Efficacy of platelets collected by semi-continuous flow centrifugation (Haemonetics Model 30)

Platelet transfusions

Ever since platelet transfusions were shown to reduce mortality from haemorrhage in patients with acute leukaemia in the 1950s, the use of this therapy has steadily grown to become an essential part of the treatment of cancer, haematological malignancies, marrow failure, and haematopoietic stem cell transplantation. Today, more than 1.5 million platelet products are transfused in the USA each year, 2.9 million products in Europe. However, platelet transfusion can transmit infections and trigger serious immune reactions and they can be rendered ineffective by alloimmunisation. There are several types of platelet components and all can be modified to reduce the chances of many of the complications of platelet transfusion. Transfusion practices, including indications for transfusion, dose of platelets transfused, and methods of treating alloimmunised recipients vary between countries, and even within countries. We review commonly used platelet components, product modifications, transfusion practices, and adverse consequences of platelet transfusions.

Platelet transfusion for patients with cancer: clinical practice guidelines of the American Society of Clinical Oncology

OBJECTIVE

To determine the most effective, evidence-based approach to the use of platelet transfusions in patients with cancer.

OUTCOMES

Outcomes of interest included prevention of morbidity and mortality from hemorrhage, effects on survival, quality of life, toxicity reduction, and cost-effectiveness.

EVIDENCE

A complete MedLine search was performed of the past 20 years of the medical literature. Keywords included platelet transfusion, alloimmunization, hemorrhage, threshold and thrombocytopenia. The search was broadened by articles from the bibliographies of selected articles.

VALUES

Levels of evidence and guideline grades were rated by a standard process. More weight was given to studies that tested a hypothesis directly related to one of the primary outcomes in a randomized design. BENEFITS/HARMS/COST: The possible consequences of different approaches to the use of platelet transfusion were considered in evaluating a preference for one or another technique producing similar outcomes. Cost alone was not a determining factor.

RECOMMENDATIONS

Appendix A summarizes the recommendations concerning the choice of particular platelet preparations, the use of prophylactic platelet transfusions, indications for transfusion in selected clinical situations, and the diagnosis, prevention, and management of refractoriness to platelet transfusion.

VALIDATION

Five outside reviewers, the ASCO Health Services Research Committee, and the ASCO Board reviewed this document.

SPONSOR

American Society of Clinical Oncology

Clinical and laboratory factors that affect the post-transfusion platelet increment

Transfusion of platelet concentrates (PC) reduced the incidence of fatal hemorrhages in several thrombocytopenic conditions. Unfortunately, long-term platelet supportive care may be complicated by the development of a state of refractoriness, resulting in inadequate recovery of functional platelets. PC handling, clinical conditions of the patients and alloimmunization are the main factors affecting refractoriness. We evaluated the post-transfusion platelet increase in 25 patients (M=6, F=19) with hypomegakaryocytic thrombocytopenia receiving random ABO-compatible PC within 24 h after collection. Quality of PC was assessed by platelet count, pH measuring, LDH release, glycocalicin levels, CD-62 and CD-42b expression. Besides history, clinical status and therapy, we searched for the presence of anti-HLA class 1 and anti-HPA 1-4-5 antibodies. Only six patients (24%) were refractory to PC transfusion, as assessed by a corrected count increment (CCI)<5000. Four of such six patients (67%) had anti-HLA antibodies, as compared to zero of 19 responders (P<0.02). No other investigated clinical or laboratory feature was significantly different in refractory and responsive patients. Although post-transfusion bleeding time was shorter in responders than in refractory patients (297.33+/-249.95 versus 673.33+/-409.96; P<0.02), it did not significantly change even in patients with adequate correct count increment. Our data confirm the importance of anti-HLA antibodies in determining adequate post-transfusion recovery or refractoriness.

The collection of platelets by apheresis procedures

Collection of platelets by apheresis has been a major advance in transfusion medicine. It has allowed the supply of a therapeutically beneficial component to grow with medical needs. Donors find fulfillment in more frequent donations than are possible with whole blood and know that their donation fills a special need. New technology allows leukocyte reduction in the collection of the component with or without the use of filtration. Matching for refractory patients is possible. However, platelets collected by apheresis have not been shown to be hemostatically different from platelets separated from whole blood donations, and thus, do not represent an advance in therapeutic efficacy. The use of apheresis platelets does reduce donor exposure, but this has not been shown to be a safety advance, although it seems intuitively obvious that transfusion risk is statistically reduced in some patients requiring only a few platelet transfusions. Support of patients by apheresis platelets may or may not reduce the risk of alloimmunization. Apheresis platelets from some equipment have less white blood cell contamination even in the absence of filtration, which may be an advantage. Apheresis platelets could be a major step in the ultimate customization of blood collection, in which some donors would preferentially donate red blood cells, whereas others would donate platelets or plasma depending on their blood type and ability to donate frequently, and the current medical need of their donation. Perhaps this would be the most significant advance from the medical progress initiated by Cohn almost 50 years ago.

