Nutritional support of the critically ill patient

Area of Science:

• Metabolic response to injury and critical illness
• Nutritional support in catabolic states

Background:

• Injury and stress induce a significant metabolic response characterized by hormonal changes (glucagon, catecholamines, glucocorticoids, etc.).
• This response leads to protein catabolism, increased fat oxidation, and altered nutrient metabolism, potentially causing lean body mass loss.

Purpose of the Study:

• To outline the metabolic alterations following injury or stress.
• To discuss the challenges and goals of nutritional therapy in critically ill patients.

Main Methods:

• Assessment of hormonal profiles and metabolic shifts (protein lysis, fat oxidation, gluconeogenesis, ureagenesis).
• Evaluation of nutrient tolerance and metabolic efficiency of parenteral energy sources (dextrose, fat emulsions).
• Measurement of urinary nitrogen losses to estimate energy and protein requirements.

Main Results:

• Elevated hormones promote catabolism, increasing lean body mass loss.
• Critically ill patients may poorly tolerate or inefficiently metabolize exogenous nutrients.
• Urinary nitrogen loss indicates the degree of stress and aids in estimating nutritional needs.

Conclusions:

• Nutritional therapy should focus on preserving lean body mass through appropriate substrate provision.
• Careful monitoring of metabolic, fluid, electrolyte, and organ function is crucial for stressed patients.
• Improving patient survival is the ultimate goal of effective nutritional management in critical illness.