Non-frozen transports of whole blood samples do not cause relevant bias for global coagulation tests in clinical trials evaluating the drug safety

Sample shipments with dry ice have a large economic impact on clinical research. Therefore, the bias caused for global coagulation tests by non-frozen transports of whole blood instead of frozen plasma was investigated experimentally and by a meta-analysis of 6-year central laboratory data. In the experiment, aliquots from 14 healthy volunteers were kept as whole blood at 20+/-2 degrees C and as frozen plasma until an analysis of prothrombin time (PT), activated partial thromboplastin time (aPTT), thrombin time (TT), and antithrombin III (ATIII) at day 0, 1, 2, and 3 from collection. Within these 3 days only PT and aPTT demonstrated any changes: in blood samples kept at 20+/-2 degrees C these amounted about 10% for both. In frozen plasma, aPTT did not change whereas PT increased by 14%. In a meta-analysis of central laboratory data, PT and aPTT results were grouped across various phase II-IV trials by the type of sample transfer, either as frozen plasma on dry ice or non-frozen as whole blood. For the latter the mean difference to a reference group of phase I trials with same-day analysis was in line with the amount of bias found in the experiment (aPTT, 34.6+/-6.0 vs. 31.6+/-3.5 s; PT, 87.7+/-13.3 vs. 97.3+/-7.9%). The consistent bias resulted in shifted, but still normal distribution curves with a total rate of clinically relevant outliers of about 1.9% for aPTT and 2.4% for PT. Biases thus appear irrelevant for a common safety evaluation within clinical trials. Non-frozen whole blood transports for the measurement of global coagulation tests appear justified for this purpose, if protocols do not require frozen shipments for other reasons. However, transit time must not exceed 2 days and pre-analytical conditions should be consistent within the same trial.     

存放时间和温度对凝血功能指标检测结果的影响

目的 探讨标本放置时间和温度对凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、凝血酶时间(TT)、纤维蛋白原(FⅠB)等凝血指标检测结果的影响.方法 选取抗凝静脉血标本50例,血浆用于立即测定凝血4项指标和在室温放置2 h、4 h、6 h和24 h后测定凝血4项指标;并分别于室温、-4 ℃和-20 ℃下保存24 h后测定凝血4项指标.抗凝血室温放置2 h,离心分离血浆后即刻进行凝血指标检测.采用血液凝固仪测定研究指标,采用随机单位组设计资料方差分析比较各组间差异.结果 与留取即刻检测相比,血浆放置2 h APTT、PT、TT和FⅠB等各种指标水平均无明显差异;血浆标本放置4 h开始,APTT、PT和TT等指标出现明显延长,且变化程度随放置时间延长加重,FⅠB水平无明显改变;抗凝血标本放置2 h留取的血浆标本各指标均有明显变化.-4 ℃下血浆标本保存24 h APTT、PT、TT和FⅠB等指标测定结果未出现明显改变,-20 ℃下24 h APTT出现明显延长.结论 对于凝血功能4项指标的测定,采集标本后应及时送检和尽快分离血浆.常温下血浆标本应在2 h内完成测定;-4 ℃下血浆标本保存24 h PT、APTT、TT和FⅠB等指标测定结果未受影响,低温保存应注意避免标本冻融过程.     

标本放置时间对凝血四项测定结果的影响

目的 :观察标本放置时间对凝血四项测定结果的影响 ,为合理安排采血时间提供依据。方法 :采集血液标本 30例测定凝血四项 ,室温放置 2h和 4h后再分别测定凝血四项 ,与即刻测定结果进行配对分析。结果 :即刻测定结果与室温放置 2h和4h后测定结果比较 ,凝血酶时间和活化部分凝血活酶时间测定结果差异有统计学意义 (P <0 .0 1)。结论 :标本久置 ,致凝血酶时间测定结果缩短和活化部分凝血活酶时间测定结果延长 ;凝血测定应在采血后 2h内完成     

Effects of temperature on stability of blood homocysteine in collection tubes containing 3-deazaadenosine

