The following is a description of how the calorie needs (kcal/day) and protein needs (gm/day) are determined for this burn patient. Because the burn is so severe, the needs are based entirely on the burn size. If this had been a minor burn (e.g., 10% burn or less), then additional considerations would be included for the tibia and fibula fractures and crushed right ankle.
Kcal needs are based on age, sex, body size and severity of burn. One way to determine total kcal needs per day for a burn patient may be to use the following calculation:
Basal Energy Expenditure (BEE)+Stress/Injury Factor
Various formulas have been developed for estimating BEE. One of the most widely used formulas is the Harris Benedict Formula.
BEE (kcal/day)=66.47 + (13.75 X Weight) + (5 X Height) - (6.76 X Age)
BEE (kcal/day)=655.1 + (9.56 X Weight) + (1.85 X Height) - (4.68 X Age)
Weight = Body weight in kg
Height = Actual height in cm
Age=Actual age in years
These estimates are then multiplied by a stress/injury factor
The stress factors used for burn patients are as follows:
Burns covering 10% to 15% of the body surface rarely show significant increases in the metabolic rate. However, for more extensive burns, a close relationship exists between burn size (or extent of open wound) and increased metabolic rate. The metabolic rate may increase 2.0 to 2.25 times the normal values(X). These values are close to the maximum increase possible. In fact, patients with greater than 50% body burns are not capable of further increases in metabolic rate (so calculated total kcal/day needs would only be about twice BEE).
Another formula used for burn patients is the Curreri Formula:
(25 kcal X kg usual body wt) + (40 X % total body surface area burned)(TBSA)
The maximum of TBSA is limited to 50%. Although the Curreri Formula is commonly used for calculating kcal/day needs of burn patients, some feel that this formula tends to over-estimate caloric needs.
Overfeeding can be as dangerous as underfeeding. Complications of overfeeding include: hyperglycemia and hyperosmolality (which can lead to osmotic diuresis, dehydration, and ketotic acidosis), and hepatic steatosis.
It is believed that beyond the infusion of 5 mg glucose/kg/min, there is no further increases in glucose oxidation or protein synthesis.
The preferred method of estimating total kcal/day needs at KUMC, according to Carolyn Dellenbaugh MS., R.D., is to estimate BEE, multiply that estimate by a stress/injury factor of 2.0, and compare the result to the estimate derived from the Curreri Formula. The smaller of the two estimates is then utilized in treatment.
The optimum amount of protein required for wound healing and maintenance of lean tissue mass is still a matter of speculation. For an extensive burn, 20 to 25 g of nitrogen per day is required the first 2 weeks after a burn.
To assure that protein is utilized for protein synthesis and NOT for meeting kcal needs, the nonprotein kcal to nitrogen ratio varying from a minimum of 100 to a maximum of 200 kcal/gm nitrogen has been recommended (1). For comparison, the ideal nonprotein kcal to nitrogen ratio for the non-injured person would be about 300 to 400 kcal/gm nitrogen.
Reference and Further Reading: