血浆凝血酶原时间测定中建立仪器区域国际敏感指数的实验探讨

目的探讨临床口服抗凝治疗时血浆凝血酶原时间(PT)监测的标准化,为临床提供比较准确的PT-国际标准化比值(PT-INR)结果.方法使用PT-INR校准血浆建立PT测定试剂在不同仪器上的区域性国际敏感度指数(Local ISI),以此对新鲜血浆进行PT测定.结果未经Local ISI校准的PT试剂测定血浆的PT时,INR结果差异较大(P<0.01).试剂经Local ISI校准后,测定血浆PT时,INR结果良好(P>0.05及Kappa>0.75).结论在PT测定时,只要建立仪器和测定试剂的Local ISI, INR结果就具有较好的一致性.     

凝血酶原时间测定标准化的几点探讨

目的探讨不同试剂、报告方式对凝血酶原时问(PT)测定结果的影响,以及标本自身因素对仪器测定PT的影响.方法采用两种不同国际敏感度指数(ISI)试剂,测定正常、异常两组标本,结果用秒数、凝血酶时间比值(PTR)、国际标准化比率(INR)表达,对检测结果做统计学分析.另用梯度溶血、黄疸、脂血标本观察仪器测定PT的干扰情况.结果两种试剂检测抗凝疗法病人血浆时,秒数和PTR差异显著(P＜0.05),而用INR表达的结果则无显著差异(P＞0.05).中度以上的溶血、黄疸、脂血标本干扰仪器测定.结论监测抗凝药物治疗时,应用INR方式报告PT值,尽量采用ISI接近1.0的试剂,中度以上的溶血、黄疸、脂血标本最好用手工法测定.     

凝血酶原时间测定标准化的几点探讨

目的 探讨不同试剂、报告方式对凝血酶原时间（PT）测定结果的影响。以及标本自身因素对仪器测定PT的影响。方法 采用两种不同国际敏感度指数（ISI）试剂、测定正常、异常两组标本,结果用秒数,凝血酶时间比值（PTR）、国际标准化比率（INR）表达, 对检测结果做统计学分析,另用梯度溶血、黄疸、脂血标本观察仪器测定PT的干扰情况。结果 两种试剂检测抗凝疗法病人血浆时,秒数和PTR差异显著（P＜0．05）,而用INR表达的结果则无显著差异（P＞0．05）。中度以上的溶血、黄疸、脂血标本干扰仪器测定。结论 监测抗凝药物治疗时,应用INR方式报告PT值,尽量采用ISI接近1．0的试剂、中度以上的溶血、黄疸、脂血标本最好用手工法测定。     

两种试剂检测凝血酶原时间、国际标准化比率、凝血酶原活动度的结果分析

目的评价仪器配套试剂与非配套试剂对检测凝血酶原时间(PT)、国际标准化比率(INR)、凝血酶原活动度(PTA)的影响以及INR、PTA与理论PTA之间的关系。方法取20例新鲜血浆混匀,用生理盐水按不同比例稀释,用两种试剂同时检测PT,结果以INR、PTA方式报告。结果两种试剂的INR结果无差异(P>0.200),PT、PTA结果差异有统计学意义(P<0.001、P<0.020);PTA测定结果与理论PTA差异有统计学意义(P<0.001),两种试剂检测的PT、INR、PTA与理论PTA之间呈高度直线相关(P<0.000 5)。结论理论PTA在100%~40%时,不同试剂对检测INR无影响,对检测PTA有影响。     