BACKGROUND: The accuracy of homocysteine (Hcy) results is currently compromised by the requirement to separate the plasma within 1 h of sample collection. We studied the effect of temperature on the stability of plasma Hcy over a 72-h time course in blood collected into evacuated tubes containing either EDTA alone or both EDTA and 3-deazaadenosine (3DA). METHODS: We recruited 100 volunteers, including both diseased and healthy individuals with a range of baseline plasma Hcy values, from two centers. Blood samples were collected into tubes containing EDTA, and EDTA plus 3DA and stored at ambient temperature (20-25 degrees C) or refrigerated (2-8 degrees C). Aliquots of blood were centrifuged at various times up to 72 h, the plasma was removed, and Hcy was measured by HPLC. RESULTS: Plasma Hcy measurement covering the sample collection and storage conditions during the whole time course was possible on samples from 59 of those recruited. One-way ANOVA for repeated measures within subjects revealed that only samples that were collected into tubes containing EDTA plus 3DA and stored refrigerated were stable over 72 h (P = 0.2761). CONCLUSIONS: A combination of 3DA and storage at 2-8 degrees C will allow collection of samples for plasma Hcy measurement outside of the hospital setting and wider population screening.     

不同处理和保存条件下体外HCV RNA稳定性研究

对献血者或病人进行HCV核酸检测时，如果标本的采集、处理、保存不当，会造成病毒核酸降解，从而影响检测结果的真实性。本研究的目的是对不同抗凝剂、不同温度、不同保存时间下的HCV RNA病毒稳定性进行研究，以考察常规采供血过程中，标本采集及保存方式对NAT检测的影响。采集7例HCV RNA阳性献血者的血样，采用不同的抗凝剂、经不同的温度和不同的时间保存后，采用荧光定量PCR方法测定HCV RNA病毒含量，考察HCV RNA的稳定性。结果表明：①不同抗凝剂抗凝的全血于4℃保存48小时过程中，病毒含量下降至原滴度的42．7％；EDTA抗凝组各时间点的滴度均低于其它3组（分别相当于其它3组的67．6％-25．1％）。②ACD抗凝的全血在4、25和37℃保存48小时．病毒含量分剐下降到原滴度的53．8％、72．5％、29．8％。③ACD抗凝的全血离心分离出血浆，4℃或25℃继续保存7天，病毒含量分别下降至原滴度的70．9％和25．1％。④ACD抗凝的全血分离的血浆，反复冻融4次，病毒含量下降到原滴度的38．9％。结论：①用于核酸检测的标本应该用无菌采血管采样；②在无菌采血管采样的前提下，核酸检测标本用未抗凝血、EDTA、ACD、CPDA抗凝血均可；③采集的全血应避免放置37℃以上，ACD抗凝全血在4℃、25℃保存48小时内、37℃保存14小时内，HCV RNA病毒仍较为稳定；④分离后的血浆应避免放置25℃以上，ACD抗凝全血分离后的血浆在4℃保存7天，25℃保存3天，HCV RNA病毒仍比较稳定；⑤血浆标本应避免多次冻融，但冻融3次的血浆HCV RNA病毒含量仍然较为稳定；⑥无菌采样对维持病毒的稳定性非常重要；单纯的机械性溶血并不会明显导致病毒的降解；只要注意无菌的问题和有合适的核酸提取方法去除血红素，HCV RNA病毒实际上比以前认为的要稳定得多。     

Refreezing previously thawed fresh-frozen plasma. Stability of coagulation factors V and VIII:C

With the growth in autologous blood programs and the increased scrutiny of the indications for transfusion of fresh-frozen plasma (FFP), an increase has been seen in the number of occasions on which FFP was requested and thawed but then not transfused. The coagulation properties of FFP units that were refrozen and then rethawed were therefore studied. Fifty-eight units of plasma were studied, with each experimental unit of FFP paired with an identical control unit. Experimental units were frozen, stored at -65 degrees C, thawed, stored at 1 to 6 degrees C for various periods of time up to 24 hours, and then refrozen, stored at -65 degrees C, rethawed, and stored again in the refrigerator for up to 24 hours. Control units were frozen once at the time the experimental units were first frozen and thawed once at the time of the second thaw of the experimental units. Aliquots of plasma were sampled periodically and were later batch-tested for prothrombin time (PT), activated partial thromboplastin time (aPTT), and factor V and VIII:C activity. The results of coagulation testing of the twice-frozen plasmas were always within the normal range. There was a slight but statistically valid prolongation of the PT and aPTT and a decrease in the factor V and VIII:C levels for twice-frozen plasma compared with control plasma. The greatest decline occurred in the level of factor VIII:C. The measured deterioration in coagulation of twice-frozen FFP is unlikely to be of clinical importance. Refreezing FFP may eventually prove useful for rare donor, autologous, and massive transfusion programs.     

