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PubMed2000

Frequency and characterization of platelet-specific antibodies in patients who received multiple platelet transfusions.

BACKGROUND AND PURPOSE: Multiple platelet transfusions may induce alloimmunization. Platelet alloimmunization involves human leukocyte antigen (HLA) antibodies and platelet-specific antibodies, which recognize platelet glycoproteins. No data are available about the frequency and characteristics of platelet-specific antibodies in patients who have received multiple platelet transfusions in Taiwan. METHODS: From June through December 1998, blood samples from 103 patients who had received multiple platelet transfusions were submitted to our laboratory for examination of platelet antibodies. The samples were first screened for HLA antibodies or platelet-specific antibodies using a solid phase method. Positive sera were further tested using an enzyme-linked immunosorbent assay (ELISA) to identify the specificities of the alloantibodies. RESULTS: Forty of the 103 patients who had received multiple platelet transfusions were positive for platelet-reactive antibodies. Further study using ELISA showed that 22 patients had both HLA and platelet-specific antibodies, 12 patients had HLA antibodies alone, and five patients produced platelet-specific antibodies in the absence of HLA antibodies. Most platelet-specific antibodies were found among patients who had HLA antibodies: 81% of platelet-specific antibodies were found in HLA-immunized patients. The most frequently involved platelet glycoprotein antigens were Ia/IIa and IIb/IIIa. CONCLUSIONS: HLA antibodies were the most frequently found platelet-reactive antibodies in Taiwanese patients who had received multiple transfusions, although platelet-specific antibodies were also common. The frequency of platelet-specific antibodies was not as low as previously reported.

Adolescent↗
PubMed1999

Optimal dosing and triggers for prophylactic use of platelet transfusions.

Despite the reliance on platelet transfusion support in patients receiving myeloablative therapy, controversies surround platelet transfusion practices. These include the appropriate platelet dose and the threshold at which prophylactic platelet transfusions will be most effective. These issues bear directly on patient outcome (donor exposure and bleeding complications), cost effectiveness of transfusion, and maintenance of adequate platelet inventories. This review examines the recent studies that have taken on the task of resolving these questions in order to provide optimal platelet transfusion guidelines. Studies now have convincingly demonstrated that a 10,000/microL threshold for prophylactic platelet transfusion is safe and effective in uncomplicated thrombocytopenic patients. Although platelet dosages vary, in general, smaller doses are both effective and inventory-sparing in the more complicated inpatient setting, while larger platelet doses allow for an increased transfusion interval for chronic outpatient support.

Humans↗
PubMed1984

Improved response of patients refractory to random-donor platelet transfusions by intravenous gamma globulin.

Because of frequent unavailability of HLA-compatible platelets or their inefficiency in increasing platelet counts in patients requiring platelet transfusions, platelet refractoriness remains a major problem. Since human gamma globulin has been shown to interfere with the binding of platelet-reactive immunoglobulin G (IgG) to platelets in vitro, and since gamma globulin has proved effective in reversing destruction of platelets in idiopathic thrombocytopenic purpura, we decided to investigate intravenous gamma globulin as an adjunct to random-donor platelet transfusions. We studied three patients, one with acute T-cell leukemia, and two with aplastic anemia. When a total dose of 2 g/kg of body weight of intravenous gamma globulin was infused over five to six days in these patients, two of them showed a remarkable increment in platelet counts and improved hemostasis with random-donor platelet transfusions. We conclude that intravenous gamma globulin may be used in critical situations to improve the response of patients refractory to random-donor platelet transfusions.

Adult↗
PubMed1986

Platelet size and mass as an indicator for platelet transfusion after cardiopulmonary bypass.

Platelet count, mean platelet volume (MPV), and plateletcrit (PCT) were studied in 51 patients after cardiopulmonary bypass (CPB). MPV was significantly lower in 10 patients who developed postoperative bleeding (bleeders) compared to 41 with no significant bleeding (nonbleeders) (7.7 +/- 0.86 vs 8.5 +/- 1.2 fl, p less than .05). Postoperative platelet count was significantly lower in the group of bleeders (93.3 +/- 22.4 vs 127.5 +/- 43 X 10(9)/liters, p less than .02). A cutoff point of MPV or platelet count that would include bleeders and exclude nonbleeders could not be found due to the large overlap between the two groups. However, such a cutoff point does exist for PCT (PCT = total platelet mass). PCT was significantly lower among the bleeders (0.072 +/- 0.02% vs 0.108 +/- 0.036%, p less than .05) and a cutoff point of PCT less than 0.1% included all the bleeders and excluded 65% of nonbleeders. The low PCT and bleeding tendency can be corrected by platelets transfusion. In 15 patients (eight bleeders and seven nonbleeders) with low postoperative PCT (0.078 +/- 0.014), transfusion of 10 platelet units increased platelet count from 101 +/- 32 to 169 +/- 22 X 10(9)/liter, increased PCT to 0.128 +/- 0.2%, and stopped bleeding in all bleeders. A finding of PCT less than 0.1% after CPB is a clear indication for platelet transfusion in patients who develop post-CPB bleeding. This supports the observation that large platelets are more active than smaller ones, and that PCT, rather than PLT counts, predicts the risk of bleeding in patients with thrombocytopenia.