凝血酶原时间ISI/INR系统测定中的一些问题及改进意见

目的对凝血酶原时间(PT)测定ISI/INR系统出现的一些问题提出相应的改进建议。方法对上海市12家医院在用的仪器和匹配的PT试剂,对日常使用的正常血浆平均凝血酶原时间(MNPT)作调研实测,将结果进行分析;调查试剂的仪器特定(spec ific)国际敏感度指数(ISI)值与世界卫生组织(WHO)的手工法ISI定标值之间的差异;用2种已知国际标准化比值(INR)的异常参比血浆代替WHO的ISI系统作质控并行比较。结果12家中有4家日常使用的平均正常凝血酶原时间(MNPT)明显偏离实测值,分别为0.8、0.9、1.0和1.8 s。用WHO CRM149R参比,用手工法标定的凝血活酶和109 mmol枸橼酸钠抗凝的不同PT值血标本,在Sysm ex1500型、C.2000型仪器上测定试剂的仪器特定ISI,其结果比手工法分别减少4.1%和4.7%,但采用HEPES-枸橼酸钠抗凝剂标本时,2种型号仪器的特定ISI比手工法分别减少16.7%及7.7%。用已知INR异常参比血浆,国产品与进口品对照的结果良好。结论受调研12家中,有4家血凝分析仪器调研时实测的MNPT明显偏离日常使用值。有几家医院试剂的仪器特定ISI值也存在问题,建议纠正。用已知INR异常参比血浆代替WHO手工法标定凝血活酶ISI法作质控,使用简便,又不需MNPT参数,值得推广。     

国际标准化比值作为肝病患者PT标准化报告方式的可行性探讨

目的　评价国际标准化比值 (INR)系统作为肝病患者PT报告方式的可行性。方法　选择病毒性肝病患者 6 1例 ,其中肝炎肝硬化 4 1例 ,慢性重型肝炎 2 0例。 4 0例口服华法林病人做对照组。采用来源不同、ISI值不同的 6种凝血活酶试剂进行PT测定。同时在两组选择INR值相近的患者检测FIB、凝血因子Ⅱ、Ⅴ、Ⅶ、Ⅸ、Ⅹ。结果　肝病组INR结果 ,6种凝血活酶试剂比较差异有显著性 (P <0 .0 5 ) ;而口服抗凝药组INR结果 ,6种试剂比较差异无显著性 (P >0 .0 5 )。在INR值相近的患者中 ,肝病组的FIB、凝血因子Ⅴ、Ⅶ和Ⅹ与口服抗凝药组比较差异有显著性意义 (P <0 .0 1) ;而Ⅱ和Ⅸ因子在两组之间比较差异无显著性 (P >0 .0 5 )。结论　INR系统不适用于肝病患者PT的标准化报告方式。     

口服抗凝治疗中凝血酶原时间测定标准化意义

目的:比较三种凝血活酶试剂对口服华法令抗凝治疗病人血标本测得的血浆凝血酶原时间(PTs),凝血酶原时间比率(PTR)和国际标准化比率(INR)间相关性及三种试剂的敏感性。方法:采用Quick一期法在凝血仪上测定50例华法令抗凝治疗病人的PT、PTR及INR值。结果:各组间PT和PTR均有显著性差异(均P<0.01),但各组间INR结果没有显著性差异(P>0.05);不同ISI凝血活酶所测定的INR变异系数不同,ISI的值越高,INR的CV值越大。结论:三种试剂均可用于口服抗凝剂治疗的PT监测,但必须用INR报告结果,便于室间质评。应选用JSI值低的组织凝血活酶试剂,以确保PT测定结果的准确性。     

乙型病毒性肝炎患者中末期凝血酶原时间标准化报告方式

目的 探讨乙型病毒性肝炎患者凝血酶原时间(PT)的标准化报告方式。方法 选择乙型病毒性肝炎患者61例,其中肝炎后肝硬化41例,慢性重型肝炎20例。20例口服华法令抗凝药患者作为对照组。采用来源不同、ISI值不同的6种凝血活酶试剂进行PT测定,以秒数、比率、活动度百分率以及国际正常化比率4种方式表示PT结果。结果 病毒性肝炎患者PT结果,当以活动度百分率和比率形式表示时,不同凝血活酶试剂之间差异没有显著性意义(F=1.289,P=0.268;F=I.992,,J=3.079),当以秒数和INR报告方式表示时,差异有显著意义(F=8.491,P=0.0001;F=2.497.P=0.031)。通过Neoplastin与其他5种试剂的PT结果作线性回归分析,当结果以活动度百分率表示时,Neoplastin与其他5种试剂之间存在高度一致性;而以秒数,比率和INR表示时,试剂之间不存在一致性。提示PT活动度百分率能使乙型病毒性肝炎中末期患者PT报告方式标准化。口服抗凝剂治疗的患者仅INR能使PT的报告方式标准化。结论 PT活动度百分率能使乙型病毒性肝炎中末期患者PT报告方式标准化,INR仅适用于抗凝治疗患者PT结果的报告。     

