved clinical outcomes seen with patient blood management.

Severe acute haemolytic transfusion reaction secondary to a plasma incompatible group B platelet transfusion

OBJECTIVES

To report a rare case of acute hemolytic transfusion reaction (AHTR) following an ABO plasma incompatible group B platelet transfusion.

BACKGROUND

AHTR is an uncommon, but potentially fatal event. Most reported cases of platelet transfusions associated with AHTR involve group O donors.

CASE REPORT

A 34-year-old man, recipient of a group AB haploidentical haematopoietic stem cell transplantation (HSCT), had received re-induction chemotherapy for leukaemia relapse. A group B whole blood-derived buffy coat platelet pool was transfused. He developed rigours/fever, profound hemolytic anaemia, and hemodynamic instability. Serological investigations revealed AHTR from passive transfer of high titre anti-A (256 for IgM and 8192 for IgG).

DISCUSSION

This case highlights the potential risks associated with ABO-mismatched transfusions, and the complexity associated with transfusing HSCT recipients and red cell transfusion recipients with dual populations of circulating red cells. The literature on minor ABO plasma incompatible transfusions, challenges in establishing local policies to limit the risks of AHTR and risk mitigation strategies are discussed.

CONCLUSION

Clinicians must maintain a high level of suspicion for AHTR after ABO plasma incompatible platelet transfusions. Patients must be aware of the risks of AHTR, and early recognition and diagnosis of this complication may be lifesaving.

Practice patterns of ABO-matching for cryoprecipitate and patient outcomes after ABO-compatible versus incompatible cryoprecipitate

BACKGROUND AND OBJECTIVES

This sub-study of the FIBRES trial sought to examine the patterns of ABO-compatible cryoprecipitate administration and to identify adverse consequences of ABO-incompatible cryoprecipitate.

MATERIALS AND METHODS

This was a post hoc analysis of data collected from the FIBRES randomized clinical trial comparing fibrinogen concentrate with cryoprecipitate in the treatment of bleeding related to hypofibrinogenemia after cardiac surgery. The primary outcome was the percentage of administered cryoprecipitate that was ABO-compatible. Secondary outcomes were adverse events at 28 days. A follow-up survey was distributed to the FIBRES participating sites to examine the rationale behind the identified cryoprecipitate ABO-matching practice patterns.

RESULTS

A total of 363 patients were included: 53 (15%) received ABO-incompatible cryoprecipitate and 310 (85%) received ABO-compatible cryoprecipitate. There was an increased incidence of post-operative anaemia in the ABO-incompatible group (15; 28.3%) in comparison to the ABO-compatible (44; 14.2%) group (p = 0.01) at 28 days, which was unrelated to haemolysis, without a significant difference in transfusion requirement. In the multivariable logistic regression models accounting for clustering by site, there was no observed statistically significant association between the administration of ABO-incompatible cryoprecipitate and any other adverse outcomes. Nine out of 11 sites did not have a policy requiring ABO-matched cryoprecipitate.

CONCLUSION

This sub-study demonstrated that most cryoprecipitate administered in practice is ABO-compatible, despite the absence of guidelines or blood bank policies to support this practice. A signal towards increased risk of post-operative anaemia may be explained by higher rates of urgent surgery (vs. elective) in the ABO-incompatible group. Future studies should prospectively examine the impact of ABO-compatible versus incompatible cryoprecipitate to conclusively establish if there is a meaningful clinical impact associated with the administration of ABO-incompatible cryoprecipitate.

Impacts of ABO-incompatible platelet transfusions on platelet recovery and outcomes after intracerebral hemorrhage

Acute platelet transfusion after intracerebral hemorrhage (ICH) given in efforts to reverse antiplatelet medication effects and prevent ongoing bleeding does not appear to improve outcome and may be associated with harm. Although the underlying mechanisms are unclear, the influence of ABO-incompatible platelet transfusions on ICH outcomes has not been investigated. We hypothesized that patients with ICH who receive ABO-incompatible platelet transfusions would have worse platelet recovery (using absolute count increment [ACI]) and neurological outcomes (mortality and poor modified Rankin Scale [mRS 4-6]) than those receiving ABO-compatible transfusions. In a single-center cohort of consecutively admitted patients with ICH, we identified 125 patients receiving acute platelet transfusions, of whom 47 (38%) received an ABO-incompatible transfusion. Using quantile regression, we identified an association of ABO-incompatible platelet transfusion with lower platelet recovery (ACI, 2 × 103cells per μL vs 15 × 103cells per μL; adjusted coefficient β, -19; 95% confidence interval [CI], -35.55 to -4.44; P = .01). ABO-incompatible platelet transfusion was also associated with increased odds of mortality (adjusted odds ratio [OR], 2.59; 95% CI, 1.00-6.73; P = .05) and poor mRS (adjusted OR, 3.61; 95% CI, 0.97-13.42; P = .06); however, these estimates were imprecise. Together, these findings suggest the importance of ABO compatibility for platelet transfusions for ICH, but further investigation into the mechanism(s) underlying these observations is required.