Adolescent↗
PubMedDate not supplied

Pyelolithotomy in a patient with Glanzmann thrombasthenia and antiglycoprotein IIb/IIIa antibodies: the shortest possible duration of treatment with recombinant activated factor VII and platelet transfusions.

Transfusion of platelet concentrates remains the first-line therapy for Glanzmann thrombasthenia in case of bleeding or preparation for surgery. However, development of antibodies to platelet glycoprotein (Gp) IIb/IIIa complex or human leukocyte antigens (HLA) is frequent and the main cause of platelet refractoriness. Recombinant activated factor VII (rFVIIa) is a potent alternative for patients with Glanzmann thrombasthenia with anti-platelet antibodies. We describe a case of Glanzmann thrombasthenia with alloantibodies to platelet Gp IIb/IIIa complex who underwent a successful pyelolithotomy operation under the coverage of recombinant activated factor VIIa and platelet transfusions.

Child, Preschool↗
PubMed1999

Risks, costs, and alternatives to platelet transfusions.

The use of platelet transfusions has increased greatly in the past decade and is likely to continue to escalate because of the risks of thrombocytopenia in patients receiving dose-intensive cancer chemotherapy, the increased use of hematopoietic progenitor cell transplantation, and the prevalence of human immunodeficiency virus infection. Despite marked advances in procedures for ensuring the safety of platelets, including intensive donor screening, infectious disease marker testing, and increased use of leukodepletion techniques, platelet transfusions carry a significant risk for immunologic disorders and transmission of bacterial, viral, and perhaps other diseases and can entail a very high cost. In addition, thrombocytopenia has the potential to interfere with delivery of chemotherapy on schedule and at the planned doses, thus potentially compromising treatment outcome. The limitations of platelet transfusions have prompted the development of agents with the potential to stimulate platelet production and thus reduce or eliminate the need for transfusions. Two such agents, interleukin-11 (IL-11) and thrombopoietin (TPO), have demonstrated promise in clinical trials. In November, 1997, IL-11 received FDA approval for the prevention of severe thrombocytopenia in high risk patients receiving myelosuppressive chemotherapy. Thrombopoietic growth factors have the potential to greatly simplify and increase the safety of transfusion medicine.

Animals↗
PubMed2004

[Survey on the threshold for platelet transfusions].

We carried out a survey on platelet transfusions performed in nine general hospitals. We evaluated 303 adults who received a total of 24455 units over 1864 platelet transfusions. The underlying diseases were hematologic disorders with chemotherapy (59.7%), hematologic disorders without chemotherapy (15.5%), hematopoietic stem cell transplantation (18.5%), and others (2.0%). The patient platelet count before transfusion (platelet trigger value) was measured in only 77.1%. The platelet trigger value differed greatly between the hospitals, with an average of 2.2 x 10(4)/microl, a minimum of 1.3 x 10(4)/microl, and maximum of 3.2 x 10(4)/microl. Only 55.3% of the platelet transfusions carried out complied with the Platelet Transfusion Guideline published by the Ministry of Health, Labour and Welfare. The hospitals surveyed could be divided into those who gave mainly around 10 units and those who gave over 10 units. The total dose of platelets transfused was more in the hospitals that used mainly 15 or more unit-PCs than in the hospitals that used mainly 10 unit-PCs. These results indicate that platelet transfusion may be greatly reduced by complying with the 2 x 10(4)/microl of platelet transfusion threshold and by selecting less than 10 units of PC per transfusion.

Data Collection↗
PubMed2002

The frequency of bleeding complications in patients with haematological malignancy following the introduction of a stringent prophylactic platelet transfusion policy.

