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Analytical Control
Systems, Inc Analytical Control Systems, Inc. |
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317-841-0458
317-841-3186
Analytical Control Systems, Inc.
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Platelet Concentration Units, PF3, Apheresis, Overnight Shipping & Spectra™ APCT Proposed Procedure for Evaluating Platelet Concentrate Units to be Used for Transfusion By Roy Speck, B.A., Dean Bonderman, Ph.D., Lloyd Cook, M.D. and Joyce Larison, M.A. at Analytical Control Systems, Inc., Fishers, IN and Medical College of Georgia, Augusta, GA July 1998.
Summary: Platelet concentrate samples from 100 units collected by apheresis at The American Red Cross Blood Bank located at Columbia, S.C. and from 31 units collected by apheresis at the Santa Barbara Tri-County Blood Bank located in Santa Barbara, CA were sent overnight to Fishers, IN and tested for platelet factor 3 activity. The maximum dilution that would support normal clotting was determined for each unit. Units with maximum dilutions of 1:100 or greater were considered to have sufficient platelet factor 3 activity to be used for a transfusion. Ninety-six percent of the units sent from Columbia, SC and 94.55% of the units sent from Santa Barbara, CA were suitable for use based on their platelet factor 3 activity. This study shows the feasibility of sending platelet concentrates long distances and the importance of testing for platelet factor 3 activity. Key words: platelet concentrate— PF3— Apheresis.
Several groups have issued guidelines for blood component therapy for the purpose of improving the clinical outcome of transfusion procedures, to minimize adverse transfusion reactions, and to decrease cost. The National Institutes of Health issued guidelines (1-3) for red blood count (RBC) transfusions, platelet therapy, and administration of fresh frozen plasma (FFP). The American College of Obstetricians and Gynecologists issued recommendations for blood component therapy in 1984 (4). The American Association of Blood Banks issued guidelines in 1990 for transfusion of patients undergoing coronary bypass surgery (5). The American College of Physicians issued recommendations for RBC transfusions in 1992 (6). The College of American Pathologists published guidelines in 1994 for the use of FFP, cryoprecipitates, and platelets (7). The American Association of Anesthesiologists in 1996 published the most current of guidelines for transfusion component therapy (8). More than 22,000,000 blood components are administered each year in the United States at an estimated direct cost between $5 and $7 billion. Of these, 7,000,000 are platelet units. Platelet units must be discarded within 5 days from the date of preparation according to Food and Drug Administration (FDA) regulations. No tests are performed on the platelet unit to assure its quality other than random pH tests. There is a total dependence on the history and physical record of the donor as an indication of quality. If the donor has a congenital or acquired platelet defect, this is not reveal at the time of the phlebotomy. Platelets are used when a quantitative or qualitative platelet defect is suspected as the cause of bleeding. The platelet count at which surgical or obstetric patients are likely to experience bleeding is not known. In non-surgical patients with platelet counts >20 X 109/L spontaneous bleeding is uncommon. It is well established that a platelet transfusion can raise the platelet count. The magnitude of the effect is influenced by the release of stored platelets in the spleen and peripheral platelet destruction. In general, one platelet unit will raise the platelet count about 5-10 X 109/L in the average adult. The average therapeutic dose is one platelet concentrate unit/10 kg body weight. None of the common coagulation tests presently available are useful in predicting the need for platelets. The bleeding time test is totally unreliable. The prothrombin time test and the activated partial thromboplastin time (APTT) test are not sensitive to the presence of platelet defects. Recently, we developed a new, patented intrinsic chemical activator composed of propyl gallate, which quantitatively releases the total platelet factor 3 (PF3) present in the platelet membrane and simultaneously activates the intrinsic coagulation pathway. This extends the properties of the APTT reagent so that PF3 may be determined. We call this test the activated plasma clotting time test (APCT) (9,10). This test may be used to measure PF3 in donors, patients, and platelet concentrates. By making dilutions of the platelet concentrate with platelet depleted plasma (PDP) the maximum dilution may be determined that would support normal clotting. The PDP supplies all of the plasma factors necessary for normal clotting except PF3. When the PF3 becomes limited, the clotting times become prolonged. The highest dilution that gives a clotting time value <40 seconds (the upper limit of normal for the APCT test) is considered the maximum dilution that will support normal clotting. Using these principles, we did a study that was intended to solve the problem of platelet concentrate supply dislocation and test the PF3 function after shipping.
Materials: 1) Spectra™ APCT reagent. ACS, Inc. Fishers, IN 46038, USA 2) Spectra™ freeze-dried platelet depleted plasma. ACS, Inc. Fishers, IN 46038 3) Pillows of platelet concentrate prepared by apheresis (100 shipped overnight from the American Red Cross at Columbia, SC by Federal Express to Fishers, IN) 4) Pillows of platelet concentrate prepared by apheresis (31 shipped overnight from Tri-County Blood Bank, Santa Barbara, CA by Federal Express to Fishers, IN) 5) Fibrometer coagulation instrument and accessories. Becton Dickinson Microbiological Systems, Downers Grove, IL 60515, USA.
Methods: Each pillow from the platelet concentrate was thoroughly mixed and a series of dilutions prepared using PDP. The APCT test was performed for each dilution using the propyl gallate APCT reagent for each dilution. The highest dilution giving an APCT value <40 seconds was considered to be the end point.
Results: Platelet concentrates with maximum dilutions of 1:100 or greater were considered to have sufficient PF3 to be good units and could be used for transfusion. Ninety-six of the samples shipped from Columbia, SC should be labeled good. Conversely, four units should be labeled as unsatisfactory. Twenty-nine of the samples shipped from Santa Barbara, CA should be labeled good and two units should be considered to be unsatisfactory.
Discussion: From this study it may be seen that platelet concentrate samples can be sent long distances and still retain their coagulation support viability. This shows that it should be possible to ship the platelet concentrate units in the same way and test these units after they reach their destination. It also follows that the donors can be tested so that the quality of the donor’s platelets may be determined and that the patient may be tested so that the patient’s need for platelets can be determined. The 1:100 dilutions was selected as a cutoff point since a smaller dilution could not supply sufficient PF3 to correct a hemostatic problem because of hemodilution. Testing donors before phlebotomy should improve the selection of donors with quality platelets. Testing the patient before the transfusion should determine when the patient needs platelets. Testing the patient after the transfusion would determine the efficacy of the therapy and the need for further platelet therapy. A more detailed study needs to be performed to test these hypotheses more thoroughly. This should lead to better medical benefits at a lower cost for those patients requiring platelet transfusion because all the platelet transfused would be good units.
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