Alterations in platelet behavior after major trauma: adaptive or maladaptive?

Platelets are damage sentinels of the intravascular compartment, initiating and coordinating the primary response to tissue injury. Severe trauma and hemorrhage induce profound alterations in platelet behavior. During the acute post-injury phase, platelets develop a state of impaired ex vivo agonist responsiveness independent of platelet count, associated with systemic coagulopathy and mortality risk. In patients surviving the initial insult, platelets become hyper-responsive, associated with increased risk of thrombotic events. Beyond coagulation, platelets constitute part of a sterile inflammatory response to injury: both directly through release of immunomodulatory molecules, and indirectly through modifying behavior of innate leukocytes. Both procoagulant and proinflammatory aspects have implications for secondary organ injury and multiple-organ dysfunction syndromes. This review details our current understanding of adaptive and maladaptive alterations in platelet biology induced by severe trauma, mechanisms underlying these alterations, potential platelet-focused therapies, and existing knowledge gaps and their research implications.

Blood Banking and Transfusion Medicine Challenges During the COVID-19 Pandemic

SARS-CoV-2 (also known as COVID-19) has been an unprecedented challenge in many parts of the medical field with blood banking being no exception. COVID-19 has had a distinctly negative effect on our blood collection nationwide forcing blood banks, blood centers, and the US government to adopt new policies to adapt to a decreased blood supply as well as to protect our donors from COVID-19. These policies can be seen distinctly in patient blood management and blood bank operations. We are also faced with developing policies and procedures for a nontraditional therapy, convalescent plasma; its efficacy and safety is still not completely elucidated as of yet.

Transfusion of ABO non-identical platelets increases the severity of trauma patients at ICU admission

BACKGROUND

Transfusion of ABO-compatible non-identical platelets (PTLs), fresh plasma (FP) and red blood cells (RBCs) has been associated with increased morbidity and mortality of recipients. Trauma victims are frequently exposed to ABO non-identical products, given the need for emergency transfusions. Our goal was to evaluate the impact of the transfusion of ABO non-identical blood products on the severity and all-cause 30-day mortality of trauma patients.

METHODS

This was a retrospective single-center cohort, which included trauma patients who received emergency transfusions in the first 24 h of hospitalization. Patients were divided in two groups according to the use of <3 or ≥3 ABO non-identical blood products. The patient severity, measured by the Acute Physiology and Chronic Health Evaluation (APACHEII) score at ICU admission, and the 30-day mortality were compared between groups.

RESULTS

Two hundred and sixteen trauma patients were enrolled. Of these, 21.3% received ≥3 ABO non-identical blood products (RBCs, PLTs and FP or cryoprecipitate). The transfusion of ≥3 ABO non-identical blood products in the first 24 h of hospitalization was independently associated with a higher APACHEII score at ICU admission (OR = 3.28 and CI95% = 1.48-7.16). Transfusion of at least one unit of ABO non-identical PTLs was also associated with severity (OR = 10.89 and CI95% = 3.38-38.49). Transfusion of ABO non-identical blood products was not associated with a higher 30-day mortality in the studied cohort.

CONCLUSION

The transfusion of ABO non-identical blood products and, especially, of ABO non-identical PLTs may be associated with the greater severity of trauma patients at ICU admission. The transfusion of ABO non-identical blood products in the trauma setting is not without risks.

Perioperative Management of Bleeding and Transfusion for Lung Transplantation

Perioperative allogeneic blood product transfusion is common in lung transplantation and has various implications on the short- and long-term outcomes of lung recipients. This review summarizes the effect of transfusion on outcomes including primary graft dysfunction, chronic lung allograft dysfunction, and all-cause mortality. We outline known risk factors for increased transfusion requirement in lung transplantation and present current evidence regarding the effect of hemostatic agents including antifibrinolytics, recombinant factor VII, and prothrombin complex concentrates. Finally, we highlight the roles of point-of-care coagulation testing and goal-directed transfusion strategies in reducing transfusion requirements in lung transplantation.