Viability of platelets collected by apheresis versus the platelet-rich plasma technique: a direct comparison

Different platelet preparation techniques have not previously been compared directly and simultaneously with respect to in vivo platelet viability. Using a dual-label technique with 111-In and 114m-In, platelet apheresis was compared with the platelet-rich plasma (PRP) procedure with respect to platelet recovery and survival (n=4). Furthermore, a continuous flow cell separator (Cobe 2997) and an intermittent apheresis system (Haemonetics V50) were compared with each other (n=4). No differences in platelet viability were found between the PRP-platelets and the apheresis-platelets. Also no differences were found between the two apheresis systems. Although different platelet preparation methods result in a varying degree of platelet activation, no difference in platelet viability has been observed.

In vitro and in vivo comparison of platelet concentrates collected by automated versus manual apheresis

Platelet concentrates collected by continuous flow automated apheresis (Fenwal CS-3000) were compared with those collected by manual apheresis to determine whether the prolonged centrifugation and vigorous resuspension affected platelet viability and in vitro function. Paired autologous reinfusion studies (111Indium) of 5 normal donors showed no significant differences in the mean percent recoveries (50.8 +/- 7.0% vs 53.8 +/- 4.0%) or survivals (174 +/- 23 h vs 188 +/- 10 h) for platelets collected by manual versus automated apheresis. Platelets collected by automated apheresis had a significantly higher level of beta-thromboglobulin release, but there were no significant differences between platelets collected by the two methods in regard to other in vitro parameters (ATP levels, LDH released, hypotonic shock response) believed to reflect platelet activation, injury, and malfunction. These results suggest that only slight activation of platelets takes place during automated apheresis.

The effects of splenectomy on engraftment and platelet transfusion requirements in patients with chronic myelogenous leukemia undergoing marrow transplantation

Granulocyte and platelet recovery as well as platelet transfusion requirements following allogeneic marrow transplantation were analyzed in 67 patients with chronic myelogenous leukemia in the chronic phase. Twenty patients had splenectomy prior to transplantation. Forty-seven patients were transplanted without splenectomy, 21 of whom had splenic enlargement by physical examination. There were no differences in the proportion of patients with granulocyte recovery, but the recovery of peripheral granulocytes to levels of 200, 500 and 1,000/mm3 occurred more rapidly in the splenectomy group than in the no-splenectomy group. Patients with splenectomy received platelet transfusions for a mean of 10 (2-36) days as compared to 20 (3-82) days for patients without splenectomy (p less than .001). Eighteen (90%) patients with splenectomy became platelet transfusion independent at a median of 16 (2-32) days after transplantation as compared to 40 (85%) patients without splenectomy who became transfusion independent at a median of 28 (15-86) days (p less than .001). The proportion of patients achieving platelet levels of 50 and 100 X 10(3)/mm3 did not differ between the two groups (p = .07), but patients in the splenectomy group achieved these levels more rapidly following transplant (p less than .001). One of 17 evaluable patients in the splenectomy group and 31 of 46 in the no-splenectomy group became refractory to random platelets (p less than .001) and required platelets from family members or unrelated completely or partially HLA matched donors. In the no-splenectomy group, splenic size did not affect the speed of granulocyte or platelet recovery or platelet transfusion requirements.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for rapid mobilization of platelets from the spleen during intensive plateletpheresis