Interference and blood sample preparation for a pyruvate enzymatic assay

BACKGROUND: To assess the severity of circulatory failure, a pyruvate enzymatic assay was performed on whole blood using lactate dehydrogenase to catalyze the conversion of pyruvate to lactate. We investigated factors related to blood sample collection and preparation that might influence the results, including the timing of blood deproteinization, temperature of sample storage, and hemolysis. METHOD: A total of 25 whole blood specimens were collected for this study. Each sample was divided into 2 parts: one stored at room temperature (RT) and another kept on ice. The samples were deproteinizied by using 8% perchloric acid (PCA) at varying times after collection; the first deproteinization was immediately after the blood was drawn (0 h), then at 1 h intervals for 6 h and also in samples kept overnight. The supernatant samples were analyzed soon after deproteinization using a COBAS Centrifugal Analyzer. In another set of samples, the blood was immediately deproteinized, and the supernatants were stored at RT and 4 degrees C and assayed for pyruvate at varying times, as above. Finally, the effect of hemolysis on the blood pyruvate enzymatic assay was also evaluated. RESULTS: When samples were stored at RT, pyruvate levels remained constant until the third h after deproteinization, when there was an approximately 13.3% increase in pyruvate concentration. When whole blood samples were kept at 4 degrees C before deproteinization, pyruvate levels were significantly reduced over time, ranging from 37.8% to 62.2% (paired t test showed a significant mean difference, P < 0.001). No significant differences in pyruvate concentration were observed in supernatant stored at either RT or 4 degrees C. Hemolysis caused a 33.7% increase in the pyruvate concentration, equivalent to 0.18 mg pyruvate per gram per deciliter of hemoglobin. CONCLUSIONS: For a pyruvate enzymatic assay, keeping a whole blood sample at RT will not cause a significant difference in the pyruvate level as long as the sample is immediately deproteinized. Whole blood samples should not be stored in an ice bath for transport, nor should hemolyzed samples be used for a blood pyruvate enzymatic assay.     

Influence of time and storage conditions on plasma HIV viral load measurements

Quantification of human immunodeficiency virus (HIV) RNA in plasma from HIV-infected patients is now widely used as a clinical indicator of disease prognosis and of response to antiretroviral therapy. However, controversy exists as to whether values obtained under different testing conditions could vary significantly, thus jeopardizing the appropriate interpretation of data. Herein, we demonstrate that results obtained after testing plasma versus whole blood, or immediate versus deferred processing, do not appear to influence viral load measurements significantly. Thirty blood samples from HIV-infected patients were analysed. The second generation branched-DNA assay was used for quantification of plasma viral load. HIV RNA remained stable for at least 24 h at room temperature, either in plasma or in whole blood, in 72.4% of the samples (< 0.2 log difference in viral load values) although lower levels of HIV RNA tend to be seen in samples after being stored as whole blood at room temperature. Only 3.4% of samples showed a decline > 0.5 log when they were left as whole blood at room temperature for 24 h in comparison with testing after immediate plasma separation. Although immediate separation and refrigeration of plasma samples may reduce the chance of significant falls in viral load measurements, this level of processing can be limited in regions where clinical blood samples cannot be processed rapidly. Our data provide confidence in the results obtained when testing specimens, either plasma or whole blood, 24 h after venepuncture and storage at room temperature, mimicking the conditions in the transport of blood samples to reference centres.     

Effects of Adenine on Clotting Factors in Fresh Blood, Stored Blood, and Stored Fresh Frozen Plasma

The addition of small quantities of adenine to whole blood may prolong the useful shelf life of bank blood. The present study was undertaken to evaluate the effects of adenine on the clotting factors in blood containing ACD and CPD. Units of whole blood were collected in ACD, ACD-adenine, CPD and CPD-adenine, and each was stored 42 days under standard blood bank conditions. Samples of fresh frozen plasma containing these anticoagulants were stored three to four months at -30 C. Assays of Factors V, VIII (AHF), IX (PTC), X (Stuart Factor), fibrinogen, and prothrombin were performed on fresh blood, stored blood and stored fresh frozen plasma. The presence of small quantities of adenine did not appear to produce any appreciable alteration in the activity of the clotting factors in fresh blood. Further, adenine did not appear either to improve or worsen the survival of the procoagulants in whole blood stored 42 days or in fresh frozen plasma stored three to four months. There was significant deterioration of Factors V and VIII in whole blood stored 42 days in ACD, ACD-adenine, CPD, and CPD-adenine, but the degree of storage loss was independent of the anticoagulant employed. Factor X, fibrinogen, and prothrombin remained stable in blood stored 42 days regardless of the anticoagulant used, but Factor IX activity increased during storage possibly as the result of contact activation. Fresh frozen plasma stored three to four months showed a uniform slight loss of Factor VIII in all four anticoagulants, but Factors V, IX, X, fibrinogen, and prothrombin remained stable in stored fresh frozen plasma regardless of the anticoagulant employed.     

