Temporal variation of oxidant stress in critically ill patients.

AIM: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.