Indications for platelet transfusion remain controversial and are frequently based on arbitrary numerical criteria. In October 2000, we introduced a stringent prophylactic-platelet transfusion policy < 10 x 109/l for stable patients and < 20 x 10(9)/l in the presence of major bleeding or additional risk factors. A trigger of < 50 x 10(9)/l was introduced for patients undergoing invasive procedures. A prospective analysis was performed measuring the frequency of minor and major bleeding events, morbidity, mortality and duration of pancytopenia. Blood product usage was assessed and health care savings measured. A total of 98 patients were evaluated on 2147 patient study days and 271 bleeding episodes were recorded. Major bleeding occurred on 1.39% (30/2147) of the study days when platelet counts were < 10 x 10(9)/l and 2.3% (50/2147) of the study days when platelet counts were 10-20 x 10(9)/l. In patients with platelets > 20 x 10(9)/l, there were 117 major bleeding episodes observed on 5.4% of the study days. In patients with no identified additional risk factors present, major haemorrhages were recorded in 0.51% (11/2147) of the study days in patients with platelet counts > or = 10 x 10(9)/l . There was a 36% reduction in platelet units transfused compared with retrospective data when an arbitrary transfusion trigger of 20 x 10(9)/l was in place (P = < 0.02). Of note, a 16% reduction in red cell transfusions was recorded. These data confirm that the introduction of a transfusion trigger of < 10 x 10(9)/l in the absence of fresh bleeding and sepsis (> 38 degrees C) is safe and has a significant impact on overall hospital transfusion costs.

Adolescent↗
PubMed1975

Effect on platelet counts and fever of platelet transfusion in leukemia.

The efficacy of platelet transfusions in pretransfused HL-1 sensitized patients has been doubtful, particularly where repeated platelet transfusions were required. The efficacy of one hundred and nine ABO-compatible, cross match negative platelet transfusions in 26 adult patients with acute leukemia was therefore studied. Although most of the patientswere old and pretransfused and although no HL-A typing could be made, a statistically significant average increase of about 11 000 platelets/mul was seen not only after the first but also after subsequent (up to 8) platelet transfusions. Moreover, significant reduction in temperature followed platelet transfusions. However, platelet recoveries were worse in severely infected patients.

Acute Disease↗
PubMed2000

Trigger for platelet transfusion.

BACKGROUND AND OBJECTIVES: The terms 'platelet transfusion trigger' are used in the scientific literature to indicate a value of the platelet count above which prophylactic platelet transfusion is usually not indicated. Most clinicians share the currently prevalent consensus published in several guidelines that a platelet transfusion trigger of 10,000 platelets per microliter is safe in stable oncohematology recipients carefully monitored at both the clinical and laboratory levels, whereas higher values may be necessary in patients with high fever, infection, splenomegaly, rapid platelet count decrease, on drugs able to affect platelet function and survival, in cases undergoing invasive maneuvers and in some pediatric patients such as premature newborns. The safety of this policy is supported by the results obtained in several randomized clinical trials and prolonged observational studies. Lowering the platelet transfusion trigger from the traditional value set at 20,000 platelets per microliter to the currently recommended value of 10,000 per microliter further stresses the importance of high-quality, sufficient and prompt platelet availability and close cooperation between clinicians and blood transfusion specialists. Furthermore, it requires a clear understanding of the discriminatory power of current automated hematology counters at very low platelet counts. In the surgical setting, where randomized clinical trials on the most appropriate platelet transfusion trigger are largely missing, current guidelines propose to maintain higher platelet count values (50,000-100,000 per microliter) during surgery and in the early postoperative period.

Hematologic Diseases↗
PubMed2002

Absence of anti-D alloimmunization in hematologic patients after D-incompatible platelet transfusions.

BACKGROUND: Rh antigens are not present on the platelet surface. However, platelet concentrates may contain enough RBCs to elicit an anti-D response. Thus, D status must be considered in platelet transfusion. In immunosuppressed patients, frequencies of D alloimmunization of up to 19 percent have been previously reported. STUDY DESIGN AND METHODS: Here a prospective study is reported in which 22 D- patients with hematologic disease received D+ platelet transfusions. Platelet concentrates were prepared from whole-blood donations according to the buffy coat method and were pooled before administration. The antibody screen test to detect anti-D was performed by LISS- IAT using the gel test. RESULTS: Our series comprises 22 immunosuppressed D+ patients with a median age of 56 years (range, 23-79). The patients received 121 D-incompatible pooled platelet transfusions. The mean +/- SD of RBC content was 4.17 +/- 1.74 mL. None of the 22 patients developed detectable anti-D after a median follow-up of 8 weeks (range, 1-37). CONCLUSION: The risk of D alloimmunization is low in patients with hematologic disease after D-incompatible platelet transfusions using platelet concentrates prepared by the buffy coat method.

