The post-platelet 100,000 count: effects of platelet collection and future

Currently, the majority of platelets transfused in the United States are collected by apheresis. The recent Food and Drug Administration guidance document published maintains that a postdonation platelet count for a donor remain >100,000/μL. During apheresis procedures, platelets are released from the splenic pool into circulation. This allows for higher postdonation platelet counts than anticipated. Some current plateletpheresis instruments take this into account when determining a safe product to be collected. On other instruments, the software does not allow for this correction. This may impact collections, but is expected to be resolved with a software update.     

A statistical model for estimating donor postdonation platelet counts after plateletpheresis

BACKGROUND: To avoid the need, in serial apheresis donors, either to delay plateletpheresis until a predonation platelet count is completed or to obtain a postdonation count after each procedure, a statistical model has been developed to predict the postdonation platelet count from the donor predonation platelet count, weight, and hematocrit. STUDY DESIGN AND METHODS: Predonation and postdonation platelet counts were measured in two groups of approximately 100 consecutive donors (Group A to test the model and Group B to validate it), and the postdonation counts were calculated with the model. Using stepwise multiple linear regression from donor data, estimated postdonation platelet counts were found to be comparable to the postdonation platelet counts actually measured. RESULTS: Estimated postdonation platelet counts × 10(9) per L (mean +/− SD) for each group, respectively, were Group A, 195 +/− 35, versus actual platelet counts of 195 +/− 39 (p = 0.43), and Group B, 183 +/− 36, versus actual platelet counts of 189 +/− 34 (p = 0.14). Sensitivity and specificity, respectively, were Group A, 57 and 99 percent and Group B, 62 and 99 percent. CONCLUSION: For most serial apheresis donors, application of this predictor model should preclude the need to obtain an extra postdonation platelet count.     

Markers of platelet activation and apoptosis in platelet concentrates collected by apheresis.

BACKGROUND: A product with well-preserved haemostatic function of platelets is the ultimate goal of platelet concentrate production. However, platelet activation and apoptosis are induced by both collection and storage of platelet concentrates. AIM OF STUDY: Platelet concentrates obtained either by two blood separators with different technology of apheresis (Haemonetics MCS+, Haemonetics Corp. Braintree, USA and Trima Accel, Gambro BCT Inc., Lakewood, USA, respectively) or derived from buffy-coat were compared using evaluation of pH, LDH, lactate, glucose, annexin V, and sP-selectin levels immediately after collecting and at the end of expiration to estimate the differences in the activation and apoptosis of platelets in these products. RESULTS: The lowest degree of platelet activation was found in products obtained by Haemonetics MCS+ apparatus at the time of collection. Platelet concentrates obtained by apheresis revealed higher rise of LDH, annexin V and sP-selectin compared to buffy-coat derived platelets. Products from Haemonetics MCS+ showed higher rise of annexin V in comparison with products from Trima separator. Increase of LDH and sP-selectin in both apheresis products was comparable. CONCLUSIONS: On the basis of changes of sP-selectin and annexin V levels it could be concluded that initial platelet activation, which is induced by apheresis, is very likely without any further impact on quality of platelets during storage. Development of platelet storage lesions is influenced especially by storage conditions and platelet concentration in products.     

Pooled platelet concentrates provide a small benefit over single-donor platelets for patients with platelet refractoriness of any etiology

BackgroundAt our institution, patients with platelet refractoriness (of any etiology) are sometimes switched from apheresis platelets to pooled platelets before human leukocyte antigen (HLA)-matched units become available.Study design and methodsSeven patients were analyzed. Platelet counts were available from 57 single-unit transfusions (26 pooled, 31 apheresis). A mixed linear effects model was used and significance was determined using a likelihood ratio test.ResultsWhen analyzed as the only fixed effect in the model, the use of pooled versus single-donor units and time from transfusion to post-transfusion blood sampling each showed a significant effect on platelet count increments. A mixed linear effect model including both factors showed that transfusing a pooled unit correlated with a 4500±2000/µL greater platelet count increment compared with a single-donor unit, and an increase in time from transfusion to post-transfusion blood sampling lowered the platelet count increment by 300±100/µL per hour.ConclusionA small but potentially clinically relevant benefit was observed in transfusing pooled random-donor platelets compared with single-donor units for patients with platelet refractoriness (of any etiology).     

Phosphatidylserine exposure in platelet concentrates during the storage period: differences between the platelets collected with different cell separators.

