Nutrition Therapy in Critically Ill Adults

In the acute phase of critical illness, adults have severe catabolism, inflammation, muscle loss, and gut dysfunction, all of which shape nutritional requirements. Early enteral nutrition supports gut integrity and microbiome health, but trials have shown that early short-term parenteral nutrition is a safe alternative when enteral feeding is not possible. Large trials have shown that early full-dose energy delivery offers no benefit over restrictive dosing and may increase gastrointestinal and metabolic complications, findings that support a restrictive nutrition strategy, especially in patients who have circulatory shock or are at risk for refeeding syndrome. Similarly, large trials have shown no advantage of high-dose over standard-dose protein and suggest harm in patients with acute kidney injury. Because adverse events are common with enteral nutrition, safe nutrition delivery requires gradual advancement, strategies for prevention of refeeding syndrome, glycemic control, and avoidance of routine gastric residual volume monitoring. Patient heterogeneity underscores the need for precise, biomarker-guided, phase-specific nutrition to preserve lean muscle mass and improve recovery.