The in vitro quality of washed, prestorage leucocyte-depleted red blood cell concentrates

Neonatal red blood cell transfusion

Transfusions are more common in premature infants with approximately 40% of low birth weight infants and up to 90% of extremely low birth weight infants requiring red blood cell transfusion. Although red blood cell transfusion can be life-saving in these preterm infants, it has been associated with higher rates of complications including necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and possibly abnormal neurodevelopment. The main objective of this review is to assess current red blood cell transfusion practices in the neonatal intensive care unit, to summarize available neonatal transfusion guidelines published in different countries and to emphasize the wide variation in transfusion thresholds that exists for red blood cell transfusion. This review also addresses certain issues specific to red blood cell processing for the neonatal population including storage time, irradiation, cytomegalovirus (CMV) prevention strategies and patient blood management. Future research avenues are proposed to better define optimal transfusion practice in neonatal intensive care units.

The Effect of Washing of Stored Red Blood Cell Transfusion Units on Post Transfusion Recovery and Outcome in a Pneumosepsis Animal Model

BACKGROUND

Septic patients are often anemic, requiring red blood cell (RBC) transfusions. However, RBC transfusions are associated with organ injury. The mechanisms of RBC-induced organ injury are unknown, but increased clearance of donor RBCs from the circulation with trapping in the organs could play a role. We hypothesized that washing of RBCs prior to transfusion may reduce clearance and trapping of donor cells and thereby reduce organ injury.

METHODS

Sprague-Dawley rats were inoculated intratracheally with 10 colony-forming units (CFU) of Streptococcus pneumoniae or vehicle as a control and transfused with either a washed or standard (non-washed) biotinylated RBC transfusion from syngeneic rats. Controls received saline. Blood samples were taken directly after transfusion and at 24 h to calculate the 24 h post transfusion recovery (PTR). After sacrifice, flow cytometry was used to detect donor RBCs in organs and blood. The organs were histologically scored by a pathologist and CFUs in the lung and blood were counted.

RESULTS

The 24h-PTR was similar between healthy and pneumoseptic rats after a standard transfusion. In healthy rats, a washed transfusion resulted in a higher PTR and less accumulation of donor RBCs in the organs compared with a standard transfusion. However, during pneumonia, this effect of washing was not seen. Transfusion did not further augment lung injury induced by pneumonia, but washing decreased bacterial outgrowth in the lungs associated with reduced lung injury.

CONCLUSION

In healthy recipients, washing increased 24h-PTR of donor RBCs and decreased trapping in organs. In pneumoseptic rats, washing reduced bacterial outgrowth and lung injury, but did not improve PTR.

Washing or filtering of blood products does not improve outcome in a rat model of trauma and multiple transfusion

BACKGROUND

Transfusion is associated with organ failure and nosocomial infection in trauma patients, which may be mediated by soluble bioactive substances in blood products, including extracellular vesicles (EVs). We hypothesize that removing EVs, by washing or filtering of blood products, reduces organ failure and improves host immune response.

MATERIALS AND METHODS

Blood products were prepared from syngeneic rat blood. EVs were removed from RBCs and platelets by washing. Plasma was filtered through a 0.22‐μm filter. Rats were traumatized by crush injury to the intestines and liver, and a femur was fractured. Rats were hemorrhaged until a mean arterial pressure of 40 mm Hg and randomized to receive resuscitation with standard or washed/filtered blood products, in a 1:1:1 ratio. Sham controls were not resuscitated. Ex vivo whole blood stimulation tests were performed and histopathology was done.

RESULTS

Washing of blood products improved quality metrics compared to standard products. Also, EV levels reduced by 12% to 77%. The coagulation status, as assessed by thromboelastometry, was deranged in both groups and normalized during transfusion, without significant differences. Use of washed/filtered products did not reduce organ failure, as assessed by histopathologic score and biochemical measurements. Immune response ex vivo was decreased following transfusion compared to sham but did not differ between transfusion groups.

