We recently developed a new technique for measuring serum NO2 and NO3 levels precisely, and we examined these parameters in severely brain-injured ICU patients who could not take nutrition intestinally. 2. Our results demonstrated that NO increased rapidly after stroke, trauma, and the occurrence of infection in all ICU patients. Elevation of NO2/NO3 was most pronounced 24 to 48 hr after trauma or ischemic stroke. This dysregulation of free radical elimination closely correlated with hemoglobin levels. 3. In most ICU patients, with the exception of those with complications of infection, the free radical potentials were maximal at 24 to 48 hr and continued to remain high for 4 to 5 days after trauma or stroke. The level of free radical potentials was closely correlated with the severity and prognosis of critically injured patients. None with radical potential values higher than 0.4 microM survived. 4. Clinically, the maintenance of hemoglobin at > 12 g/dl and lower body temperature were demonstrated to be successful in the management of these free radical reactions.
