A systematic review and meta-analysis of traumatic intracranial hemorrhage in patients taking prehospital antiplatelet therapy: Is there a role for platelet transfusions?

BACKGROUND

Platelet transfusion has been utilized to reverse platelet dysfunction in patients on preinjury antiplatelets who have sustained a traumatic intracranial hemorrhage (tICH); however, there is little evidence to substantiate this practice. The objective of this study was to perform a systematic review on the impact of platelet transfusion on survival, hemorrhage progression and need for neurosurgical intervention in patients with tICH on prehospital antiplatelet medication.

METHODS

Controlled, observational and randomized, prospective and retrospective studies describing tICH, preinjury antiplatelet use, and platelet transfusion reported in PubMed, Embase, Cochrane Reviews, Cochrane Trials and Cochrane DARE databases between January 1987 and March 2019 were included. Investigations of concomitant anticoagulant use were excluded. Risk of bias was assessed using the Newcastle-Ottawa scale. We calculated pooled estimates of relative effect of platelet transfusion on the risk of death, hemorrhage progression and need for neurosurgical intervention using the methods of Dersimonian-Laird random-effects meta-analysis. Sensitivity analysis established whether study size contributed to heterogeneity. Subgroup analyses determined whether antiplatelet type, additional blood products/reversal agents, or platelet function assays impacted effect size using meta-regression.

RESULTS

Twelve of 18,609 screened references were applicable to our questions and were qualitatively and quantitatively analyzed. We found no association between platelet transfusion and the risk of death in patients with tICH taking prehospital antiplatelets (odds ratio [OR], 1.29; 95% confidence interval [CI], 0.76-2.18; p = 0.346; I = 32.5%). There was no significant reduction in hemorrhage progression (OR, 0.88; 95% CI, 0.34-2.28; p = 0.788; I = 78.1%). There was no significant reduction in the need for neurosurgical intervention (OR, 1.00; 95% CI, 0.53-1.90, p = 0.996; I = 59.1%; p = 0.032).

CONCLUSION

Current evidence does not support the use of platelet transfusion in patients with tICH on prehospital antiplatelets, highlighting the need for a prospective evaluation of this practice.

LEVEL OF EVIDENCE

Systematic Reviews and Meta-Analyses, Level III.

How do you… decide which platelet bacterial risk mitigation strategy to select for your hospital-based transfusion service?

The United States Food and Drug Administration Final Guidance for Industry titled, "Bacterial Risk Control Strategies for Blood Collection Establishments and Transfusion Services to Enhance the Safety and Availability of Platelets for Transfusion" provides nine strategies for platelet bacterial risk mitigation. Even if it is assumed all strategies are comparable in terms of safety and efficacy, the decision of which to implement remains challenging. Some additional factors that warrant evaluation before selecting a strategy include the financial impact, process for implementation, logistics upon implementation, institutional acceptance by blood bank staff, administration and clinicians, and effect on platelet availability. To assist with this difficult choice, a panel of transfusion service physicians who have expertise on the topic and have already selected strategies for their transfusion services were recruited to provide varied perspectives. In addition, the use of a decision-making tool that objectively evaluates defined criteria for assessment of the nine strategies is described.

Thrombocytopenia and platelet transfusion in the neonate

Neonatal thrombocytopenia is widespread in preterm and term neonates admitted to neonatal intensive care units, with up to one-third of infants demonstrating platelet counts <150 × 10(9)/L. Thrombocytopenia may arise from maternal, placental or fetal/neonatal origins featuring decreased platelet production, increased consumption, or both mechanisms. Over the past years, innovations in managing neonatal thrombocytopenia were achieved from prospectively obtained clinical data on thrombocytopenia and bleeding events, animal studies on platelet life span and production rate and clinical use of fully automated measurement of reticulated platelets (immature platelet fraction). This review summarizes the pathophysiology of neonatal thrombocytopenia, current management including platelet transfusion thresholds and recent developments in megakaryopoietic agents. Furthermore, we propose a novel index score for bleeding risk in thrombocytopenic neonates to facilitate clinician's decision-making when to transfuse platelets.

Quality of transfusion products in blood banking

The primary goal in transfusion medicine and cellular therapies is to promote high standards of quality and produce ever safer and more efficacious products. The establishment of a transfusion service quality management system, which includes several organizational structures, responsibilities, policies, processes, procedures, and resources, is now mandatory and widely regulated worldwide. In this review, we summarize the current knowledge on the quality system in transfusion medicine as applied to the production of blood components, including red blood cells, platelets, and fresh frozen plasma.

Real-time amplification of glyceraldehyde-3-phosphate dehydrogenase gene for quality control of leukopoor platelets

BACKGROUND

Leukoreduction of blood products is crucial to prevent white blood cell (WBC)-associated complications during transfusion. Of the widely accepted methods for quantifying WBCs in blood components, Nageotte hemocytometry is time-consuming and laborious whereas a specialized instrument is required for flow cytometry. A reliable and affordable method to assess WBC count in blood products is of particular interest.

STUDY DESIGN AND METHODS

Real-time polymerase chain reaction (PCR) of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene was developed for quantifying WBCs in leukopoor platelets (LPPs). After normalization by the cell-free prefiltrated and postfiltrated plasma DNA, the relative copy number of GAPDH gene in the platelet (PLT) concentrate and its corresponding LPPs was calculated according to the equation of 2(-ΔΔCt) of which Ct is defined as the threshold cycle. The percentage and the number of WBCs that remained in LPPs were consequently determined. This method was compared to Nageotte hemocytometry and was validated by using serially diluted PLT concentrate and 10 pairs of PLT concentrate-LPP samples.

