Oxygen transport and organ dysfunction in the older trauma patient.

OBJECTIVES

To determine baseline values of cardiac index (CI) and oxygen transport variables in patients with multiple trauma within 24 hours of admission to a level I trauma center.

METHOD

This project was part of a larger study comparing methods of measuring oxygen consumption (VO2) in 38 severely injured patients. Measurements of CI, oxygen delivery (DO2), and VO2 were performed every 6 hours for 24 hours. Patients were monitored for multiple organ dysfunction syndrome.

RESULTS

The mean age was 59 (+/- 17) years, with 74% (n = 28) of patients 50 years or older. Patients 65 years or older had significantly lower levels of CI, DO2, and VO2. Initial age-related differences in CI (P < .001) persisted at each time period (P < .0136). Younger patients generated a higher DO2 at each time period (P < .0005). Even though there were persistent age-related differences in VO2 over time (P < .0001), no interaction between age and time was found. Survivors had lower scores for multiple organ dysfunction syndrome than did nonsurvivors (P < .0001), all of whom were 50 years or older. Mortality was 21%.

CONCLUSIONS

All patients were hypermetabolic, but older patients were much less so. Younger patients progressively had increased CI and DO2 levels, whereas older patients started with low levels that remained so. Patients in each age group appeared to lock into a level of VO2 that did not change over time. These findings underscore the vulnerability of older patients to poor outcomes. As the magnitude of the postinjury response is partly age-dependent, future research should differentiate patient characteristics associated with positive outcomes among elderly trauma patients.