Acute Disease↗
PubMed2004

Prophylactic platelet transfusion for haemorrhage after chemotherapy and stem cell transplantation.

BACKGROUND: Platelet transfusions are used in modern clinical practice to prevent and treat bleeding in thrombocytopenic patients with bone marrow failure. Although considerable advances have been made in platelet transfusion therapy in the last 30 years, some areas continue to provoke debate, especially the use of prophylactic platelet transfusions for the prevention of thrombocytopenic bleeding. OBJECTIVES: To determine the optimal use of platelet transfusion for the prevention of haemorrhage (prophylactic platelet transfusion) in patients with haematological malignancies undergoing chemotherapy or stem cell transplantation. SEARCH STRATEGY: Randomised controlled trials (RCTs) were searched for in the Cochrane Central Register of Controlled Trials (CENTRAL). Searching was also undertaken on the OVID versions of MEDLINE and EMBASE using an RCT search filter strategy. SELECTION CRITERIA: Randomised controlled trials involving transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis, and given prophylactically to prevent bleeding in patients with haematological malignancies and receiving treatment with chemotherapy and/or stem cell transplantation. DATA COLLECTION AND ANALYSIS: All electronically derived citations and abstracts of papers identified by the review search strategy were initially screened for relevancy by one reviewer. Studies clearly irrelevant were excluded at this stage. The full text of all potentially relevant trials was then formally assessed for eligibility by two reviewers independently. Two reviewers completed data extraction independently. Missing data were requested from the original investigators, as appropriate. Disagreements were resolved by discussion with the other reviewers. MAIN RESULTS: Eight completed published trials, with a total of 390 participants in the intervention groups and 362 participants in the control groups, were included in the review for further analysis. The eight studies were classified as: * three trials relevant to prophylactic platelet transfusions versus therapeutic platelet transfusions; * three trials relevant to prophylactic platelet transfusion with one trigger level versus prophylactic platelet transfusion with another trigger level; * two trials relevant to prophylactic platelet transfusion with one dose schedule versus prophylactic platelet transfusion with another dose schedule. The few reports of controlled trials addressing prophylactic versus therapeutic transfusions contained small numbers of patients and were all undertaken over 25 years ago. None of these three studies explicitly clarified whether the lack of a reported difference was a reflection of insufficient power in the trials. The findings of the meta-analyses for this group of three small studies must be interpreted with caution. In contrast, more contemporary trials addressed the question of what platelet count thresholds should apply for prophylactic transfusion; three identified studies broadly compared platelet transfusion thresholds of 10 versus 20 x 109/litre for different clinical groups of patients. There were no statistically significant differences between the groups with regards to mortality, remission rates, number of participants with severe bleeding events or red cell transfusion requirements. However, it was unclear whether the studies had sufficient power to demonstrate in combination non-inferiority in terms of safety of the lower threshold, 10 x 109/litre. Insufficient randomised trials have been undertaken to make clinically relevant conclusions about the effect of different platelet doses. REVIEWERS' CONCLUSIONS: There are no reasons to change current practice but uncertainty about the practice of prophylactic transfusion therapy should be recognised, particularly in the light of concerns about the scenario that blood products, including platelets, could become an increasingly scarce resource in the future and for which adequate alternatives do not exist. Consideration should be given to developing adequately powered trials comparing strategies of prophylaxis versus therapeutic platelet transfusion.

Hemorrhage↗
PubMedDate not supplied

Determination of the rate of reduction in platelet counts in recipients of hematopoietic stem and progenitor cell transplant: clinical implications for platelet transfusion therapy.