四种凝血活酶试剂的比较

为了探讨不同来源、不同制备的凝血活酶试剂对凝血酶原时间(PT)测定结果的影响,使用四种不同的凝血活酶试剂以手工方法对正常人及口服抗凝药治疗的病人血浆进行了PT测定,以INR及PT秒两种方式报告结果,根据不同试剂测定结果分组分段进行统计分析,结果表明,以PT秒报告结果时,相同的测定方法、相同的标本用不同的凝血活酶试剂测定,当INR＜2.0时测定结果无显著性,INR≥2.0时测定结果可有显著性,同时表明不同种属制备的凝血活酶试剂测定结果可有显著差异,同种属不同制备的凝血活酶试剂测定结果也可有显著差异.     

凝血酶原时间ISI/INR系统测定中的一些问题及改进意见

目的 对凝血酶原时间（PT）测定ISI／INR系统出现的一些问题提出相应的改进建议。方法 对上海市12家医院在用的仪器和匹配的胛试剂，对日常使用的正常血浆平均凝血酶原时间（MNPT）作调研实测，将结果进行分析；调查试剂的仪器特定（specific）国际敏感度指数（ISI）值与世界卫生组织（WHO）的手工法ISI定标值之间的差异；用2种已知国际标准化比值（INR）的异常参比血浆代替WHO的ISI系统作质控并行比较。结果 12家中有4家日常使用的平均正常凝血酶原时间（MNPT）明显偏离实测值，分别为0．8、0．9、1．0和1．8S。用WHO CRM149R参比，用手工法标定的凝血活酶和109mmol枸橼酸钠抗凝的不同胛值血标本，在Sysmex1500型、C．2000型仪器上测定试剂的仪器特定ISI，其结果比手工法分别减少4．1％和4．7％，但采用HEPES-枸橼酸钠抗凝剂标本时，2种型号仪器的特定ISI比手工法分别减少16．7％及7．7％。用已知INR异常参比血浆，国产品与进口品对照的结果良好。结论 受调研12家中，有4家血凝分析仪器调研时实测的MNPT明显偏离日常使用值。有几家医院试剂的仪器特定ISI值也存在问题，建议纠正。用已知INR异常参比血浆代替WHO手工法标定凝血活酶ISI法作质控，使用简便，又不需MNPT参数，值得推广。     

Coagulometer international sensitivity index (ISI) derivation,a rapid method using the prothrombin time/international normalized ratio (PT/INR) Line: a multicenter study

Summary. Background: The original WHO procedure for prothrombin time (PT) standardization has been almost entirely abandoned because of the universal use of PT coagulometers. These often give different international normalized ratio (INR) results from the manual method, between individual makes of instruments and with instruments from the same manufacture. Method A simple procedure is required to derive local INR with coagulometers. The PT/INR Line method has recently been developed using five European Concerted Action on Anticoagulation (ECAA) certified plasmas to derive local INR. This procedure has been modified to derive a coagulometer PT/INR Line providing International Sensitivity Index (ISI) and mean normal PT (MNPT) for coagulometers and give local INR. Results have been compared with conventional ISI calibrations at the same laboratories. Results: With human thromboplastins, mean ISI by local calibration was 0.93 (range: 0.77–1.16). With the PT/INR Line, mean coagulometer ISI was higher, for example 0.99 (0.84–1.23) but using the PT/INR Line derived MNPT there was no difference in local INR. Between‐centre INR variation of a certified validation plasma was reduced with human and bovine reagents after correction with local ISI calibrations and the PT/INR Line. Conclusion: The PT/INR Line–ISI with its derived MNPT is shown to provide reliable local INR with the 13 different reagent/coagulometer combinations at the 28 centres in this international study.     

Guidelines on preparation, certification, and use of certified plasmas for ISI calibration and INR determination.

