Storage of Platelet Concentrates R. A. KAHN,AND H. T. MERYMAN From the American National Red Cross Blood Research Laboratory, Bethesda, Maryland
The American National Red Cross has initiated a cooperative clinical study designed to evaluate the therapeutic effectiveness of fresh platelets and platelets stored at 4 or 22 C for up to 72 hours. Preliminary results, in confirmation of earlier work, indicate an inverse relationship between platelet count and bleeding time in patients with thrombocytopenia transfused with fresh platelets. Also, the observed rise in platelet count immediately following transfusion of fresh platelets is generally maintained for four to eight hours after which time it declines significantly.
conflicting evidence. Becker and co-workers' have reported 4 C stored platelets to be clearly superior in their therapeutic effectiveness whereas Murphy and Gardnerg-" and Slichter and H a r k e P have found 22 C to be superior. These conflicting reports emphasize the difficulties involved in assessing the effectiveness of platelet transfusions in patients. It is important to recognize that there are a variety of recipient factor^^*^^'^ and technical detailss*'5that can influence the efficacy of a platelet transfusion and which should be taken into consideration when designing studies. For example, fever or splenic enlargement will influence results and the degree to which the response following transfusion was influenced by prior alloimmunization should be examined or controlled. In early 1974, the American National Red Cross initiated a study designed to compare the therapeutic effectiveness of platelets stored at 4 or 22 C following storage intervals up to 72 hours in length. In order to obtain a large number of patient studies, a number of Regional Red Cross Centers and their affiliated hospitals were asked to collaborate in the study. Collaborating investigators are: Drs. G. Becker, Badger Red Cross Blood Center (RCBC), Madison; S. Rivers, Atlanta RCBC, Atlanta; I. Szymanski, Massachusetts RCBC, Boston; M. Kennedy, Central Ohio RCBC, Columbus; W. Miller, Missouri-Illinois RCBC, St. Louis; E. Fuller, Louisville RCBC, Louisville; and W. Mallin, Washington RCBC, District of Columbia. As of February, 1975, we have collected data from 32 patients (27 with leukemia, five with aplastic anemia) who received both fresh
PLATELETS STORED at 22 C have been reported to have good in vivo survival; however, studies in aspirin-treated recipients suggest that the platelets stored at room temperature have a storage lesion which interferes with their immediate hemostatic effectiveness but which heals after several hours in the c i r c ~ l a t i o n . ' *Platelets ~*~ stored at 4 C, on the other hand, have markedly shortened life span but when infused into aspirin-treated recipients, their immediate hemostatic effectiveness appears equal to or perhaps even better than that of fresh plateAlso, platelet function in vitro is maintained better at 4 C.1.6910.14These reports have led to the recommendation that platelet concentrates be stored at 22 C for use in prophylaxis and at 4 C for use in the control of active bleeding.' The degree to which results obtained from studies of aspirin-treated volunteers can be applied to the treatment of patients with thrombocytopenia has not been established, and the effectiveness of platelet transfusions can only be properly assessed under clinical circumstances. Previous studies of the effectiveness in thrombocytopenic patients of platelets stored at 4 or 22 C have resulted in Contribution No. 314 from the American National Red Cross Research Laboratory.
13 Transfusion Jan.-Fcb. 1976
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KAHN A N D MERYMAN
platelets ( < 12 h o u r s old) and platelets s t o r e d for either 24,48, or 72 h o u r s at either 4 or 22 C. It is too early for conclusions to b e d r a w n regarding t h e effectiveness of prolonged s t o r a g e a t either temperature. However, some preliminary observations can be reported on t h e effect of transfusing platelet concentrates which have been stored f o r less t h a n 12 hours.
