Jones P J, Winthrop A L, Schoeller D A, Filler R M, Swyer P R, Smith J, Heim T
Department of Medicine, University of Chicago Medical Center, IL 60637.
Am J Clin Nutr. 1988 May;47(5):799-804. doi: 10.1093/ajcn/47.5.799.
Change in abundance of 2H and 18O in dietary water during a doubly labeled water energy period may introduce error into the calculated carbon dioxide production rate (RCO2). To examine the accuracy of 2H2(18)O during changing nutritional regimens, we compared 2H2(18)O and periodic open-circuit respiratory gas exchange (RGE) in postsurgical infants who were changing from parenteral to alternative parenteral and/or oral nutrition. The two methods were compared before and after correction for shifts in isotopic abundance of the infant water pools during the energy-expenditure period. Baseline corrections were predicted using the difference between abundances of the initial body water and final nutrient solutions. Before isotopic correction, 2H2(18)O underestimated RCO2 in eight subjects by 11.8 +/- 20.1% (mean +/- SD). After correction, agreement between the two methods improved; the underestimate was then -8.7 +/- 12.9%. To obtain maximum precision of 2H2(18)O, subjects should be maintained on the same nutritional regimen before and during the study unless valid correction formulae are used.
在双标记水能量测定期间，膳食水中2H和18O丰度的变化可能会给计算出的二氧化碳产生率（RCO2）带来误差。为了检验在营养方案改变期间2H2(18)O的准确性，我们比较了接受手术的婴儿从肠外营养改为肠外和/或口服替代营养时的2H2(18)O和定期开路呼吸气体交换（RGE）。在对能量消耗期间婴儿水池中同位素丰度的变化进行校正前后，对这两种方法进行了比较。使用初始身体水分和最终营养液丰度之间的差异来预测基线校正。在进行同位素校正之前，2H2(18)O在8名受试者中低估了RCO2 11.8 +/- 20.1%（平均值 +/- 标准差）。校正后，两种方法之间的一致性有所改善；此时低估率为-8.7 +/- 12.9%。为了获得2H2(18)O的最高精度，除非使用有效的校正公式，否则在研究前和研究期间应让受试者保持相同的营养方案。