BACKGROUND AND OBJECTIVES: Platelet alterations occur during the production and storage of platelet concentrates, the so called "storage lesion". We studied the platelet alterations during the storage period in apheresis concentrates, employing flow cytometry for phosphatidylserine (PS) detection on platelets during the five days of storage. MATERIAL AND METHODS: Twenty-seven single donor platelet concentrates harvested with the Cobe Trima, Baxter Amicus, or Haemonetics MCS+ were analyzed for PS exposure by flow cytometry on the day of production (day 1) and on days 3 and 5 of storage. Furthermore PS expression was analyzed in platelet donors' blood samples withdrawn before plateletpheresis. RESULTS: PS expression on platelets gave the following median values: in blood donors before apheresis it was 1.12% (0.13-1.78) in platelets concentrates on the first day (2 h after apheresis) 2.06% (0.66-15.2), the third day 6.57% (1.98-51.13) and the fifth day 23.04% (3.86-80.23). All differences between median values of PS expression in blood samples before apheresis, and platelets concentrates on days 1, 3 and 5 of storage, are statistically significant. The expression of PS in platelet concentrates was analyzed in relation to the blood cell separator used for the collection procedure and showed the following results: on day 1 the median values of PS in platelet concentrates collected with the three different blood cell separators, Trima, Cobe and MCS, did not show statistically significant differences. On day 3, the platelets concentrates collected with the Trima and with the MCS showed differences that were statistically significant. Those were respectively 10.59% (4.56-51.13) and 3.53% (1.98-12.61), p = 0.005. The PS expression in platelet concentrates collected with the Trima and MCS showed differences that are also statistically significant on day 5 at respectively 32.4% (9.61-80.23) and 8.57% (3.86-48.42), p = 0.005. CONCLUSIONS: PS exposure in platelet concentrates on days 3 and 5 rise to levels that could compromise the quality of the platelet units. Improvements in standardized platelet quality controls, and in platelet collection systems are required to reduce the storage lesions in platelets concentrates.     

Platelet Recruitment during Multiple Donor Platelet Apheresis Differs between Cell Separators

SUMMARY: BACKGROUND: Recruitment of platelets (PLT) during donor PLT apheresis may facilitate the harvest of multiple units within a single donation. METHODS: We compared two PLT apheresis procedures (Amicus and Trima Accel) in a prospective, randomized, paired cross-over study in 60 donors. The 120 donations were compared for depletion of circulating PLT in the donors, PLT yields and PLT recruitment. A recruitment was defined as ratio of total PLT yield and donor PLT depletion > 1. RESULTS: Despite comparable differences of pre- and post-apheresis PLT counts (87 × 10(9)/l in Trima Accel vs. 92 × 10(9)/l in Amicus, p = 0.383), PLT yields were higher with Trima Accel (7.48 × 10(11) vs. 6.06 × 10(11), p < 0.001), corresponding to a higher PLT recruitment (1.90 vs. 1.42, p < 0.001). We observed a different increase of WBC counts after aphereses, which was more pronounced with Trima Accel than with Amicus (1.30 × 10(9)/l vs. 0.46 × 10(9)/l, p < 0.001). CONCLUSION: Both procedures induced PLT recruitment. This was higher in Trima Accel, contributing to a higher yield in spite of a comparable depletion of circulating PLT in the donors. This recruitment facilitates the harvest of multiple units within a single donation and seems to be influenced by the procedure utilized. The different increases of circulating donor white blood cells after donation need further investigation.     

不同型号血细胞分离机对献血者细胞参数与机采血小板采集效率比较

目的比较不同型号血细胞分离机对献血者细胞参数与机采血小板采集效率。方法选取2018年1月至2019年11月我站的318例献血者,其中159名献血者应用AmiCORE、MCS+及Trima血细胞分离机捐献双份血小板,平均分为3组,另外159名献血者应用AmiCORE、MCS+及Trima血细胞分离机捐献单份血小板,平均分为3组。比较三组的单份及双份血小板细胞参数不合格率及分离机性能。结果MCS+组单份血小板细胞参数不合格率低于AmiCORE组和Trima组,差异具有统计学意义(P<0.05)。MCS+组单份血小板采集效率及时间高于AmiCORE组及Trima组,差异具有统计学意义(P<0.05);Trima组抗凝剂使用量及全血处理量多于MCS+组及AmiCORE组(P<0.05)。三组双份血小板细胞参数不合格率比较,差异均无统计学意义(P>0.05)。MCS+组双份血小板采集效率高于AmiCORE组及Trima组,差异具有统计学意义(P<0.05);AmiCORE组采集时间长于MCS+及Trima组,Trima组抗凝剂使用量及全血处理量多于MCS+及AmiCORE组,差异具有统计学意义(P<0.05)。结论AmiCORE、MCS+及Trima血细胞分离机对产品采集具有较高采集效率,符合国家有关标准,血液制备和采集过程可供,各机型血小板细胞参数不合格率、血小板分离机性能存在区别。血液制备及血液采集过程具有可控性,应依据献血者自身特点选择不同血细胞分离机。     

