Therapeutic effectiveness and safety of outdated human red blood cells rejuvenated to restore oxygen transport function to normal, frozen for 3 to 4 years at −80 C, washed, and stored at 4 C for 24 hours prior to rapid infusion

Human red blood cell concentrates with hematocrit values of 75 V% were prepared from citrate-phosphate-dextrose (CPD) blood, stored at 4 C for 20 to 28 days, and biochemically modified with a solution containing pyruvate, inosine, glucose, phosphate, and adenine (PIGPA Solution A). The rejuvenated red blood cells were frozen with 40% W/V glycerol in a polyolefin plastic bag and were stored at ?80 C. After three to four years of frozen storage, the units were thawed, washed, and stored at 4 C in a sodium chloride-glucose-phosphate solution for 24 hours prior to transfusion. Red blood cell recovery was 97 per cent after thawing and 90 per cent after washing. An automated differential agglutination procedure (ADA) showed 24-hour survival values of about 80 per cent, and long-term survival values of about 85 days depending on the disease state of the recipient. The red blood cells had normal affinity for oxygen on the day of transfusion. Plasma hemoglobin levels measured immediately after transfusion indicated extravascular removal of nonviable donor red blood cells. There was no increase in the uric acid level during the 24-hour posttransfusion period. A pool of three to ten units of rejuvenated washed previously frozen red blood cells was transfused rapidly to each of 19 anemic elderly patients. The red blood cells which had normal oxygen delivery capacity immediately upon transfusion increased the recipient's red blood cell mass and produced no untoward effects.     

Therapeutic effectiveness and safety of outdated human red blood cells rejuvenated to improve oxygen transport function, frozen for about 1.5 years at 80 C, washed, and stored at 4 C for 24 hours prior to rapid infusion

After storage at 4 C for 20 to 28 days, red blood cells were biochemically modified to improve their oxygen transport function which had deteriorated during liquid storage. The solution used for rejuvenation contained pyruvate, inosine, glucose, phosphate, and adenine (PIGPA Solution B). The rejuvenated red blood cells were frozen with 40% W/V glycerol in a polyolefin plastic bag and were stored in the frozen state for about 1.5 years at −80 C. After thawing and washing the red blood cells were stored at 4 C in a sodium chloride- glucose-phosphate solution for 24 hours before transfusion. A pool of four to ten units was rapidly transfused to each of 14 elderly anemic recipients, 11 of whom had cardiopulmonary insufficiency. Recovery of the red blood cells after the freeze-thaw process was about 97 per cent, and after the freeze-thaw-wash process about 90 per cent. The 24− hour posttransfusion survival values were about 75 per cent, and the long-term survival values were about 85 days depending on the disease state of the recipient. The red blood cells had 1.5 times normal 2.3- DPG levels and a decreased affinity for oxygen at the time of transfusion and were able to delivery oxygen at high oxygen tension immediately after the rapid infusion of pools of from four to ten units through a 40-or 170-micron filter. Plasma hemoglobin levels were consistent with extravascular sequestration of nonviable red blood cells, and uric acid levels were not increased during the immediate 24− hour posttransfusion period.     

Cryopreserved red blood cells for pediatric transfusion. Frozen storage of small aliquots in polyvinyl chloride (PVC) plastic bags

Human nonrejuvenated and rejuvenated red bood cells were prepared for cryopreservation and subsequent pediatric transfusion. Glycerol was added to the red blood cells in the primary polyvinyl chloride plastic collection bag to achieve a concentration of 40 per cent W/V. The red blood cells were concentrated by centrifugation, and the supernatant glycerol was discarded. Each glycerolized unit was divided into four equal aliquots in the individual 600-ml bags of a dry quadruple polyvinyl chloride plastic system, and each aliquot was frozen and stored at −80 C. After thawing, sodium chloride solutions were used to wash the aliquots in the IBM Blood Processor 2991-1 or 2991-2 or the Haemonetics Blood Processor 115, and the washed aliquots were stored in a sodium chloride-glucose-phosphate solution at 4 C for 24 hours. Freeze-thaw recovery of the red blood cells was about 97 per cent, and freeze-thaw-wash recovery was about 84 per cent. Twenty-four-hour posttransfusion survival values were about 92 per cent for both nonrejuvenated and indated-rejuvenated red blood cells. Nonrejuvenated red blood cells, those frozen within three to five days of collection without biochemical modification, had normal oxygen transport function at the time of transfusion; rejuvenated red blood cells, those biochemically treated with PIGPA Solution A after three to five days of storage at 4 C, had improved oxygen transport function at the time of transfusion.     

