What factors influence protein synthesis and degradation in critical illness?

PURPOSE OF REVIEW: The optimal approach to improve protein metabolism in critical illness is not yet fully defined. Here, we have summarized recent literature dealing with the main catabolic and anabolic factors influencing protein kinetics in acute hypercatabolic patients. RECENT FINDINGS: Protein/amino acid intake levels should be adapted to type and severity of illness, keeping in mind that energy overfeeding is associated with poor outcome. A number of anticatabolic nutraceuticals and drugs have been tested in acute patients. The encouraging results have been obtained with β-hydroxy-β-methylbutyrate, omega-3 fatty acids, oxandrolone, propranolol, and metformin. Their efficacy and lack of side-effects need to be confirmed. Physical therapy, including muscle electro-stimulation, appears a very promising intervention, both effective and safe. SUMMARY: Protein catabolism can be minimized in acute patients by adequate nutritional support, early mobilization, and, possibly, pharmacological and nutraceutical interventions. A combination of these strategies should be tested in randomized controlled trials