Frezzotti A, Margarucci Gambini A M, Coppa G, De Sio G
Laboratorio di Analisi Chimico Cliniche e Microbiologiche, Azienda Ospedaliera Umberto I-Torrette, Ancona, Italy.
Clin Chem Lab Med. 1998 Jan;36(1):43-6. doi: 10.1515/CCLM.1998.008.
We evaluated the performance of an enzymatic method using dry chemistry for serum total carbon dioxide (tCO2) determination using a Vitros 500 analyser. Imprecision results were acceptable and the linearity was verified for concentrations within a range of 5.5-39.2 mmol/l, i.e. Y(measured) = 0.93 x(calculated) + 1.32, r = 0.99. The Vitros tCO2 method was unaffected by haemoglobin at all concentrations tested. Significant interference was caused by bilirubin at concentrations higher than 30 mumol/l; the addition of bilirubin lowered the apparent values for tCO2 dose-dependently. Serum tCO2 results were practically the same as those for plasma. The reference interval for venous tCO2 concentrations in a healthy population was: 22.4-34.2 mmol/l (mean: 28.3 mmol/l). Comparison of venous serum tCO2 results assayed using the Vitros method with bicarbonate (HCO3-) values calculated by blood gas determination of pCO2 and pH in arterial blood samples gave poor agreement, r = 0.58. The data revealed a mean difference of 5.48 +/- 3.09 mmol/l between the tCO2 measurements and calculated bicarbonate. This was statistically (p = 0.01) and clinically significant. We conclude that the Vitros method provides reliable tCO2 results in venous serum but this method must not be used as an interchangeable alternative to calculated arterial bicarbonate in order to avoid confusion, misinterpretation of results and erroneous therapeutic decisions.
我们使用Vitros 500分析仪评估了一种采用干化学法测定血清总二氧化碳（tCO2）的酶法的性能。不精密度结果可接受，并且在5.5 - 39.2 mmol/l范围内验证了线性，即Y（测量值）= 0.93×（计算值）+ 1.32，r = 0.99。在所有测试浓度下，Vitros tCO2方法不受血红蛋白影响。胆红素浓度高于30 μmol/l时会产生显著干扰；添加胆红素会使tCO2的表观值呈剂量依赖性降低。血清tCO2结果与血浆结果基本相同。健康人群静脉tCO2浓度的参考区间为：22.4 - 34.2 mmol/l（均值：28.3 mmol/l）。使用Vitros方法测定的静脉血清tCO2结果与通过动脉血样本的pCO2和pH血气测定计算的碳酸氢盐（HCO3-）值进行比较，一致性较差，r = 0.58。数据显示tCO2测量值与计算的碳酸氢盐之间的平均差异为5.48±3.09 mmol/l。这在统计学上（p = 0.01）和临床上均具有显著意义。我们得出结论，Vitros方法可在静脉血清中提供可靠的tCO2结果，但为避免混淆、结果误判和错误的治疗决策，该方法绝不能用作计算动脉碳酸氢盐的可互换替代方法。