Transfusion medicine: A research agenda for the coming years

The important scientific and clinical advances of the last century in transfusion medicine include methods for avoiding hemolytic transfusion reactions and preventing transmission of viral infectious diseases. The next great clinical advances will require improving the efficacy and safety of transfusions, as well as acknowledgement of the now proven serious complications of transfusion, including nosocomial infection, thrombosis, inflammation and multi-organ failure. Possible strategies include (1) universal leukoreduction to mitigate transfusion immunomodulation effects and improve storage conditions, (2) minimizing transfusion of ABO incompatible antibodies and cellular/soluble antigens, (3) substituting use of safer solutions for normal saline during apheresis, component infusion and washing (4) new techniques to improve the efficacy and safety of blood components, including improved storage solutions/conditions, supernatant removal by washing, and rejuvenation and (5) maximizing the risk to benefit ratio of transfusions by employing more restrictive and physiologic indications for transfusion (including patient blood management) and improving clinical decision making through novel laboratory and bedside tests such as thromboelastography.

Indications for red cell transfusions in pediatric patients

Red cell transfusions are amongst the most common therapeutic procedures in seriously ill children, particularly in the inpatient setting. This is despite the fact that there is no evidence base for most clinical settings, with the exception of patients with hemoglobinopathies, particularly thalassemia and sickle cell anemia. Obviously exsanguinating hemorrhage and life threatening anemia are urgent indications for which no other therapeutic approach is currently available. Most transfusions are, however, given prophylactically to prevent the complications of hypoxia or hemodynamic stability, based upon expert opinion and a faith in the oxygen carrying capacity and beneficial hemodynamic properties of transfused red cells. The question confronting current day pediatric practice is to what extent transfused red cells prevent adverse events, other than in thalassemia and sickle cell anemia, as opposed to causing them. Do transfusions of red cells prevent organ failure, stroke, etc. or not? There is epidemiologic evidence in the adult randomized trial literature that liberal red cell transfusion likely causes more such adverse events than it prevents. The relevance of such studies to children, particularly neonates, is uncertain. Randomized trials in critically ill neonates have yielded little to no evidence that liberal red cell transfusion is beneficial, but the data are not definitive. In critically ill older children the data suggest there is no benefit to liberal red cell transfusion, but the indications for red cell transfusion are uncertain. Most practitioners would agree that combining laboratory data such hemoglobin/hematocrit with clinical indications for transfusions (evidence of end organ hypoxia such as tachycardia, shortness of breath, etc.) is the only viable strategy at present, until more definitive randomized trial data are available.

Coagulation Management During Liver Transplantation: Use of Fibrinogen Concentrate, Recombinant Activated Factor VII, Prothrombin Complex Concentrate, and Antifibrinolytics

Coagulation management, and transfusion practice in liver transplantation (LT) have been evolving in the recent years due to better understanding of coagulation abnormalities in end-stage liver disease, and clinical management of LT patients. Avoidance of allogeneic blood components is feasible in some patients, but multi-modal coagulation therapies may be necessary in others who develop complex coagulopathy due to hemorrhage, hemodilution, hypothermia, and acid-base disturbances. Transfusions of plasma and cryoprecipitate remain to be the mainstay therapy for procoagulant factor replacement during LT. Clinical efficacy and safety of these products are limited by logistic issues (eg, thawing), and mostly noninfectious complications. Considering potential alternatives to conventional transfusion is thus important to improve hemostatic resuscitation in complex LT cases. The present review is mainly focused on procoagulant properties of plasma and platelet transfusion, and currently available plasma-derived and recombinant factor concentrates, and antifibrinolytic agents in LT patients. The role of viscoelastic coagulation tests to guide specific component therapies will be also discussed.

