Lipid peroxidation, antioxidant status and selenium levels in patients requiring prolonged ventilatory support

Introduction

Recently free oxygen radicals have been implicated as possible mediators of respiratory muscle dysfunction, particularly diaphragm fatigue. The aim of the study was to evaluate lipid peroxidation, antioxidant status and selenium levels in patients with sepsis requiring ventilatory support and during weaning.

Methods

After institutional approval 40 critically ill patients were prospectively studied during ventilatory support and weaning, three patients due to death were excluded. All patients were weaned according to standard weaning protocol. Blood samples were drawn daily and collected until analysis. Malondialdehyde (MDA) serum levels, total glutathion (GSH), glutathion-peroxidase (GPX) and superoxid-dismutase (SOD) activity in erythrocytes and serum selenium levels were estimated at the time of admission to ICU (T1), on the last day of full ventilatory support (T2), on the day when weaning was started (T3) and on the first day of spontaneous ventilation (T4). After successful weaning patients were divided in two groups according to the length of weaning (W): group S (W ≤ 3 days, n = 15), group L (W > 3 days, n = 22). t-test or Mann Whitney Rank Sum test were used for statistical analysis (SigmaStat, Jandel Co., USA), values are expressed as mean (SD) or median (25%–75% percentiles), P < 0.05 was considered statistically significant.

Results

Summarized selenium values (μmol/1) were 0.63 (0.28) in Group S and 0.57 (0.16) in Group L.

Discussion

Prolonged ventilatory support and weaning longer than 3 days were associated with higher MDA levels and lower GPX levels, also selenium levels were insignificantly lower in patients with prolonged ventilatory support. The clinical importance of these findings needs to be further studied.

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