Protein metabolism in critical illness

Area of Science:

• Critical care medicine
• Nutritional science
• Muscle physiology

Background:

• Critically ill patients face significant skeletal muscle wasting, impacting survival and functional recovery.
• Effective protein metabolism is crucial for dietary protein to improve outcomes in critical illness.
• Muscle protein synthesis (MPS) is a key process affected by nutritional status in critical care.

Purpose of the Study:

• To review recent literature on protein delivery, digestion, amino acid absorption, and MPS in critically ill adults.
• To understand the challenges and limitations in assessing protein metabolism in critical illness.
• To inform strategies for optimizing protein intake and utilization in critically ill patients.

Main Methods:

• Literature review of studies on protein metabolism in critically ill adults.
• Analysis of data on protein delivery, digestion, absorption, and MPS.
• Examination of the impact of protein intake on muscle mass, strength, and function.

Main Results:

• Actual protein delivery often falls short of prescribed doses in critically ill patients.
• Higher protein doses in trials have generally not improved muscle outcomes.
• While digestion and absorption may be minimally affected, postprandial MPS is impaired in critical illness.

Conclusions:

• Impaired postprandial MPS in critically ill patients contributes to muscle wasting.
• Future studies must assess both protein delivery and utilization before increasing protein doses.
• Optimizing protein metabolism is essential for mitigating muscle loss in critical care settings.