Validity and reliability of a new whole room indirect calorimeter to assess metabolic response to small calorie loads

To provide an overview of our whole room indirect calorimeter (WRIC), demonstrate validity and reliability of our WRIC, and explore a novel application of Bayesian hierarchical modeling to assess responses to small carbohydrate loads.Seven gas infusion studies were performed using a gas blender and profiles designed to mimic resting and postprandial metabolic events to assess WRIC validity. In a crossover design, 16 participants underwent fasting and postprandial measurements, during which they consumed a 75-kcal drink containing sucrose, dextrose, or fructose. Linear mixed effects models were used to compare resting and postprandial metabolic rate (MR) and carbohydrate oxidation. Bayesian Hierarchical Modeling was also used to model postprandial carbohydrate oxidation trajectories for each participant and condition.Mean total error in infusions were 1.270.67% and 0.420.70% for VO2 and VCO2 respectively, indicating a high level of validity. Mean resting MR was similar across conditions (=1.050.03 kcal/min, p=0.82, ICC: 0.91). While MR increased similarly among all conditions (~13%, p=0.29), postprandial carbohydrate oxidation parameters were significantly lower for dextrose compared with sucrose or fructose.Here, we provide evidence of validation of our WRIC and a novel application of statistical methods useful for research using WRIC.

为全面概述我们的整体房间间接式热量计（WRIC），验证WRIC的有效性和可靠性，并探讨贝叶斯分层模型在评估小碳水化合物负荷反应中的创新应用，本研究进行了七项气体混合研究。利用气体混合器和模拟静息及餐后代谢事件的轮廓，评估了WRIC的有效性。在交叉设计中，16名受试者在空腹和餐后期间进行了测量，期间他们饮用了一款含有蔗糖、葡萄糖或果糖的75千卡饮料。线性混合效应模型被用于比较静息和餐后代谢率（MR）及碳水化合物氧化。此外，贝叶斯分层模型也被用于模拟每位受试者及每种条件下的餐后碳水化合物氧化轨迹。气体注入的平均总误差分别为1.27±0.67%和0.42±0.70%的氧消耗量（VO2）和二氧化碳排放量（VCO2），这表明了高度的有效性。静息MR在所有条件下均相似（=1.05±0.03千卡/分钟，p=0.82，ICC: 0.91）。尽管所有条件下的MR增加相似（约13%，p=0.29），但与蔗糖或果糖相比，葡萄糖的餐后碳水化合物氧化参数显著较低。本研究为WRIC的验证提供了证据，并展示了统计方法在WRIC研究中的创新应用。