Mild Brain Hypothermia Suppresses Oxygen Free Radicals in Patients with Neuroemergency: An Ex Vivo Electron Spin Resonance Study

Oxygen free radicals play important roles in brain injury, and one of the most important effects of brain hypothermia treatment is to suppress the generation of free radicals. In the present study, alkoxyl radical was determined utilizing ex vivo electron spin resonance (ESR) spectroscopy. Brain hypothermia was induced in traumatic brain injury (TBI) patients (n = 12) and global ischemic (GI) patients after cardiac arrest (n = 3) for 72h. Whole blood was sampled from the jugular vein and the radial artery at each stage of the treatment. In TBI patients, the radical intensity of the jugular vein (RIJV) was significantly higher than that of the control group and decreased gradually (P < 0.05: Student’s t-test). Conversely, the radical intensity of the radial artery (RIRA) gradually increased throughout the treatment. In GI patients, high RIJV and RIRA were observed in comparison with those of TBI patients. These data reflect the oxidative stresses of patients under brain hypothermia, and the ex vivo ESR method is useful for determination of the kinetics of oxygen free radical generation.