Trauma, including operative damage, may have the following nutritional sequels:
- total energy expenditure:
- in minor trauma and even quite large operations such as gastrectomy and colectomy, total energy expenditure is not necessarily increased. Active metabolic expenditure is reduced as the patient is usually sedentary and this compensates for an increased resting metabolic rate, typically of 10-15%.
- in major trauma, surgery and other hypercatabolic states, total energy expenditure is increased as a result of large increases in resting metabolic rate e.g. 100% with severe burns, and frequently, an inability to increase nutritional intake.
- protein: the type of operation determines the amount of protein loss. Muscle mass lost is significantly greater than that of protein mass; the ratio is 1 gram of protein to 5 grams of muscle. Hence, if catabolism is expressed as nitrogen loss per day in grams:
- herniotomy 3g/day
- appendectomy 6g/day
- cholecystectomy 12g/day
- fractured femur 15g/day
- peritonitis 18g/day
Physiologically, the changes in metabolism with increasing severity of insult are a result of:
- inflammatory and necrotic cells releasing cytokines, particularly TNF, IL-1 and IL-6
- adrenaline and glucagon causing early glycogenolysis
- cortisol and glucagon stimulating gluconeogenesis
- growth hormone, glucagon and noradrenaline increasing lipolysis