Prophylactic platelet transfusions in children with acute leukemia: a dose response study

Platelet Transfusion: A Dose-Response Study

Early recommendations on prophylactic transfusion of thrombocytopenic patients involved a standard platelet dose of about 0.5 × 1011/10 kg body weight. Given the lack of data supporting this dose, we prospectively studied the dose response to platelet transfusions in adults and children with hematologic malignancies. Each patient received, in similar clinical conditions, a medium, high, and very high dose of fresh (< 24 hours old) ABO-compatible platelets, in the form of apheresis platelet concentrates (APC). For the adults, the medium dose was defined as APC containing between 4 and 6 × 1011 platelets, the high dose between 6 and 8 × 1011, and the very high dose > 8 × 1011; for the children, the three doses corresponded to 2 to 4, 4 to 6, and > 6 × 1011 platelets. The end points were the platelet increment, platelet recovery, and the transfusion interval, and the results were compared with a paired t-test. Sixty-nine adults and 13 children could be assessed. Recoveries in the adults were similar with the three doses (from 28% to 30%), but the high and very high doses led to a significantly better platelet increment (52 and 61 × 109/L, respectively) than the medium dose (33 × 109/L, P < .01). The main difference was in the transfusion interval, which increased with the dose of platelets transfused, from 2.6 days with the medium dose to 3.3 and 4.1 days with the high and very high doses, respectively (P< .01). The positive effect of the high dose was observed regardless of pretransfusional clinical status, but was more marked in patients with no clinical factors known to impair platelet recovery. In these patients, a platelet dose of 0.07 × 1011 per kg of body weight led to a transfusion interval of more than 2 days in 95% of cases. In patients with clinical factors favoring platelet consumption, the proportion of transfusions yielding an optimal platelet increment and transfusion interval increased with the dose of platelets.The platelet dose-effect was also significant in the children, in whom the high and very high doses led to 1.5-fold to twofold higher posttransfusion platelet counts and transfusion intervals. We conclude that transfusion of high platelet doses can reduce the number of platelet concentrates required by thrombocytopenic patients and significantly reduce donor exposure.

© 1998 by The American Society of Hematology.

Platelet Transfusion: A Dose-Response Study

Early recommendations on prophylactic transfusion of thrombocytopenic patients involved a standard platelet dose of about 0.5 × 1011/10 kg body weight. Given the lack of data supporting this dose, we prospectively studied the dose response to platelet transfusions in adults and children with hematologic malignancies. Each patient received, in similar clinical conditions, a medium, high, and very high dose of fresh (&lt; 24 hours old) ABO-compatible platelets, in the form of apheresis platelet concentrates (APC). For the adults, the medium dose was defined as APC containing between 4 and 6 × 1011 platelets, the high dose between 6 and 8 × 1011, and the very high dose &gt; 8 × 1011; for the children, the three doses corresponded to 2 to 4, 4 to 6, and &gt; 6 × 1011 platelets. The end points were the platelet increment, platelet recovery, and the transfusion interval, and the results were compared with a paired t-test. Sixty-nine adults and 13 children could be assessed. Recoveries in the adults were similar with the three doses (from 28% to 30%), but the high and very high doses led to a significantly better platelet increment (52 and 61 × 109/L, respectively) than the medium dose (33 × 109/L, P &lt; .01). The main difference was in the transfusion interval, which increased with the dose of platelets transfused, from 2.6 days with the medium dose to 3.3 and 4.1 days with the high and very high doses, respectively (P&lt; .01). The positive effect of the high dose was observed regardless of pretransfusional clinical status, but was more marked in patients with no clinical factors known to impair platelet recovery. In these patients, a platelet dose of 0.07 × 1011 per kg of body weight led to a transfusion interval of more than 2 days in 95% of cases. In patients with clinical factors favoring platelet consumption, the proportion of transfusions yielding an optimal platelet increment and transfusion interval increased with the dose of platelets.The platelet dose-effect was also significant in the children, in whom the high and very high doses led to 1.5-fold to twofold higher posttransfusion platelet counts and transfusion intervals. We conclude that transfusion of high platelet doses can reduce the number of platelet concentrates required by thrombocytopenic patients and significantly reduce donor exposure.

© 1998 by The American Society of Hematology.

