Temporal variation of oxidant stress in critically ill patients

Our aim was to investigate indicators of lipid peroxidation via observing temporal changes or daily fluctuations in cytoprotective enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), and serum components possessing antioxidant activity against free radicals and malondialdehyde (MDA) such as uric acid. This study was conducted in a small number of critically ill patients versus healthy volunteers in order to design an effective antioxidant therapy regimen under oxidative stress.

Six critically ill patients and 6 young healthy volunteers were recruited. Blood samples were collected 6 times a day with 4 h intervals starting from 8 a.m. From the blood samples, SOD and GSH-PX activities and uric acid and MDA levels were determined. One-way ANOVA and unpaired t-test were used to assess differences within and between the groups, respectively. A two dimensional table curve cosine formulation was performed to elucidate rhythmycity.

No significant differences were found in SOD and GSH-PX activities or uric acid levels within the 24 h period or between the groups. MDA levels were significantly higher in the study group at 8 p.m. than that of control group (P<0.05), but no significant difference was found within the 24 h period. We showed that GSH-PX activities in control and study groups revealed temporal variation, whereas uric acid levels varied temporally only in the study group.

We concluded that there are signs of oxidative stress in ICU patients that vary in time but further studies are required in order to design appropriate antioxidant treatments.