According to the current literature data, free oxygen radicals and mechanism of lipoperoxidation play an important role during development of muscular system dysfunction during sepsis and septic shock. Muscular dysfunction can affect respiratory muscles and contribute to muscular fatigue with subsequent need for ventilatory support. The aim of the study was to assess the degree of lipoperoxidation and capacity of antioxidatory apparatus in patients during weaning period. In 37 mechanically ventilated patients we prospectively monitored the concentrations of malonedialdehyd, glutathion, glutathionperoxidase activity and superoxiddismutase activity; betacaroten concentrations and selenium concentrations. The values were obtained on admission, last day of mechanical ventilation, at the start of weaning and after 24 hours of spontaneous breathing after disconnecting from ventilatory support. According to the length of weaning, patients were divided into two groups: group S, weaning period Ł 3 days, n = 15; group L, weaning period > 3 days, n = 22. Patients weaned for more than three days had significantly higher concentrations of malonedialdehyd on admission, significantly lower activity of glutathionperoxidase level when successfully weaned, non-significantly lower levels of beta-caroten and selenium. Prolonged ventilatory support and weaning period longer than three days were associated with higher degree of lipoperoxidation on admission and with a decrease of concentrations of selected markers of antioxidatory protective mechanisms. The results support an assumption that lipoperoxidation may play a role in the development of muscular system dysfunction in patients during the weaning period.

        Key words: sepsis – muscular dysfunction – weaning from ventilator – lipoperoxidation – selenium