Transfusion Therapy with Platelet Concentrates

At the end of 1960, the concept that platelet transfusion could reduce the death rate due to hemorrhage was confirmed by the reduction of life-threatening bleeding and prolonged survival in thrombocytopenic patients affected with acute leukemia and aplastic anemia. Thrombocytopenia is the result of an imbalance between platelet production and destruction: usually no bleeding problem will occur until circulating platelets fall below 20000/μl and even a platelet count of 5000/μl may be present in many patients without bleeding. Because of the high risk of alloimmunization in multiply transfused thrombocytopenic patients with random platelet concentrates, the main dilemma is the choice of strategy: “prophylactic”versus “therapeutic” treatment with platelet concentrates of cancer patients and the platelet count selected as the “transfusion trigger” for platelet support in patients without active bleeding. We describe our experience of 367 retrospective non-randomized leukemic patients transfused with platelet concentrates. A total of 225 patients (61.3%) received support therapy: the transfusions were administered prophylactically at a platelet count below 20000/μl in the group of patients with acute lymphoblastic leukemia (35% transfused) and acute myeloblastic leukemia (78% transfused). Only14 hemorrhagic episodes were observed in 148 patients receiving prophylactic platelets (9%), while 21 severe hemorrhages (27%) were documented in patients treated with therapeutic platelet concentrates. Several studies have concluded that maintaining the platelet count above 20000/μl was not justified in the majority of cancer patients. In the absence of more definitive data, a “transfusion trigger” of 10000/μl is selected for platelet transfusion support in leukemic non-bleeding patients receiving chemotherapy.

Hemostatic complications in renal disorders of the young

This review focuses on the hemorrhagic and thrombotic complications sometimes associated with the most common renal disorders in children. A Medline search of the literature was conducted from 1966 to January 1995, using combinations of key words appropriate for each disorder. Additional references were located through the bibliographies of the publications and recent journals were searched independently. The most common renal disorders with hemostatic complications in children were: renal vein thrombosis (268 children in 80 publications), hemolytic uremic syndrome (473 children in 29 publications), nephrotic syndrome (4,158 children in 51 publications), renal transplantation (3,976 children in 14 publications), glomerulonephritis (20 publications), end-stage renal disease, and dialysis (22 publications). The age distribution, clinical presentation, etiology, diagnosis, treatment, and outcome of the affected children were analyzed for each disorder. Children with inherited pre-thrombotic disorders usually do not present during childhood unless there is a secondary risk factor. Similarly, most children with renal disease do not develop thromboembolic complications. Therefore, when a child with a renal disorder develops a thromboembolic event, evaluation for an inherited pre-thrombotic disorder should be seriously considered. Guidelines for the use of heparin and warfarin in these children (both therapeutically and prophylactically) are given. At this time, the risk/benefit of thrombolytic therapy in children is not known and a general recommendation for thrombolytic therapy cannot be made.

Platelet support and the use of cytokines

Severe thrombocytopenia and clinical bleeding remain major clinical problems in leukemic patients undergoing remission induction and those receiving high dose chemotherapy. Prophylactic platelet transfusions have made a major impact on hemorrhagic deaths over the last 20 years. The effectiveness of platelet transfusions is influenced by a number of clinical factors including the status of the spleen, prior bone marrow transplantation, the presence of disseminated intravascular coagulation and the presence of HLA antibodies. Optimal platelet transfusion therapy requires that transfusions be monitored routinely by post-transfusion counts and that a refractory group be clearly defined. The cytokine granulocyte colony stimulating factor (G-CSF) has not had a clinically significant impact on thrombocytopenia. Granulocyte-macrophage colony stimulating factor (GM-CSF) also probably has little clinical relevance, although in a randomized study, thrombocytopenia was worse in GM-CSF-treated patients. Interleukin-3 (IL-3) can increase platelet count and has the potential to protect against thrombocytopenia in patients receiving chemotherapy. This hypothesis is currently being tested in on-going clinical trials.

A randomized, controlled trial of platelet transfusions in thrombocytopenic premature infants

A multicenter prospective, randomized controlled trial was conducted to determine whether early use of platelet concentrates would reduce the incidence or extension of intracranial hemorrhage or both in sick preterm infants with thrombocytopenia. The effects on bleeding as reflected by the amount of blood product support administered and a shortened bleeding time were assessed as secondary outcomes. Premature infants with a platelet count < 150 x 10(9)/L within the first 72 hours of life were randomly assigned to receive either conventional therapy or conventional therapy plus platelet concentrates (10 ml/kg). The platelet count was maintained < 150 x 10(9)/L until day 7 of life by one to three platelet transfusions. In 22 (28%) of the 78 treated infants and 19 (26%) of the 74 control infants, either a new intracranial hemorrhage developed or an already-present one became more extensive (p = 0.73). Similar numbers of infants had each grade of intracranial hemorrhage on both initial and follow-up ultrasonography. Similar numbers of infants received fresh frozen plasma and packed red blood cells, but treated infants received less of both. The bleeding time was prolonged in the treated group before the infusion of platelet concentrates but subsequently shortened (mean difference, 79.0; 95% confidence interval, 73.1 to 84.9). Subanalysis of the control group showed that infants with platelet counts < 60 x 10(9)/L (n = 21) on at least one occasion received more fresh frozen plasma and packed red blood cells than did those with platelet counts > 60 x 10(9)/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Guidelines for platelet transfusions. British Committee for Standards in Haematology, Working Party of the Blood Transfusion Task Force

