Impact of acute renal failure on antioxidant status in multiple organ failure.

BACKGROUND: Acute renal failure (ARF) can be triggered or aggravated by reactive oxygen species (ROS) but established ARF per se might also affect the antioxidant defence mechanisms of the organism. We evaluated a broad pattern of antioxidants in critically ill patients with multiple organ failure with (MOF-ARF) and without acute renal failure (MOF) to identify any potential involvement of renal dysfunction in the depletion of the antioxidant system. METHODS: Observational study; 13 patients with MOF were investigated (9 with and 4 without ARF), and 17 healthy subjects served as controls. Blood samples were drawn after establishment of MOF. Plasma levels of ascorbate, alpha-tocopherol, retinol, beta-carotene, selenium and lipid peroxidation products (MDA) were determined and the activities of the antioxidant enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione-peroxidase (GSH-PX) in erythrocytes were measured. In addition, ROS production (superoxide anion and hydrogen peroxide) in activated neutrophils was assessed. RESULTS: Plasma levels of ascorbate, beta-carotene and selenium were reduced in both patient groups, when compared to controls. Decrease in selenium was more pronounced in the MOF-ARF group. MDA levels were increased in both groups, again being more pronounced in MOF-ARF patients compared to MOF patients. Hydrogen peroxide production by neutrophils from both patient groups was lower than from controls. CONCLUSION: A depression of the antioxidative system is present in critically ill patients with MOF. In patients with associated ARF this was even more pronounced and plasma MDA levels were higher, suggesting an additional effect on the antioxidative potential in the presence of renal dysfunction and/or renal replacement therapy.

Antioxidant status in patients with acute respiratory distress syndrome.

OBJECTIVES: Reactive oxygen species (ROS) have been implicated in the pathophysiology of ARDS. We investigated the pattern of antioxidants in plasma and ROS production by neutrophils in patients with ARDS over 6 days. DESIGN: Observational study. Blood samples were taken when the diagnosis was made (D0) and after 3 (D3) and 6 days (D6) during therapy. SETTING: Intensive care units at a University Hospital. PATIENTS: Eight patients with ARDS were investigated, 17 healthy volunteers served as controls. MEASUREMENTS AND RESULTS: Plasma levels of ascorbate, alpha-tocopherol, retinol, beta-carotene, selenium and lipid peroxidation products (MDA) were determined and the activities of the antioxidative enzymes catalase (CAT), superoxide dismutase (SOD) and glutathione-peroxidase (GSH-PX) in erythrocytes were measured. In addition, ROS production (superoxide anion and hydrogen peroxide) in activated neutrophils was assessed. Plasma levels of alpha-tocopherol, ascorbate, beta-carotene and selenium were reduced from the onset of illness. MDA plasma levels were increased throughout the illness. ROS generation from neutrophils was normal on D0 and decreased to D6 in ARDS patients. CONCLUSION: The antioxidative system is severely compromised in patients with ARDS. Plasma levels of alpha-tocopherol, ascorbate, beta-carotene and selenium are decreased. Elevated MDA levels provide further evidence of massive oxidative stress. The routine replacement of micronutrients according to recommended daily allowances was inadequate to compensate for the increased requirements.