Alfred J. Katz

Occurrence of the Release Reaction during Preparation and Storage of Platelet Concentrates

To determine the degree of damage occurring during preparation and storage of platelet concentrates, the percent release of B‐thromboglobulin (BTG) and percent leakage of the cytosolic protein lactic dehydrogenase was determined sequentially from phlebotomy to the end of storage for 72 h at 20–24°C. The effect of storage temperature, pH, and radiation was also evaluated. The results showed that during preparation of platelet concentrate a large degree of release was found after resuspension of the platelet button formed after the high‐speed centrifugation. During storage the percent BTG release increased from 18.1 to 40.2% (p<0.05). The percent release seen during storage at 4°C (72 h) was 19.2%, while that seen for platelets subjected to temperature cycling at 4–37 °C was 24.9%. Both of these values were significantly less (p<0.05) than that seen for concentrates stored at room temperature. A negative correlation between pH and BTG release was found (r=‐0.64). Irradiation to 10,000 rad did not induce the release reaction or lactic dehydrogenase leakage. We conclude that the degree of in vitro platelet release is dependent on the preparative manipulations, and gentler protocols for preparation and storage of platelets should be investigated.

Simulation Analysis of Platelet Production and Inventory Management

Abstract. To maximize the availability of platelet concentrates (PC) and minimize their outdate, competing criteria, a computer simulation model of platelet production and distribution was developed. Based on 2 years of actual platelet orders placed with a regional blood center, the simulation program generated daily platelet orders, and also calculated mean demand and standard deviation of demand for each day of the week. The number of PC to be produced on a given day was calculated from: PC to be produced = (mean demand for that day of the week) +T× (standard deviation of demand for that day of the week) — (PC in inventory on the given day), where T is a selected multiple of the standard deviation. As T increases, availability is maximized, but outdating is expected to increase. Conversely, lower T is associated with less availability, but lower outdate. At the simulated platelet demand level (about 735 PC per week), with 3‐day platelet storage life, 99% availability is associated with 1% outdate and distribution of PC of less than 1 day average age. 100% availability, with no outdate is predicted for a 5‐day storage life, with no further improvement in logistics with 7‐day storage life, at this level of demand. Although logistics of platelet production and distribution vary from center to center, the simulation analysis is generally applicable, and a formal plan has the great advantage of predictive, rather than reactive, platelet production.

Patterns of Blood Use in Connecticut

Blood use patterns were studied in a setting essentially free of the constraints of shortage, high‐cost, nonreplace‐ment penalties, and high hepatitis risk. Connecticuts hospitals used an average of 0.299 unit of blood per patient discharge in 1978. Interhospital variation was great, with large hospitals using more blood per discharge. The percentages of blood ordered by individual hospitals as red blood cells ranged from 38.9 to 96.2 per cent. Frozen red blood cells were ordered in greater proportion by large hospitals. Relative plasma use was greater in large hospitals, ranging from 0.003 to 0.232 unit per unit of blood. Hospital outdating ranged from 0.1 to 21.3 per cent, with large hospitals outdating proportionately less. Such striking variations suggest that habits and personal preferences may determine the pattern of a hospitals blood use, and, therefore, the costs of blood provision. Statewide from 1971 to 1978, red blood cell ordering increased from 13.8 to 63 per cent of total blood order. Plasma use has increased from 0.025 to 0.130 unit per unit of blood. Blood use per patient discharge has also increased, but more slowly.

Optimizing recovery of platelets in platelet rich plasma by the simplex strategy.

A Simplex is an empirical, geometric feedback strategy which progressively programs a series of experiments according to the results of the preceeding experiments. It leads to definition of conditions which maximize or minimize the result of experiments in two or more variables. When applied to study a laboratory method it dictates simultaneous variation of the conditions of an experiment, differing from the usual approach in which variables are altered sequentially and arbitrarily. A two variable Simplex (force and duration of centrifugation) has been applied to maximize platelet recovery in platelet rich plasma (PRP). The technique of Simplex is described. Maximal recovery of platelets in PRP was reached by centrifugation at 2160 ×g for 2.7 minutes.

Removal of thymic-derived lymphocytes during pheresis procedures.

