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

Abstract

RATIONALE: Critical illness impairs the muscle protein synthetic response to protein administration. Whether increased protein dose can overcome this anabolic resistance is unknown. OBJECTIVES: 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. METHODS: Mechanically ventilated patients were randomized to 40 or 20 g of whey protein isolate delivered intraduodenally over 1 h. Primed continuous intravenous L-[ring-13C6]-phenylalanine and L-[3,5-2H2]-tyrosine infusions were applied with repeated arterial blood and skeletal muscle ..