RESULTS

Consistent with the removal of WBCs after filtration, the Ct values for the LPP samples were increased when compared to their corresponding PLT concentrate. As revealed by real-time PCR of GAPDH gene, there is a correlation between the calculated and theoretical WBC count in the serially diluted PLT concentrate (correlation coefficient, 0.9532). The WBC counts for the 10 LPP samples were comparable between Nageotte and real-time PCR method and were all below 3.3 × 10(6) WBCs/L.

CONCLUSION

The real-time PCR method we report in this study is applicable for routine quality assurance during leukoreduction process.

Bacterial contamination of platelet concentrates produced in New Zealand

AIMS

To identify the rate of bacterial contamination of platelet concentrates in New Zealand and compare with other countries who use the BacT/ALERT screening system. To report on septic transfusion reactions associated with platelet transfusion in New Zealand.

METHODS

Six mL of platelet concentrate is inoculated into a BacT/ALERT BPA (aerobic culture) bottle on Day 2 post-collection. Bottles that are flagged as positive are sent to the microbiology laboratory, with the associated unit, for confirmatory testing. Platelet units that have expired are sampled again. Results from the four blood processing sites in New Zealand were reviewed.

RESULTS

59,461 (65%) platelet components were sampled on Day 2 and 15,560 (17%) were re-sampled post-expiry, between December 2003 and September 2011. The rate of confirmed bacterial contamination was 0.04% for Day 2 sampling and 0.04% for post-expiry sampling. The rate in the published literature ranges from 0.01-0.74% and is lower (0.01-0.18%) when diversion of the initial flow of blood is utilised. There were five bacterial transfusion transmitted infections associated with platelet transfusion reported during the study period.

CONCLUSIONS

BacT/ALERT screening reduces the transfusion of bacterially contaminated platelet concentrates. Day 2 sampling does not identify all contaminated units.

Using lean techniques to define the platelet (PLT) transfusion process and cost-effectiveness to evaluate PLT dose transfusion strategies

BACKGROUND

Platelet (PLT) doses of 1.1 × 10(11), 2.2 × 10(11), and 4.4 × 10(11) /m(2) body surface area are equally effective in preventing bleeding. These different dose strategies involve different numbers of transfusions. We conducted a cost analysis of three separate PLT dose therapies.

STUDY DESIGN AND METHODS

A process map of preparation and administration of a PLT transfusion identified 46 steps (23 steps in the blood bank and 23 steps on the care unit). Time studies were conducted for these 46 steps. Supply costs and personnel costs were estimated based on time studies. We conducted a cost analysis of three separate treatment regimes involving 16 transfusions per patient for the low-dose, 12 transfusions for medium-dose, and eight transfusions for high-dose regimes.

RESULTS

The time and the cost of the transfusion process for the blood bank were 32.41 minutes and $21.93 per unit, and for the patient care unit, 58.36 minutes and $57.71 per unit. The total cost for a course of PLT therapy per patient ranged from $4503.77 to $7014.59 for three different PLT doses. For a simulated bone marrow transplantation unit with 259 patients annually, there would be approximately a $700,000 difference among the clinically equivalent low-, medium-, and high-dose treatment options.

CONCLUSIONS

The overall cost of transfusion therapy is more influenced by the cost of the product than the cost of providing the transfusion. Depending on the cost adjustment by the supplier for different doses of PLTs, a low-dose transfusion strategy can be less costly.

In vitro platelet quality in storage containers used for pediatric transfusions

BACKGROUND

The in vitro quality of small-volume platelet (PLT) aliquots for pediatric transfusions was assessed to determine the best practice approach.

STUDY DESIGN AND METHODS

Small volumes (50 mL) of single apheresis PLT components (APCs), collected on either CaridianBCT Trima or Haemonetics MCS+ instruments, were aliquoted on Days 2, 3, 4, and 5 postcollection into Fenwal PL1240 or 4R2014 bags or 60-mL polypropylene syringes. Samples were tested for in vitro quality at their recommended expiry times (4 hr for 4R2014 bags and syringes or Day 5 for PL1240 bags). Assays included pH, CD62P expression, and metabolic measures.

RESULTS

CD62P expression increased throughout storage in all containers. Among the small-volume containers, pH, pCO(2) , lactate, and bicarbonate varied considerably. Regardless of the day of aliquoting, pCO(2) was significantly higher and pO(2) was significantly lower in gas-impermeable syringes than other containers. No bacterial growth was detected in any sample.

CONCLUSION

The quality of APCs aliquoted into small-volume containers meets regulatory requirements and is generally equivalent to that of full-volume APCs at expiry.

Massive transfusion: an evidence-based review of recent developments

The design and implementation of massive transfusion protocols with ratio-based transfusion of blood and blood products are important and active areas of investigation. A significant yet controversial body of literature exists to support the use of hemostatic resuscitation in massive transfusion and new data to support the use of adjuncts, such as recombinant factor VIIa and tranexamic acid. We review the developments in massive transfusion research during the past 5 years, including protocol implementation, hemostatic resuscitation, the use of tranexamic acid, and goal-directed therapy for coagulopathy. Furthermore, we provide a level of evidence analysis of the data surrounding the use of component therapy and recombinant factor VIIa in massive transfusion, summary recommendations for the various agents of resuscitation, and new methods of goal-directed therapy.

A comprehensive program to minimize platelet outdating

BACKGROUND

Platelet (PLT) transfusions are essential for patients who are bleeding or have an increased risk of bleeding due to a decreased number or abnormal function of circulating PLTs. A shelf life of 5 days for PLT products presents an inventory management challenge. In 2006, greater than 10% of apheresis PLTs made in the United States outdated. It is imperative to have a sufficient number of products for patients requiring transfusion, but outdating PLTs is a financial burden and a waste of a resource.

STUDY DESIGN AND METHODS

We present the approach used in our institution to anticipate inventory needs based on current patient census and usage. Strategies to predict usage and to identify changes in anticipated usage are examined. Annual outdating is reviewed for a 10-year period from 2000 through 2009.

