Oxidative stress in critically ill patients with systemic inflammatory response syndrome

Objective: To evaluate whether critically ill patients with systemic inflammatory response syndrome, on admission to an intensive care unit, had more severe oxidative stress than those without this syndrome. Design: A prospective, cohort study. Setting: A mixed medical and surgical adult intensive care unit with 12 beds. Patients: A total of 68 consecutive patients admitted to the intensive care unit. Interventions: Venous blood samples were routinely obtained within 24 hrs of admission. Measurements and Main Results: Patients' plasma total antioxidant capacity, the lipid peroxidation products malondialdehyde and 4-hydroxynonenal, reduced sulfhydryl groups, and nitrites/nitrates were measured by spectrophotometric technique at admission to the intensive care unit. Myeloperoxidase (enzyme-linked immunosorbent assay) and polymorphonuclear elastase (immuno-activation assay) were also measured on admission to the intensive care unit. The patients with criteria of systemic inflammatory response syndrome (n = 20) had higher Acute Physiology and Chronic health Evaluation Ill scores (determined by collecting the worst value within 24 hrs after admission to the intensive care unit) and plasma concentrations of lipid peroxidation products and nitrites/nitrates and lower plasma concentration of reduced sulfhydryl groups and plasma total antioxidant capacity than patients without the syndrome (n = 48). Moreover, the markers for leukocyte activation, myeloperoxidase and polymorphonuclear elastase, presented higher concentrations in the plasma of patients with systemic inflammatory response syndrome. Conclusions: Patients admitted to the intensive care unit with criteria of systemic inflammatory response syndrome had a more severe oxidative stress than patients without this syndrome.