Pre-analytical in-vitro stability of [-2]proPSA in blood and serum

Objectives[-2]proPSA may discriminate prostate cancer from benign biopsy results. We characterized the pre-analytical stability of [-2]proPSA.Design and methods22 volunteers, total PSA of 4.5–19.3 µg/L, had blood drawn simultaneously. Baseline measurements were performed and samples were stored under various conditions prior to measurements. Freeze–thaw cycles were performed. [-2]proPSA was measured with the p2PSA automated research use only immunoassay on the Access analyzer.ResultsMean [-2]proPSA increases with clotting time, exceeding 10% change in recovery after 3 h. In serum, [-2]proPSA values decline over time under investigated storage conditions. Serum samples kept frozen show less than 10% variation in recoveries over the course of 2 freeze–thaw cycles.ConclusionsFor proper measurement of [-2]proPSA, blood samples should be centrifuged within 3 h of blood draw. Serum may be stored at RT or refrigerated (+ 4 °C) for a maximum of 48 h and should be frozen if stored for a longer period. Two freeze–thaw cycles have no effect on [-2]proPSA stability.     

Platelet concentrates prepared after a 20- to 24-hour hold of the whole blood at 22°C

BACKGROUND: The Food and Drug Administration (FDA) requires that red blood cells must be refrigerated within 8 hours of whole blood collection. Longer storage of whole blood at 22°C before component preparation would have many advantages. STUDY DESIGN AND METHODS: Two methods of holding whole blood for 20 to 24 hours at room temperature were evaluated, refrigerated plates or a 23°C incubator. After extended whole blood storage, platelet (PLT) concentrates were prepared from PLT‐rich plasma on Day 1 postdonation, and the PLTs were stored for 6 more days. On Day 7 of PLT storage, blood was drawn from each subject to prepare fresh PLTs. The stored and fresh PLTs were radiolabeled and transfused into their donor. RESULTS: Eleven subjects' whole blood was stored using refrigerated butanediol plates (Compocool, Fresenius), and 10 using an incubator. Poststorage PLT recoveries averaged 47 ± 13% versus 53 ± 11% and survivals averaged 4.6 ± 1.7 days versus 4.7 ± 0.9 days for Compocool versus incubator storage, respectively (p = NS). With all results, poststorage PLT recoveries averaged 75 ± 10% of fresh and survivals 57 ± 13% of fresh; PLT recoveries met FDA guidelines for poststorage PLT viability but not survivals. CONCLUSION: Seven‐day poststorage PLT viability is comparable when whole blood is stored for 22 ± 2 hours at 22°C using either refrigerated plates or an incubator to maintain temperature before preparing PLT concentrates.     

Sysmex CA7000血凝仪试剂仓试剂放置时间对血凝四项检测结果的影响

本研究旨在探讨Sysmex CA7000血凝仪试剂仓开封试剂放置不同时间对血浆凝血酶原时间（PT）、纤维蛋白原（FIB）、活化部分凝血活酶时间（APTT）及凝血酶时间（TT）检测结果的影响。采用凝固法采集21例患者凝血标本,使用Sysmex CA7000型全自动血凝分析仪及其原装配套试剂及放置一定时间的试剂和新鲜试剂测定每1例标本的PT、APTT、TT及Fib。各试剂放置时间分别为Thromborel S（TS）：12、24、36、48、60、72 h;Dade Actin（DA）：24、48、72、96、120 h;Test Thrombin（TT）：2、4、6、8、10、12 h;Thrombin Reagent（TR）：4、8、12、16、20、24 h;Owren＇s Veronal Buffer（OVB）：1、2、3、4、5、6 h。以试剂仓放置一定时间为各试验组,以其新鲜试剂（0 h,即时配置）为对照组,计算各试验组PT、APTT、TT及Fib检测值与其对照组间统计学差异,分析放置时间对检测结果的影响。结果表明,当TS、DA、TT、TR及OVB在试剂仓分别放置≥48、96、10、16、4 h时,其PT、APTT、TT及Fib结果与新鲜试剂差异均有统计学意义（P〈0.01）;当放置时间分别达到48-72、96-120、10-12、16-24及4-6 h时,其检测结果与0h间差异百分比分别在-2.6%-10.8%、-3.44%-4.8%、-3.9%-5.52%、-10.8%-3.3%及-17.2%-0.5%之内,其中TS对PT及OVB对Fib影响较为明显;随着试剂放置时间的延长,PT、APTT、TT均呈现延长趋势,而Fib呈现下降趋势。结论：常规检测血凝四项时,需及时更换试剂仓试剂,以保证标本检测结果的准确性。     