RESULTS

From January 1, 2000, through December 2009, there were 128,207 PLT transfusions given to 15,265 patients. The methods used to anticipate usage and adjust inventory resulted in an annual outdate rate of approximately 1% for the 10-year period reviewed. In addition we have not faced situations where inventory was inadequate to meet the needs of the patients requiring transfusions.

CONCLUSION

We have identified three elements of our transfusion service that can minimize outdate: a knowledgeable proactive staff dedicated to PLT management, a comprehensive computer-based transfusion history for each patient, and a strong two-way relationship with the primary product supplier. Through our comprehensive program, based on the principles of providing optimal patient care, we have minimized PLT outdating for more than 10 years.

[Photochemical inactivation of pathogens in platelets and plasma: five years of clinical use in routine and hemovigilance. Towards a change of paradigm in transfusion safety]

The transfusion of labile blood products is vital and essential for patients in absence of alternative treatment. Patients and doctors have always feared transfusion-transmitted infections by blood, blood components and blood-derived drugs. Photochemical inactivation of platelet concentrates and plasma, using a technique associating amotosalen and UVA, has been used for five years in a French region for the whole population and a large spectrum of patients, with efficacy and safety. It would seem wise to introduce labile blood products, submitted to pathogen inactivation by a technique already approved by a regulatory agency and not to wait for a perfect system including red blood cells concentrates. Universal implementation of pathogen inactivation in labile blood products is a major and key step to improve safety against infection in transfusion.

A noninvasive near infrared system for detection of platelet components contaminated with bacteria

BACKGROUND

Platelet (PLT) transfusion-associated bacterial sepsis has remained a substantial patient risk, primarily due to lacking effective and point-of-issue measures to detect bacterial contamination. This study describes near infrared (NIR) spectroscopy to examine inoculated PLTs without sampling within a few seconds.

STUDY DESIGN AND METHODS

This study evaluated apheresis PLTs inoculated with low concentrations of Bacillus cereus and Staphylococcus epidermidis, comparing with sterile bags. Short-wavelength NIR spectra over the range from 700 to 1100 nm in the transmittance mode were obtained using research (NIRS6500, Foss NIRSystems) and portable (NIRGun, Shizuoka Shibuya Seiki) instruments at 6-hour intervals from 0 to 72 hours after inoculation (HAI).

RESULTS

The sensitivity of the NIRS6500 was 100% (43/43) and 98% (50/51) after incubating PLTs inoculated with B. cereus for 42 HAI or more and with S. epidermidis for 54 HAI or more, respectively. Difference spectra calculated by subtracting the NIR spectra of stored PLTs with that of the same PLTs measured at 0 HAI improved the discrimination results compared with conventional second derivative spectra.

CONCLUSION

The NIRS6500 system can provide a PLT monitoring system based on difference spectra. The chemical components of PLTs that were influenced by bacterial metabolism seemed to play an important role in the calibration structure. Further studies should examine samples spiked with various species of prevalent bacteria.

Recognition and management of antibodies to human platelet antigens in platelet transfusion-refractory patients

Platelet transfusion refractoriness is a problem for parous and multiply transfused patients, placing them at higher risk for morbidity and mortality when posttransfusion count increments are significantly lower than expected. Although nonimmune causes of transfusion refractoriness are very common, HLA alloantibodies are the most important of the less frequent immune factors responsible for inadequate count increments. As universal leukoreduction decreases the occurrence of HLA antibody formation, antibodies to human platelet antigens (HPAs), an even less common immune factor, may rise proportionately. Carefully matched apheresis platelets can substantially improve platelet count increments in the setting of HLA and HPA alloantibody-mediated transfusion refractoriness. An evidence-based HPA testing strategy is described along with the incidence and specificity of HPA antibodies in platelet transfusion refractoriness. Optimal strategies to manage patients with HPA or combined HPA and HLA antibodies are presented. Ultimately, close cooperation between ordering physicians and the blood provider is critical in choosing the correct tests and assuring platelet availability during intensive support of these challenging patients.

Consensus and controversies in platelet transfusion: trigger for indication, and platelet dose

Platelet transfusion is about to commemorate its 50th year since its introduction in therapeutics. It is then surprising to see, that in spite of reaching this respectful age, we have not been able to definitely establish all the aspects related to its clinical use. Some of these facets are platelet transfusion threshold and the platelet dose to administer. Historically, two different transfusion triggers have been used for prophylactic and therapeutic platelet transfusions. For prophylactic platelet transfusion an increasing body of evidences suggests that a transfusion trigger of 10 x 10(9) per liter is appropriate for most clinical settings. In contrast, evidence for supporting a certain therapeutic transfusion trigger is lacking. Nevertheless, there is consensus that the platelet count should not be allowed to fall below 50 x 10(9) per liter in patients with acute bleeding. Another important aspect still pending of clear definition is the issue of the platelet dose to be transfused. It has been addressed by some small studies but a definite answer to this important clinical issue is, at least so far, still pending. The results of two ongoing trials, one sponsored by NIH through the Clinical Trials Network in Transfusion Medicine and Hemostasis and the other promoted by the BEST Collaborative Group are expected to help us to clearly defining the more effective and efficient way to transfuse platelet concentrates.

Investigation of the thrombin-generating capacity, evaluated by thrombogram, and clot formation evaluated by thrombelastography of platelets stored in the blood bank for up to 7 days

BACKGROUND AND OBJECTIVES

Transfusion based on the Thrombelastograph (TEG) results reduces transfusion requirements in cardiac surgery and in liver transplantation. Taking the pivotal role of thrombin generation in the coagulation process into consideration, the clinical utility of the TEG may, in part, depend on its reflection of the dynamics of thrombin generation.