Reliable international normalized ratio (INR) determination depends on accurate values for international sensitivity index (ISI) and mean normal prothrombin time (MNPT). Local ISI calibration can be performed to obtain reliable INR. Alternatively, the laboratory may determine INR directly from a line relating local log(prothrombin time [PT]) to log(INR). This can be done by means of lyophilized or frozen plasmas to which certified values of PT or INR have been assigned. Currently there is one procedure for local calibration with certified plasmas which is a modification of the WHO method of ISI determination. In the other procedure, named 'direct' INR determination, certified plasmas are used to calculate a line relating log(PT) to log(INR). The number of certified plasmas for each procedure depends on the method of preparation and type of plasma. Lyophilization of plasma may induce variable effects on the INR, the magnitude of which depends on the type of thromboplastin used. Consequently, the manufacturer or supplier of certified plasmas must assign the values for different (reference) thromboplastins and validate the procedure for reliable ISI calibration or 'direct' INR determination. Certification of plasmas should be performed by at least three laboratories. Multiple values should be assigned if the differences between thromboplastin systems are greater than 10%. Testing of certified plasmas for ISI calibration may be performed in quadruplicate in the same working session. It is recommended to repeat the measurements on three sessions or days to control day-to-day variation. Testing of certified plasmas for 'direct' INR determination should be performed in at least three sessions or days. Correlation lines for ISI calibration and for 'direct' INR determination should be calculated by means of orthogonal regression. Quality assessment of the INR with certified plasmas should be performed regularly and should be repeated whenever there is a change in reagent batch or in instrument. Discrepant results obtained by users of certified plasmas should be reported to manufacturers or suppliers.     

A comparison of INRs after local calibration of thromboplastin international sensitivity indexes.

There are approximately 300 reagent/instrument combinations for performing prothrombin times/international normalized ratios (PT/INR) in the United States. Manufacturers and laboratories continually struggle to ensure that the International Sensitivity Index (ISI) of their thromboplastin is accurate for assaying PT/INR. OBJECTIVE: This study reports the feasibility of a new method to locally calibrate ISI of thromboplastin using the mechanical STA automated coagulation analyzer (Diagnostica-Stago Inc.) and two photo-optic coagulation analyzers, the BCS (Dade-Behring) and CA-540 (Sysmex). DESIGN: Neoplastine CI+ (CI+) (Diagnostica-Stago Inc); Thromboplastin C+ (TC+); Thromborel S (TRS); and Innovin (I) (Dade-Behring) were used in this study. A mean normal PT (MNPT) was determined for each reagent/instrument combination using samples from 25 normal individuals. Manufacturer instrument specific ISI values were not available for the STA with TC+, TRS and I. The CA540 had no ISI value for CI+ and the BCS system had no manufacturer assigned ISI values for TC+ and I; generic photo-optic and mechanical ISI manufacturer values were used for these two systems. Local on-site calibration was performed using frozen plasma calibrators to determine ISI values for each thromboplastin. Post-calibration, 95 patient samples were assayed for each reagent/instrument system combination using the manufacturer ISI and the local calibrated ISI to determine the INR result. PATIENTS: Patients from whom samples were obtained included five with a lupus anticoagulant, 30 on heparin therapy, and 60 on coumadin therapy. RESULTS: Differences between manufacturer versus local calibrated ISI ranged from 0.9% to 18.9% for normal sample INRs and from 0.8% to 16.4% for patient sample INRs. The number (or proportion) of patient specimens with clinically significantly different INR values (>10.0% difference) ranged from zero for several reagent combinations to more than half (or >50.0%) of those tested for several other combinations. CONCLUSION: Our results indicated that by locally calibrating ISI values, each laboratory may eliminate variability and guesswork between different reagent/instrument systems for ISI values when performing PT/INR assays and potentially improve the clinical accuracy of their patients' PT/INR results.     

