Iresjö Britt-Marie, Körner Ulla, Larsson Bo, Henriksson Bengt-Ake, Lundholm Kent
Department of Surgery, Surgical Metabolic Research Laboratory at Lunderberg Laboratory for Cancer Research, Göteborg, Sweden.
JPEN J Parenter Enteral Nutr. 2006 Jul-Aug;30(4):277-85. doi: 10.1177/0148607106030004277.
Previous work has demonstrated a relationship between arterial amino acid concentrations and uptake of amino acids across peripheral tissues in healthy volunteers, as well as in chronically and acutely ill patients. The aim of the present study was to evaluate whether different amino acid profiles in commercially available amino acid formulations are translated into significantly different arterial amino acid concentrations presumably high enough to promote protein metabolism in intensive care unit (ICU) patients.
Nonprotein calories (60% glucose: 40% lipid) were simultaneously and constantly infused over 72 hours. Different free amino acid solutions were infused at random to each patient for 24 hours in order to determine the appearance of steady-state arterial concentrations of individual amino acids. Basal metabolic and nutrition states were defined after a 12-hour infusion period with glucose in each patient. Healthy volunteers receiving a standardized oral meal served as reference subjects in measurements of venous amino acid concentrations after normal oral food intake.
The sum of all amino acids in arterial plasma increased significantly during steady-state infusions of all the free amino acid solutions vs basal state in ICU patients. Only glutamine, taurine, and tyrosine did not increase at all vs basal state during steady-state infusions of the 3 formulations. Alanine, arginine, citrulline, glycine, histidine, serine, methionine, phenylalanine, valine, and ornithine showed different concentration among the amino acid solutions during infusions. Healthy volunteers had significantly higher overall concentrations of amino acids in both fasted and fed state compared with ICU patients, which indicates that free amino acid solutions remain a limiting component in artificial nutrition to patients to promote arterial amino acid concentrations in the artificially fed state.
It appears important to continue further improvement of composition profile in solutions of free amino acids to promote adequate uptake across organ beds in promotion of protein balance in artificially nourished patients.
此前的研究已证实，在健康志愿者以及慢性病和急性病患者中，动脉氨基酸浓度与外周组织对氨基酸的摄取之间存在关联。本研究的目的是评估市售氨基酸制剂中不同的氨基酸谱是否会转化为显著不同的动脉氨基酸浓度，这些浓度可能高到足以促进重症监护病房（ICU）患者的蛋白质代谢。
在72小时内同时持续输注非蛋白质热量（60%葡萄糖：40%脂质）。将不同的游离氨基酸溶液随机输注给每位患者24小时，以确定各个氨基酸稳态动脉浓度的出现情况。在每位患者输注葡萄糖12小时后确定基础代谢和营养状态。正常口服食物后，接受标准化口服餐的健康志愿者作为测量静脉氨基酸浓度的参考对象。
与ICU患者的基础状态相比，在所有游离氨基酸溶液的稳态输注期间，动脉血浆中所有氨基酸的总和显著增加。在三种制剂的稳态输注期间，与基础状态相比，只有谷氨酰胺、牛磺酸和酪氨酸根本没有增加。输注期间，丙氨酸、精氨酸、瓜氨酸、甘氨酸、组氨酸、丝氨酸、蛋氨酸、苯丙氨酸、缬氨酸和鸟氨酸在氨基酸溶液中的浓度有所不同。与ICU患者相比，健康志愿者在禁食和进食状态下的氨基酸总体浓度显著更高，这表明游离氨基酸溶液仍然是人工营养中促进人工喂养状态下患者动脉氨基酸浓度的一个限制因素。
继续进一步改善游离氨基酸溶液的组成谱，以促进在人工营养患者中跨器官床的充分摄取，从而促进蛋白质平衡，这似乎很重要。