Washed hyperpacked frozen and shelf red blood cells

In order to determine the maximum degree to which blood units could be packed and still be effective, shelf stored blood and previously frozen red blood cells were washed and hyperpacked to hematocrits of 90 to 98 per cent. These products had average volumes of 180 and 162 ml, respectively. When transfused into a group of patients with stable nonhemolytic anemias or with slow or intermittent blood loss, the hyperpacked shelf stored blood resulted in average hematocrit increments of 4.4 per cent; the hyperpacked frozen red blood cells resulted in average hematocrit increments of 3.4 per cent. Conventionally packed unwashed red blood cells had approximately 10 per cent more hemoglobin and volumes of 270 to 330 ml, but resulted in average hematocrit elevations of only 2.8 per cent. Unwashed blood hyperpacked to hematocrits of 90 per cent with removal of the visible buffy coat took much longer to administer. Thus, by washing and hyperpacking shelf stored blood or previously forzen red blood cells, transfusions with the minimal amount of extraneous material can be given.     

Automated Differential Agglutination Technic to Measure Red Cell Survival

The survival after transfusion of ACD-stored and of previously frozen red cells was measured by means of an automated differential agglutination technic which permitted simultaneous quantitation in the same recipient of red cells preserved by two different methods. The previously frozen red cells were preserved with a high concentration of glycerol, using the slow freeze-thaw technic, and were recovered by agglomeration.
Severely damaged red cells in both ACD-stored and previously frozen blood were removed during the transfusion, and less deteriorated red cells were removed at an accelerated rate, usually over the initial 24-hour posttransfusion period. The mean loss in vitro of red cells related to the freezing process was 28 per cent. The transfused previously frozen blood contained nonviable red cells in amounts comparable to ACD blood which had been stored at 4 C for longer than two weeks, Red cells remaining in circulation 24 hours after transfusion were usually removed at a slower constant rate, and the mean life spans of viable cells from either ACD-stored or previously frozen blood were similar.     

Therapeutic transfusions of previously frozen washed human platelets

The platelets used in this study were collected by serial centrifugation, and within four hours of collection were frozen with 5% dimethylsulfoxide (DMSO) at an overall rate of 2 to 3 C per minute by storage in a mechanical refrigerator at −80 C. The frozen platelets were stored for four to ten weeks before thawing and washing. After washing, the units were kept at room temperature for six to eight hours before transfusion. The units were pooled, and an average of eight units was given to each of four patients, with a range of three to 14 units per transfusion. In vitro recovery after washing was about 65 per cent and in vivo recovery of the 51chromium labeled (51Cr) platelets was about 35 per cent. The infusion of these previously frozen washed platelets corrected prolonged bleeding times in patients. The homologous platelets were transfused along with other blood products to treat patients with hematologic disorders. The circulation and function of the donor platelets were influenced by compatibility of the platelets, the quality of platelet preservation and the patient's disease state.     

The Purification of Red Cells for Transfusion by Freeze Preservation and Washing

In the study of 125 units of washed, previously frozen red blood tells approximately 96.6 per cent of the leukocytes and 98.9 per cent of the platelets were removed. Less than 0.5 mg of plasma protein remained per unit. The length of storage as whole blood at 4 C prior to glycerolization of the red blood cells influenced the number of leukocytes in the washed, previously frozen red blood cells. Red blood cells frozen on the day of collection had 7.2 per cent residual white cells, whereas those stored at 4 C for 10 days or longer prior to glycerolization, freezing, and washing had 1.1 per cent residual leukocytes. When red blood cells were stored at 4 C for longer than one week, glycerolized, and washed without freezing, they had about 2 per cent residual leukocytes and platelets. The washing procedure removed at least 95 per cent of the platelets from nonfrozen and previously frozen red blood cells. Because of the removal of large numbers of leukocytes and platelets during the freeze-preserva-tion procedure and the excellent recovery of the red blood cells, washed, previously frozen glycerolized red cells are recommended for patients requiring red blood cells depleted of leukocytes, platelets, and plasma protein.     

