Protein supplementation in critical illness: why, when and how?

Area of Science:

• Critical care medicine
• Nutritional science
• Intensive care unit (ICU) management

Background:

• Optimal protein delivery in critically ill patients is challenging due to inconsistent international guidelines and a lack of high-quality evidence.
• Patients in the ICU often experience muscle wasting, leading to poor long-term functional outcomes, highlighting the need for effective nutritional strategies.
• This review focuses on the critical role of protein in ICU nutrition, examining recent literature on its purpose, timing, and method of delivery.

Approach:

• Review of recent scientific literature on protein delivery in critically ill patients.
• Analysis of studies examining the impact of protein dose and timing on clinical and functional outcomes.
• Discussion of current evidence regarding the benefits and limitations of protein supplementation in the ICU.

Key Points:

• Recent studies, primarily observational, show limited effects of protein supplementation on mortality, muscle strength, or function.
• Some evidence suggests protein intake may attenuate muscle volume loss, particularly when combined with muscle activation.
• There is currently no strong evidence supporting supplementation with specific amino acids for ICU patients.

Conclusions:

• Despite the likely importance of adequate protein, definitive conclusions on optimal dosing and timing remain elusive due to conflicting results and varied study methodologies.
• The heterogeneity in study designs and outcome measures complicates the establishment of uniform recommendations for protein intake in the ICU.
• Ongoing large clinical trials are expected to provide further clarity on protein delivery strategies for critically ill patients.