Efficacy and safety of plateletpheresis by donors with low-normal platelet counts

Our practice is to defer donors with blood platelet (PLT) counts of <180 × 10⁹/L because PLT yields are low, when compared to PLT units collected from donors with higher counts. In an attempt to minimize deferral, we determined whether 33 donors, who repeatedly demonstrated low-normal PLT counts (150–180 × 10⁹/L) on multiple occasions during the prestudy period, might safely donate satisfactory apheresis PLT units simply by extending the apheresis collection time by 20 min (men) and 40 min (women). Repeat plateletpheresis procedures were scheduled at ≥28-day intervals. The mean PLT yield (N = 92) was 5.8 × 10¹¹ with 97% of units containing ≥4.0 × 10⁹ PLTs. Although donors entered the study only after they had repeatedly exhibited predonation PLT counts of <180 × 10⁹/L, PLT counts were not always below this level at the time of study collections. However, analyzing only donations with true predonation PLT counts of <180 × 10⁹/L (N = 35), the mean PLT yield was excellent—5.4 × 10¹¹ with 97% of units containing ≥4.0 × 10¹¹ PLTs. The average fall in donor blood PLT counts (pre- vs. postdonation) was 36%, with only ten of 99 postdonation counts being <100 × 10⁹/L; the lowest was 69 × 10⁹/L. Thus, extending the apheresis collection time permitted donors who in the past were routinely deferred because of low PLT counts to safely donate satisfactory PLT units.     

Apheresis platelets: Emerging issues related to donor platelet count,apheresis platelet yield,and platelet transfusion dose

Emerging issues in stimulating apheresis platelet donors with platelet growth factors, the relative costs of apheresis and random donor platelet concentrates, optimal platelet transfusion dose, and leucoreduction of platelet products have caused renewed debate regarding apheresis products vs. random, pooled concentrates. The future role of apheresis products in platelet transfusion therapy will in large part be determined by costs, which are increasingly recognized to be influenced by donor platelet count, apheresis yield, and platelet transfusion dose. J. Clin. Apheresis 13:114–119, 1998. © 1998 Wiley-Liss, Inc.     

Pseudothrombocytopenia in plateletpheresis donors

BACKGROUND: EDTA pseudothrombocytopenia (PTCP) is an in vitro artifact in which the anticoagulation of blood with EDTA is associated with in vitro agglutination of platelets, resulting in a spuriously low platelet count. In apheresis donors, whole-blood samples for complete blood counts are routinely drawn into tubes anti-coagulated with EDTA. STUDY DESIGN AND METHODS: Records of apheresis donors were examined to identify persons in whom the postdonation counts were less than 100 × 10(9) per L. Identified donors were studied to confirm the presence of PTCP by drawing blood samples into EDTA, heparin, and trisodium citrate for serial platelet counts at room-temperature incubation. Platelet counts in citrated plasma were measured before and after the addition of EDTA. A single HLA-matched component from an identified PTCP donor was monitored for response by corrected count increment in the recipient. RESULTS: A total of nine donations were identified, involving 2 donors from a population of 945 donors (prevalence 0.2%). On testing, both donors were confirmed to have PTCP. The addition of EDTA to citrated plasma did not affect the platelet count. Response in a recipient to an HLA-matched component showed an acceptable corrected count increment. CONCLUSION: PTCP may occur in plateletpheresis donors and result in needless medical referral or donor deferral. PTCP does not appear to alter the yield content of the component or to be passively transferred to a recipient.     

The role of sodium citrate during extended cold storage of platelets in platelet additive solutions

Background

Cold-stored platelets are increasingly being used to treat bleeding. Differences in manufacturing processes and storage solutions can affect platelet quality and may influence the shelf life of cold-stored platelets. PAS-E and PAS-F are approved platelet additive solutions (PAS) in Europe and Australia, or the United States respectively. Comparative data are required to facilitate international transferability of laboratory and clinical data.

Study Design and Methods

Single apheresis platelets from matched donors (n = 8) were collected using the Trima apheresis platform and resuspended in either 40% plasma/60% PAS-E or 40% plasma/60% PAS-F. In a secondary study, platelets in PAS-F were supplemented with sodium citrate, to match the concentration in PAS-E. Components were refrigerated (2–6°C) and tested over 21 days.