Effect of Resuspension Medium on in Vivo Survival and Supernatant Hemoglobin of Erythrocytes Preserved with Glycerol

The observations reported are for erythrocytes frozen at -80 C for one month. Deglycerolized red blood cells resuspended in autologous plasma and stored at 4 C for 21 days after reconstitution have acceptable 24 hour survival, that is 70 per cent or greater. Deglycerolized red blood cells resuspended in 5 per cent Hyland albumin medium and stored at 4C for up to 12 days after reconstitution have acceptable 24-hour survival. Deglycerolyzed red blood cells resuspended in 5 per cent outdated albumin medium have acceptable 24-hour chromium survival when stored at 4 C for up to six days. The mode of removal of the nonviable erythrocytes in nonsurgical patients is primarily through an extravascular mechanism. The clinical acceptability of a reconstituted unit of preserved blood is dependent not only on the survival of the preserved red blood cells but equally on the mode of removal of the nonviable erythrocytes and the total amount of free supernatant hemoglobin. It is recommended that the total amount of free supernatant hemoglobin in reconstituted, previously frozen units should be measured on the day of transfusion because of the variability and unpredictability of the levels observed in this study.     

Simplification of the methods for adding and removing glycerol during freeze-preservation of human red blood cells with the high or low glycerol methods: biochemical modification prior to freezing

Simple methods have been developed for adding and removing glycerol during freeze-preservation with 20 per cent W/V glycerol at –150 C, or with 40 per cent W/V glycerol at –80 C. A one-step method with a 35 per cent W/V glycerol solution is used to prepare 20 per cent W/V glycerolized red blood cells, and a two-step method with a 57 per cent W/V glycerol solution is used to prepare 40 per cent W/V glycerolized red blood cells. The systems for washing glycerolized red blood cells have been simplified. This method consists of dilution of the thawed glycerolized red blood cells prior to recovery, followed by on-line dilution of these red blood cells with wash solutions during continuous flow centrifugation. This can be done in any of three commercially available washing systems, and they all use the same sodium chloride solutions. For the 40 per cent W/V glycerolized red blood cells, this process takes about 30 minutes and uses 2.2 to 3.2 liters of the sodium chloride solutions, whereas the 20 per cent W/V glycerolized red blood cells can be processed in about 20 minutes using 1.5 to 2.5 liters. After storage in CPD for three days at 4 C, red blood cells can be freeze-preserved with 40 per cent W/V glycerol at –80 C or with 20 per cent W/V glycerol at –150 C. When the thawed red blood cells are washed in the Fenwal Elutramatic, the IBM Blood Processor, or the Haemonetics Blood Processor and stored at 4 C in sodium chloride-glucose-phosphate for at least 24 hours before transfusion, they have excellent posttransfusion survival values and normal or slightly decreased oxygen transport function. Alternatively, these red blood cells can be rejuvenated before freeze-preservation so that their 2,3-DPG levels are increased and their affinity for oxygen is reduced. Red blood cells that are stored in CPD at 4 C for as long as 28 days can be rejuvenated with a solution containing pyruvate, inosine, glucose, phosphate, and adenine (PIGPA, Solution A) before freeze-preservation with 40 per cent W/V glycerol at –80 C. Any one of the above systems can be used to wash these red blood cells and they can be stored at 4 C in a sodium chloride-glucose-phosphate solution for four days and have acceptable posttransfusion survival. Before transfusion the red blood cells are concentrated, the supernatant solution is removed, and the hematocrit is adjusted to about 90 V per cent. Any of the washing procedures will effectively recover the red blood cells and remove most of the products of hemolysis, glycerol, ¹²⁵I albumin, and additives used for rejuvenation.     

Elution of Chromium Label from Preserved Red Blood Cells Transfused During Surgery

⁵¹Cr labelled red blood cells were transfused into nine patients during surgery, and the rate of chromium elution in vivo was determined. Similar studies were performed on seven nonsurgical patients. Three of the surgical and two of the nonsurgical patients received liquid‐stored red blood cells, while six of the surgical and five of the nonsurgical patients received previously frozen agglomerated red blood cells. The rapid component of chromium elution was observed in both surgical and nonsurgical patients. Approximately 6.7 per cent of the chromium eluted rapidly from liquid‐preserved red blood cells, and about 9.9 per cent from previously frozen red blood cells. No further elution was detected in the red blood cells transfused during surgery, whereas further elution (the slow component of ⁵¹Cr elution) was observed in nonsurgical patients. These data suggest that general anesthesia may have influenced the slow component of chromium elution.     