BACKGROUND: To investigate how a delay between pretransfusion platelet count measurement and actual platelet transfusion affects the assessment of platelet transfusion responses, the rate of reduction in platelet counts was determined in 30 patients with relatively uncomplicated thrombocytopenia. STUDY DESIGN AND METHODS: Fifteen adult and 15 pediatric patients admitted for hematopoietic stem and progenitor cell transplantation were studied. Platelet counts before and after myeloablative conditioning and after prophylactic platelet transfusions were determined and studied as a function of time. The rates of reduction in platelet counts were determined by linear regression analysis. RESULTS: Platelet counts were reduced at linear rates after myeloablative conditioning or prophylactic platelet transfusion in all 30 patients. The average rates of reduction in platelet counts after myeloablation were 1261 +/- 583 and 1070 +/- 492 platelets per microL per hour (mean +/- SD) for adult and pediatric patients, respectively. The average rate of reduction after platelet transfusions during the thrombocytopenic phase was 740 +/- 280 and 820 +/- 288 platelets per microL per hour (mean +/- SD) for adult and pediatric patients, respectively. The rates of reduction in platelet counts between the two phases were significantly different in the two age groups (adult, p < 0.0001; pediatric, p < 0.015) and were proportionally correlated with initial platelet counts immediately before myeloablation and after prophylactic platelet transfusions. CONCLUSION: The rate of reduction in platelet count can have a significant impact on the evaluation of platelet transfusion responses when there is a delay between pretransfusion measurement of platelet count and the initiation of platelet transfusion. In addition, the rate of platelet reduction determined from this study can be used to confirm an accelerated rate of platelet consumption in thrombocytopenic patients.

Adolescent↗
PubMed1986

Efficacy of platelet transfusions in immune thrombocytopenia.

Records of 11 patients with immune thrombocytopenia (idiopathic and quinidine-induced) were evaluated retrospectively for response to platelet transfusion. Good post-transfusion platelet count increments occurred on one or more occasions in seven of the 11 patients, with 13 of 31 platelet transfusions (42 percent) resulting in immediate post-transfusion increments of 20,000/mm3 or more. Next-day platelet counts remained elevated in association with five of these 13 transfusions. This study demonstrates that, contrary to common opinion, platelet transfusions can raise the platelet count in many patients with immune thrombocytopenia, and therefore may be beneficial in actively bleeding or high-risk patients with this disorder.

Adult↗
PubMed1997

Platelet transfusion requirements during autologous peripheral blood progenitor cell transplantation correlate with the pretransplant platelet count.

The use of primed peripheral blood progenitor cells (PBPC) has improved platelet engraftment following autologous bone marrow/PBPC transplantation (ABMT). The thrombocytopenia associated with ABMT generally lasts 14-18 days, and is associated with variable platelet transfusion requirements. Little, if any, data exist examining prognostic parameters for platelet transfusion requirements during autologous transplantation. We retrospectively examined 286 consecutive patients undergoing autologous transplantation from 1 January 1994 to 1 June 1996 with respect to platelet engraftment and platelet transfusion requirements. One hundred and fifty four patients were transplanted for breast cancer (54%), 72 for non-Hodgkin's lymphoma (25%), 35 for Hodgkin's disease (12%), 13 for acute leukemia (5%), eight for myeloma (3%), and four for other malignancy (1%). The median age was 44. All patients received cytokine priming, usually with G-CSF, for the procurement of PBPC. The median number of CD34+ cells collected was 4.3 x 10(6)/kg. All patients received a chemotherapeutic preparative regimen and all received an autologous transplant using PBPC alone. The median time to a platelet count of 20 x 10(9)/l was 13 days. Patients beginning the transplant with a less than normal platelet count (less than 150 x 10(9)/l) engrafted in 17 days, and received a median number of seven platelet transfusions, as compared with platelet engraftment of 12 days, and four platelet transfusions, for patients beginning the transplant with a normal platelet count (P = 0.001). Both groups of patients received an equivalent dose of CD34+ cells. We conclude that thrombocytopenia at the initiation of autologous transplantation is associated with increased platelet transfusion requirements, independent of the dose of CD34+ cells infused.

Adult↗
PubMed1981

Transfusion strategy: use of HLA-matched platelet transfusions for alloimmunized patients.

Platelet concentrates from HLA-compatible donors frequently provide satisfactory posttransfusion platelet responses in patients who, for immunologic reasons, are refractory to pooled random-donor platelet transfusions. The use of donors who have HLA antigens "crossreactive" with those of the recipient has increased the number of donors available for individual patients. Occasionally, successful transfusions occur with donors mismatched for HLA. Immunologic explanations include a restricted pattern of HLA antibody production and a variable expression of HLA antigens on the platelet surface. Immunologic reasons for poor response to HLA-matched transfusions include ABO incompatibility, antibodies directed against platelet-specific antigens. HLA-Bw4/Bw6 incompatibility, and as yet undefined incompatibilites. The one-hour posttransfusion platelet count may be useful in identifying patients who are alloimmunized and have non-immunologic reasons for shortened platelet survival such as fever, sepsis, or a coagulopathy. Caution must be used in evaluating results of currently available platelet crossmatch tests.

Blood Donors↗