Cooper Jamie A, Watras Abigail C, O'Brien Matthew J, Luke Amy, Dobratz Jennifer R, Earthman Carrie P, Schoeller Dale A
Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA.
J Am Diet Assoc. 2009 Jan;109(1):128-32. doi: 10.1016/j.jada.2008.10.004.
The Deltatrac Metabolic Monitor (DTC) (VIASYS Healthcare Inc, SensorMedics, Yorba Linda, CA), one of the most popular indirect calorimetry systems for measuring resting metabolic rate (RMR) in human subjects, is no longer being manufactured. This study compared five different gas analysis systems to the DTC. RMR was measured by the DTC and at least one other instrument at three study sites for a total of 38 participants. The five indirect calorimetry systems included the MedGraphics CPX Ultima (Medical Graphics Corp, St Paul, MN), the MedGem (Microlife USA, Golden, CO), Vmax Encore 29 System (VIASYS Healthcare Inc, Yorba Linda, CA), the TrueOne 2400 (Parvo Medics, Sandy, UT), and the Korr ReeVue (Korr Medical Technologies, Salt Lake City, UT). Validity was assessed using paired t tests to compare means; reliability was assessed by using both paired t tests and root mean square calculations with F tests for significance. Within-subject comparisons for validity of RMR revealed a significant difference between the DTC and the Ultima system. Bland-Altman plot analysis showed significant bias with increasing RMR values for the Korr and MedGem systems. Respiratory exchange ratio (RER) analysis showed a significant difference between the DTC and the Ultima system and a trend for a difference with the Vmax system (P=0.09). Reliability assessment for RMR revealed that all instruments had a significantly larger coefficient of variation (CV) (ranging from 4.8% to 10.9%) for RMR compared to the 3.0% CV for the DTC. Reliability assessment for RER data showed none of the instrument CVs was significantly larger than the DTC CV. The results were quite disappointing because none of the instruments equaled the within-person reliability of the DTC. The TrueOne and Vmax systems were the most valid instruments in comparison with the DTC for both RMR and RER assessment. Further testing is needed to identify an instrument with the reliability and validity of the DTC.
Deltatrac代谢监测仪（DTC）（VIASYS Healthcare公司，SensorMedics，加利福尼亚州约巴林达）是用于测量人体静息代谢率（RMR）的最常用间接热量测定系统之一，现已不再生产。本研究将五种不同的气体分析系统与DTC进行了比较。在三个研究地点，用DTC和至少一种其他仪器对总共38名参与者测量了RMR。这五种间接热量测定系统包括MedGraphics CPX Ultima（Medical Graphics公司，明尼苏达州圣保罗）、MedGem（美国Microlife公司，科罗拉多州戈尔登）、Vmax Encore 29系统（VIASYS Healthcare公司，加利福尼亚州约巴林达）、TrueOne 2400（Parvo Medics公司，犹他州桑迪）和Korr ReeVue（Korr Medical Technologies公司，犹他州盐湖城）。使用配对t检验比较均值来评估效度；通过配对t检验和均方根计算并进行F检验以确定显著性来评估信度。RMR效度的受试者内比较显示，DTC与Ultima系统之间存在显著差异。Bland-Altman图分析显示，Korr和MedGem系统的RMR值增加时存在显著偏差。呼吸交换率（RER）分析显示，DTC与Ultima系统之间存在显著差异，与Vmax系统存在差异趋势（P = 0.09）。RMR的信度评估显示，与DTC的3.0%相比，所有仪器的RMR变异系数（CV）均显著更大（范围为4.8%至10.9%）。RER数据的信度评估显示，没有一种仪器的CV显著大于DTC的CV。结果相当令人失望，因为没有一种仪器能达到DTC的个体内信度。与DTC相比，TrueOne和Vmax系统在RMR和RER评估方面是最有效的仪器。需要进一步测试以确定一种具有DTC信度和效度的仪器。