The prothrombin time/international normalized ratio (PT/INR) Line: derivation of local INR with commercial thromboplastins and coagulometers – two independent studies

Summary. Background: The WHO scheme for prothrombin time (PT) standardization has been limited in application, because of its difficulties in implementation, particularly the need for mandatory manual PT testing and for local provision of thromboplastin international reference preparations (IRP). Methods: The value of a new simpler procedure to derive international normalized ratio (INR), the PT/INR Line, based on only five European Concerted Action on Anticoagulation (ECAA) calibrant plasmas certified by experienced centres has been assessed in two independent exercises using a range of commercial thromboplastins and coagulometers. INRs were compared with manual certified values with thromboplastin IRP from expert centres and in the second study also with INRs from local ISI calibrations. Results: In the first study with the PT/INR Line, 8.7% deviation from certified INRs was reduced to 1.1% with human reagents, and from 7.0% to 2.6% with rabbit reagents. In the second study, deviation was reduced from 11.2% to 0.4% with human reagents by both local ISI calibration and the PT/INR Line. With rabbit reagents, 10.4% deviation was reduced to 1.1% with both procedures; 4.9% deviation was reduced to 0.5% with bovine/combined reagents with local ISI calibrations and to 2.9% with the PT/INR Line. Mean INR dispersion was reduced with all thromboplastins and automated systems using the PT/INR Line. Conclusions: The procedure using the PT/INR Line provides reliable INR derivation without the need for WHO ISI calibration across the range of locally used commercial thromboplastins and automated PT systems included in two independent international studies.     

Comparison of local International Sensitivity Index calibration and ''Direct INR'' methods in correction of locally reported International Normalized Ratios: an international study

BACKGROUND: It is no longer feasible to check local International Normalized Ratios (INR) by the World Health Organization International Sensitivity Index (ISI) calibrations because the necessary manual prothrombin time technique required has generally been discarded. OBJECTIVES: An international collaborative study at 77 centers has compared local INR correction using the two alternative methods recommended in the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis guidelines: local ISI calibration and 'Direct INR'. METHODS: Success of INR correction by local ISI calibration and with Direct INR was assessed with a set of 27 certified lyophilized plasmas (20 from patients on warfarin and seven from normals). RESULTS: At 49 centers using human thromboplastins, 3.0% initial average local INR deviation from certified INR was reduced by local ISI calibration to 0.7%, and at 25 centers using rabbit reagents, from 15.9% to 7.5%. With a minority of commercial thromboplastins, mainly 'combined' rabbit reagents, INR correction was not achieved by local ISI calibration. However, when rabbit combined reagents were excluded the overall mean INR deviation after correction was reduced further to 3.9%. In contrast, with Direct INR, mean deviation using human thromboplastins increased from 3.0% to 6.6%, but there was some reduction with rabbit reagents from 15.9% to 10% (12.3% with combined reagents excluded). CONCLUSIONS: Local ISI calibration gave INR correction for the majority of PT systems but failed at the small number using combined rabbit reagents suggesting a need for a combined reference thromboplastin. Direct INR correction was disappointing but better than local ISI calibration with combined rabbit reagents. Interlaboratory variability was improved by both procedures with human reagents only.     

Use of lyophilized calibrant plasmas for simplified international normalized ratio determination with a human tissue factor thromboplastin reagent derived from cultured human cells

BACKGROUND: For monitoring of treatment with oral anticoagulants, the clotting time obtained in the prothrombin time (PT) test is transformed to the International Normalized Ratio (INR) with use of a system-specific International Sensitivity Index (ISI). The calibrant plasma procedure (CPP) is an alternative approach to INR calculation based on the use of a set of lyophilized plasmas with assigned INRs. METHODS: With the CPP, a linear relationship is established between log(PT) and log(INR), using orthogonal regression. CPP was validated for Simplastin HTF, a new human tissue factor reagent derived from cultured human cells. CPP precision was assessed as the CV of the slope of the regression line. The accuracy of the CPP was determined by comparing the INR obtained with the CPP with that obtained with the established ISI-based reference method. INRs of the calibrants were assigned by different routes: by manufacturer (consensus labeling) or by use of Simplastin HTF or International Reference Preparations (IRPs; rTF/95 or RBT/90). RESULTS: The mean CV of the CPP regression slope ranged from 1.0% (Simplastin HTF reagent-specific INR) to 2.4% (INR assigned with rTF/95). INRs calculated with the CPP were similar to those obtained with the reference method, but when the routes for assigning INRs to the calibrant plasmas were compared, the mean difference in INR between CPP and the reference method was smaller with Simplastin HTF reagent-specific values. In several (but not all) cases, this difference was significant (P <0.05, t-test). CONCLUSION: CPP can be used for local INR determination, but better precision and accuracy are obtained with reagent-specific INRs compared with INR assignment by consensus labeling or IRP.     

