以血液氣體分析儀替代生化分析儀測定TCO_2之可行性評估

Assessment of Replacing Blood Gas Analyzer with Biochemical Analyzer for Measuring TCO_2

張智凱(Chih-Kai Chang) ； 張錦標(Jin-Biou Chang)

《中華職業醫學雜誌》 25卷3期 (2018/07) Pp. 201-209

摘要

目的：TCO_2檢驗結果為臨床醫師作為診斷慢性代謝性酸中毒之依據之一。目前國內TCO_2分析包括生化分析儀測定、外送至代檢機構執行，以及因成本考量不開放臨床申請。本研究主要探討TCO_2以血液氣體分析儀執行的可行性，評估血液氣體分析儀與生化分析儀之間的相關性及結果差異，提供臨床醫師診斷慢性代謝性酸中毒之依據。材料與方法：以隨機方法收集2017年5月份的Blood gas檢體102件、生化檢體101件及健康檢查者生化檢體20件，共計223件血液檢體。使用Olympus AU 680生化自動分析儀測定TCO_2及Siemens Rapidlab 1265血液氣體分析儀的ctCO_2計算值，分別分析血漿及血清之CO_2濃度。以20位健康者之血清做為生物參考值驗證。以SPSS 22.0版統計軟體進行相關性及差異性分析，以p＜0.05具統計之差異。結果：不論以血漿或血清分析TCO_2，血液氣體分析儀分析都大於生化自動分析儀之結 果(r＝0.99)。以生化自動分析儀TCO_2之生物參考值區分＜21 mmol/L、21-31 mmol/L、＞31 mmol/L，分別統計其差異性，血漿平均值分別為1.1 mmol/L、1.1mmol/L、1.3 mmol/L，血清平均值分別為0.5 mmol/L、1.5 mmol/L、1.9 mmol/L。血液氣體分析儀分析大於生化自動分析儀分析值平均大於1 mmol/L (r＝0.99，p＜0.05)。生物參考值驗證，20支健康者TCO_2都落在參考值內。結論：因國內TCO_2檢驗，除檢驗室自行以生化儀器分析外，部分檢驗室外送代檢機構分析，主要因TCO_2檢驗的檢體收集與處理有特別之限制與要求，影響結果差異太大，因此不建議TCO_2檢驗委外代檢。本研究結果證實，檢驗室以血液氣體分析儀分析血清檢體，可做為TCO_2檢驗的替代方法，以血液氣體分析儀分析ctCO_2的結果減1 mmol/L，可做為TCO_2的分析結果，並可套用生化分析儀生物參考值，提供臨床醫師診斷慢性代謝性酸中毒之依據。

關鍵字

TCO_2 ； ctCO_2 ； 慢性代謝性酸中毒

並列摘要

Objective: TCO_2 (Total CO_2) is an analyte that is widely used to diagnose the chronic metabolic acidosis of patients; however, there are various approaches to measure TCO_2, which is not only analyzed by biochemistry analyzers, but transported to reference laboratories for analysis. Moreover, laboratory department in certain hospitals in Taiwan takes into account of a large cost, so they have no choice but to cancel TCO_2 tests. The aim of this study was to assess the feasibility of blood gas analyzer for alternative method to TCO_2 test and evaluate the correlation and difference of results of TCO_2 concentration between blood gas analyzer and biochemistry analyzer. Methods and material: A randomized sampling approach was used that 223 blood samples were collected, including blood gases (n=102), biochemical specimens drawn from patients (n=101) and from healthy adults (n=20) in May 2017. The Siemens Rapidlab 1265 blood gas analyzer was used for calculated total CO_2 (ctCO_2), while the Olympus AU680 was utilized for measured TCO_2. The validity of reference interval was tested by 20 serum samples from healthy adults. Statistical analysis, including correlation and difference of values, was performed using SPSS 22.0 version. P values ＜0.05 were considered significant. Results: The Rapidlap 1265 blood gas analyzer had a higher TCO_2 concentration than the Olympus AU680 biochemistry analyzer showed in plasma or serum (r=0.99). In addition, we used 3 groups of TCO_2 reference interval-＜21 mmol/L, 21-31 mmol/L, and ＞31 mmol/L for comparing individual mean difference of values, in which results of plasma were 1.1 mmol/l, 1.1 mmol/L, and 1.3 mmol/L, and that of serum were 0.5 mmol/L, 1.5 mmol/L, and 1.9 mmol/L. We noted that mean TCO_2 concentration was more than 1 mmol/L with ctCO_2 higher for the Rapidlab 1265 than TCO_2 for the Olympus AU680 (r=0.99, p＜0.05). For the validity of reference interval, all of results of 20 serum samples were within interval. Conclusion: Approaches for measurement of TCO_2 concentration in Taiwan are analyzed by biochemistry analyzers or transported to reference laboratories. With the strict requirements to collect and process specimens of TCO_2 testing, transported to reference laboratories for analysis is not recommended. It is because transportation from long distance to reference laboratories affect a large difference for TCO_2 testing. This study has evidenced that blood gas analyzer can be an alternative method for TCO_2 testing. Also, substracting 1 mmol/L from the values of ctCO_2 of blood gas analyzers and being applied with laboratory interval of biochemistry analyzers offer clinical physicians a quick data for diagnosing chronic metabolic acidosis of patients.

並列關鍵字

TCO_2 ； ctCO_2 ； chronic metabolic acidosis