Potential impact of complement regulator deficiencies on hemolytic reactions due to minor ABO-mismatched transfusions

Minor ABO-mismatched transfusions are a common occurrence, although infrequent transfusion reactions occur. We sought to investigate the regulation of complement C3 activation induced by anti-A. In vitro complement C3 activation was observed with 10 of 30 group O samples and correlated with immunoglobulin M (IgM) anti-A titers. We developed an in vitro paroxysmal nocturnal hemoglobinuria (PNH) model of hemolysis in which group A1 red blood cells (RBCs) were chemically treated with 2-aminoethylisothiouronium (AET) to alter regulators of complement C3 activation. Intravascular hemolysis was simulated by incubating an IgG nonhemolytic group O plasma (titer = 32) with A1 RBCs. IgG was detected on the RBCs, but hemolysis was observed with AET-treated RBCs only. When treated and untreated RBCs were tested together (1:4), we determined that the failure to observe C3b/d deposition on RBCs was due to the complete hemolysis of the AET-treated minor RBC population. A group O patient with a 9% CD59-deficient PNH clone was sensitized with an IgM anti-I. Hemolysis, with a weak positive direct antiglobulin test (DAT) resulting from C3b/d, was observed after incubation with fresh AB serum. Flow cytometry showed an 86% reduction of the PNH clone. Our work indicates that the transfusion of minor ABO-mismatched plasma could cause hemolysis with a negative DAT C3b/d. We propose that the presence of a PNH clone is 1 possible cause of unexplained anemia for recipients of ABO-mismatched product. This work suggests that other acquired or inherited defects of decay-accelerating factor and membrane inhibitor of reactive lysis could be responsible for infrequent but clinically important hemolysis after ABO-mismatched transfusions.

Management of Platelet Disorders and Platelet Transfusions in ICU Patients

Thrombocytopenia or receipt of antiplatelet drugs, with or without bleeding, is a common indication for platelet transfusions in the ICU. However, there is almost no evidence base for these practices other than expert opinion. Also common is use of platelet transfusions prior to invasive procedures or surgery in patients with thrombocytopenia. Likewise, there is no high-quality evidence that such practices are efficacious or safe. Recently, it has become clear that, whether causal or not, patients receiving prophylactic platelet transfusions experience high rates of nosocomial infection, thrombosis, organ failure, and mortality, which increase the urgency and need for randomized trials to assess these practices. Investigational methods of improving the safety and efficacy of platelet transfusions include use of alternate strategies such as antifibrinolytics; use of ABO-identical, leukoreduced, and washed platelet transfusions; and improved storage solutions.

Current trends in platelet transfusions practice: The role of ABO-RhD and human leukocyte antigen incompatibility

Platelet transfusions have contributed to the revolutionary modern treatment of hypoproliferative thrombocytopenia. Despite the long-term application of platelet transfusion in therapeutics, all aspects of their optimal use (i.e., in cases of ABO and/or Rh (D incompatibility) have not been definitively determined yet. We reviewed the available data on transfusion practices and outcome in ABO and RhD incompatibility and platelet refractoriness due to anti-human leukocyte antigen (HLA) antibodies. Transfusion of platelets with major ABO-incompatibility is related to reduced posttransfusion platelet (PLT) count increments, compared to ABO-identical and minor, but still are equally effective in preventing clinical bleeding. ABO-minor incompatible transfusions pose the risk of an acute hemolytic reaction of the recipient that is not always related to high anti-A, B donor titers. ABO-identical PLT transfusion seems to be the most effective and safest therapeutic strategy. Exclusive ABO-identical platelet transfusion policy could be feasible, but alternative approaches could facilitate platelet inventory management. Transfusion of platelets from RhD positive donors to RhD negative patients is considered to be effective and safe though is associated with low rate of anti-D alloimmunization due to contaminating red blood cells. The prevention of D alloimmunization is recommended only for women of childbearing age. HLA alloimmunization is a major cause of platelet refractoriness. Managing patients with refractoriness with cross-matched or HLA-matched platelets is the current practice although data are still lacking for the efficacy of this practice in terms of clinical outcome. Leukoreduction contributes to the reduction of both HLA and anti-D alloimmunization.

Platelet transfusion - the new immunology of an old therapy

Platelet transfusion has been a vital therapeutic approach in patients with hematologic malignancies for close to half a century. Randomized trials show that prophylactic platelet transfusions mitigate bleeding in patients with acute myeloid leukemia. However, even with prophylactic transfusions, as many as 75% of patients, experience hemorrhage. While platelet transfusion efficacy is modest, questions and concerns have arisen about the risks of platelet transfusion therapy. The acknowledged serious risks of platelet transfusion include viral transmission, bacterial sepsis, and acute lung injury. Less serious adverse effects include allergic and non-hemolytic febrile reactions. Rare hemolytic reactions have occurred due to a common policy of transfusing without regard to ABO type. In the last decade or so, new concerns have arisen; platelet-derived lipids are implicated in transfusion-related acute lung injury after transfusion. With the recognition that platelets are immune cells came the discoveries that supernatant IL-6, IL-27 sCD40L, and OX40L are closely linked to febrile reactions and sCD40L with acute lung injury. Platelet transfusions are pro-inflammatory, and may be pro-thrombotic. Anti-A and anti-B can bind to incompatible recipient or donor platelets and soluble antigens, impair hemostasis and thus increase bleeding. Finally, stored platelet supernatants contain biological mediators such as VEGF and TGF-β1 that may compromise the host versus tumor response. This is particularly of concern in patients receiving many platelet transfusions, as for acute leukemia. New evidence suggests that removing stored supernatant will improve clinical outcomes. This new view of platelets as pro-inflammatory and immunomodulatory agents suggests that innovative approaches to improving platelet storage and pre-transfusion manipulations to reduce toxicity could substantially improve the efficacy and safety of this long-employed therapy.