CONCLUSION

Filtering or washing of blood products improved biochemical properties and reduced EV counts, while maintaining coagulation abilities. However, in this trauma and transfusion model, the use of optimized blood components did not attenuate organ injury or immune suppression.

Towards bedside washing of stored red blood cells: a prototype of a simple apparatus based on microscale sedimentation in normal gravity

BACKGROUND AND OBJECTIVES

Infusion of by-products of red blood cell (RBC) storage-induced degradation as well as of the residual plasma proteins and the anticoagulant-preservative solution contained in units of stored blood serve no therapeutic purpose and may be harmful to some patients. Here, we describe a prototype of a gravity-driven system for bedside washing of stored RBCs.

MATERIALS AND METHODS

Stored RBCs were diluted to 10% haematocrit (Hct) with normal saline, matching the conventional washing procedure. The dilute RBC suspensions were passed through a column of coiled tubing to allow RBC sedimentation in normal gravity, thus separating them from the washing solution. Washed RBCs were collected using bifurcations located along the tubing. Washing efficiency was quantified by measuring Hct, morphology, deformability, free haemoglobin and total-free protein.

RESULTS

The gravity-driven washing system operating at 0·5 ml/min produced washed RBCs with final Hct of 36·7 ± 3·4% (32·3-41·2%, n = 10) and waste Hct of 3·4 ± 0·7% (2·4-4·3%, n = 10), while removing 80% of free haemoglobin and 90% of total-free protein. Washing improved the ability of stored RBCs to perfuse an artificial microvascular network by 20%. The efficiency of washing performed using the gravity-driven system was not significantly different than that of conventional centrifugation.

CONCLUSIONS

This proof-of-concept study demonstrates the feasibility of washing stored RBCs using a simple, disposable system with efficiency comparable to that of conventional centrifugation, and thus represents a significant first step towards enabling low-cost washing of stored blood at bedside.

Quality Assessment of Established and Emerging Blood Components for Transfusion

Blood is donated either as whole blood, with subsequent component processing, or through the use of apheresis devices that extract one or more components and return the rest of the donation to the donor. Blood component therapy supplanted whole blood transfusion in industrialized countries in the middle of the twentieth century and remains the standard of care for the majority of patients receiving a transfusion. Traditionally, blood has been processed into three main blood products: red blood cell concentrates; platelet concentrates; and transfusable plasma. Ensuring that these products are of high quality and that they deliver their intended benefits to patients throughout their shelf-life is a complex task. Further complexity has been added with the development of products stored under nonstandard conditions or subjected to additional manufacturing steps (e.g., cryopreserved platelets, irradiated red cells, and lyophilized plasma). Here we review established and emerging methodologies for assessing blood product quality and address controversies and uncertainties in this thriving and active field of investigation.

Reduction of biological response modifiers in the supernatant of washed paediatric red blood cells

BACKGROUND

Washing of red blood cells (RBC) can reduce unwanted biological response modifiers (BRMs) that can mediate transfusion complications in infants. The aim of this study was to examine the in vitro quality and the changes in BRMs following washing in paediatric RBC units.

MATERIALS AND METHODS

A pool and split design was used to prepare RBC (either 1 or 4 days old; n = 26 pairs). One unit was washed with 0·9% saline by centrifugation and then resuspended in SAG-M, while the other remained unwashed. Each RBC unit was divided to produce four units of paediatric-sized components. Samples were taken after 3 h and subsequently on days 1, 2, 7 and 14 post-wash.

RESULTS

Washing of RBC resulted in some red cell loss, with a minor increase in haemolysis. Washing effectively reduced supernatant potassium and IgA, as well as cytokines and complement proteins. RBC microparticles were significantly reduced in RBC washed at 1, but not 4 days post-collection. Incubation with supernatant from unwashed but not washed RBC led to endothelial cell activation, with increased cell surface expression of CD62E (E-selectin) and CD106 (VCAM).

