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THE
BURN NUTRITION MODULE
Section
IX
Metabolic
Response to Burn Injury During ‘Stress Phase’ Effect of Optimal
Nutrition
- Nutrition
Attenuates "Stress" changes
- Increased
Metabolic Rate Persists
- Lean
Mass Loss Decreased By Half
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Providing
the necessary energy in the form of carbohydrates (50-55% of calories)
and fat (25% of calories) will decrease the degree of gluconeogenesis
and the degree of lean mass loss as long as sufficient protein is
provided for synthesis.
The
protein should be given at 1.5-2g/kg/day approximately 20% of the
protein will still be burned for fuel due to the abnormal metabolic
activity. However sufficient protein will remain to continue
protein synthesis need for tissue repair and wound healing.
Protein intake in excess of 2g/kg/day does not appear to be more
beneficial.
Since
the hypermetabolic-catabolic stress response continues, optimum
nutrition will attenuate (by about 50%) but by itself cannot eliminated
the erosion of lean mass. Wound closure and resolution of the
stress response is required.
Having
discussed the basics of nutritional support we can now put this
information together into a basic schema of how it should work.
Recognizing the deleterious effects on body composition in the patient
without nutritional support, we can now discuss optimum nutrition and
its impact on the metabolic dysfunction. Nutrition provided in the
correct nutrient mix attenuates but does not shut off the protein
loss. Providing the necessary increased calories being consumed (35/40
Kcal/day) is essential. The appropriate mix is carbohydrates 55-60%,
fat is no more than 25% and the rest is protein (1.5-2g/kg/day) or
20-25% of calories. Provision of increased micronutrients is also
essential.
Nutritional support does not prevent the amino acid use for glucose.
Also there is no change in the hormonal imbalance, therefore metabolic
rate, heat production, gluconeogenesis and limited use of the fat
depot persists.
Providing the high protein intake allows for increased amino acids
available for protein synthesis, especially for wound healing.
Specific amino acids such as glutamine become depleted (if not
replaced) but net protein loss and lean mass loss are attenuated.
Occluding or closing the burn wound will decrease energy loss. Also
adding an anabolic stimulus can further increase protein synthesis.
The most important impact of nutritional support is first to provide
adequate energy and the second is the attenuation of lean mass loss.
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