de Betue Carlijn T I, Garcia Casal Xiomara C, van Waardenburg Dick A, Schexnayder Stephen M, Joosten Koen F M, Deutz Nicolaas E P, Engelen Marielle P K J
Intensive Care and Department of Pediatric Surgery, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands.
Department of Pediatric Cardiology & Critical Care Medicine, Arkansas Children's Hospital, Little Rock, AR, USA.
Clin Nutr. 2017 Jun;36(3):876-887. doi: 10.1016/j.clnu.2016.12.023. Epub 2017 Jan 4.
BACKGROUND & AIMS: The reference method to study protein and arginine metabolism in critically ill children is measuring plasma amino acid appearances with stable isotopes during a short (4-8 h) time period and extrapolate results to 24-h. However, 24-h measurements may be variable due to critical illness related factors and a circadian rhythm could be present. Since only short duration stable isotope studies in critically ill children have been conducted before, the aim of this study was to investigate 24-h appearance of specific amino acids representing protein and arginine metabolism, with stable isotope techniques in continuously fed critically ill children.
In eight critically ill children, admitted to the pediatric (n = 4) or cardiovascular (n = 4) intensive care unit, aged 0-10 years, receiving continuous (par)enteral nutrition with protein intake 1.0-3.7 g/kg/day, a 24-h stable isotope tracer protocol was carried out. L-[ring-H]-phenylalanine, L-[3,3-H]-tyrosine, L-[5,5,5-H]-leucine, L-[guanido-N]-arginine and L-[5-C-3,3,4,4-H]-citrulline were infused intravenously and L-[N]-phenylalanine and L-[1-C]leucine enterally. Arterial blood was sampled every hour.
Coefficients of variation, representing intra-individual variability, of the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline were high, on average 14-19% for intravenous tracers and 23-26% for enteral tracers. No evident circadian rhythm was present. The pattern and overall 24-h level of whole body protein balance differed per individual.
In continuously fed stable critically ill children, the amino acid appearances of phenylalanine, tyrosine, leucine, arginine and citrulline show high variability. This should be kept in mind when performing stable isotope studies in this population. There was no apparent circadian rhythm.
NCT01511354 on clinicaltrials.gov.
研究危重症儿童蛋白质和精氨酸代谢的参考方法是在短时间（4 - 8小时）内用稳定同位素测量血浆氨基酸表现，并将结果外推至24小时。然而，由于危重症相关因素，24小时测量结果可能存在差异，并且可能存在昼夜节律。由于此前仅对危重症儿童进行过短时间的稳定同位素研究，本研究的目的是采用稳定同位素技术，在持续喂养的危重症儿童中，研究代表蛋白质和精氨酸代谢的特定氨基酸的24小时表现。
对8名年龄在0至10岁、入住儿科（n = 4）或心血管（n = 4）重症监护病房、接受持续（肠内或肠外）营养且蛋白质摄入量为1.0 - 3.7 g/kg/天的危重症儿童，实施了一项24小时稳定同位素示踪方案。静脉输注L-[环-H]-苯丙氨酸、L-[3,3-H]-酪氨酸、L-[5,5,5-H]-亮氨酸、L-[胍基-N]-精氨酸和L-[5-C-3,3,4,4-H]-瓜氨酸，经肠给予L-[N]-苯丙氨酸和L-[1-C]亮氨酸。每小时采集动脉血样。
苯丙氨酸、酪氨酸、亮氨酸、精氨酸和瓜氨酸的氨基酸表现的变异系数（代表个体内变异性）较高，静脉示踪剂平均为14 - 19%，肠内示踪剂平均为23 - 26%。未出现明显的昼夜节律。全身蛋白质平衡的模式和总体24小时水平因人而异。
在持续喂养的稳定危重症儿童中，苯丙氨酸、酪氨酸、亮氨酸、精氨酸和瓜氨酸的氨基酸表现具有高度变异性。在该人群中进行稳定同位素研究时应牢记这一点。未出现明显的昼夜节律。
clinicaltrials.gov上的NCT01511354。