CONCLUSION

Although washing affected some aspects of the in vitro quality of RBC, it effectively reduced the concentration and activity of BRMs in the supernatant of RBC. Such a reduction may be clinically beneficial in selected patient groups.

Modifications to Blood Components: When to Use them and What is the Evidence?

Blood component modifications can be performed by the hospital blood bank for select clinical indications. In general, modification of blood components increases costs and may delay availability of the blood component because of the additional time required for some modification steps. However, the benefit of blood product modification may outweigh these concerns. Common modifications include leukoreduction, irradiation, volume reduction, splitting, and washing. Modification availability and selection practice may vary from hospital to hospital. In this article, available blood component modifications are described along with the benefits, drawbacks, and specific clinical indications supporting their use.

Quality of red blood cells washed using a second wash sequence on an automated cell processor

BACKGROUND

Washed red blood cells (RBCs) are indicated for immunoglobulin (Ig)A-deficient recipients when RBCs from IgA-deficient donors are not available. Canadian Blood Services recently began using the automated ACP 215 cell processor (Haemonetics Corporation) for RBC washing, and its suitability to produce IgA-deficient RBCs was investigated.

STUDY DESIGN AND METHODS

RBCs produced from whole blood donations by the buffy coat (BC) and whole blood filtration (WBF) methods were washed using the ACP 215 or the COBE 2991 cell processors and IgA and total protein levels were assessed. A double-wash procedure using the ACP 215 was developed, tested, and validated by assessing hemolysis, hematocrit, recovery, and other in vitro quality variables in RBCs stored after washing, with and without irradiation.

RESULTS

A single wash using the ACP 215 did not meet Canadian Standards Association recommendations for washing with more than 2 L of solution and could not consistently reduce IgA to levels suitable for IgA-deficient recipients (24/26 BC RBCs and 0/9 WBF RBCs had IgA levels < 0.05 mg/dL). Using a second wash sequence, all BC and WBF units were washed with more than 2 L and had levels of IgA of less than 0.05 mg/dL. During 7 days' postwash storage, with and without irradiation, double-washed RBCs met quality control criteria, except for the failure of one RBC unit for inadequate (69%) postwash recovery.

CONCLUSION

Using the ACP 215, a double-wash procedure for the production of components for IgA-deficient recipients from either BC or WBF RBCs was developed and validated.

Red blood cell transfusions for thalassemia: results of a survey assessing current practice and proposal of evidence-based guidelines

BACKGROUND

In the absence of curative treatment, such as stem cell transplant, regular transfusions remain the mainstay of therapy for individuals with thalassemia major, a syndrome that results from marked ineffective erythropoiesis and the resultant anemia. The primary objectives of transfusion therapy are twofold: to suppress ineffective erythropoiesis and to ensure appropriate growth and development through childhood. In practice, a number of different transfusion protocols are in use across the developed world, with on-demand transfusion still being the paradigm in most of the developing world with limited resources.

STUDY DESIGN AND METHODS

To investigate perceived differences in transfusion practice, a self-reported electronic survey was disseminated to eight US thalassemia treatment centers in February 2011. The survey was divided into sections ranging from laboratory and clinical practices to emerging transfusion-transmitted diseases.

RESULTS

The survey response rate was 100%. The total number of transfused patients was 411. One-hundred percent of institutions used leukoreduced blood. No centers routinely provided cytomegalovirus-seronegative red blood cells (RBCs). Half the centers provided irradiated RBCs; only one routinely provided washed RBCs, and none transfused RBCs of defined storage age. Seventy-five percent of centers routinely phenotyped thalassemia patients' RBC antigens; 50% prophylactically matched for Rh and K antigens. The frequency of antibody investigations varied widely, and 25% of centers routinely medicated patients before transfusion.

CONCLUSION

Eight thalassemia centers in the United States were surveyed to determine the uniformity of transfusion practice. The variability of the results was surprising. Consequently, we performed a literature review and propose an evidence-based protocol for routine transfusion therapy for patients with thalassemia.