Glucose variation in centrifuged serum and lithium-heparin gel tubes stored for up to 96 hours at room temperature or 4 °C

Abstract

This study aimed to verify glucose stability within centrifuged serum and lithium-heparin tubes stored at room temperature (RT) or 4?°C. Sixty paired serum (plus gel separator), lithium-heparin (plus gel separator) and K₂-EDTA tubes were centrifuged within 30?min from collection. Thirty serum and lithium-heparin tubes were then stored at RT, whilst the other 30 serum and lithium-heparin tubes were kept at 4?°C. Complete cell blood count was performed in serum and plasma after centrifugation, as well as in K₂-EDTA paired whole blood tubes. Glucose was measured immediately after centrifugation and 3, 6, 24, 48, 72 and 96?h afterwards. Immeasurable blood cells values were found in serum, whilst residual leukocytes and platelets were present in lithium-heparin plasma. Regardless of storage conditions, glucose concentration decreased 3?h after centrifugation in lithium-heparin tubes, displaying uninterrupted reduction until 96?h. Mean decrease per hour was higher in plasma tubes stored at RT than at 4?°C. Performance specification was exceeded between 6 and 24?h of storage in most plasma tubes. Glucose concentration significantly decreased in serum tubes between 24 and 48?h, regardless of storage conditions. The mean glucose variation never exceeded performance specification throughout the study period. Mean glucose decrease per hour in plasma was not associated with blood cells counts before and after centrifugation, and was probably attributable to the presence of blood cells entrapped within the gel. Delayed glucose measurement in centrifuged serum tubes may be clinically viable up to 96?h, whilst it may be unadvisable in centrifuged lithium-heparin tubes.     

Pre-analytical variation in alanine aminotransferase

To determine the effect of pre-analytical variation of alanine aminotransferase in blood specimens with normal activity concentrations of this enzyme, we stored serum and whole blood samples at 4 and 22 degrees C and assayed aliquots of each specimen at intervals up to 72 h. Analysis of variance revealed no statistically significant increase or decrease in activity of the enzyme for up to 72 h in either specimen type, whether stored at room temperature or refrigerated.     

Reference interval for whole blood ionized magnesium in a healthy population and the stability of ionized magnesium under varied laboratory conditions

Objective: To establish a reference interval for ionized magnesium (iMg), to evaluate the stability of whole blood iMg under varied laboratory storage conditions, and to study the correlation between total and iMg in healthy volunteers and in an intensive care unit (ICU) population.

Methods: Blood specimens were collected anaerobically from 125 healthy volunteers and 200 ICU patients into tubes containing lithium heparin, transported to the laboratory on ice, stored at 4 °C and analyzed within 2 h on a NOVA 8 Electrolyte Analyzer. Additional specimens were stored under different conditions before analysis to assess the stability of iMg.

Results: In healthy volunteers, the mean whole blood iMg level was 0.52 mmol/L with a range of 0.44 to 0.59 mmol/L. The iMg/total serum Mg ratio was at 0.60 (0.50–0.69). Regression analysis of iMg vs total Mg produced a correlation coefficient (r) of 0.48 (p < 0.0001). Ionized Mg levels were comparable between males and females (0.52 ± 0.04 vs 0.51 ± 0.03, p = 0.38). In the ICU group, a wider range of iMg results was observed (0.35–0.78 mmol/L) and the correlation between iMg and total Mg was r = 0.71 (p < 0.0001). Storage of whole blood specimens in uncapped tubes at room temperature resulted in a small, but significant, decrease in iMg over a 6-h period. Little change was seen in capped tubes stored either at room temperature or at 4 °C. over 6 h, or at 4 °C. over 5 days.

