The Bottom and Top System: A New Technique for Blood Component Preparation and Storage

Abstract

A new, automated technique for the preparation of blood components is described. A system of 3 or 4 integrally connected plastic containers (Optipac®) is handled by a new type of extractor (Optipress®). The container in which the blood is collected has an outlet at the top and another at the bottom. After normal centrifugation to obtain separation of the blood components, these are squeezed out from the top and bottom simultaneously under control of a photocell. The primary separation step results in three components: a leukocyte-poor red-cell suspension in SAGM medium, CPD plasma, and a buffy-coat preparation. The system has been tested in two laboratories (lab A and lab B). A ‘heavy-spin’ centrifugation to obtain a maximum yield of cell-poor plasma gave the best removal of leukocytes from the red cells; the remaining leukocyte content was 0.46 ± 0.25 (lab A) and 0.5 ± 0.4 (lab B)x 10⁹/red-cell unit. Platelet concentrates can be prepared either the normal way via platelet-rich plasma or from buffy coat. Red-cell 24-hour autologous posttransfusion survival using labeling with ⁵¹Cr was 87.5 ± 4.1% (lab A) after 35 days, and 84.2 ± 4.2% (lab A) and 77.5 ± 1.5% (lab B) after 42 days. Red-cell morphology and fluidity compared favorably to previous studies using the same additive solution in traditional plastic-bag systems. The total adenine nucleotide concentration was maintained normal for 42 days. Storage hemolysis after 6 weeks was slightly higher after a heavy spin, 0.52 ± 0.19% (lab A) and 0.23 ± 0.10% (lab B), than after a light spin, 0.31 ± 0.15 and 0.20 ± 0.09%, respectively. The formation of fibrinopeptide A was very low during the first 2 weeks and then increased to 15 ± 15 nmol/1 after a heavy spin and to 33 ± 11 nmol/1 after a light spin. Kallikrein and spontaneous proteolytic activity increased from day 14 on in the light-spun units but not in the heavy-spun ones. Clinical studies were made in two hospitals. A total of 1,492 transfused blood components prepared with the new system were compared with 1,169 components prepared with a traditional four-container system for making buffy-coat poor red-cell suspensions. No unexpected transfusion reactions occurred. The frequency of febrile reactions was 3/516 (new method) and 2/466 (controls) in a group of patients with predominantly myeloproliferative diseases. The system appears to be a significant improvement for automated preparation of high-quality blood components.