Washing older blood units before transfusion reduces plasma iron and improves outcomes in experimental canine pneumonia

In a randomized controlled blinded trial, 2-year-old purpose-bred beagles (n = 24), with Staphylococcus aureus pneumonia, were exchanged-transfused with either 7- or 42-day-old washed or unwashed canine universal donor blood (80 mL/kg in 4 divided doses). Washing red cells (RBC) before transfusion had a significantly different effect on canine survival, multiple organ injury, plasma iron, and cell-free hemoglobin (CFH) levels depending on the age of stored blood (all, P < .05 for interactions). Washing older units of blood improved survival rates, shock score, lung injury, cardiac performance and liver function, and reduced levels of non-transferrin bound iron and plasma labile iron. In contrast, washing fresh blood worsened all these same clinical parameters and increased CFH levels. Our data indicate that transfusion of fresh blood, which results in less hemolysis, CFH, and iron release, is less toxic than transfusion of older blood in critically ill infected subjects. However, washing older blood prevented elevations in plasma circulating iron and improved survival and multiple organ injury in animals with an established pulmonary infection. Our data suggest that fresh blood should not be washed routinely because, in a setting of established infection, washed RBC are prone to release CFH and result in worsened clinical outcomes.

In vitro comparison of two different methods of cell washing

The storage of red blood cells (RBC) results in increased concentrations of plasma free hemoglobin, potassium, glucose, and lactate, among other undesirable substances. These concentrations continue to increase as RBC products age and can cause deleterious effects to the patient. In the setting of cardiac surgery, the autotransfusion devices are routinely used to wash blood that is shed from the surgical site. These devices could also be used to wash stored RBC units obtained from the blood bank. The objective of this study was to compare the product created by washing a unit of RBCs with the AutoLog autotransfusion device in the operating room to the washed products from a standard cell washer in the blood bank.

Eleven outdated RBC units (stored for >42 days at 4°C) were split in half. One half was washed using the Medtronic AutoLog device; the other half was washed using the blood bank’s Cobe 2991 Cell Processor. Analytes were measured on samples from the unwashed parent unit and from the washed daughter units. The parameters measured included hematocrit, free hemoglobin, lactate, lactate dehydrogenase (LDH), potassium, glucose, and pH.

When compared to the original untreated RBCs, the glucose, lactate, and potassium levels were decreased when washed in an autotranfusion device. Additionally, the free hemoglobin and LDH levels were significantly lower with the Medtronic Autolog cell saver than in the COBE 2991 Cell Processor.

Washing the RBC donor units in an autotransfusion device prior to transfusion can effectively attenuate the increases seen in glucose, potassium, free hemoglobin, and LDH associated with RBC storage lesion.

Washing of banked blood by three different blood salvage devices

BACKGROUND

Storage lesions in red blood cells (RBCs) lead to an accumulation of soluble contaminants that can compromise the patient. Organ failures, coagulopathies, and cardiovascular events including lethal cardiac arrest have been reported, especially with massive transfusion or in pediatric patients. Washing improves the quality of stored RBCs, and autotransfusion devices have been proposed for intraoperative processing, but these devices were designed for diluted wound blood, and limited data on their performance with RBCs are available.

STUDY DESIGN AND METHODS

Three autotransfusion devices (Electa, Sorin; CATS, Fresenius; OrthoPAT, Haemonetics) differing in function of their centrifugation chambers were evaluated with RBCs at the end of their shelf life and with dilutions thereof. Elimination rates of potassium, plasma free hemoglobin, total protein, citrate, acid equivalents, and iomeprol added as a marker substance were analyzed, in addition to RBC recoveries.

RESULTS

Product hematocrit (Hct) levels ranged between 54.8 and 72.6%. RBC recovery rates were between 62.7 and 95.0%, the lowest being with the OrthoPAT processing of undiluted RBCs. Plasma elimination rates increased with predilution and ranged from 46.6% to 99.5%, the lowest being with the CATS and undiluted RBCs. Washing did not change pH and buffering capacity of RBCs.

