In clinical practice, the oxidative stress is related to circulatory shock, sepsis, acute lung injury, and acute respiratory distress syndrome. There are some questions on the oxidative stress of the critical illness. First, the investigators want to search out the effects of the past history, smoking, alcohol drinking, use of antioxidants, different diseases, and different duration of SIRS on the degree of oxidative stress. Second, besides total count of ROS, the investigators used new techniques to determine superoxide(O2●-), hydrogen peroxide (H2O2), and hypochlorous acid(HOCl). Furthermore, we want to investigate the correlation of the degree of different reactive oxygen species and the severity of SIRS or shock. Third, we try to investigate the correlation between the change of oxidative stress and the prognosis of the patients.

The investigators wish this study will help them to investigate the effect of oxidative stress on critical ill patients, to modulate the oxidative stress, to decrease the occurrence of SIRS, shock, and multiorgan failure, and to improve the long term outcome of patients.