Department of Perioperative Medicine and Intensive Care (PMI), Karolinska University Hospital Huddinge, Stockholm, Sweden.
Division of Anesthesia and Intensive Care, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden.
PLoS One. 2020 Oct 5;15(10):e0240045. doi: 10.1371/journal.pone.0240045. eCollection 2020.
Enteral nutrition (EN) is a ubiquitous intervention in ICU patients but there is uncertainty regarding the optimal dose, timing and importance for patient-centered outcomes during critical illness. Our research group has previously found an improved protein balance during normocaloric versus hypocaloric parenteral nutrition in neurosurgical ICU patients. We now wanted to investigate if this could be demonstrated in a general ICU population with established enteral feeding, including patients on renal replacement therapy.
Patients with EN >80% of energy target as determined by indirect calorimetry were randomized to or 50% or 100% of current EN rate. After 24 hours, whole-body protein kinetics were determined by enteral and parenteral stable isotope tracer infusions. Treatment allocation was then switched, and tracer investigations repeated 24 hours later in a crossover design with patients serving as their own controls.
Six patients completed the full protocol. During feeding with 100% EN all patients received >1.2 g/kg/day of protein. Mean whole-body protein balance increased from -6.07 to 2.93 µmol phenylalanine/kg/h during 100% EN as compared to 50% (p = 0.044). The oxidation rate of phenylalanine was unaltered (p = 0.78).
It is possible to assess whole-body protein turnover using a stable isotope technique in critically ill patients during enteral feeding and renal replacement therapy. Our results also suggest a better whole-body protein balance during full dose as compared to half dose EN. As the sample size was smaller than anticipated, this finding should be confirmed in larger studies.
肠内营养（EN）是 ICU 患者普遍采用的干预措施，但对于危重疾病患者，最佳剂量、时机以及患者为中心结局的重要性尚不确定。我们的研究小组之前发现，神经外科 ICU 患者接受正常热量与低热量肠外营养时，前者的蛋白质平衡得到改善。现在，我们想在接受肠内喂养且已开始肾脏替代治疗的一般 ICU 患者中调查是否也能观察到这种效果。
通过间接热量测定，将接受 EN 且能量目标达到 80%以上的患者随机分为 50%或 100%当前 EN 率。24 小时后，通过肠内和肠外稳定同位素示踪剂输注来测定全身蛋白质动力学。然后切换治疗分配，以交叉设计在 24 小时后重复示踪剂研究，患者作为自身对照。
6 名患者完成了完整方案。在接受 100%EN 喂养时，所有患者的蛋白质摄入量均超过 1.2 g/kg/天。与 50%EN 相比，100%EN 时全身蛋白质平衡从-6.07 增加到 2.93 µmol 苯丙氨酸/kg/h（p = 0.044）。苯丙氨酸的氧化率未改变（p = 0.78）。
在接受肠内喂养和肾脏替代治疗的危重患者中，使用稳定同位素技术评估全身蛋白质周转率是可行的。我们的结果还表明，与半剂量 EN 相比，全剂量 EN 时全身蛋白质平衡更好。由于样本量小于预期，这一发现需要在更大的研究中得到证实。