CONCLUSION

Autotransfusion devices offer a practical and obviously economical option to wash banked RBCs intraoperatively to prevent hyperkalemia and other disturbances in massive transfusion or pediatric patients. Predilution improves elimination rates, especially in devices that produce high product Hct levels. With a Y-tubing the RBCs should bypass reservoir and vacuum, and the procedure should be guarded by a policy and procedure manual and a quality management system.

Effects of helicopter transport on red blood cell components

BACKGROUND

There are no reported studies on whether a helicopter flight affects the quality and shelf-life of red blood cells stored in mannitol-adenine-phosphate.

MATERIALS AND METHODS

Seven days after donation, five aliquots of red blood cells from five donors were packed into an SS-BOX-110 container which can maintain the temperature inside the container between 2 °C and 6 °C with two frozen coolants. The temperature of an included dummy blood bag was monitored. After the box had been transported in a helicopter for 4 hours, the red blood cells were stored again and their quality evaluated at day 7 (just after the flight), 14, 21 and 42 after donation. Red blood cell quality was evaluated by measuring adenosine triphosphate, 2,3-diphosphoglycerate, and supernatant potassium, as well as haematocrit, intracellular pH, glucose, supernatant haemoglobin, and haemolysis rate at the various time points.

RESULTS

During the experiment the recorded temperature remained between 2 and 6 °C. All data from the red blood cells that had undergone helicopter transportation were the same as those from a control group of red blood cell samples 7 (just after the flight), 14, 21, and 42 days after the donation. Only supernatant Hb and haemolysis rate 42 days after the donation were slightly increased in the helicopter-transported group of red blood cell samples. All other parameters at 42 days after donation were the same in the two groups of red blood cells.

DISCUSSION

These results suggest that red blood cells stored in mannitol-adenine-phosphate are not significantly affected by helicopter transportation. The differences in haemolysis by the end of storage were small and probably not of clinical significance.

Hemolysis of red blood cells after cell washing with different automated technologies: clinical implications in a neonatal cardiac surgery population

BACKGROUND

In subsets of pediatric cardiac surgery patients, red blood cells (RBCs) are often washed to reduce extracellular potassium (K) to avoid hyperkalemia, but mechanical manipulation and time delay in issuing washed products may increase hemolysis and K. This study's purpose was to evaluate the quality of washed RBCs with regard to hemolysis and extracellular K using different cell washers as a function of postprocessing time.

STUDY DESIGN AND METHODS

Fresh (<4 days old) RBCs were washed on COBE 2991 blood cell processors (Model 1 and Model 2) or the Fresenius Continuous AutoTransfusion System (CATS), and K and hemolysis index (HI) were analyzed. Academic pediatric hospitals were surveyed to ascertain practice trends regarding indications for washing, washing device, and expiration time for washed RBCs.

RESULTS

K concentration at 24 hours for units washed with the COBE devices met or exceeded prewash values. At 12 hours, there was a significant difference (p < 0.001) in K concentration between all devices, with the CATS maintaining the lowest K concentration. HI increased immediately after wash on all devices and showed a significant difference between the COBE devices and CATS at times of more than 6 hours (p < 0.01). At storage times beyond 4 hours, hemoglobin exceeded 100 mg/dL on the COBE Model 1. Survey of pediatric hospitals indicated that COBE devices are commonly used, and storage time after washing was 12 hours or more in blood banks queried.

CONCLUSIONS

Hemolysis levels vary among different cell washers. Decreasing the expiration time of units after washing may be warranted.

Prion reduction of red blood cells: impact on component quality

BACKGROUND

A filter has been developed (P-Capt, MacoPharma) to remove infectious prions from red blood cells (RBCs). We sought to assess 1) its operational use, 2) the quality of filtered components, and 3) whether filtration resulted in any significant changes to blood group antigens.