Transfusion of ABO non-identical platelets does not influence the clinical outcome of patients undergoing autologous haematopoietic stem cell transplantation

BACKGROUND

There are ABO antigens on the surface of platelets, but whether ABO compatible platelets are necessary for transfusions is a matter of ongoing debate. We retrospectively reviewed the ABO matching of platelet transfusions in a subset of patients undergoing autologous haematopoietic progenitor cell transplantation during a 14-year period. Our aim was to analyse the characteristics and outcomes of patients who received platelet transfusions that were or were not ABO identical.

MATERIAL AND METHODS

We analysed 529 consecutive patients with various haematological and non-haematological diseases who underwent 553 autologous progenitor stem cell transplants at the University Hospital la Fe between January 2000 and December 2013. We retrospectively analysed and compared transfusion and clinical outcomes of patients according to the ABO match of the platelet transfusions received. The period analysed was the time from transplantation until discharge.

RESULTS

The patients received a total of 2,772 platelet concentrates, of which 2,053 (74.0%) were ABO identical and 719 (26.0%) ABO non-identical; of these latter 309 were compatible and 410 incompatible with the patients' plasma. Considering all transplants, 36 (6.5%) did not require any platelet transfusions, while in 246 (44.5%) cases, the patients were exclusively transfused with ABO identical platelets and in 47 (8.5%) cases they received only ABO non-identical platelet transfusions. The group of patients who received both ABO identical and ABO non-identical platelet transfusions had higher transfusion needs and worse clinical outcomes compared to patients who received only ABO identical or ABO non-identical platelets.

DISCUSSION

In our hospital, patients undergoing autologous haematopoietic stem cell transplantation who received ABO identical or ABO non-identical platelet transfusions had similar transfusion and clinical outcomes. The isolated fact of receiving ABO non-identical platelets did not influence morbidity or survival.

Comparison of two platelet transfusion strategies to minimize ABO-nonidentical transfusion, outdating, and shortages using a computer-simulated "virtual blood bank"

BACKGROUND

Transfusion of ABO-incompatible platelets (PLTs) is associated with reduced PLT recovery and a risk of transfusion reactions. However, a policy of transfusing only ABO-identical PLTs may increase wastage due to product outdating. A prospective study attempting to compare the effects of different ABO compatibility strategies could be costly and disruptive to a blood bank's operations.

STUDY DESIGN AND METHODS

We designed a "virtual blood bank," a stochastic computer program that models the stocking and release of products to meet demand for PLT transfusion in a simulated hospital population. ABO-nonidentical transfusions (ABOni), outdates, and inventory shortages were recorded and compared under two different transfusion strategies: ABO-First, a strategy that prioritizes transfusion of ABO-identical PLTs, and Age-First, a strategy that minimizes outdating by transfusing products closest to expiration.

RESULTS

The ABO-First strategy resulted in fewer ABOni but more outdates than the Age-First strategy. Under conditions that mimic a large hospital blood bank, the ABO-First strategy was more cost-effective overall than the Age-First strategy if avoiding an ABOni is valued at more than $19 to $26. For a small blood bank, the ABO-First strategy was more cost-effective if avoiding an ABOni is valued at more than $104 to $123.

CONCLUSION

Based on a virtual blood bank computer simulation, the cost of avoiding an ABOni using the ABO-First strategy varies greatly by size of institution. Individual blood banks must carefully consider these management strategies to determine the most cost-effective solution.