MATERIAL AND METHODS

The kinetics of thrombin generation of platelets stored for 2 and 7 days, respectively, was assessed by calibrated automated thrombogram (CAT) and the lag time (min), time to peak (ttPeak; min), peak (nm thrombin) and endogenous thrombin potential (ETP; nm thrombin*min) were registered. Clot formation was evaluated by TEG and the R time (min), maxial amplitude (MA; mm), time to maximum thrombus generation (TMG; min) and maximum thrombus generation (MTG; dynes cm(-2) s(-1)) and total thrombus generation (TTG; dyne cm(-2)) were registered.

RESULTS

Platelets become more procoagulant, evaluated both by TEG and CAT during storage. The reduction in CAT lag time and the ttPeak correlated with a decrease in the TEG R time and TMG (P < 0.0001) as did the CAT peak thrombin generation and the TEG MTG (P = 0.0035). No correlation between ETP and TTG was found (P = 0.65).

CONCLUSION

The kinetics of thrombin generation, as evaluated by CAT, correlates with the thrombus generation, as evaluated by thrombelastography and this may in part explain the clinical utility of the TEG in identifying clinically relevant coagulopathies, secondary to impaired thrombin generation.

Efficacy of prophylactic transfusions using single donor apheresis platelets versus pooled platelet concentrates in AML/MDS patients receiving allogeneic hematopoietic stem cell transplantation

Superiority of single-donor apheresis platelets (SDAP) over pooled platelet concentrates (PPC) transfusions is largely assumed, but unproven. We hypothesized that prophylactic SDAP and PPC transfusions are clinically equivalent after allogeneic hematopoietic stem cell transplants (HSCT). We studied all transfusions administered to 33 patients with AML/MDS during the first 100 days after busulfan-based, myeloablative HSCT. All donor-recipient pairs were ABO identical. Transfusion threshold was a platelet count < or =15 x 10(9)/l. The corrected increment (CCI) was used for all comparisons. Median time to platelet engraftment was 13 days (n=30). PPC transfusions (n=105) were ABO compatible, while 10% of 41 SDAP were not (P=0.006). Median post-transfusion platelet count was 51K/microl (5-118K) after SDAP and 36K/microl (3-115K) after PPC (P=0.0004). Median CCI was 14.178 (SDAP) versus 7.793 (PPC) (P=0.0001). Median time to another transfusion was 3 days (SDAP) and 2 days (PPC; P=0.3). In the week following any given transfusion, the median number of new transfusions was similar (n=2), as well as the need of further transfusion (16 versus 24%, P=0.2). A total of 17% of SDAP and 30% of PPC transfusions were labeled 'ineffective' (P=0.1). There were two non-lethal hemorrhage episodes (6%). SDAP transfusions produced better platelet counts, but SDAP and PPC were equally effective in preventing hemorrhage.

Transfusion of platelets containing ABO-incompatible plasma: a survey of 3156 North American laboratories

CONTEXT

Hemolytic transfusion reactions due to platelet transfusions containing ABO-incompatible plasma (ie, group O platelets into a non-group O patient) have been reported in the literature. However, limited data describe the extent to which transfusion services manage such platelet transfusions or the methods used to limit the risk of such reactions.

OBJECTIVE

To determine transfusion services' current practices regarding the use of platelets containing ABO-incompatible plasma.

DESIGN

In a College of American Pathologists' Transfusion Medicine Proficiency Testing Survey, supplemental questions asked participants whether a policy existed for the use of platelets containing ABO-incompatible plasma and, if a policy existed, what elements were part of the policy.

RESULTS

Of 3156 laboratories that transfused platelets, 3152 responded to the question of whether they had a policy. Of these respondents, 83% (n = 2623) had a policy. One or more elements were reported for transfusions in adults: only ABO-compatible plasma products (n = 1363); only ABO-compatible plasma and platelet products (n = 679); notification of medical director (n = 646); notification of ordering physician (n = 637); volume limit of ABO-incompatible plasma allowed (n = 255); volume-reduction of ABO-incompatible products (n = 168); screening for critical titer of anti-A or anti-B (n = 53). A total of 529 laboratories indicated that they did not have a policy.

CONCLUSIONS

A majority of laboratories have a policy, but most do not include a method to limit the risk of hemolysis if platelets containing ABO-incompatible plasma must be transfused. When such platelets are used, there does not appear to be consensus on a specific method to minimize the transfusion of anti-A or anti-B.

Assessment of education and computerized decision support interventions for improving transfusion practice

BACKGROUND

Overuse of blood products is common, but prior efforts to improve transfusion decisions have met with limited success.

STUDY DESIGN AND METHODS

This study examines transfusion practices before and after a conventional educational intervention followed by a randomized controlled trial of a decision support (DS) intervention with computerized physician order entry (CPOE) for red blood cell, platelet, and fresh-frozen plasma orders. The study was conducted in an academic medical center between April 2003 and June 2004. Orders originating from units not using CPOE with DS (e.g., the emergency department) were excluded. Junior housestaff were randomly assigned into a control group and an intervention group who received DS for transfusion orders. Transfusion orders were initially classified according to guideline rules as DS-agree or DS-disagree. Chart reviews assessed inappropriateness for all DS-disagree orders and a sample of DS-agree orders. The total of inappropriate transfusion orders included chart review confirmed DS-disagree orders and DS-agree orders reclassified as inappropriate.

RESULTS

The percentages of inappropriate nonemergent transfusion orders during the baseline phase for the entire staff and randomly assigned junior housestaff were 72.6 percent (2154/2967) and 71.9 percent (1259/1752) and improved after conventional education to 63.8 percent (1699/2663; p < 0.0001) and 63.3 percent (1263/1996; p < 0.0001), respectively. The percentage of inappropriate orders in the DS intervention group continued to improve (59.6%, 804/1350; p < 0.0001). Physicians accepted 14 percent (133/939) of new DS-recommended orders, especially recommendations to increase transfusion doses (73%).