STUDY DESIGN AND METHODS

A total of 272 leukoreduced RBC units, including units processed using "top-and-top" (TAT) and "bottom-and-top" (BAT) methods, were prion reduced using the P-Capt filter. All RBCs were assessed using standard in vitro tests of RBC quality. Changes to blood group antigen expression were also investigated, including the exposure of cryptantigens and the ability of filtered RBCs to be crossmatched.

RESULTS

Ninety-nine percent of TAT units and 58% of BAT units had a hemoglobin (Hb) content of more than 40 g. Hemolysis increased immediately after filtration, but units remained within UK specification throughout storage. Prion reduction resulted in the loss of 7 to 8 g of Hb and reductions in hematocrit of 6% to 9% due to the filter containing 40 mL of saline, adenine, glucose, and mannitol. Other RBC quality data, including extracellular potassium, 2,3-diphosphoglycerate, and adenosine triphosphate were similar to historical control data. There was no evidence of any immunologic changes of clinical relevance to the RBC membrane after filtration.

CONCLUSIONS

Prion filtration does not appear to have a detrimental effect on basic in vitro measures of RBC quality or on blood group antigens as assessed by in vitro methods. However, prion filtration using the P-Capt filter results in loss of Hb.

Effects of physiological parameters on the electrical properties of blood bank stored erythrocyte suspensions

In this study, the physiological parameters such as extracellular (SAGM+CPD+residual plasma) Na+, K+, Cl-, pH, 2,3-DPG and ATP together with the Cole-Cole parameters were measured using erythrocyte suspensions from 51 male donors (31 donors form the training set and 20 donors are used for testing), on the 0th, 10th, 21st, 35th and 42nd days of storage. Accordingly, electrical parameters were all correlated with Na+, K+, Cl-, pH and ATP, at varying levels. By applying the multi-regression analysis, it is concluded that Ri, Re and Cm are appropriate for modeling Na+, K+, Cl-, pH and ATP during blood bank storage and predicting blood quality.

Washing of stored red blood cells by an autotransfusion device before transfusion

BACKGROUND AND OBJECTIVES

The use of an autotransfusion device to wash blood of the incision site is increasing. After washing, this blood is retransfused without side effects caused by activated plasma factors and cell release products. This procedure could be extended to washing of donor blood, which may be particularly useful for red blood cells (RBCs) stored for more than 4 weeks that contain high concentrations of free haemoglobin, potassium, lactate and other metabolites. It is not known whether stored RBCs can withstand the cell washing procedure with the use of an autotransfusion device, while keeping their primary functions intact. The objective of this study was to determine the quality of RBCs, after cell washing in comparison to untreated RBCs.

MATERIALS AND METHODS

RBCs were studied in terms of integrity (free haemoglobin), stored energy (2,3-diphosphoglycerate, adenosine triphosphate), metabolites (lactate, potassium) and physical characteristics (osmotic resistance, aggregability, deformability).

RESULTS

After washing, free lactate and potassium were significantly reduced as compared to the levels before washing. The osmotic resistance of RBCs slightly improved, whereas aggregation capacity reduced after washing. Fifteen per cent of haemoglobin was lost during washing. The deformability and free haemoglobin levels remained unchanged.

CONCLUSION

Washing stored blood before transfusion may be of benefit, because the waste products are effectively removed from the stored RBC.

