基于Westgard西格玛规则的血气分析室内质量控制及评价

Internal quality control and evaluation of blood gas analysis based on Westgard sigma rules

目的分析某品牌血气分析仪检测系统性能,并根据Westgard西格玛规则比较血气分析仪内部自动质量控制(简称质控)与外部室内质量控制(IQC)数据,指导IQC方案设计和仪器质量改进。方法收集血气分析仪内部自动质控及同期外部IQC数据,根据仪器实验室内变异系数(CV)、偏移(Bias)等参数和美国临床实验室改进修正法规(CLIA'88)标准或仪器说明书提供的允许总误差(TEa),分别计算16个血气分析项目仪器内部自动质控及外部IQC的西格玛(σ)值,根据Westgard西格玛规则设计相应质控方案,分析内、外部质控结果符合率。结果16个血气分析项目中,氧分压内、外部质控结果均<3σ,其他项目均>5σ,有14个项目达到6σ水平。根据Westgard西格玛规则,氧分压、pH值及二氧化碳分压3项内、外部质控结果存在部分不一致,其结果符合率分别为36.11%、94.44%、93.06%,其他项目内、外部质控结果符合率为100%。结论评价的血气分析仪氧分压性能需要改进,其他项目分析性能为优。与外部IQC比较,内部自动质控系统相对稳定、操作便捷,但外部IQC可包含更多来源引起误差的因素。内部自动质控系统应采用合理的质控规则,或配合外部IQC,以确保实验室为临床提供客观、可信的检测结果。

Objective To evaluate the performance of a blood gas analyzer,to compare the internal quality control(IQC)results from both the automatic quality control(QC)data in the instrument and external manual QC data according to Westgard sigma rules,and to guide the IQC scheme and improve the measurement performance.Methods Parameters,such as coefficient of variation(CV)and bias(Bias),were used.Allowable total error(TEa)was provided by the Clinical Laboratory Improvement Amendments of 1988(CLIA'88)standard or instruction from the manufacturer.The sigma(σ)values for 16 blood gas items in the automatic and external manual IQC systems were calculated,respectively.Corresponding QC scheme was designed according to Westgard sigma rules,and the consistency rates of the 2 IQC systems were analyzed.Results Among all the 16 blood gas items,the measurement performance of partial pressure of oxygen[p(O2)]was<3σ,while the other items showed measurement performance>5σ,and 14 items reached 6σ.According to Westgard sigma rules,there were inconsistencies between the automatic and external manual IQC results for items including p(O2),pH and partial pressure of carbon dioxide[p(CO2)].The consistency rates were 36.11%,94.44%and 93.06%for p(O2),pH and p(CO2),respectively,while 100%for the others.Conclusions The measurement performance of this blood gas analyzer is good except that the analyzing quality of p(O2)needs to be improved.Compared with the external manual IQC,the results of automatic QC system in the instrument are relatively stable and easy to operate.However,external manual IQC may include more error causing factors rising from other sources.The automatic QC system in the instrument should adopt reasonable IQC rules and cooperate with external IQC to ensure that the clinical laboratory provides objective and reliable indicators for clinical use.