A longitudinal evaluation of oxidative stress in trauma patients.

Background: The purpose of this study was to determine the course of oxidative stress in trauma patients as measured by antioxidant disappearance and modulation of DNA damage. The study also explored the role of injury severity and the effect of changes in plasma lipoprotein concentration as the result of hemodilution on lipid-soluble plasma antioxidant concentrations.
Methods: The study population included 17 adult male trauma patients in an urban level-1 trauma hospital and 12 healthy adult male controls. Blood was collected immediately after admission in the emergency room, and on days 2, 3, 4, 6, and 8 of admission. Plasma antioxidant concentrations and total cholesterol concentrations were evaluated. DNA damage was evaluated using the ratio of 8-hydroxydeoxyguanosine to deoxyguanosine (8OhdG to dG). Admission data were compared with data from controls.
Results: Plasma antioxidant concentrations (except alpha-tocopherol) significantly decreased by 9.9% to 34.3% in the 24 hours after trauma and remained depressed throughout day 8. Repeated measures regression analysis for trend showed a significant increase in unadjusted alpha-tocopherol from day 1 to day 8 (p < .008). No other unadjusted antioxidant or plasma cholesterol showed a significant change. After individually adjusting antioxidant concentrations by total cholesterol, only gamma-tocopherol (22.2%) and lycopene (22.6%) were decreased (p < .04) in the 24 hours after trauma. Repeated measures regression analysis for trend for the cholesterol-adjusted antioxidants showed a significant decrease from day 1 to day 8 for cholesterol-adjusted alpha-carotene (p < .007) and beta-carotene (p < .007). Trauma patients were divided into more and less severely injured groups based on Injury Severity Score (ISS). Decreases in antioxidant concentration from day 1 to day 2 were found for the patients in the more injured group, with no significant differences from day 1 to day 2 in the less severely injured group. Cholesterol-adjusted gamma-to copherol (29.7%, p < .003) and lycopene (32.7%, p < .05) decreased from day 1 to day 2 in the more severely injured group. Using repeated measures regression analysis for trend, the only antioxidant that was significantly different in the high versus low ISS groups from day 1 through day 6 was cholesterol-adjusted lutein-zeaxanthin (p < .02). Compared with controls, trauma patients had significantly lower (27.3% to 64.9%) concentrations of all cholesterol-adjusted antioxidants at day 1 except for lycopene. Trauma patients had higher leukocyte 8OhdG to dG ratios at admission (42.6%, p < .05), but 8OhdG to dG ratios tended to decrease over the 24 hours after trauma (p < .07). This decrease was greater in the 3 trauma patients with an admission 8OhdG to dG ratio greater than 6 x 10(-5) (59.3% versus 0.05%, p < .03).
Conclusions: The difference in antioxidant concentrations between trauma patients and controls may have been associated with oxidative stress or with a poorer diet. The difference between antioxidant concentrations and cholesterol-adjusted antioxidant concentrations is likely caused by hemodilution or by changes in plasma lipid levels as a result of trauma. Therefore, individually adjusting lipid-soluble antioxidant concentrations by total cholesterol concentrations is important in trauma patients. Leukocyte 8OhdG to dG ratios were already elevated in trauma patients on admission but returned nearly to control levels 24 hours later, indicating short-term responsiveness to DNA oxidation in trauma patients and an extensive capacity for DNA repair within 24 hours.