Conclusions: Using the NOVA 8 Electrolyte Analyzer, we established a reference interval for whole blood iMg in a healthy Canadian population. The correlation between ionized Mg and total Mg was weak, but statistically significant. Ionized Mg levels in lithium heparin tubes were stable over 5 days when specimens were stored at 4 °C, suggesting that specimens may be stored at least overnight prior to processing.     

实验前相关因素对测定新生儿血浆PT、APTT的影响

目的探讨抗凝、离心、黄疸等实验前相关因素对测定新生儿血浆凝血酶原时间（PT）、活化部分凝血活酶时间（API]r）的影响,从而进一步优化试验条件。方法本试验选取100名外科术前体检无异常发现的新生儿,所有入选新生儿均无血栓性疾病及出凝血功能障碍,无心、肾、肝等重要脏器疾病。将此100名新生儿分为3组,分别为抗凝剂比例影响组（包括抗凝剂比例9：1组和抗凝剂比例校正组）、离心条件影响组[2000r／min（离心半径为10cm）离心10min;3000r／min（离心半径为10em）离心10min组;2500r／min（离心半径为10cm）离心15min组]、生理性黄疸影响组。利用STAGO全自动血凝分析仪对以上几个处理组的标本进行检测,并且使用SPSS13．0统计软件对得到的数据进行比较,从而逐步优化实验条件。结果在相同离心条件下,抗凝剂9：1组的PT、APlTr明显延长。在抗凝剂比例经过校正的情况下,2000r／min（离心半径为10em）离心10min组的PT、APTT明显延长;3000r／min（离心半径为10cm）离心10min组中大部分标本PT、APTT正常,个别出现溶血的标本PT明显延长。2500r／min（离心半径为10cm）离心15min是新生儿检测胛、APTT的最适离心条件。在抗凝剂比例经过校正,2500r／min（离心半径为10cm）离心15min的条件下,生理性黄疸组与无生理性黄疸组的胛、APTT比较差异无统计学意义。结论在处理新生儿血浆标本时,应进行抗凝剂比例校正,离心转速不宜过快,否则容易引起溶血,从而引起实验误差。可以通过适当降低离心速度,延长离心时间来避免这种情况的发生。生理性黄疸基本不影响PT、APTT的测定。     

Effects of syringe material, sample storage time, and temperature on blood gases and oxygen saturation in arterialized human blood samples

BACKGROUND: The practice of on-ice storage of arterial-blood samples in plastic syringes for delayed analysis continues, and the effects of storage time and temperature on the measurement of blood-oxygen-saturation values (S(aO2)) have not been adequately described. OBJECTIVE: To determine the effects of syringe material, storage time, and storage temperature on normal arterialized blood gas and S(aO2) values. METHODS: We used a temperature-controlled extracorporeal circuit to "arterialize" 500 mL of fresh, whole human blood at 37 degrees C, and we used certified calibration gases of 12% O2 and 5% CO2 to produce normal blood-gas values. From that arterialized blood we took 90 samples and randomly assigned them to 6 groups, until there were 15 samples in each group. The groups were (1) plastic syringe, analyzed immediately, (2) plastic syringe, stored 30 min at 0-4 degrees C, (3) plastic syringe, stored 30 min at 22 degrees C, (4) glass syringe, analyzed immediately, (5) glass syringe, stored 30 min at 0-4 degrees C, and (6) glass syringe, stored 30 min at 22 degrees C. RESULTS: Compared to the samples that were analyzed immediately, the P(O2) of the samples stored in plastic syringes for 30 min at 22 degrees C and at 0-4 degrees C was significantly higher, with a clinically important magnitude of 11.9-13.7 mm Hg. The P(CO2) of blood stored in glass for 30 min at 0-4 degrees C was significantly lower, although the magnitude of the difference (1.5 mm Hg) was not clinically important. There were no statistically significant differences in pH or oxygen saturation among the 6 groups. CONCLUSION: For accurate arterial-blood-gas results, samples drawn in plastic syringes should be analyzed immediately. If the analysis is going to be delayed, the samples should be drawn and stored in glass.     

