Impact of Protein and Nutritional Support on the Muscular Status of Critically Ill Patients: A Pilot, Perspective, and Exploratory Study.

Background: Malnutrition and muscle weakness are highly prevalent in critically admitted patients. To overcome sarcopenia and muscle weakness, physical activity and neuromuscular electric stimulation have been introduced with limited efficacy. Thus, several anabolic remedies have been introduced. An adequate increase in protein support according to indirect calorimetry and body composition and methyl hydroxybutyrate (HMB) is emerging. Therefore, we wanted to investigate the impact of HMB-enriched whey formula on the nutritional status, muscle weakness, and clinical course of critically ill patients undergoing nutritional status multimodal assessment and physical rehabilitation.

Methods: We consecutively enrolled critically ill adult patients admitted to the intensive care unit (ICU) of "Santa Maria Hospital", Terni, Italy. All patients underwent preliminary anthropometric, laboratory tests, nutritional (bioimpedance vector analysis and indirect calorimetry), and ultrasound muscle assessment at admission (T0). Laboratory tests monitoring continued throughout the ICU stay. Nutritional and muscle strength assessment was taken weekly throughout the patient's ICU stay. All patients were enterally administered with a whey protein-enriched formula. Ten days after admission (during the physical rehabilitation period), patients were randomly administered a mixture of essential amino acids and methyl hydroxybutyrate (HMB).

Results: We consecutively enrolled 54 ICU patients. At the baseline, survivors (n = 46) were significantly younger than non-survivors. The latter had a worse SAPS II score, nutritional status, and risk, with no significant difference in basal metabolism. Prealbumin values significantly correlated with improved nutritional status and metabolism. Starting from 10 days upon ICU admission, the pennation angle (used as a measure of muscle strength) significantly correlated with the improvement in nutritional status. Whey proteins were well tolerated. Its administration showed a tendency to improve the pennation angle. No specific effect of the mixture containing essential amino acids and methyl hydroxybutyrate was observed. Nutritional status improvement and the rise of basal metabolism were significantly correlated with the extubation time. On the other hand, the reduction in muscle weakness was not significantly correlated with the timing of extubation.

Conclusions: Whey protein formula administration can significantly improve nutritional status and basal metabolism in ICU patients. This is reflected in improved muscle strength. Whey protein administration shows a tendency toward a rise in pennation angle. A similar and non-specific trend was observed upon HMB mixture add-one. Further prospective large-scale controlled studies are needed to confirm these promising results.