B: PROTEIN REQUIREMENTS

The protein demands to achieve adequate protein synthesis in the surgical patient are at least 50% of above the recommended daily allowance (RDA) of 0.8/g/kg/day.  Because of the “stress response” seen with virtually any wound, a catabolic state is present.  A burn injury requires 1.5 to 2 g/kg/day.  Of note is that just being elderly (over 70 years of age) requires a higher protein content then the young adult due to less endogenous anabolic activity.  An increase in protein content in excess of 2g/kg/day will not increase protein synthesis any further and protein is simply used for calories.

Increasing anabolic drive with resistance exercise or addition of an anabolic agent will however increase net protein synthesis as long as adequate protein intake is provided.

Carbohydrate is the preferred fuel for most tissues, but there is a clear limit to the amount of carbohydrate that will be used, especially in the hypermetabolic burn or septic patient.  Current recommendations are that carbohydrate infusion not exceed 5 to 7 mg per kilogram per minute or 1800 to 2200 carbohydrate calories per day.  Excess carbohydrate will only result in fat formation, which is energy requiring rather than energy producing, and the RQ approaches 8 for this process, leading to a marked increase in carbon dioxide production.

Fat can be safely used to provide calories not provided by carbohydrate: fat can be used to provide up to 30 percent of estimated calories. Excess fat can be deleterious, being deposited in the liver.  Also, triglycerides exceeding 250mg/dl can result in complications of fat, deposition in visceral organs.  A triglyceride level is a good marker of the adequacy of fat clearance and utilization.  Levels should be less than 250mg/dl.