Storage of Blood Components Does Not Decrease Haemostatic Potential: In vitro Assessment of Fresh versus Stored Blood Components Using Thromboelastography

Summary

Background

Major surgery and severe trauma typically lead to massive blood loss requiring rapid transfusion of large amounts of blood products. It has been suggested that fresh, unrefrigerated whole blood provides a haemostatic advantage in this setting. The aim of the current study was to compare the clot formation parameters of fresh, unrefrigerated whole blood and whole blood reconstituted from components stored for varying periods of time, using rotational thromboelastography (ROTEM®).

Methods

Fresh whole blood and reconstituted whole blood using combinations of non-leucoreduced red cell units (stored for 7, 14, 21, 28, or 35 days), platelet concentrates (stored for 1, 3 or 5 days), and fresh frozen plasma (stored for 6 months) were analysed using ROTEM. Measurements of the clotting time (CT), clot formation time (CFT), and maximal clot firmness (MCF) were compared between units of fresh whole blood and reconstituted whole blood samples.

Results

There was no difference in the haemostatic parameters measured of fresh whole blood and reconstituted whole blood using red cell units stored for less than 21 days. ROTEM demonstrated that the CT and CFT were significantly shorter for reconstituted whole blood samples using red cells stored for longer than 21 days when compared to fresh whole blood and to reconstituted whole blood samples using red cell units stored for less than 21 days. The CT was inversely correlated to the duration of platelet storage. The MCF was unchanged regardless of duration of blood product storage.

Conclusion

Fresh unrefrigerated whole blood and blood products stored for short duration (less than 21 days) were not superior to those stored for longer durations.     

Effects of telavancin on coagulation test results

Background: The lipoglycopeptide antibiotic, telavancin, may interfere with some laboratory coagulation tests including prothrombin time (PT) and activated partial thromboplastin time (aPTT). Objective: To evaluate the effects of telavancin on PT and aPTT assays in common use. Methods: Pooled normal human plasma was spiked with telavancin 10, 20, 100 or 200 μg/ml (equivalent to trough, 2 × trough, peak and 2 × peak clinical plasma concentrations, respectively) or diluent control (0.9% sodium chloride). Samples were analysed using 16 PT reagents and seven aPTT reagents. Results: Telavancin 200 μg/ml (corresponding to 2 × peak clinical plasma concentration), produced significant PT prolongation (> 9% difference vs. diluent control) with all the 16 PT reagents (range 12% to > 600%). At lower telavancin concentrations, PT prolongation was dose‐dependent and varied among reagents, but appeared greatest with preparations containing recombinant tissue factor. With telavancin 10 μg/ml (equivalent to trough), PT prolongation was 10% with HemosIL^® PT‐Fibrinogen Recombinant, while ranging from 5% to –1% with all other reagents. Significant (> 34% difference vs. baseline) and dose‐dependent aPTT prolongation was observed with all the seven reagents in samples spiked with telavancin 100 or 200 μg/ml (range 65–142% at 200 μg/ml). aPTT reagents containing a silica activator appeared to be more sensitive to telavancin interference. Telavancin 10 μg/ml was not associated with increased aPTT with any of the reagents tested. Conclusions: Telavancin has the potential to prolong both PT and aPTT in vitro. It is recommended that samples for PT or aPTT be obtained just prior to a telavancin dose (trough).     

Reference intervals for coagulation tests in adults with different ABO blood types

IntroductionCoagulation tests are affected by many factors, such as age, race, and gestation. Although coagulation test results vary by ABO blood type, reference intervals of different ABO blood groups remain to be determined. This study aims to investigate the reference ranges of coagulation tests for different ABO blood groups in the Han population in South China.MethodsA retrospective study was conducted in the First Affiliated Hospital of Shantou University Medical College. In all, 9600 individuals aged between 20 and 79 years were included. Coagulation tests, including prothrombin time (PT), international normalized ratio (INR), activated partial thromboplastin time (aPTT), thrombin time, and fibrinogen, were performed.ResultsThere was a significant difference in PT, INR, and aPTT among ABO blood groups. PT and INR varied slightly between ABO blood groups. There was a higher aPTT value in individuals in the O blood group than in those in non‐O blood groups, in both males and females across the included age range. No differences were found in thrombin time and fibrinogen between the ABO blood groups.ConclusionThe study provides reference data on coagulation tests from ABO blood groups in South China. The established reference intervals specific to ABO blood type, sex, and age may improve clinical decisions based on coagulation tests.