Increasing protein dose does not further augment muscle protein synthesis in critical illness: a randomized, controlled clinical trial.

Whether increased protein dose can overcome this anabolic resistance is unknown.

尚不清楚增加蛋白质剂量是否可以克服这种合成阻力。

Background

To assess the impact of a single intraduodenal bolus of 40 g protein compared to 20 g of protein in mechanically ventilated critically ill patients on the primary outcome of postprandial muscle protein synthesis rates.

评估单次经十二指肠给予40克蛋白质与20克蛋白质对机械通气的危重病患者餐后肌肉蛋白质合成率（主要结果指标）的影响。

Methods

Mechanically ventilated patients were randomized to 40 or 20 g of whey protein isolate delivered intraduodenally over 1 h.

机械通气的患者被随机分配接受40克或20克的乳清蛋白分离物，通过十二指肠在1小时内给予。

Primed continuous intravenous L-[ring-13C6]-phenylalanine and L-[3,5-2H2]-tyrosine infusions were applied with repeated arterial blood and skeletal muscle tissue sampling over 2 h fasting and 6 h postprandial periods to assess plasma amino acid responses and rates of fasting and postprandial muscle protein synthesis (primary outcome).

通过在2小时禁食和6小时餐后期间应用持续的静脉注射L-[环-13C6]-苯丙氨酸和L-[3,5-2H2]-酪氨酸，并进行反复的动脉血和骨骼肌组织采样，以评估血浆氨基酸反应以及禁食和餐后肌肉蛋白合成率（主要结果指标）。

Data are mean ± SD and area under the curve (AUC), analyzed with ANCOVA adjusted for fasting rate and paired t-tests (P < .05).

数据表示为平均值±标准差和曲线下面积（AUC），使用ANCOVA进行分析，调整了禁食率，并使用配对t检验（P < .05）。

measurements_and_main_results

Twenty patients (n = 10/group: 40 g: 90% male, 49 ± 21 y and 20 g: 80% male, 51 ± 13 y) were studied.

研究了20名患者（每组n=10：40克组90%为男性，平均年龄49±21岁；20克组80%为男性，平均年龄51±13岁）。

Postprandial muscle protein synthesis rates (primary outcome) did not differ between groups (40 g vs 20 g: 0.030 ± 0.012 vs 0.025 ± 0.010%·h-1; adjusted mean difference 0.007 (95% CI, -0.003 to 0.016) %·h-1; P = .152).

餐后肌肉蛋白合成率（主要结果指标）在两组间无差异（40克组与20克组：0.030 ± 0.012 vs 0.025 ± 0.010%·h-1；调整后平均差异为0.007（95%置信区间，-0.003至0.016）%·h-1；P = .152）。

Postprandial plasma leucine and tyrosine availability (AUC) were higher following 40 g vs 20 g protein (leucine: 263 ± 87 vs 194 ± 54 µmol·L-1, P = .005; tyrosine: 92 ± 24 vs 63 ± 17 µmol·L-1, P = .006).

餐后血浆亮氨酸和酪氨酸的可用性（AUC）在40克蛋白质后比20克蛋白质高（亮氨酸：263 ± 87 vs 194 ± 54 µmol·L-1，P = .005；酪氨酸：92 ± 24 vs 63 ± 17 µmol·L-1，P = .006）。

Fasting muscle protein synthesis rates did not differ between groups (40 g vs 20 g: 0.020 ± 0.012 vs 0.025 ± 0.023%·h-1; P = .558).

空腹肌肉蛋白质合成率在两组之间没有差异（40克 vs 20克：0.020 ± 0.012 vs 0.025 ± 0.023%·h-1；P = .558）。

The post hoc uncontrolled analysis of muscle protein synthesis rates from fasting to postprandial periods increased in the 40 g group only (P = .005).

事后无对照分析显示，从禁食期到餐后期间，仅40克组的肌肉蛋白质合成率增加（P = .005）。

Conclusions

Higher enteral protein does not further augment postprandial muscle protein synthesis rates to overcome -anabolic resistance during critical illness, despite increased plasma amino acid availability.

尽管血浆氨基酸可用性增加，但较高的肠内蛋白并不能进一步增加餐后肌肉蛋白质合成率以克服重症患者的抗合成状态。

trial_registration_number

Australia New Zealand Clinical Trials Registry Identifier: ACTRN12620000776909.

澳大利亚新西兰临床试验注册处标识符：ACTRN12620000776909。