Platelet Transfusion: A Dose-Response Study

Plateletpheresis efficiency: a comparison of the spectra LRS and AMICUS separators

BACKGROUND

Optimizing the yields of plateletpheresis by increasing collection efficiencies may provide several benefits: to patients, by increasing the dose in single-donor platelet (SDP) units; to the collection center, by increasing the percentage of components that may be split into double units; and/or to the donor, by reducing the duration of donation.

STUDY DESIGN AND METHODS

A prospective, randomized study was undertaken to compare the efficiency of platelet collection in paired donations by 21 donors on two cell separators (Spectra LRS, version [v] 5.1; and AMICUS, v2.37). The order of donation was randomly assigned; donations were performed at least 2 weeks apart. A fixed blood volume (4000 mL) was processed by utilizing standard protocols. Findings were confirmed in a retrospective, matched study that compared the two separators by using fixed collection times (90 min).

RESULTS

The AMICUS and Spectra LRS separators consistently produced white cell-reduced (<1 x 10(6) white cells) components. The AMICUS harvested 32 percent more platelets on average (median, 4.9 x 10(11); range, 1.5-8.7 x 10(11)) than the Spectra LRS (median, 3.7 x 10(11); range, 2.1-7.7 x 10(11)) (p = 0.03), with mean times of 71.5 and 66.0 minutes (p = 0.03), respectively, to process 4000 mL. Mild donor reactions tended to be more common on the AMICUS separator, which used significantly more ACD (median 482 mL vs. 389 mL; p<0.0001) than on the Spectra LRS.

CONCLUSIONS

The AMICUS separator harvested more platelets per unit of blood volume processed than the Spectra LRS. Possible benefits include increased dose in each single-donor unit, increased double-unit harvests, and/or shorter donation time.

Clinical consequences of alterations in platelet transfusion dose: a prospective, randomized, double-blind trial

BACKGROUND

The dose-response relationship for platelet transfusion has become increasingly important as the use of platelet transfusion has grown.

STUDY DESIGN AND METHODS

One hundred fifty-eight prophylactic apheresis platelet transfusions were administered to 46 patients undergoing high-dose therapy followed by hematopoietic progenitor cell transplantation in a prospective, randomized, double-blind, multiple-crossover study. Transfusions were administered in pairs, differing only in platelet content. Each pair consisted of a lower-dose platelet component (LDP) and a higher-dose platelet component (HDP) administered in random order to the same patient. LDPs contained a mean of 3.1 x 10(11) platelets (range, 2.3-3.5 x 10(11)), and HDPs contained a mean of 5.0 x 10(11) platelets (range, 4.5-6.1 x 10(11)). Patients with active bleeding and those who were refractory to platelet transfusions were excluded.

RESULTS

The mean posttransfusion platelet count increment with LDP was 17,010 per microL, and that with HDP was 31,057 per microL (p<0.0001). Only 37 percent of LDPs resulted in platelet count increments of at least 20,000 per microL, whereas 81 percent of HDPs resulted in increments above this level (p<0.0001). The mean transfusion-free interval with LDP was 2.16 days, whereas that with HDP was 3.03 days (p<0.01). Administration of LDPs was associated with a 39 to 82 percent increase in the relative risk (per day) of requiring subsequent platelet transfusions (p<0.0001).

CONCLUSION

As compared to the administration of HDPs, the administration of LDPs for prophylactic transfusion in hematopoietic progenitor cell transplant patients results in a lower platelet count increment, a lower likelihood of obtaining a posttransfusion platelet increment >20,000 per microL, a shorter transfusion-free interval, and a greater relative risk per day of requiring additional transfusions.

Supportive care in hematological malignancies: hematopoietic growth factors, infections, transfusion therapy

This article focuses on a selected number of topics among recent developments in the supportive care of hematological malignancies. The first section focuses on the role of hematopoietic growth factors, such as granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, thrombopoietin, interleukin-11, and keratinocyte growth factor. The following sections discuss the management of fungal and viral infections as well as changes in the current policies of platelet transfusion. The focus of this review is on the clinical utility and economic feasibility of the published findings.

Progress in the development of systems for in vitro expansion of human hematopoietic stem cells

Hematopoietic stem cells are the cells primarily responsible for short term and long term hematological reconstitution when a graft is infused into a myeloablated host. The number and quality of hematopoietic stem cells within a graft are the major determinants of the time to and durability of hematological reconstitution of a transplant recipient. Ex vivo hematopoietic stem cell expansion is, therefore, a critical component of several potentially important clinical strategies including gene therapy, tumor purging and graft engineering. Recent clinical trials using a variety of ex vivo hematopoietic stem cells expansion systems have, to date, met with limited success. Recognition of the consequences of hematopoietic stem cell self-replication will assist in the development of new approaches to hematopoietic stem cell expansion. The use of suitable in vivo models to assay the marrow repopulating potential of expanded hematopoietic stem cell products is a vital step prior to entry again into clinical trials.

Thrombocytopenia-Platelet Support or Growth Factors?

The prevention and treatment of hemorrhage in patients with severe thrombocytopenia following cytotoxic chemotherapy and/or radiotherapy remain important issues in the supportive care of these patients. Platelet transfusions have been available for this purpose for over 30 years, and there have been recent initiatives to refine the way in which they are used and to improve their safety. An alternative to platelet transfusions is the enhancement of platelet recovery through the use of hemopoietic growth factors, and the recent identification of thrombopoietin and its potential for clinical use are exciting developments. Further work is needed to ensure its safety, and to define the appropriate indications for its use. Another alternative to platelet transfusions is the use of platelet substitutes, and a number of products are being developed. The clinical use of hemopoietic growth factors and platelet substitutes raises the prospect of reducing the current high demand for platelet concentrates. However, it remains to be seen whether their potential will be fully realised, and platelet transfusions will continue to be needed for the forseeable future.