Recommendations for the optimal transfusion support of patients likely to receive repeated platelet transfusions. 1. Determine policy for prophylactic platelet support, and select the platelet count below which platelet transfusions will be used. 2. Consider using leucocyte depletion of red cell and platelet concentrates to prevent HLA alloimmunization from the outset. 3. Type patients for HLA-A and B antigens at an early stage. 4. Use random donor platelet concentrates for initial platelet support (either single or multiple donor, depending on availability). 5. If refractoriness occurs, determine whether clinical factors, which may be associated with non-immune consumption of platelets, are present and test the patient's serum for HLA antibodies. 6. Use HLA-matched platelet transfusions if HLA alloimmunization is the most likely cause of refractoriness. 7. If there is no improvement with HLA-matched transfusions, platelet crossmatching may identify the cause of the problem and help with the selection of compatible donors. 8. Discontinue prophylactic platelet support if a compatible donor cannot be found. Use platelet transfusions from random donors to control bleeding and increase the dose, if necessary.

The definition of refractoriness to platelet transfusions

The relationship between the 1 and 20 h post-transfusion platelet count and three parameters used to define refractory transfusions, namely the corrected increment (CI), platelet increment (PI), and percentage platelet recovery (%REC), was studied in 437 non-HLA matched platelet transfusions given to 102 patients with bone marrow failure. The percentage agreement between common definitions of refractoriness was calculated based on these parameters. As the maintenance of platelet counts above 20 x 10(9)/l is a relevant clinical goal for platelet support, the values of the CI, PI and %REC, which best corresponded to 1- and 20-h post-transfusion counts of 20 x 10(9)/l, were identified. A 1-h post-transfusion CI < 3 (PI < 7 x 10(9)/l or % REC < 8%) corresponded to clinically unsuccessful transfusions with a 1-h platelet count < 20 x 10(9)/l. A 1-h CI > or = 5.5 (PI > or = 12 x 10(9)/l or %REC > or = 14%) corresponded to clinically successful transfusions with a 20-h post-transfusion count of > or = 20 x 10/l. These data tie together the end points reported in the literature for defining refractory transfusions.

ESPRE: a knowledge-based system to support platelet transfusion decisions

ESPRE is a knowledge-based system which aids in the review of requests for platelet transfusions in the hospital blood bank. It is a microcomputer-based decision support system written in LISP and utilizes a hybrid frame and rule architecture. By automatically obtaining most of the required patient data directly from the hospital's main laboratory computers via a direct link, very little keyboard entry is required. Assessment of time trends computed from the data constitutes an important aspect of this system. To aid the blood bank personnel in deciding on the appropriateness of the requested transfusion, the system provides an explanatory report which includes a list of patient-specific data, a list of the conditions for which a transfusion would be appropriate for the particular patient (given the clinical condition), and the conclusions drawn by the system. In an early clinical evaluation of ESPRE, out of a random sample of 75 platelet transfusion requests, there were only three disagreements between ESPRE and blood bank personnel.

Bleeding due to thrombocytopenia in acute leukemias and reevaluation of the prophylactic platelet transfusion policy

Prophylactic platelet administration is indicated at counts below 20 X 10(9)/l. The bleeding tendency and severity were compared between thrombocytopenic patients with acute-lymphocytic leukemia (ALL) and acute non-lymphocytic leukemia (ANLL) in the ranges of 10-20 X 10(9)/l platelets, while prophylactic platelet administration was given only below 10 X 10(9)/l. The bleeding tendency for ALL was quite similar at platelet counts above or below 10 X 10(9)/l. The bleeding tendency was significantly lower (p less than 0.001) when the platelets were above this level in ANLL patients. When the thrombocytopenia was caused by chemotherapy, the bleeding was significantly lower in both types of leukemia above 10 X 10(9)/l (p less than 0.05 for ALL, p less than 0.001 for ANLL) as compared with lower counts. When the thrombocytopenia was caused by leukemia, the bleeding tendency was similar in both types of leukemia and at all platelet counts (below 20 X 10(9)/l). Fever, not associated with sepsis, augmented the bleeding severity of patients with ANLL. Stable or rising counts of platelets were associated with significantly lower bleeding tendency above 10 X 10(9)/l only in ANLL patients. The decision for prophylactic platelet administration at counts below 20 X 10(9)/l should be guided by the type of the leukemia (ALL vs. ANLL), the cause of thrombocytopenia (chemotherapy vs. leukemia per se), the trend of the platelet counts, presence of fever and patient's age (below or above 18 years).(ABSTRACT TRUNCATED AT 250 WORDS)

Transbronchial biopsy in the thrombocytopenic patient

Twenty-five flexible fiberoptic bronchoscopic procedures with transbronchial lung biopsies were performed in 24 severely thrombocytopenic immunocompromised patients (mean platelet count of 30,000/cu mm, with a range of 7,000/cu mm to 60,000/cu mm) during the diagnostic evaluation of pulmonary infiltrates. Three patients had self-limited endobronchial bleeding. A single death was attributable to massive hemorrhage after transbronchial biopsy and brushing. Specific etiologic diagnoses were established by bronchoscopy in nine cases.