Measurements have been made of the absolute T‐cell loss experienced by normal donors undergoing three methods of pheresis used for the preparation of platelets and/or granulocytes for transfusion. Filtration leukapheresis was associated with a mean loss per donation of 1.7×108 T cells. The technique of intermittent flow centrifugation platelet pheresis resulted in a mean loss per donation of 3 × 109 T cells. When this latter technique was utilized for leukapheresis, with hydroxyethyl starch and prednisone taken 12 h before the donation, the mean loss per donation was 3.9×109 T cells. When an intravenous dose of dexamethasone at the commencement of the procedure was used instead of prednisone for leukapheresis by intermittent flow centrifugation, the mean cell loss per donation was 2.2×109 T cells. We have examined the immediate effects of these procedures on circulating T lymphocytes and their responsiveness to mitogens. The only change of significance was an increased responsiveness to phytohemagglutinin after leukapheresis of the lymphocytes of those donors who had received prednisone. Replacement of T cells appears to be inefficient in adult life and thus functionally important numbers of T lymphocytes may be removed by repeated pheresis procedures. Careful examination of the potential immunological and clinical consequences of repeated pheresis appears warranted.

Statewide Support of Thrombocytopenic Patients with ABO Matched Single Donor Platelets

Use of ABO matched, HLA nonmatched platelet units obtained from single donors by pheresis, using the Haemonetics 30 Cell Separator, has a lowered hepatitis risk, and possibly delays the onset of the refractory state. Pheresis also offers a method of obtaining HLA matched platelets for the already refractory patient. A mean of 4.2 × 1011 platelets are collected in about 1 1/2; hours. ABO matched, HLA nonmatched platelets produced corrected increments of more than 2500/mm3 per 7 × 1010 platelets infused in 67 per cent of transfusions to nonselected recipients. The procedure is simple, safe, and requires little time. It is a worthwhile large‐scale program for a regional blood center to undertake in order to provide optimal therapy for thrombocytopenic patients.

Storage of Platelets Prepared by Discontinuous Flow Centrifugation

Platelet concentrates were prepared by plateletpheresis using discontinuous flow centrifugation. Platelet units were stored in PL‐146 bags of 300 ml and 2,000 ml capacity, and in vitro measures helpful in predicting platelet viability were compared. Storage in bags of 300 ml capacity led to significant fall in pH, decreased recovery from osmotic stress, and deterioration of morphology in 24 hours. Storage lesions were significantly decreased by use of 2,000 ml capacity bags.

Redistribution of Platelets During Discontinous Flow Platelet Pheresis

Abstract. Greater numbers of platelets are recovered during discontinuous flow centri‐fugation than can be simply accounted for by the decrease in total circulating platelets in the donor. There is a linear relationship between the logarithm of the circulating platelet count and the number of plateletpheresis bowls filled. The disappearance of platelets from the peripheral circulation occurs at a greater rate in splenectomized donors than in normal donors, and the rate of platelet disappearance in normal donors is less than what would be expected if there were no in vivo platelet storage pools. The data suggest the redistribution of platelets from the spleen in normal donors during the time course of the procedure.

Factors affecting the efficiency of filtration leukapheresis.

Continuous flow filtration leukapheresis was performed on normal volunteer donors with and without intravenous administration of dexamethasone. Although granulocyte counts were increased in steroid treated donors and almost 20 per cent more cells were presented to the filters, the final yield of granulocytes was slightly decreased and the efficiency of collection during a two‐ to three‐hour leukapheresis was statistically significantly decreased.

Platelets and factor VIII as functions of blood collection time.

Plasma and platelet concentrates were prepared from whole blood collected in less than eight minutes, and from blood collected in 8 to 12 minutes. Comparison was made between the two collection groups, of Factor VIII activity in fresh plasma, and of Factor VIII activity in fresh frozen plasma. Using the rank sum test, no significant difference was found between Factor VIII activities in either fresh or fresh frozen plasma. The number of platelets in concentrates prepared from blood collected in less than eight minutes were compared with those in concentrates from blood collected in 8 to 12 minutes. Mean numbers of platelets were 6.89 × 1010 and 7.12 × 1010, respectively. No significant difference was found between the two groups when compared by the rank sum test, or the “t” test. Current guidelines recommending maximum eight‐minute collection times for component preparation may be inappropriately restrictive.