Department of Foods and Nutrition, University of Georgia, Athens, Georgia, USA.
Department of Nutritional Sciences, University of Wisconsin, Madison, Wisconsin, USA.
Nutr Clin Pract. 2018 Apr;33(2):206-216. doi: 10.1002/ncp.10070.
Several indirect calorimetry (IC) instruments are commercially available, but comparative validity and reliability data are lacking. Existing data are limited by inconsistencies in protocols, subject characteristics, or single-instrument validation comparisons. The aim of this study was to compare accuracy and reliability of metabolic carts using methanol combustion as the cross-laboratory criterion.
Eight 20-minute methanol burn trials were completed on 12 metabolic carts. Respiratory exchange ratio (RER) and percent O and CO recovery were calculated.
For accuracy, 1 Omnical, Cosmed Quark CPET (Cosmed), and both Parvos (Parvo Medics trueOne 2400) measured all 3 variables within 2% of the true value; both DeltaTracs and the Vmax Encore System (Vmax) showed similar accuracy in measuring 1 or 2, but not all, variables. For reliability, 8 instruments were shown to be reliable, with the 2 Omnicals ranking best (coefficient of variation [CV] < 1.26%). Both Cosmeds, Parvos, DeltaTracs, 1 Jaeger Oxycon Pro (Oxycon), Max-II Metabolic Systems (Max-II), and Vmax were reliable for at least 1 variable (CV ≤ 3%). For multiple regression, humidity and amount of combusted methanol were significant predictors of RER (R = 0.33, P < .001). Temperature and amount of burned methanol were significant predictors of O recovery (R = 0.18, P < .001); only humidity was a predictor for CO recovery (R = 0.15, P < .001).
Omnical, Parvo, Cosmed, and DeltaTrac had greater accuracy and reliability. The small number of instruments tested and expected differences in gas calibration variability limits the generalizability of conclusions. Finally, humidity and temperature could be modified in the laboratory to optimize IC conditions.
有几种间接测热仪（IC）可供商业使用，但缺乏比较有效性和可靠性的数据。现有数据受到协议、受试对象特征或单一仪器验证比较不一致的限制。本研究的目的是比较使用甲醇燃烧作为实验室间标准的代谢车的准确性和可靠性。
12 台代谢车完成了 8 次 20 分钟的甲醇燃烧试验。计算呼吸交换率（RER）和 O 和 CO 的回收率。
在准确性方面，1 台 Omnical、Cosmed Quark CPET（Cosmed）和 Parvo 公司的两台（Parvo Medics trueOne 2400）均在 2%的范围内测量了所有 3 个变量的真实值；DeltaTrac 和 Vmax Encore System（Vmax）在测量 1 或 2 个变量的准确性方面表现相似，但并非所有变量都如此。在可靠性方面，有 8 台仪器被证明是可靠的，其中 2 台 Omnical 排名最佳（变异系数[CV] < 1.26%）。Cosmeds、Parvos、DeltaTrac、1 台 Jaeger Oxycon Pro（Oxycon）、Max-II 代谢系统（Max-II）和 Vmax 都至少有 1 个变量（CV ≤ 3%）是可靠的。对于多元回归，湿度和燃烧的甲醇量是 RER 的显著预测因子（R = 0.33，P <.001）。温度和燃烧的甲醇量是 O 回收率的显著预测因子（R = 0.18，P <.001）；只有湿度是 CO 回收率的预测因子（R = 0.15，P <.001）。
Omnical、Parvo、Cosmed 和 DeltaTrac 具有更高的准确性和可靠性。测试的仪器数量较少，以及气体校准变异性的预期差异限制了结论的普遍性。最后，可以在实验室中修改湿度和温度以优化 IC 条件。