Paroxysmal nocturnal hemoglobinuria and the transfusion of washed red cells. A myth revisited

Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon, acquired clonal stem cell disorder primarily affecting red cells that have an abnormal sensitivity to complement lysis. Since 1948, the use of saline-washed red cells (WRBCs) has been advocated to minimize hemolysis after transfusion to patients with PNH. Thirty-eight years of experience (1950 through 1987) with patients who had PNH were reviewed. Twenty-three patients with a positive Ham's test had been transfused with 556 blood components, including 431 RBC products: 94 units of whole blood, 208 units of packed RBCs, 80 units of white cell-poor RBCs, 38 units of WRBCs, 5 units of frozen RBCs, and 6 units of intraoperatively salvaged RBCs. Only one documented episode of posttransfusion hemolysis related to the underlying diagnosis of PNH was found, and it was associated with the transfusion of a unit of type O whole blood to an AB-positive individual. This unit contained ABO-incompatible plasma; this case was similar to one in an earlier report from which originated the recommendation for using WRBCs. The posttransfusion increment in hemoglobin concentration in patients receiving ABO-identical packed RBCs was comparable to that in patients receiving frozen or washed RBCs. These findings indicate that the use of WRBCs is unnecessary and that patients with PNH should be transfused with group-specific blood and blood products.     

Factors Influencing the 24-Hour Posttransfusion Survival and the Oxygen Transport Function of Previously Frozen Red Cells Preserved with 40 Per Cent W/V Glycerol and Frozen at —80 C

A 6.2 M glycerol solution was added directly to concentrated red blood cells before storage at — 80 C for at least two and one-half years. The glycerol was removed from the thawed red blood cells by one of four different washing procedures, and the washed cells were stored at 4 C for an additional 24 hours before transfusion. Recovery in vitro was about 90 per cent, and the posttransfusion survival was about 85 per cent. The CPD anticoagulant maintained the oxygen transport much better than ACD during storage of the red blood cells at 4 C for one week prior to freezing. Results were similar whether glycerolized red blood cells were washed in reusable stainless steel bowls, disposable polycarbonate bowls, or collapsible disposable polyvinylchloride plastic bags. The composition of the wash solution had no significant effect on the posttransfusion survival or oxygen transport function. When the washed red blood cells were stored in a sodium chloride-glucose-phosphate solution at 4 C for 24 hours before transfusion, the 24-hour posttransfusion survival and oxygen transport function was satisfactory. Freeze-preservation of red blood cells with hematocrits of about 40 V per cent and postthaw storage at 4 C for 24 hours resulted in an accumulation of supernatant hemoglobin and extracellular potassium. At the time of transfusion, the red blood cells were concentrated by centrifugation, the supernatant medium was removed, and the hematocrit adjusted to 70 V per cent.     

Studies of the recovery and the cost of low-glycerol cryopreserved human red blood cells

Red blood cells were equilibrated with 28 per cent (v/v) glycerol and 3 per cent mannitol in 0.65 g/100 ml sodium chloride. The units were frozen by immersion into liquid nitrogen and stored at -160 C. After thawing, they were reconstituted and washed using the IBM 2991 Blood Cell Processor. Freeze-thaw rate curves, the effect of thawing techniques, the effect of varying postthaw washing and processing techniques, estimates of red blood cell losses because of hemolysis, and in vitro recovery were determined. In vivo recovery was determined by 51Cr techniques 24 hours after infusion and Ashby survivals and subsequent life span were measured. Metabolic, scanning electronmicroscopy, cost estimates and quality control studies were done on the reconsituted red blood cells. Recipients were evaluated before and after transfusion for metabolic erythrocyte characteristics and for evidence of hemolysis. The modified method requires less wash solution and less technician time than does the standard low-glycerol method. Two units for the same recipient could be passed through the IBM software with no alteration of cell survival or loss. Revision of the IBM 2991 processing procedure provided excellent recovery of viable previously frozen red blood cells at probably a lower cost.     

