Plasma redox status relates to severity in critically ill patients.

OBJECTIVE: To determine the relation between plasma redox status and severity of illness for patients admitted to an intensive care unit (ICU).
DESIGN: A prospective cohort study.
SETTING: A mixed medical and surgical adult ICU with 12 beds. PATIENTS: A total of 73 consecutive patients admitted to the ICU.
INTERVENTIONS: Venous blood samples were routinely obtained within 24 hrs of admission.
MEASUREMENTS AND MAIN RESULTS: Plasma total antioxidant capacity and lipoperoxides were measured by spectrophotometric technique at admission to the ICU. The plasma ratio total antioxidant capacity (mM)/lipoperoxides (microM) was used as an index of plasma redox status. Plasma concentration of the markers of leukocyte activation myeloperoxidase (enzyme-linked immunosorbent assay) and polymorphonuclear-elastase (immunoactivation assay) were also measured at admission to the ICU. Analysis of correlation between plasma ratio total antioxidant capacity/lipoperoxides and APACHE III score showed a negative association (p < .001, Spearman correlation test). Myeloperoxidase and polymorphonuclear-elastase correlated positively with Acute Physiology and Chronic Health Evaluation III scores (r2 = 0.58; p < .001; and r2 = 0.05; p = .035; respectively).
CONCLUSIONS: Plasma redox status relates to severity in critically ill patients. We propose that it would be reasonable to provide antioxidant therapy as part of routine management of patients admitted to a mixed ICU, regardless of the specific reason for ICU admission. Plasma redox status might become useful to evaluate the risk in critically ill patients.