CONCLUSIONS

Education and computerized DS both decreased the percentage of inappropriate transfusions, although the residual amount of inappropriate transfusions remained high.

[New container of sample: role in the reduction of bacterial contamination of standard platelet units]

BACKGROUND

Bacterial contamination of unstable blood products constitutes today the most frequent infectious risk transmitted by blood transfusion. Platelet concentrates are often incrimineted. As responsible germs are in general of cutaneous origin, a sample procedure with diversion of the first 20 ml during blood donation is studied. The aim of this study is to evaluate the results of this technique on bacterial contamination rate of standard platelet units prepared at the regional blood transfusion center in Casablanca.

STUDY DESIGN AND METHODS

A comparative study of two types of sample pockets is made: 500 Standard Platelet concentrates (CPS) are prepared after collection using standard triple bags (Baxter) (group 1) and 560 pockets of CPS were prepared after collection using triple bags with Sample Diversion Pouch sampling system for elimination of the first 20 ml of donation (Macopharma and Terumo) (group 2). The skin was disinfected in two times with alcohol 70%. The bacteriological study was made in the two groups at the third day of conservation.

RESULTS

Six CPS of group 1 were contaminated, of which five were staphylococci coagulase negative and one bacillus sp. Six CPS of group 2 were contaminated, of which five were staphylococci coagulase negative and one staphylococcus aureus. The bacteria isolated were those of cutaneous flora at 100%. Diversion of first 20 ml of blood donation results in a 16.6% reduction in bacterial contamination of CPS (P>0.05).

CONCLUSION

The non-significant reduction in the prevalence of the bacterial infection of CP formulates the problem of the indication of the sampling devices with derivation of first 20 ml during blood collection.

Evaluation of platelet transfusion triggers in a tertiary-care hospital

BACKGROUND

Our 1100-bed referral hospital uses approximately 12,000 units of random-donor platelets (PLTs) and 1,900 units of single-donor apheresis PLTs per year with a mean of 23 percent outdating. An analysis of patterns of utilization has been undertaken to evaluate practice.

STUDY DESIGN AND METHODS

Over a 9-month period, data were collected on a total of 1682 transfusion episodes in 464 patients. When the pretransfusion count was greater than 10 x 10(9) per L an attempt was made to identify the specific indications for PLT transfusions such as bleeding.

RESULTS

The majority (78%) of PLTs were transfused when the counts were above 10 x 10(9) per L. The mean pretransfusion counts for different services were: bone marrow transplant (BMT) 17.4 x 10(9) per L, hematology-oncology 14.6 x 10(9) per L, the Heart Institute 3 x 10(9) per L, and other services 36 x 10(9) per L. The percentage of transfusions given to patients with a count greater than 10 x 10(9) per L varied by service with 79 percent in BMT, 60 percent in hematology and oncology, 98 percent at the Heart Institute, and 81 percent in other services. Routine monitoring of counts shows a mean increment of 10.2 x 10(9) per L per transfusion. One hour posttransfusion counts, 24-hour posttransfustion counts, and documentation of clinical justification for transfusions was often not available.

CONCLUSIONS

The data show that most patients who receive PLTs have pretransfusion counts of more than 10 x 10(9) per L and more than one-third have pretransfusion counts of greater than 20 x 10(9) per L. The medical literature supports prophylactic PLT transfusion based solely on the count when the PLT number is 10 x 10(9) per L or less. Above this level additional justification is needed although there are different points of view concerning the appropriate triggers. Our data suggest that there is a need for clear hospital transfusion guidelines and ongoing monitoring of PLT use.

Platelet utilization and the transfusion trigger: a prospective analysis

BACKGROUND

Prophylactic platelet (PLT) transfusion practices have become more conservative as studies support a threshold for transfusions at 10 x 10(9) per L. This change in practice may reduce our use of PLT transfusions.

STUDY DESIGN AND METHODS

Data were prospectively collected to assess the impact at one academic hospital when the transition from a 20 x 10(9) to a 10 x 10(9) per L threshold prophylactic transfusion was made.

RESULTS

A total of 503 patients received 7401 PLT transfusions. Seventy-four percent of the transfusions were prophylactic. During the first phase of the study, only 53 percent of transfusions were given at a pretransfusion PLT count of less than 20 x 10(9) per L and 20 percent less than 10 x 10(9) per L. In the second phase of the study when the transfusion trigger was 10 x 10(9) per L, 28 percent of transfusions were given at this level.

CONCLUSION

Many prophylactic PLT transfusions were given at PLT counts higher than the recommended trigger. Although the new transfusion guidelines altered transfusion practice, only a minor change in overall PLT usage was observed. Other changes in transfusion practices, such as dose per transfusion or sampling interval, will be required before significant reduction in the costs and hazards of prophylactic PLT transfusions can be realized.

Development of proficiency testing for detection of bacterial contamination of platelet products

BACKGROUND

Accrediting agencies now require quality control for minimizing platelet (PLT) bacterial contamination (PBC). A proficiency testing (PT) strategy for PBC testing was developed.

STUDY DESIGN AND METHODS

During Phase 1, validation of the pH meter and an enhanced bacteria detection system (Pall eBDS)--methods used in our blood bank--was accomplished with two aliquots of an apheresis PLT unit inoculated with Escherichia coli (ATCC 25922, 70 CFU/mL) or Staphylococcus aureus (ATCC 27217, 46 CFU/mL) with an uninoculated aliquot serving as a negative control. Quantitative plate culture was the reference method. PLTs were stored on a rotator at 22 degrees C. Units were sampled in duplicate at 0, 24, and 48 hours. pH testing was considered positive when the pH value was less than 6.6. eBDS was positive when the oxygen concentration was less than 9.4 percent. During Phase 2, synchronized PT of pH and eBDS was performed at four independent sites. PLT samples were inoculated and incubated as above, and aliquots were removed at Time 0 for eBDS testing and at 48 hours for pH testing.