Effect of freezing on the in vivo recovery of irradiated red cells

BACKGROUND: Transfusion-associated graft-versus-host disease can be prevented by gamma radiation of blood components. The increased use of blood components donated for patients by their family members has resulted in an increased demand for the storage and handling of irradiated units, and the ability to freeze the cells would allow storage beyond their current expiration date. STUDY DESIGN AND METHODS: To assess the effect of freezing and deglycerolization on irradiated red cells, studies of autologous radiolabeled red cell recovery were performed using normal volunteers. Each unit of CPDA-1 red cells was immediately divided into two equal volumes. Further handling of each half was identical except that one was irradiated (3500 cGy). The units were grouped under three protocols: I, irradiated on Day 0 and frozen on Day 5 (n = 4); II, irradiated on Day 7, rejuvenated, and frozen on Day 14 (n = 5); and III, irradiated on Day 14, rejuvenated, and frozen on Day 18 (n = 3). All cells were frozen for 3 to 10 months at -80 degrees C. RESULTS: Irradiated and control units showed no significant differences in supernatant potassium or hemoglobin. Autologous 24-hour posttransfusion recoveries (mean +/− SD) for the three groups were: I, 89.7 +/− 5.6 percent (control, 90.6 +/− 3.2%); II, 85.3 +/− 5.7 percent (control, 83.7 +/− 3.0%); and III, 79.5 +/− 1.4 percent (control, 82.6 +/− 5.2%). CONCLUSION: Irradiated red cells can be frozen after being stored under various conditions and can still meet established guidelines requiring 75-percent recovery 24 hours after transfusion.     

Characteristics of red cells irradiated and subsequently frozen for long-term storage

Irradiation of blood components eliminates the risk of transfusion- associated graft-versus-host disease. Freezing directed or rare red cell units that are irradiated but not transfused would facilitate inventory management and would increase the transfusion options for the involved patients. However, no studies have been performed to evaluate whether prestorage irradiation damages subsequently frozen red cells. Ten normal volunteers donated a unit of whole blood on two separate occasions. One unit was irradiated with 15 Gy (1500 rad), stored at 4 degrees C for 6 days, and then frozen and stored at -75 degrees C for 56 days. The other unit (control) was similarly stored but was not irradiated. Aliquots of the units were tested on Day 0 and Day 6 and, after deglycerolization, on Day 62. Comparison of means and changes in means showed no significant differences in red cell ATP, 2,3 DPG, or supernatant hemoglobin and glucose in control and irradiated units. The difference in the change in supernatant potassium from Day 0 to Day 6 in control and irradiated units was significant (1.5 to 28.6 mmol/L vs. 1.5 to 48.5 mmol/L: p < 0.0001). Irradiation did not cause significant differences in postdeglycerolization red cell recovery (control, 84.5% vs. irradiated, 81.2%) or in 24-hour posttransfusion autologous red cell survival (control, 91.1% vs. irradiated, 90.9%). Red cells can be irradiated, stored at 4 degrees C for 6 days, and subsequently frozen with no increase in detectable damage as compared to controls that were not irradiated.     

Lactic acidemia in baboons after transfusion of red blood cells with improved oxygen transport function and exposure to severe arterial hypoxemia

Baboons were bled one-third of their blood volume and then transfused with an equivalent volume of compatible donor red blood cells with 160 per cent of normal 2,3-diphosphoglycerate (2,3-DPG) levels and improved capacity to release oxygen to tissue. The mixture of baboon donor- recipient red blood cells in the circulation had a 2,3-DPG level of 130 per cent of normal. After transfusion, the baboon's inspired oxygen was first lowered from 21 to 10 per cent to produce severe arterial hypoxemia with a PO2 tension of less than 40 mm Hg for two hours and then restored to 21 per cent. Lactic acidemia occurred when the alveolar oxygen tension was reduced so as to produce an arterial oxygen tension of less than 40 mm Hg, even though oxygen consumption was maintained. The data suggest that when red blood cells with normal or improved oxygen delivering capacity are transfused to patients, the alveolar oxygen tension should be sufficient to maintain an arterial oxygen tension of greater than 40 mm Hg.     

The purification of red cells for transfusion by freeze-preservation and washing. IV. The use of micropore filtration to reduce the residual HL-A antigenicity of previously frozen, washed red cells

Using a semi-quantitative HL-A antibody adsorption assay, a reduction in HL-A antigenicity was observed in 15 of 22 units of previously frozen and washed red blood cells after passage through a micropore transfusion filter. Red blood cell viability was unaffected by this procedure. Micropore filtration was a simple adjunct to the freezing and washing of red blood cells that may further reduce histocompatibility antigen exposure in transfused recipients.     