The role of the spleen as a reservoir capable of adding platelets to the circulating blood cells has been well documented in animals but poorly documented in humans. As part of a program of platelet cryopreservation, we have intensively plateletpheresed a group of patients with acute leukemia in remission who had undergone splenectomy. The results of the 64 plateletphereses in these 11 patients (average platelet yield 4.2 X 10(11) +/- 2.4, range 1.2-12.4) were compared with 50 consecutive plateletphereses in nonsplenectomized leukemia patients (average yield 4.9 X 10(11) +/- 3.2, range 2.1-18.3) and 50 consecutive plateletphereses in normal donors (average yield 3.8 X 10(11) +/- 1.4, range 1.7-7.6). There was no difference in the prepheresis platelet counts among the three groups. Plateletphereses were done in 1.5-3 hr by intermittent flow differential cell centrifugation technique. The expected platelet yield was calculated by multiplying the pre-platelet count - (pre-hct/post-hct X post plt count) by the estimated blood volume (70 ml/per kg body weight). The mean ratios of the observed platelet yield to expected platelet yield were similar for the nonsplenectomized leukemia patients (mean ratio = 1.32 +/- 0.50, range 0.73-3.04) and normal donors (mean ratio = 1.31 +/- 0.49, range .52-2.9), implying mobilization of platelets from outside of the blood pool. In contrast, in the splenectomy group, the mean ratio (0.76 +/- 0.32, range 0.31-2.9) was significantly lower (p less than .001). These data indicate that there is replenishment of the circulating platelet pool by the spleen in response to the rapid removal of platelets.

Platelet cryopreservation. 1. In vitro aggregation studies

Platelets were harvested by a Hemonetics Model-30 discontinuous cell separator from 20 normal volunteers and were cryopreserved in the presence of 5% DMSO at a controlled rate of freezing of -1 degrees C/min and stored in liquid nitrogen for up to 3 months. A significant loss of platelets occurred at the platelet concentration step through adhesion of platelets to the bag walls. A small reduction in aggregation associated with this was also seen and may reflect some damage to the platelets during the pheresis procedure. A small, but significant loss of platelet aggregation was seen with all agents following cryopreservation. Mean percentage aggregation post-thaw for all the agents was 75.4% (range 74-78%) and platelet recovery was approximately 90%. No significant changes in aggregation or recovery were seen over the 3 months' storage period. The cryoprotectant DMSO was shown to have no deleterious effect on platelet function in vitro.

Plateletpheresis experience with the Haemonetics Blood Processor 30, the IBM Blood Processor 2997, and the Fenwal CS-3000 Blood Processor

Comparisons were made of the apheresis instruments Haemonetics Blood Processor 30, IBM Blood Processor 2997 and Fenwal CS-3000, for collection of platelets from normal donors. With each instrument the mean recovery was at least 4 x 10(11) platelets per procedure, and each instrument afforded a safe and reliable collection. The Haemonetics Blood Processor gave the lowest recovery of platelets per minute per procedure. The IBM Blood Processor 2997 required the longest time for set-up and priming and processed 1.5 liters more donor blood per collection than the other instruments. The Fenwal CS-3000, which is a computer-controlled instrument, was the least time consuming. The donor suffered a significantly greater drop in platelet count after collection with the IBM Blood Processor 2997 (31%) than after collection with the other instruments (19%), and we were unable to account for this observation.

Recovery, life span, and function of stored plateletpheresis units

Plateletpheresis units collected using the Haemonetics Model 30 or the IBM 2997 cell separator were stored for 24 h at 22 degrees C. Autologous recovery and life span measurements averaged 64 +/- 13% (1 SD) and 8.9 +/- 1.3 (1 SD) days. The hemostatic effectiveness of these preparations were satisfactory; the corrected increment 4-6 h and 18-24 posttransfusion was 20,400 and 13,400/microliter/m2, respectively, and the bleeding time showed improvement in each patient. There was no significant difference in these parameters between collection devices.

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.

Cost accounting in plateletpheresis: comparison of two techniques

Cost comparison of two comparably effective techniques of plateletpheresis, a manual method and an automated discontinuous flow centrifugation technique, is presented using a hypothetical model. The former procedure costs $62.48 per pheresis for disposables and labour as opposed to $78.32 per pheresis for disposables and labour for the latter. The annual volume of plateletpheresis at which the accumulated costs equal the total charges, i.e. the 'break-even' point, is calculated and found to be 63.7 for the automated technique and 10.9 for the manual method, if the charge for each is $200.00. For the manual method at a current charge of $80.00, the break even point is 85.8. The assumptions underlying this hypothetical model are examined, and the effects of deviation from these assumptions are analyzed in terms of the break even point. Cost accounting of plateletpheresis is shown to be dependent upon the choice of approach to allocation of costs, the assumptions of the cost accounting model, and the selection of an appropriate charge.