Ronald O. Gilcher

Convenience, the bane of our existence, and other barriers to donating

BACKGROUND:  To prevent donor loss and improve retention, it is important to understand the major deterrents to blood donation and to identify factors that can be effectively addressed by blood centers.

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome: Diagnosis and management

Thrombotic thrombocytopenic purpura‐hemolytic uremic syndrome (TTP‐HUS) is a clinical syndrome defined by the presence of thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent etiology. Patients may also have multiple other symptoms and signs including neurologic and renal abnormalities and fever. In the era prior to effective therapy with plasma exchange, most patients developed multisystem abnormalities and the syndrome was more easily recognized. Now, since there is urgency to begin treatment, sufficient diagnostic criteria for TTP‐HUS are only thrombocytopenia and microangiopathic hemolytic anemia without a clinically apparent cause; patients may have no neurologic symptoms, renal abnormalities, or fever. This has lead to an apparent increased incidence because of both the increased importance of early recognition and the decreased specificity of the diagnostic criteria. Effective treatment has also revealed new aspects of the clinical course of TTP‐HUS following the initial response to plasma exchange treatment: prompt exacerbations, which are common when plasma exchange is diminished in frequency or discontinued, and later relapses, which may occur many years after the initial episode. This review describes the evolution of the syndrome of TTP‐HUS in the current era of effective treatment, and describes the management and clinical outcomes among patients treated by the Oklahoma Blood Institute. J. Clin. Apheresis 13:120–125, 1998.

Evaluation of a new Trypanosoma cruzi antibody assay for blood donor screening.

BACKGROUND: This multicenter prospective study was designed to evaluate the performance characteristics of a new commercially available enzyme‐linked immunosorbent assay (ELISA) for the detection of antibodies to Trypanosoma cruzi in blood donors, the ORTHO T. cruzi ELISA Test System (Ortho‐Clinical Diagnostics).

Red blood cells, plasma, and other new apheresis-derived blood products: Improving product quality and donor utilization

T HE DEVELOPMENT of apheresis collection techniques began with processes to collect white cells or platelets from donors. These techniques have been in use for more than 20 years and also have been developed into various therapeutic procedures. The purpose of this review is to discuss the products that have been made available through more recently developed instruments. Products include apheresis plasma, apheresis red blood cells, combinations of red blood cells and plasma, or red blood cells and platelets. In addition, the collection of apheresis plasma has allowed the subsequent processing of this material to permit the development of apheresis cryoprecipitate, and apheresis cryo-poor-plasma (cryo-supernatant plasma). A variety of instruments have been developed that allow for the collection of these various products, and they are discussed in sections dealing with each of the different products. The aims in the development of apheresisderived product collections are severalfold: apheresis inherently allows for application of good manufacturing practices and thus improves the quality of the product. Not only is the product improved from the standpoint of component materials but also it yields improved safety by reducing the number of donor exposures per transfusion. Apheresis also allows for improved yields of components from the donor. This allows for increased efficiency in terms of products collected per donor visit. The outcome is that many donors are able to give one or more transfusable doses of a product in a single apheresis donation.

In vitro bleeding time test can diagnose thrombotic thrombocytopenia purpura and can possibly monitor therapeutic plasma apheresis.

Thrombotic thrombocytopenia purpura (TTP) is perplexing, mainly because of its difficult diagnosis and dramatic clinical presentations, high mortality rates, and the effectiveness of empirical plasma infusions and plasma exchanges. Scientific evidence supports the hypothesis that TTP results from platelet hyperagglutination. To support this, a new in vitro bleeding time (Platelet‐Stat™) test was used. Eleven patients had a mean in vitro bleeding time of 7.3 ± 2.1 seconds prior to plasma exchange and eight patients had a mean of 13.6 ± 4.7 seconds after the plasma exchange procedure. Normal controls were 14 ± 2 seconds. The test was used to monitor plasma exchanges in two patients. At the time the platelet count and LDH returned to normal, the Platelet‐Stat™ remained shortened. The two patients relapsed and required continued plasma exchanges until Platelet‐Stat™ corrected to normal. These results suggest that plasma exchanges may be effectively monitored by Platelet‐Stat™ rather than the traditional parameters, i.e., LDH. Therefore, the Platelet‐Stat™ test may be a useful test to diagnose TTP and monitor therapy in this disease. J. Clin. Apheresis 15:161–168, 2000.