School of Human Kinetics and Recreation, Memorial University of Newfoundland, St John's, Newfoundland, Canada.
School of Physical Therapy Faculty of Health and Rehabilitation Sciences, Western University, London, Ontario, Canada.
PeerJ. 2022 Aug 29;10:e13882. doi: 10.7717/peerj.13882. eCollection 2022.
Indirect calorimetry (IC) systems measure the fractions of expired carbon dioxide (FCO), and oxygen (FO) recorded at the mouth to estimate whole-body energy production. The fundamental principle of IC relates to the catabolism of high-energy substrates such as carbohydrates and lipids to meet the body's energy needs through the oxidative process, which are reflected in the measured oxygen uptake rates (V̇O) and carbon dioxide production rates (V̇CO). Accordingly, it is important to know the accuracy and validity of V̇Oand V̇CO measurements when estimating energy production and substrate partitioning for research and clinical purposes. Although several techniques are readily available to assess the accuracy of IC systems at a single point for V̇CO and V̇O, the validity of such procedures is limited when used in testing protocols that incorporate a wide range of energy production (, basal metabolic rate and maximal exercise testing). Accordingly, we built an apparatus that allowed us to manipulate propane burn rates in such a way as to assess the linearity of IC systems. This technical report aimed to assess the accuracy and linearity of three IC systems using our in-house built validation procedure.
A series of trials at different propane burn rates (PBR) (, 200, 300, 400, 500, and 600 mL min) were run on three IC systems: Sable, Moxus, and Oxycon Pro. The experimental values for V̇O and V̇CO measured on the three IC systems were compared to theoretical stoichiometry values.
A linear relationship was observed between increasing PBR and measured values for V̇Oand V̇CO (99.6%, 99.2%, 94.8% for the Sable, Moxus, and Jaeger IC systems, respectively). In terms of system error, the Jaeger system had significantly ( < 0.001) greater V̇O(mean difference ( = -0.057, standard error ( = 0.004), and V̇CO( = -0.048, = 0.002) error compared to either the Sable (V̇O, = 0.044, = 0.004; V̇CO, = 0.024, = 0.002) or the Moxus (V̇O2, = 0.046, = 0.004; V̇CO, = 0.025, = 0.002) IC systems. There were no significant differences between the Sable or Moxus IC systems.
The multiple PBR approach permitted the assessment of linearity of IC systems in addition to determining the accuracy of fractions of expired gases.
间接测热法（IC）系统通过测量口腔呼出的二氧化碳（FCO）和氧气（FO）的分数来估算全身能量产生。IC 的基本原理涉及到高能底物（如碳水化合物和脂肪）的分解代谢，以通过氧化过程满足身体的能量需求，这反映在测量的氧气摄取率（V̇O）和二氧化碳产生率（V̇CO）中。因此，当研究和临床目的需要估计能量产生和底物分配时，了解 V̇O 和 V̇CO 测量的准确性和有效性非常重要。尽管有几种技术可用于在单点评估 IC 系统的 V̇CO 和 V̇O 的准确性，但当在包含广泛能量产生范围的测试方案中使用时，这些程序的有效性是有限的（，基础代谢率和最大运动测试）。因此，我们构建了一种设备，可以控制丙烷燃烧速度，从而评估 IC 系统的线性度。本技术报告旨在使用我们内部构建的验证程序评估三种 IC 系统的准确性和线性度。
在三种 IC 系统上进行了一系列不同丙烷燃烧率（PBR）的试验（，200、300、400、500 和 600 mL min）：Sable、Moxus 和 Oxycon Pro。在三种 IC 系统上测量的 V̇O 和 V̇CO 的实验值与理论化学计量值进行了比较。
随着 PBR 的增加，V̇O 和 V̇CO 的测量值呈线性关系（Sable、Moxus 和 Jaeger IC 系统分别为 99.6%、99.2%和 94.8%）。就系统误差而言，与 Sable（V̇O，=0.044，=0.004；V̇CO，=0.024，=0.002）或 Moxus（V̇O2，=0.046，=0.004；V̇CO，=0.025，=0.002）IC 系统相比，Jaeger 系统的 V̇O（平均值差异（= -0.057，标准误差（= 0.004）和 V̇CO（= -0.048，= 0.002）误差显著（<0.001）。Sable 或 Moxus IC 系统之间没有显着差异。
多 PBR 方法除了确定呼出气体分数的准确性外，还允许评估 IC 系统的线性度。
