Abstract：
Although numerous observational studies associated underfeeding with poor outcome, recent randomized controlled trials (RCTs) have shown that early full nutritional support does not benefit critically ill patients and may induce dose-dependent harm. Some researchers have suggested that the absence of benefit in RCTs may be attributed to overrepresentation of patients deemed at low nutritional risk, or to a too low amino acid versus non-protein energy dose in the nutritional formula. However, these hypotheses have not been confirmed by strong evidence. RCTs have not revealed any subgroup benefiting from early full nutritional support, nor benefit from increased amino acid doses or from indirect calorimetry-based energy dosing targeted at 100% of energy expenditure. Mechanistic studies attributed the absence of benefit of early feeding to anabolic resistance and futile catabolism of extra provided amino acids, and to feeding-induced suppression of recovery-enhancing pathways such as autophagy and ketogenesis, which opened perspectives for fasting-mimicking diets and ketone supplementation. Yet, the presence or absence of an anabolic response to feeding cannot be predicted or monitored and likely differs over time and among patients. In the absence of such monitor, the value of indirect calorimetry seems obscure, especially in the acute phase of illness. Until now, large feeding RCTs have focused on interventions that were initiated in the first week of critical illness. There are no large RCTs that investigated the impact of different feeding strategies initiated after the acute phase and continued after discharge from the intensive care unit in patients recovering from critical illness.
摘要：
尽管许多观察性研究将喂养不足与不良结果相关，最近的随机对照试验(RCT)表明,早期全面营养支持并不能使危重病患者获益,并且可能导致剂量依赖性损害.一些研究人员认为，RCT缺乏益处可能是由于被认为营养风险低的患者比例过高。或营养配方中氨基酸与非蛋白质能量剂量过低。然而,这些假设尚未得到有力证据的证实。RCT尚未发现任何受益于早期全面营养支持的亚组，也不受益于增加氨基酸剂量或基于间接量热法的能量剂量，目标是100％的能量消耗。机制研究将早期进食的益处归因于合成代谢抗性和额外提供的氨基酸的徒劳分解代谢，以及摄食诱导的抑制恢复增强途径，如自噬和生酮，这为禁食模仿饮食和补充酮开辟了前景。然而，对进食的合成代谢反应的存在与否无法预测或监测,并且可能随着时间和患者之间的不同而不同.如果没有这样的监视器，间接量热法的价值似乎很模糊，尤其是在疾病的急性期。直到现在,大型饲喂RCT的重点是在危重疾病的第一周开始的干预措施.没有大型的随机对照试验来调查急性期后开始的不同喂养策略的影响，并在重症监护病房出院后继续进行。