Method The following protocol was designed (see acknowledgment) for the evaluation of platelets stored for up to three days at 4 and at 22 C. Although the data reported in this paper are concerned only with the effectiveness of fresh platelets, the protocol is presented in its entirety to elucidate the rationale of the study. Selection oj’ Patients The patient can be a male or female of any age who has a platelet count below 30,000 mm3 as a result of a failure to produce platelets. This population will include patients with aplastic anemia and leukemia but not those patients with idiopathic thrombocytopenic purpura or disseminated intravascular coagulation. The patient’s spleen should not be palpable on resting respiration. Patients with fever over 101 F, bacterial sepsis, or active hemorrhage requiring a red blood cell transfusion should not be included in this study. The patient should not have taken any nonsteroidal anti-inflammatory drugs for at least 48 hours prior to transfusion. If possible, patients in this study should not be given the antibiotic carbenicillin. Also, every effort should be made to keep the dosage of all drugs administered to a patient constant throughout the term of the study. Preparation of Platelets Donors must be ABO compatible with the patient except that Group 0 donor platelets can be given to all patients. All blood should be collected in CPD. Following collection, the blood must be tested for Hb,Ag. Following collection, the whole blood must be held and processed at room temperature (22 2 C). Speed and time of centrifugation in the preparation of the concentrate can be a t the discretion of the investigator. Each concentrate should contain a t least 5.5 x 1 O ’ O platelets. When the platelets are to be stored at 4 C , the volume of the concentrate should be 25 to 35 ml. If the platelets are to be used within 12 hours (fresh platelets) or stored at room temperature,
Transfusion Jan.-Feb. 1976
the volume of the concentrate should be 45 to 55 ml but absolutely no less than 40 ml. Following preparation of the concentrate, the platelets should be allowed to sit undisturbed for 90 minutes a t room temperature. After this incubation period, resuspend the platelets by either gentle kneading or by placing them on a rotator. If platelet clumping is visible a t this time, the unit should be discarded. After resuspension, the concentrates should be stored a t either 6 C undisturbed or at room temperature (20-24 C) with gentle rotation. If platelet clumping occurs during or immediately following storage, the unit must still be used for transfusion and the fact that it was clumped recorded. The storage intervals for 10 platelets (i.e.. 24, 48, or 72 hours) can be hours. Dosage and Administration All patients should receive 0.2 units of platelet concentrate/kilogram body weight. The units should be pooled prior to infusion. Platelets stored at 4 C should be allowed to come to room temperature without manipulation before pooling (takes approximately 45 minutes). The pooled platelets should be administered as rapidly as can be tolerated by the patient through a filter. The choice of whether a patient receives platelets stored a t 4 or 22 C should be made on a fixed alternate basis. For example, patient # 1 receives 4 C platelets, patient #2 receives 22 C platelets, #3 receives 4 C platelets and so on. Transfusion Each patient should undergo three transfusions, each of which should consist of sufficient platelets to raise the patient’s circulating platelet count to a t least 50,000/mm3. The first will be with fresh platelets (i.e.. platelets not more than 12 hours old). This first transfusion will determine if the patient is refractory to platelets and will also provide control values to be used to evaluate the response obtained with stored platelets. The second transfusion will be administered after the patient’s platelet count returns to below 30,000/ mm3 and will be with stored platelets. The third transfusion will again be with fresh platelets, and administered after the platelet count is allowed to drop below 30,000/mm3. The third transfusion insures that the response obtained with stored platelets was not influenced by alloimmunization. It is permissible to omit the first or third transfusion of each platelets (but not both) with patients having no history of prior transfusion. Measurements on Patients Measurements of the patient’s bleeding time (template method) and platelet count (by phase microscopy) prior to and following transfusion
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should be taken according to the following schedule. Platelet counts are determined pretransfusion, 15 minutes to one hour, four to eight hours, and 18 to 24 hours after transfusion. Bleeding times are determined at the same time intervals when stored platelets are transfused but only 18 to 24 hours after the fresh platelet transfusions.
normal bloadlng Ytima
111. 0 0
Results and Discussion Figure 1 depicts the relationship between platelet count and bleeding time 24 hours following the transfusion of fresh platelets. Although there is a significant linear relationship between these two parameters, with an intercept at the normal bleeding time when the platelet count is 97,000 per mm3, a substantial portion of the variation in the bleeding time is unrelated to the platelet count ( 1 4 = 0.61). Harker and Slichter5 have reported a very close linear relationship between platelet count and bleeding time with an intercept at the normal bleeding time when the platelet count reached 100,000 mm3. The difference between the degree of correlation they have reported and our observations may be due to the fact that their patients were mostly stable clinically and were not receiving any medication. In contrast, our patients were receiving an average of six drugs, had an average hematocrit of 28 per cent, and most had some evidence of bleeding prior to transfusion. Murphyg has reported that the prolonged bleeding time in patients with thrombocytopenia can be corrected if the platelet count is raised to above 50,000/ mm3. However, our data and the report of Harker and Slichter5 indicate that the bleeding time does not approach normal (