Chapter 10. Surgical Metabolism & Nutrition
Which of the following is not a proposed mechanism by which enteral feeding decreases bacterial intestinal wall translocation when compared to IV nutrition?
A. Preserved local cytokine expression pattern
B. Increased villous height and over all mucosal mass
C. Bactericidal activity of enteral nutritioncomponents
D. Stimulation of intraluminal IgA transportation
C. Bactericidal activity of enteral nutrition components. Multiple mechanisms have been proposed for the morphological and functional differences observed in the intestinal epithelium with parenteral nutrition (PN) when compared to enteral nutrition. It has repeatedly been demonstrated that small bowel mucosal mass is lost with only PN. Yang and colleagues demonstrated that the administration of 25% enteral nutrition reversed the abnormal IL-10, IL-4, and IL-6 messenger RNA (mRNA) expression that had resulted from only PN support in animal models. This is of particular significance as these changes in cytokine expression were associated with epithelial leak and an increased rate of enterocyte apoptosis.
It has also been shown that the type and route of nutrition affect pIgR expression in an organ-specific manner; pIgR represents the exclusive transport pathway for IgA to move from the lamina propria, through the epithelia, into the lumen of the gut where it acts as a key component in the gut’s defense. Enteral nutrition components are not bactericidal and actually help preserve normal flora.
Which of the following stressors results in the greatest increase in energy expenditure above basal metabolic needs?
D. Burns. Energy requirements above basal needs are approximately 10% for elective operations, 10%-30% for trauma, 50%-80% for sepsis, and 100%-200% for burns. Burns covering more than 40% total body surface area (TBSA) are typically followed by a period of severe stress, characterized by an exaggerated catabolic state. Increases in catecholamine, glucocorticoid, glucagon, and dopamine secretion are thought to initiate the cascade of events leading to the acute hypermetabolic response with its ensuing catabolic state. Appropriate nutrient delivery can be accomplished by feeding 1.2-1.4 times the measured resting energy expenditures (REEs).
Regarding centrally administered parenteral nutrition in the critically ill patient, which of the following is not true?
A. An initial formulation for nonamino acid calories is generally advised to consist of 70% dextrose and 30% fat emulsion.
B. TPN should be avoided if anticipated use is less ...