Age-related differences in the metabolic response to injury

Objective: To investigate the effect of age on the metabolic response to in jury. Methods: Fifty-two trauma patients meeting entrance criteria were prospecti vely enrolled. Patients were grouped by age: elderly, >60 years; and young, less than or equal to 60 years, After 4 days of nutrition support, physiol ogic and laboratory data were collected. Energy and nitrogen metabolism, an d body composition were evaluated. Results: Elderly patients demonstrated a reduced incidence of fever (48% vs . 77%, p = 0.027). Independent of body composition, temperature, and injury severity, oxygen consumption was 8% lower in the elderly (p = 0.0032), How ever, nitrogen loss and myofibrillar catabolic rate was not altered by age. Elderly subjects were more often hyperglycemic (38% vs. 0%, p < 0.0001) an d azotemic (62% vs. 22%, p = 0.004), despite similar carbohydrate and prote in intake. Conclusion: Fever is less common and oxygen consumption Lower in elderly tr auma patients. Postinjury myofibrillar protein catabolism and nitrogen loss are not influenced by aging, Metabolic complications of nutrition support (hyperglycemia, azotemia) are more common in elderly trauma patients.