RESULTS

In Phase 1, on inoculated bags eBDS was positive at all time periods but pH was positive only at 48 hours. In Phase 2, synchronized results showed positive eBDS at Time 0 and positive pH at 48 hours on inoculated bags with agreement between paired sites.

CONCLUSIONS

This strategy may serve as a useful model for developing PT materials for PBC detection. eBDS was able to identify low levels of PBC, and pH testing, only much higher levels. It is important to carefully coordinate and standardize handling of PT materials and reporting of results.

Update on multi-center clinical trials in the United States

This article reviews numerous multi-center clinical trials, either ongoing or in planning stages, which involve diverse clinical applications and emerging technologies in apheresis and transfusion medicine. The investigations summarized herein involve the following specific areas: platelet dosing strategy, thrombotic thrombocytopenia purpura, inflammatory bowel disease, seven-day platelet storage, dendritic cell vaccines, and age-related macular degeneration.

Guidelines for the transfusion of platelets

Recommendations aiming at standardising and rationalising clinical indications for the transfusion of platelets in Belgium were drawn up by a working group of the Superior Health Council. To this end the Superior Health Council organised an expert meeting devoted to "Guidelines for the transfusion of platelets" in collaboration with the Belgian Hematological Society. The experts discussed the indications for platelet transfusions, the ideal platelet concentrate and the optimal platelet transfusion therapy. The recommendations prepared by the experts were validated by the working group with the purpose of harmonising platelet transfusion in Belgian hospitals.

Factors affecting platelet yield and their impact on the platelet increment of patients receiving single donor PLT transfusion

The aim of this study was to analyze the impact of various donor and machine parameters on PLT yield in 127 PLT apheresis procedures, to optimize PLT yield achieving clinical and economic advantages. One hundred and twenty-seven apheresis procedures were analyzed. Age, gender, volume processed, Hb, and PLT precounts were included as donor predicting variables. AC infusion rate, processing time, and plasma volume collected with PLTs were assessed as machine parameters. We evaluated the post-transfusion effectiveness in 23 patients with thrombocytopenia, studying the effect of PLT dose, ABO group, and PLT storage time. Females gave higher yields, compared to males, P<0.01. PLT yield correlated positively with PLT precount (r=0.512), and TBV (r=0.404), and negatively with donor preapheresis Hb (r=-0.306). Processing time and AC infusion rate had a positive impact on PLT yield. Post-apheresis decrease in PLT count was 53.6+/-26.3x10(11). Donors with Hb>or=12 g/dl, donated safely. Most of the complications were citrate related (13.4% of all procedures). PLT increments in transfused patients correlated positively with the number of units transfused (r=0.41), and negatively with PLT storage days (r=-0.342). PLT increments in patients receiving ABO-compatible PLTs were 75% higher, compared to the increments in patients receiving incompatible PLTs. PLT count and volume processed were the main predictors of PLT yield. Increasing the processing time, the AC infusion rate, or the volume of plasma obtained with PLTs can increase PLT yields. High PLT dose, short storage time, as well as ABO compatibility should be considered during PLT transfusion.

[Current status and problem of platelet transfusion for hematopoietic diseases: results from a questionnaire survey]

We carried out a survey on platelet transfusions performed in hospitals certified by the Japanese Society of Hematology. The average values of the pretransfusion platelet count (trigger value) for the day on which the transfusion was ordered, and the values on each day in the interval between the order and actual transfusion, were compared with the Guidelines. The average trigger value in aplastic anemia and myelodysplastic syndrome patients (A group) (1.41 x 10(4)/microl) for the same day on which the transfusion was ordered was higher than the Guideline, whereas those patients with hematological disorders undergoing chemotherapy (B group) and hematopoietic stem cell transplantation (C group), namely 2.08 x 10(4)/microl and 2.1 x 10(4)/microl, respectively, were acceptable values when compared with the Guidelines. On the other hand, in all groups, the transfusion trigger values at one or two days after ordering were higher than the Guidelines, being 2.56 x 10(4)/microl in the A group, 3.15 x 10(4)/microl in the B group, and 2.59 x 10(4)/microl in the C group. We have tried to formulate platelet count criteria for ordering a transfusion based on one day before the actual transfusion, because these platelet counts on ordering were relatively high. The criteria are 1.0-1.5 x 10(4)/microl in group A, 3.0 x 10(4)/microI in group B, and 3.0 x 10(4)/microl in group C. In order to perform platelet transfusion according to the Guidelines, the platelet count on ordering should be decreased as we proposed.

Transfusion support to Dengue patients in a hospital based blood transfusion service in north India

We evaluated transfusion requirements in a retrospective study of 245 patients with various categories of Dengue infection. The majority (155/245) of our patients were of the Dengue fever (DF) category. There was no correlation between clinical bleed and platelet count as 81 non-bleeding patients were having counts < 20 x 10(3)/microL. Coagulopathy was observed in 37% of the patients with Dengue hemorrhagic fever or Dengue shock syndrome. A rapid response to platelet and fresh frozen plasma (FFP) transfusion was observed in all cases. However, inappropriate transfusion was a major concern as transfusion of 21.5% platelet concentrates was considered inappropriate.

Viability and function of 8-day-stored apheresis platelets

BACKGROUND

Methods of bacterial detection and pathogen inactivation of platelets (PLTs) may allow extended storage of PLTs as long as PLT quality is maintained.