Effect of fresh-frozen plasma transfusion on prothrombin time and bleeding in patients with mild coagulation abnormalities

BACKGROUND: Fresh-frozen plasma (FFP) is frequently transfused to patients with mild prolongation of coagulation values under the assumption that FFP will correct the coagulopathy. There is little evidence to support this practice, however. To determine the effect of FFP on coagulation variables and correlation with bleeding in patients with mildly prolonged coagulation values, a prospective audit of all FFP transfusions at the Massachusetts General Hospital between September 2, 2004, and September 30, 2005, was performed. STUDY DESIGN AND METHODS: All patients transfused with FFP for a pretransfusion prothrombin time (PT) between 13.1 and 17 seconds (international normalized ratio [INR], 1.1-1.85) and with a follow-up PT-INR within 8 hours of transfusion were included. Of 1091 units of FFP transfused, follow-up coagulation values within 8 hours were available for 121 patients (324 units). RESULTS: Transfusion of FFP resulted in normalization of PT-INR values in 0.8 percent of patients (95% confidence interval [CI], 0.0020-0.045) and decreased the PT-INR value halfway to normalization in 15.0 percent of patients (95% CI, 0.097-0.225). Median decrease in PT was 0.20 seconds (median decrease in INR, 0.07). Pretransfusion PT-INR, partial thromboplastin time, platelet count, and creatinine values had no correlation with red blood cell loss. CONCLUSION: It is concluded that transfusion of FFP for mild abnormalities of coagulation values results in partial normalization of PT in a minority of patients and fails to correct the PT in 99 percent of patients.     

European Concerted Action on Anticoagulation (ECAA): an assessment of a method for ISI calibration of two whole blood point-of-care PT monitor systems based on lyophilized plasmas using whole blood equivalent PT

Summary.  Previously, the attempt to simplify the International Sensitivity Index (ISI) calibration of the CoaguChek Mini whole blood point-of-care test prothrombin time (PT) monitor system was successful using lyophilized plasmas from coumarin-treated patients but not with lyophilized artificially depleted plasmas. With the TAS PT-NC monitor system, both types of plasma failed to provide reliable calibrations. The present study assesses a procedure for the ISI calibration of a TAS PT-NC and CoaguChek Mini whole blood point-of-care test PT monitor systems using lyophilized plasmas. Using lyophilized artificially depleted and coumarin plasma calibrations, we have evaluated a correction for the monitor displayed PT. This was based on a 'line of equivalence' derived from the relationship between whole blood and fresh plasma PT with both types of monitor system. With the TAS PT-NC, the use of this 'line of equivalence' resulted in reliable ISI with both lyophilized coumarin and artificially depleted plasmas. There was no significant difference between mean monitor and mean reference International Normalized Ratio (INR) with the artificially depleted plasmas. With the lyophilized coumarin plasma calibrations there was only a small INR difference. Correction with the 'line of equivalence' therefore facilitates calibration of the TAS PT-NC with lyophilized plasmas. With the CoaguChek Mini, the correction based on the 'line of equivalence' did not improve results but was not required with this system.     

肝衰竭患者凝血酶原时间报告形式的探讨

目的 :探讨在肝衰竭病人的凝血酶原时间 (PT)以秒数、比率、活动百分率计 ,还是以国际正常化比率(INR)表示。方法 :采用 ISI 1.11,1.76和 2 .0 5的三种凝血活酶对 5 2例肝衰竭病人和 5 0例口服华法令的换瓣术后的病人进行 PT测定。以上述四种方式表示结果。结果 :肝衰竭病人 ,PT百分率能消除变异的可能性 (P<0 .0 5 ) ,而其他表示形式仍有明显的差异 (P>0 .0 1)。患者口服抗凝治疗后仅 INR能较准确地反映 PT的结果。结论 :INR不能用于表达非抗凝治疗患者的 PT结果。 PT活动的百分率是为肝衰竭病人的最好报告形式。