Metabolism of fibrinogen in children with acute lymphoblastic leukaemia

The metabolism and in vivo kinetics of fibrinogen were studied using homologous 125I-labelled fibrinogen in 21 children with acute lymphoblastic leukaemia (ALL). Ten patients were undergoing induction therapy, 11 children were in complete remission on maintenance therapy. Results in the patients undergoing induction therapy were: plasma fibrinogen levels were normal in all except one patient, the plasma fibrinogen pool was elevated in six cases, seven patients had a shortened fibrinogen half-life and increased fractional catabolic rate for fibrinogen. The absolute catabolic rate for fibrinogen was elevated in six cases. This shortened fibrinogen half-life together with the correcting effect of heparinisation on the fibrinogen turnover indicated that fibrinogen was consumed by chronic disseminated intravascular coagulation. Inhibition of the fibrinolytic system with epsilon-aminocaproic acid in five patients had no influence on the fibrinogen half-life in three of them but resulted in its prolongation in two patients. All except two children in complete remission had normal fibrinogen levels. Six patients had elevated plasma fibrinogen pools and in all of the cases survival and fractional catabolic rate of fibrinogen were normal. The absolute catabolic rate for fibrinogen was normal in eight, elevated in three of the patients. This observation indicates that fibrinogen synthesis remains accelerated in some cases of ALL in complete remission, but the cause of this is not known.

Transfusion therapy with platelets and leukocytes

Supportive care of the child with leukemia and solid tumors has improved dramatically due to advances in blood component preparation and use. Despite these advances, unsolved questions remain which will require research into better component preparation and randomized clinical trials. The prevention of post-transfusion graft-vs-host disease in the immunocompromised patient will require research into optimum radiation dosages for blood products and the appropriate choice of patients to receive these products. Alloimmunization to platelet concentrates will continue to be a problem as children receive more ablative cancer therapy. The use of leukocyte-poor platelets and allogeneic cryopreserved platelets may aid some of these patients, but the value of these products needs to be proven by more clinical trials. Finally, crossmatching of platelet products may become more readily available and may prove useful for more adequate selection of donors. If bone marrow transplantation becomes a therapeutic modality following remission induction for a large number of leukemic patients, the use of blood products pretransplantation will require intense investigation. Graft rejection in these children may be linked to the kind, number, and cytomegalovirus status of blood products given during their acute leukemic phase. The blood bank provides an important resource for procurement of blood products and for specialized product preparation. In addition, it should serve as a resource for new ideas and experimental blood products for use of the clinician caring for the child with cancer.

The Johns Hopkins Oncology Clinical Information System

The Johns Hopkins Oncology Center has developed and maintains a clinical information system to support patient care, education, research, and administrative functions. It operates on a dedicated minicomputer (PDP-11) programmed in MUMPS. Clinical information collected includes patient medical status and laboratory values. Data are used daily in patient care and also in support of retrospective and prospective research. The use of the system to manage a large blood pheresis program and to study and treat infectious disease is described. Administrative functions include patient and personnel scheduling, program evaluation, and projects directed toward control of costs.

Oncology Grand Rounds. Platelet transfusion--clinical applications in the oncology setting

The increased availability of platelets for transfusion has been a major factor in the improved prognosis noted in patients with acute nonlymphocytic leukemia. This review summarizes our current understanding of the proper use of platelet transfusion for patients with leukemia and cancer, with a particular emphasis on the management of alloimmunized patients. The need for careful and close collaboration between the blood bank and the referring clinicians is emphasized. Cryopreservation of autologous platelets, which can be of considerable assistance in the management of alloimmunized patients, and a summary of the large number of questions that still require further investigation are presented.

Platelet transfusion therapy

Platelet transfusions are of unquestionably proven benefit for the correction of thrombocytopenia or functional platelet disorders, and they have allowed for more intensive antineoplastic therapy. With the advent of blood component therapy most modern blood banks now have the capabilities for supplying at least limited quantities of platelets. Refinements in procurement methods will inevitably lead to a greater supply of platelets and the establishment of larger transfusion programs. These programs will need to incorporate facilities for platelet storage, recruitment of suitable donors, selection of special donors for refractory patients, and methods for quality control. As antineoplastic therapy becomes more aggressive, such transfusion programs will become an integral part of the operation of cancer treatment centers.