Changes in urinary 8-hydroxy-2-deoxyguanosine in patients with global brain ischemia undergoing brain hypothermia therapy: comparison of whole body and selective head cooling

Introduction

Oxygen free radicals play an important role in global brain ischemia after cardiac arrest. Brain hypothermia therapy is effective in suppressing free radical expression. The aim of this study was to assess free radical expression under brain hypothermia, and to compare the expression between whole body and selective head cooling.

Methods

The subjects were 12 patients treated with mild brain hypothermia (34 ± 1°C) after resuscitation following cardiac arrest in our ICU; five patients received whole body cooling and seven patients received selective head cooling. We examined the hemodynamic changes and the urinary concentration of 8-hydroxy-2-deoxyguanosine (determined by HPLC) during brain hypothermia therapy. Furthermore, we compared the prognosis at 28 days after admission to the ICU.

Results

The induction time for whole body cooling was significantly shorter than that for selective head cooling. The rewarming time for head cooling was significantly shorter than that for whole body cooling. The mean arterial pressure and heart rate were both stable in the head cooling group. The urinary 8-hydroxy-2-deoxyguanosine concentrations decreased significantly in both groups, but data were significantly lower in the whole body cooling group compared with the selective head cooling group. Five and seven patients, respectively, exhibited good recovery 28 days after admission, in the whole body and selective head cooling groups.

Conclusion

Mild brain hypothermia therapy suppressed the production of free radicals following global brain ischemia. Whole body cooling had a stronger effect of suppression of free radicals compare with selective head cooling. It is considered that selective head cooling exhibits neuroprotection similar to whole body cooling.