Results

Cold-stored platelets in PAS-F had a lower pH, a greater propensity to form visible (and micro-) aggregates, and higher activation markers compared to PAS-E. These differences were most pronounced during extended storage (14–21 days). While the functional capacity of cold-stored platelets was similar, the PAS-F group displayed minor improvements in ADP-induced aggregation and TEG parameters (R-time, angle). Supplementation of PAS-F with 11 mM sodium citrate improved the platelet content, maintained the pH above specifications and prevented aggregate formation.

Discussion

In vitro parameters were similar during short-term cold storage of platelets in PAS-E and PAS-F. Storage in PAS-F beyond 14 days resulted in poorer metabolic and activation parameters. However, the functional capacity was maintained, or even enhanced. The presence of sodium citrate may be an important constituent in PAS for extended cold storage of platelets.     

手工与机采血小板疗效的临床观察

目的 比较手工血小板和机采血小板的疗效,为临床输血提供参考依据.方法 样本来源于该院经过血小板输注治疗的住院患者,其中134例患者输用6 756 U手工血小板为A组;74例患者输用2 880 U机采血小板为B组.分别观察两组患者输注24 h后血小板校正增加指数（CCI）、血小板回收率（PPR）、临床出血症状有无改善、有无输血反应等进行输注后疗效判断.结果 与B组比较,A组CCI、PPR、总的输注有效率、输注反应率比较差异均无统计学意义（P〉0.05）.结论 对于未产生同种免疫的患者,输注手工血小板或机采血小板,具有同等的安全性和有效性.因此,手工血小板的应用能够节约血液资源,缓解血小板供应紧张的现状.     

单采新鲜血小板与冰冻血小板的输注效果分析．

[目的]探讨单采新鲜血小板与冰冻血小板的临床输注效果。[方法]76例血小板减少或血小板功能障碍患者输注单采血小板,随机分为两组,48例输注单采新鲜血小板,28例输注冰冻血小板,观察输注前后24h外周血血小板计数及出血止血情况。[结果]输注新鲜血小板组与输注冰冻血小板组在止血效果方面无明显差异,但在提高外周血血小板计数方面,新鲜血小板组明显优于冰冻血小板组。[结论]提倡新鲜血小板输注,冰冻血小板可以用于急救由于血小板减少导致的出血性疾病。     

Fingerstick blood samples in platelet donor screening: Reliability and impact on predict yield programs

Although widely used, the reliability of fingerstick platelet counts for determining donor eligibility and for use with plateletpheresis predict yield programs has not been established. We compared platelet counts obtained from fingerstick vs. venous samples in several aspects of apheresis platelet collection. Analysis of 25 paired fingerstick and venous predonation samples demonstrated a poor correlation between platelet counts (r² = .43), with fingerstick counts having a 20% lower mean value (P < .05). The effect of using fingerstick vs. venous predonation platelet counts with apheresis instrument predict yield calculations to obtain target yields was determined. Mean yields collected using fingerstick/predict yield were 12% (Fenwal CS3000 PLUS) and 15% (Haemonetics MCS+) higher than venous/predict yield units (P < .05). The coefficients of variation (CV) of fingerstick/predict yield and venous/predict yield collections were comparable (15% vs. 14% [CS3000] and 23% vs. 21% [MCS+], respectively), indicating that possible differences in accuracy between fingerstick and venous platelet counts had little effect on the variability of predict yield collections. A retrospective analysis of the CV of 100 fingerstick/predict yield units vs. 100 units collected by processing standard volumes showed no difference: 22% vs. 20% (F = 0.99, CS3000), and 22% vs. 24% (F = 0.89, MCS+), respectively. We conclude that fingerstick platelet counts are systematically lower and correlate poorly with venous counts, though their use seldom results in false disqualification of donors. We also conclude that fingerstick count/predict yield collections do not produce more consistent yields of platelets than standard volume collections. J. Clin. Apheresis 12:105–109, 1997. © 1997 Wiley-Liss, Inc.     

The use of historical platelet counts from blood donors to program apheresis platelet donation: An Australian perspective

Background

For Australian apheresis platelet donations, in-centre haematology analysers provided the platelet count used to program the platelet collection machines. When the haematology analysers were not functional, historical platelet counts from previous donations were used. This study aimed to confirm that the routine use of historical platelet counts for programming apheresis collection machines would maintain platelet yields within the donated units and that haematology analysers could be removed.