STUDY DESIGN AND METHODS

Twenty normal volunteers had their PLTs collected with an apheresis machine (Haemonetics Corp.). A variety of in vitro PLT function and metabolic assays were performed both on Day 0 and after 8 days of storage. On Day 8, a small blood sample was drawn from each donor to obtain fresh PLTs. The fresh and stored autologous PLTs were labeled with either (51)Cr or (111)In, and the radiolabeled PLTs were transfused. Posttransfusion serial blood samples were drawn to determine the relative posttransfusion recoveries and survivals of the fresh versus the stored PLTs.

RESULTS

Although the in vitro assays showed some differences between the two trial sites, the results were generally within the ranges expected for fresh and stored PLTs. Overall, PLT recoveries averaged 66 +/- 16 percent versus 53 +/- 20 percent and survivals averaged 8.5 +/- 1.6 days versus 5.6 +/- 1.6 days, respectively, for fresh compared to 8-day-stored PLTs. There were no significant differences in the in vivo PLT data between the trial sites or based on the radiolabel used for the measurements.

CONCLUSION

After 8 days of storage, the in vivo posttransfusion recovery and survival of autologous Haemonetics apheresis PLTs meet the proposed standards for poststorage PLT quality.

Bacterial contamination of platelet concentrates prepared by different methods: results of standardized sterility testing in Germany

BACKGROUND AND OBJECTIVES

National guidelines for monitoring the bacterial contamination rate of blood components were introduced in Germany in 1997. The objective of this study was to present and evaluate the results of sterility testing of platelet concentrates (PCs) prepared by different methods.

MATERIALS AND METHODS

The analysis of results of sterility testing of blood component production from transfusion medicine centres in Germany in 1998 and 2001 was based on information collected using standardized questionnaires.

RESULTS

The bacterial contamination rates for single-donor PCs derived from whole blood and apheresis (0.210% vs. 0.156%) were comparable and showed no significant difference. However, pooled PCs produced from four buffy coats using the sterile docking procedure showed a significantly higher bacterial contamination rate compared with single-donor PCs derived from whole blood and apheresis (0.184% vs. 0.604%).

CONCLUSIONS

Use of standardized methods for sterility monitoring is sufficient to assess collection and production processes in terms of hygiene and yields reliable data on bacterial contamination rates of blood components. The methods described are suitable for using to analyse the efficiency of newly introduced methods to reduce bacterial contamination rates of blood components (e.g. diversion, bacteria screening and pathogen inactivation).

Release of potential immunomodulatory factors during platelet storage

BACKGROUND

Blood platelets (PLTs) link the processes of hemostasis and inflammation. Recent studies have demonstrated that PLTs promote immunity and inflammation mainly by means of the CD40/CD40L pathway. Our objective was to describe the accumulation of cytokines in PLT concentrates during storage.

STUDY DESIGN AND METHODS

Pools of PLT concentrates were prepared, separated from plasma, and resuspended in clinical-grade storage medium; samples were taken on Days 0, 1, 2, 3, and 5 for analysis, without replacement (i.e., without soluble protein dilution). Interleukin (IL)-6, IL-8, PLT-derived growth factor (PDGF)-AA, soluble CD40 ligand (sCD40L), RANTES, and transforming growth factor-beta production were measured by specific enzyme-linked immunosorbent assays.

RESULTS

Over time, the levels of RANTES, IL-8, and IL-6 were stable. In contrast, the levels of PDGF-AA and sCD40L increased. Ex vivo production of sCD40L was quantified at levels sufficient to induce B-cell effects based on previous studies of in vitro induced B-cell activation and differentiation by sCD40L. Cytokine and/or chemokine levels were generally higher in PLT concentrate supernatants and/or PLT lysates in comparison to PLT-free plasma, allowing the determination of which cytokine and/or chemokine was absorbed or secreted by transfusion-grade PLTs over time.

CONCLUSION

Our data provide evidence that stored PLTs contain molecules with known immunomodulatory competence and secrete them differentially over time during storage for transfusion purposes.

Evolution of surveillance methods for detection of bacterial contamination of platelets in a university hospital, 1991 through 2004

BACKGROUND

Platelet (PLT) bacterial contamination (PBC) is the most common transfusion-associated infection. It is important to understand the impact of interventions addressing this problem.

STUDY DESIGN AND METHODS

PBC was studied by prospective (active) and transfusion-reaction triggered (passive) surveillance from July 1991 to December 2004. Active surveillance, utilized for 10 years, included bacterial culture of all or 4- and 5-day-old PLTs at issue and intermittent use of Gram stain, pH measurements, and early (24-hr) culture of single-donor plateletpheresis (SDP) units.

RESULTS

Active surveillance detected 38 instances of PBC, 7 in SDP units (1:2213) and 31 in random-donor PLT units (1:2090 units, p = 0.89; or 1:418 pools of 5 units, p < 0.001). Contaminants were coagulase-negative staphylococci (CONS; n = 27), Staphylococcus aureus (4), Bacillus cereus (1), Serratia marcescens (2), streptococci (2 S. bovis, 1 S. uberis), and CONS with viridans group streptococcus (1). Only one instance of contamination, caused by Pseudomonas aeruginosa, was detected by passive surveillance, with fatal outcome. Colony counts of contaminants ranged from 0.5 x 10(2) to 4 x 10(11) colony-forming units per mL at time of issue. PBC was interdicted before transfusion in 6 cases through Gram stain screening. Transfusion reactions occurred in 13 of 32 recipients (41%), with 9 severe reactions (28%) and 3 deaths (9%). pH testing failed to detect 5 contaminated units and resulted in discard of nearly 2 percent of units, whereas culture of SDP units at 24 hours failed to identify a contaminated unit.

CONCLUSION

Improved active surveillance methods for detecting PBC are needed to improve the safety of PLT transfusions.