Storage effects on the Cole-Cole parameters of erythrocyte suspensions

Chemical alterations of red blood cells (RBCs) during storage eventually affect the electrical properties of blood. In this study, the physiological parameters such as extracellular (SAGM + CPD + residual plasma) Na(+), K(+), Cl(-), pH, 2,3-DPG and ATP together with the Cole-Cole parameters were measured using erythrocyte suspensions from 51 male donors (31 donors form the training set and 20 donors are used for testing), on the 0th, 10th, 21st, 35th and 42nd days of storage. During storage, while the surrounding fluid resistance (R(e)) and the effective cell membrane capacitance (C(m)) increased progressively with time, the intracellular fluid resistance (R(i)) has decreased. Storage of RBCs resulted in a rise in K(+) and a fall in Na(+), Cl(-), pH, 2,3-DPG and ATP. Accordingly, electrical parameters were all correlated with Na(+), K(+), Cl(-), pH and ATP at varying levels. By applying multi-regression analysis, it is concluded that R(i), R(e) and C(m) are appropriate for modeling Na(+), K(+), Cl(-), pH and ATP during storage.

Up to 21-day banked red blood cells collected by apheresis and stored for 14 days after automated wash at different times of storage

BACKGROUND AND OBJECTIVES

A closed-system technology (ACP-215, Haemonetics, Braintree, MA) enables automated washing and extended storage of frozen red blood cells (RBC). This technology was applied to wash banked RBC for removal of undesirable protein and metabolites before transfusion. We studied protein and metabolite depletion as well as RBC metabolism and viability up to 14 days postwash with regard to various pre-storage times.

MATERIALS AND METHODS

Thirty RBC units were collected by means of apheresis and subdivided into three arms based on prewash storage time period (6 days/group 1, 14 days/group 2, 21 days/group 3). Wash efficacy (protein depletion, IgA), RBC metabolism (pH, lactate, potassium, haemolysis) and cell viability (ATP) were analysed immediately and 14 days after washing.

RESULTS

Total protein and IgA postwash were lowered by automated wash in all groups and uniformly met EC guidelines. Potassium (mmol/l) was below 1.2 mmol/l postwash and significantly below prewash values in all groups, even after 14 days of storage (prewash vs. postwash; P < 0.05). RBCs washed after 14 and 21 days, respectively, showed significantly lower pH values and lower ATP content than RBCs washed after only 6 days of storage. Haemolysis rate remained significantly below 0.8%, the maximum level recommended by the EC guidelines, immediately and 14 days after washing in all units.

CONCLUSION

Our data confirm that RBC units banked up to 21 days can be effectively protein- and potassium-depleted with the ACP-215 independent from prewash storage time. With respect to high ATP levels and pH, postwash storage of 2 weeks should be limited to units not older than 7 days before wash. This new washing technology ensures better standardization in washed RBC and provides blood centres with a logistical alternative to 24-h washed RBC products.

Washing platelets with new additive solutions: aspects on the in vitro quality after 48 hours of storage

BACKGROUND

Rare clinical conditions cause the need for washed platelet (PLT) concentrates (PCs). Saline-washed PCs can only be stored shortly, however, owing to lack of substrates for PLT metabolism. New PLT additive solutions (PASs) contain such substrates and might be used alternatively. The in vitro quality of apheresis PCs washed with Composol-PS or modified PAS-III (PAS-IIIM) stored up to 48 hours after wash was compared.

STUDY DESIGN AND METHODS

Twelve blood donors underwent two apheresis procedures (A and B) collecting 6.0 x 10(11) PLTs in 500 mL of plasma with a least 2 weeks in between. The PCs collected by Apheresis A were stored for 3 days and then split in two equal units before washing with Composol-PS or PAS-IIIM. The PCs collected by Apheresis B were split after collection. One unit was released for transfusion and 1 unit was stored unwashed up to Day 6 and used as reference unit. In vitro testing was performed before and after washing as well as 24 and 48 hours after wash.

RESULTS

After 48 hours of postwash storage, the units washed with either PAS showed acceptable results for hypotonic shock response (HSR), P-selectin expression, and pH, whereas PLT aggregability was significantly impaired. Throughout the storage, unwashed units showed better in vitro quality. HSR and P-selectin expression were similar before and immediately after the washing procedure.

CONCLUSION

Based on these in vitro results, 48-hour postwash storage of washed PCs with the two PASs seems to be feasible. In vivo recovery studies, however, must confirm this finding in the future.