Platelet transfusion - the art and science of compromise

SUMMARY

Many modern therapies depend on platelet (PLT) transfusion support. PLTs have a 4- to 7-day shelf life and are frequently in short supply. In order to optimize the inventory PLTs are often transfused to adults without regard for ABO compatibility. Hemolytic reactions are infrequent despite the presence of 'high titer' anti-A and anti-B antibodies in some of the units. Despite the low risk for hemolysis, some centers provide only ABO identical PLTs to their recipients; this practice might have other beneficial outcomes that remain to be proven. Strategies to mitigate the risk of hemolysis and the clinical and laboratory outcomes following ABO-matched and mismatched transfusions will be discussed. Although the PLTs themselves do not carry the D antigen, a small number of RBCs are also transfused with every PLT dose. The quantity of RBCs varies by the type of PLT preparation, and even a small quantity of D+ RBCs can alloimmunize a susceptible D- host. Thus PLT units are labeled as D+/-, and most transfusion services try to prevent the transfusion of D+ PLTs to D- females of childbearing age. A similar policy for patients with hematological diseases is controversial, and the elements and mechanisms of anti-D alloimmunization will be discussed.

Alterations of platelet function and clot formation kinetics after in vitro exposure to anti-A and -B

BACKGROUND

ABO-mismatched platelets (PLTs) are commonly transfused despite reported complications. We hypothesized that because PLTs possess A and B antigens on their surface, ABO-mismatched transfused or recipient PLTs could become activated and/or dysfunctional after exposure to anti-A or -B in the transfused or recipient plasma. We present here in vitro modeling data on the functional effects of exposure of PLTs to ABO antibodies.

STUDY DESIGN AND METHODS

PLT functions of normal PLTs of all ABO types were assessed before and after incubation with normal saline, ABO-identical plasma samples, or O plasma samples with varying titers of anti-A and anti-B (anti-A/B). Assays used for this assessment include PLT aggregation, clot kinetics, thrombin generation, PLT cytoskeletal function, and mediator release.

RESULTS

Exposure of antigen-bearing PLTs to O plasma with moderate to high titers of anti-A/B significantly inhibits aggregation, prolongs PFA-100 epinephrine closure time, disrupts clot formation kinetics, accelerates thrombin generation, reduces total thrombin production, alters PLT cytoskeletal function, and influences proinflammatory and prothrombotic mediator release.

CONCLUSIONS

Our findings demonstrate a wide range of effects that anti-A/B have on PLT function, clot formation, thrombin generation, PLT cytoskeletal function, and mediator release. These data provide potential explanations for clinical observations of increased red blood cell utilization in trauma and surgical patients receiving ABO-nonidentical blood products. Impaired hemostasis caused by anti-A/B interacting with A and B antigens on PLTs, soluble proteins, and perhaps even endothelial cells is a potential contributing factor to hemorrhage in patients receiving larger volumes of ABO-nonidentical transfusions.

Providing ABO-identical platelets and cryoprecipitate to (almost) all patients: approach, logistics, and associated decreases in transfusion reaction and red blood cell alloimmunization incidence

BACKGROUND

There are multiple benefits to transfusing only ABO-identical blood components. Historically our institution routinely transfused ABO-nonidentical platelets (PLTs) and cryoprecipitate to surgical patients. In April 2005, we implemented a policy of transfusing only ABO-identical components whenever feasible, regardless of outdating or logistic considerations.

STUDY DESIGN AND METHODS

Technical staff closely monitored product usage and adjusted blood center orders based on recent utilization and planned transfusions. When unable to provide ABO-identical PLTs, ABO-compatible PLTs were washed to remove incompatible plasma. Data on outdating were collected for 18 months before and after implementation. We compared transfusion reaction and red blood cell (RBC) alloimmunization incidence for 4 years preceding (2001-2004) and subsequent (2006-2009) to implementation.

RESULTS

In the year after implementation, only 11 of 410 surgical patients received ABO-nonidentical PLTs (2.7%). There was a 5.6% increase in outdating of PLTs. Transfusing ABO-identical components was associated with significant reductions in febrile (-46%; 8.0 to 4.3 per 10,000 components; p < 0.0001) and allergic transfusion reactions (-23%; from 7.0 to 5.4 per 10,000 components; p = 0.025). A progressive reduction in de novo RBC alloimmunization incidence also occurred (-50% by 2009; p = 0.03).

CONCLUSIONS

Providing ABO-identical PLTs to almost all patients was feasible in our setting by changing ordering and inventorying procedures and making the ABO-identical policy a staff priority. Unexpected and striking reductions in febrile and allergic reactions and RBC alloimmunization were observed, of uncertain causal relationship to this ABO policy change, which will require further study.