献血者单采血小板前后外周血小板变化分析及血小板冲红独立危险因素调查

目的探讨献血者单采血小板前后外周血小板变化及血小板冲红的独立危险因素。方法选择我院2018年5月至2019年5月接待的单采血小板者120例,收集患者基础信息,分别于采前、采后(单采后10~20 min)采集献血者外周血并检测分析血液数据,以明确外周血小板变化,并统计单采血小板冲红患者例数,采用单因素、多因素logistic回归分析明确单采血小板冲红的独立危险因素。结果经血液样本分析,单采血小板前、后的外周血小板检测值分别为(208.2±28.4)109/L、(169.2±29.9)109/L,且单采后10~20 min,献血者外周血小板可恢复到采前的(81.1±9.4)%;献血者单采血小板冲红例数为22例,冲红发生率为18.33%,多因素logistic回归分析,单采血小板冲红独立危险因素有RBC、HCT及脂肪血水平(P<0.05)。结论单采血小板后(10~20 min)外周血小板值可恢复到采前的(81.1±9.4)%,针对单采血小板冲红的独立危险因素,应加强防控措施,减少血小板冲红发生。     

机采血小板检测前过程质量控制的研究

目的探讨机采血小板检测前过程的质量控制。方法留取机采单份血小板、机采双份血小板样本各100份,以1∶1、1∶3及1∶7稀释度进行稀释,采用全自动血液细胞计数仪检测血小板计数。另采集机采血小板样本100份,室温下静置0、30、60、90、120min,以1∶3稀释后,检测其血小板计数。结果机采单份或双份血小板样本以1∶1与1∶3稀释后检测血小板计数的差异及1∶3与1∶7稀释后检测的差异均有统计学意义（P〈0.05）。静置0、30min检测的血小板计数与静置60、90、120min的检测值的差异有统计学意义（P〈0.05）。结论机采血小板检测前过程的质量控制对采集后的血小板计数十分重要。     

Sustained decreases in platelet count associated with multiple, regular plateletpheresis donations

BACKGROUND: Transient but significant decreases in platelet counts have been documented to occur in donors undergoing single and serial short-term plateletpheresis collections. The effect of long-term regular plateletpheresis on donor platelet counts has not been characterized. STUDY DESIGN AND METHODS: A retrospective study was performed to evaluate the effects of long-term regular plateletpheresis donation on donor platelet counts. A computerized database containing records of 11,464 apheresis collections from 939 donors over a 4-year period was queried for serial preapheresis platelet counts. Donors were categorized by sex, age, and cumulative number of donations. The average difference in platelet counts (mDeltaPC) between each donor's first and last platelet count during this period was calculated for each category. A subgroup of frequent donors was selected for analysis of mDeltaPC, using the baseline platelet count obtained before the first plateletpheresis procedure. RESULTS: A significant and sustained decrease in platelet count was identified for all donation frequency categories. The frequency of donation correlated directly with decrease in platelet count for all but the highest-frequency donation group, in which deferrals for low platelet count blunted the extent of the mDeltaPC. A mean decrease of 40,000 per microL from baseline occurred in the frequent-donor subgroup. A total of 84 donors (9%) were deferred for low platelet count. The majority returned to donate successfully after temporary deferral. CONCLUSIONS: Regular plateletpheresis donors develop sustained decreases in platelet count. However, clinically significant thrombocytopenia is unusual when rigorous ongoing review and prudent deferral policies are established and followed.     

两种血小板制剂应用于儿科血液病的临床观察

目的观察并比较机器单采法及手工法分离制备血小板制剂用于儿科血液病输注的效果。方法输注机器单采血小板患儿463例次为机采制剂组,输注手工分离血小板制剂患儿155例次为手工制剂组,分别在输注后24、48及72h作外周血血小板计数,观察临床止血效果、有无输血反应发生,计算血小板计数增加校正指数(CCI)、血小板回升率(PPR)、输注无效率、输血反应发生率等指标。结果输注后24、48、72h,机采制剂组:CCI分别为18.9、15.4、14.1,PPR分别为33.4%、27.8%、25.0%;手工制剂组:CCI分别为11.3、9.4、2.9,PPR分别为20.3%、10.3%、3.8%;机采法制剂组均明显高于手工制剂组(P<0.01)。机采制剂组输注无效率10.58%、输血反应发生率3.02%,手工制剂组相应为32.90%及11.61%,机采组虽都明显低于手工组,但两组均达到较好的临床止血目的,组间无差异。结论输注机器单采血小板制剂能更有效地提高血液病患儿的血小板值,减少其血小板输注无效及输血反应的发生。     

Differences in levels of platelet-derived microparticles in platelet components prepared using the platelet rich plasma,buffy coat,and apheresis procedures

Background

There has been an increased interest in platelet-derived microparticles (PMPs) in transfusion medicine. Little is known about PMP status during the preparation of platelet concentrates for transfusion.