Platelets do not adsorb HLA class I molecules during storage of pooled platelet concentrates

The origin of HLA class I molecules on platelets is still under discussion. Adsorption of HLA molecules on platelets using specific experimental conditions has been described. The study presented investigates whether there is a significant elution and adsorption of HLA class I molecules on platelets during storage of pooled random platelet concentrates (PRPC) under routine conditions. Platelet concentrates (PCs) from whole blood were prepared from HLA-A2-positive and HLA-A2-negative donors, pooled and stored under routine conditions. In addition, platelets from HLA-A2-negative donors were pelleted and resuspended in cell-free plasma from HLA-A2-positive donors. HLA-A2-positive PCs (positive control), HLA-A2-negative PCs (negative control) and HLA-A2-negative platelets in plasma from HLA-A2-negative donors were stored simultaneously. Binding of FITC-conjugated monoclonal murine antihuman HLA-A2 antibodies (anti-HLA-A2-mab) was measured during 5-day storage by flow cytometry. An increased binding of anti-HLA-A2-mab during storage was found on HLA-A2-negative platelets (P < 0.005) independently whether they were incubated with cell-free plasma or platelets from HLA-A2-positive donors or autologous HLA-A2-negative cell-free plasma. However, non-specific binding of IgG controls increased equally, whereas anti-HLA-A2-mab binding to platelets from HLA-A2-positive donors did not decrease during storage. This study suggests that there is no significant elution and adsorption of HLA class I antigens of platelets in pooled PCs during storage under the usual conditions for platelet storage. Increased anti-HLA-A2-mab signal was due to non-specific binding. Therefore, HLA class I compatible platelets should maintain their compatibility for an immunized patient when stored in a pool with HLA incompatible platelets and shortened survival after transfusion should not be expected.

Freeze-dried rehydrated human blood platelets regulate intracellular pH

BACKGROUND

Long-term storage of platelets (PLTs) in the dry state would greatly improve options for PLT storage. Whether trehalose-loaded freeze-dried and rehydrated PLTs could regulate intracellular pH (pHi) was evaluated.

STUDY DESIGN AND METHODS

Previously it was shown that human PLTs can be successfully preserved by freeze-drying with trehalose. Trehalose-loaded freeze-dried rehydrated PLTs and fresh control PLTs were labeled with the pH dye BCECF-AM. pHi was measured in resting cells, cells acidified with nigericin, and cells treated with thrombin. The sodium-proton pump was blocked by treatment with 5-(N-methyl-N-isobutyl)amiloride (MIA).

RESULTS

The pHi of rehydrated PLTs is the same as that of fresh control PLTs, 7.27+/-0.03 (SD; n=5) and 7.27+/-0.02 (n=5), respectively. Nigericin treatment of cells showed that the recovery in pHi was Na+-dependent and followed Michaelis-Menten kinetics. The Vmax values (DeltapH/9 sec) were 0.21+/-0.039 (n=3) and 0.22+/-0.025 (n=3) for rehydrated and control PLTs, respectively. The exchange constants were 17.7+/-2.3 mmol per L (n=3) and 17.0+/-1.9 mmol per L (n=3) for rehydrated and control PLTs, respectively. Treatment of cells with MIA showed that NHE1 remained sensitive to the inhibitor after freeze-drying and rehydration.

CONCLUSION

The results show that the pHi regulation system is largely preserved during freeze-drying and rehydration of PLTs.

Summary of the AABB Interorganizational Task Force on Bacterial Contamination of Platelets: Fall 2004 impact survey

BACKGROUND

New voluntary standards in the United States regarding bacterial contamination of platelets (PLTs) led to the formation of the AABB Interorganizational Task Force on Bacterial Contamination of Platelets. This article summarizes a survey conducted by the Task Force to assess the impact of bacterial detection.

STUDY DESIGN AND METHODS

An Internet-based survey of AABB member institutions was conducted from September 17, 2004, to October 1, 2004. The survey was designed principally to assess PLT usage, supply, and outdating and the currently used bacteria detection methods.

RESULTS

Of 900 facilities surveyed, 350 responded (38%). These facilities collected approximately 43.3 and 65.9 percent and transfused approximately 19.1 and 22.2 percent of the whole blood-derived PLT concentrates (WBPCs) and apheresis PLTs in the United States, respectively. Most facilities (64-91%) indicated that their ability to provide PLTs for transfusion had not been affected. Approximately half (50-57.1%) indicated no changes in their PLT inventory. Two-thirds (66-68%) indicated no increased PLT outdating. More than 90 percent of apheresis PLTs are tested with a culture-based method, whereas WBPCs are tested with a variety of methods (mostly non-culture-based) resulting in a 4.6-fold decrease in the confirmed positive detection rate compared with apheresis PLTs (p < 0.001).

CONCLUSION

After the implementation of AABB Standard 5.1.5.1, the majority of facilities responding to this survey experienced no (or modest) impact on PLT availability or outdating. Nevertheless, a substantial portion of facilities experienced both increased outdating and decreased availability. Some facilities were greatly impacted. Based on the data gathered, it is impossible to conclude whether such shortages resulted from production or distribution problems or were due to decreased shelf life and increased outdates.

Methods for counting platelets in severe thrombocytopenia

Accurate platelet counts in severe thrombocytopenia are critical in clinical practice to facilitate decisions at prophylactic platelet-transfusion thresholds. Until recent years, the accuracy of platelet counts has been limited by the reliance of hematology analyzers on calibration material values derived from the manual platelet counting method. The calibration of hematology analyzers in thrombocytopenia and the reduction of variation between instruments have been hindered by a lack of adequate quality control materials, making the accuracy of automated methodologies in routine practice difficult to assess. This situation could now be vastly improved by the use of the International Reference Method (IRM) to assign calibration materials and by further knowledge of the accuracy and limitations of the particular types of automated platelet count available to the clinician. These changes will improve clinical confidence in the accuracy of a platelet count and thus inform clinical decisions at the current level of prophylactic platelet transfusions.