Effect of rejuvenation and frozen storage on 42-day-old AS-1 RBCs

BACKGROUND: The FDA has approved a 42-day storage period for RBCs stored in ADSOL (AS-1). This study was undertaken to provide data for the FDA about the feasibility of salvaging AS-1 RBCs at the end of their storage period by rejuvenation and freezing. STUDY DESIGN AND METHOD: The investigation, consisting of a study (n = 10) and control (n = 6) arm, was carried out in two centers. In both centers, eight healthy volunteers donated a unit (450 mL) of whole blood. The RBC concentrates were stored at 4 degrees C in AS-1 for 42 days. The study units were rejuvenated, whereas the control units were not. All units were stored frozen at -80 degrees C, then deglycerolized and kept for an additional 24 hours at 4 degrees C. RESULTS: After the 42-day storage period, ATP had declined to 62 percent of the original value, 2,3 DPG was zero, and MCV was significantly larger than that of fresh RBCS: Following rejuvenation and deglycerolization, the mean ATP level was 141 percent, the mean 2,3 DPG level was 109 percent, and the MCV was normal. The freeze-thaw-wash recovery of the rejuvenated and nonrejuvenated RBCs was similar, 88.4 and 84.0 percent, respectively. There was no difference in hypoxanthine, inosine, and uric acid levels in the rejuvenated and nonrejuvenated units, which indicated that the chemicals in the rejuvenation solution and their by-products had been removed during processing. In both centers, the mean 24-hour survival of rejuvenated, deglycerolized RBCs exceeded 75 percent, whereas that of nonrejuvenated RBCs did not. The long-term survival rates of viable study and control RBCs were similar. CONCLUSION: Forty-two-day-old AS-1 RBCs that have been rejuvenated and then frozen have more than 75 percent viability and normal oxygen delivery function. Rejuvenation of RBCs does not introduce additional safety hazards to blood transfusion.     

The In Vivo Survival, Mode of Removal of the Non-Viable Cells, and the Total Amount of Supernatant Hemoglobin in Deglycerolized, Resuspended Erythrocytes

The data presented indicate that with the use of the Cohn fractionator to add and remove the intracellular additive, glycerol, and using the slow freeze technic with storage in the frozen state at —80 C or —120 C, the viability of erythrocytes can be maintained for at least two months. The thawed, deglycerolized erythrocytes can then be resuspended in either autologous plasma or in an artificial 5% Hyland albumin resuspension medium, stored up to 8 days at 4C, and transfused to the original donor with acceptable red blood cell survival. ACD blood can be stored for up to seven days at 4 C prior to glycerolization with acceptable 24-hour posttransfusion survival. The mode of removal of the non-viable erythrocytes is primarily through an extravascular mechanism without detectable hemoglobinemia. A limiting factor in the clinical acceptability of deglycerolized, resuspended erythrocytes is the amount of free supernatant hemoglobin present in the unit on the day of transfusion. Washing units of deglycerolized erythrocytes resuspended in autologous plasma and stored for up to 12 days at 4 C is effective in reducing the total amount of supernatant hemoglobin, and the saline washed erythrocytes show acceptable posttransfusion survival. However, deglycerolized red blood cells resuspended initially in the 5% Hyland albumin medium and stored at 4 C for five days or longer do not tolerate saline washing; 24-hour survival of less than 70 per cent was observed and intravascular liberation of hemoglobin was noted in this group only.
This paper reports the total in vitro loss of hemoglobin associated with preservation and with the saline wash used to remove the excessive supernatant hemoglobin which accumulates during the post-thaw period at 4C.     

Citrate-Phosphate-Dextrose Solution for Preservation of Human Blood: A Further Report

A comparison of clinically significant in vitro characteristics of ACD and CPD blood is presented.
In clinical trials conducted at three hospitals, 586 units of blood collected in CPD in plastic bags were utilized for 622 individual treatments as single units or subdivided aliquots of whole blood, and as packed red cells in 332 patients. The expiration period was 28 days, and five bloods were discarded as outdated. There was one reported pyrexial reaction and one proven bacterial contamination.
Forty-two per cent of the bloods or components were issued during the first week, 43 per cent during the second and third weeks, and 15 per cent during the fourth week of storage.
Of the total bloods or components issued, 9 per cent of the whole bloods, 25 per cent of the subdivided blood aliquots, and 23 per cent of the packed red cells were transfused during the fourth week of storage.
No difficulty with clotting was observed during collection, storage, or transfusion.