Changes in cerebral oxygen metabolism in patients with severe head injury and its significance

Objective:To investigate the changes in cerebral oxygen metabolism following head injury and its relationship with intracranial pressure (ICP).Methods:15 patients with acute severe head injury were studied,and 10 healthy objects were used as the control.By using a technique of jugular catheterization and blood sampling,the changes in oxygen saturation of jugular blood (SjO 2),cerebral extraction of oxygen (CEO 2) and cerebral arteriovenous difference of oxygen(AVDO 2) were observed.Furthermore,the relationship of these parameters with ICP was analyzed.Results:On the first day postinjury,SjO 2 decreased,CEO 2 and AVDO 2 increased;on the secondfourth day,SjO 2 increased,CEO 2 and AVDO 2 decreased.With mild to moderate elevations of ICP,SjO 2 increased,CEO 2 and AVDO 2 decreased;with severe elevation of ICP,SjO 2 decreased,CEO 2 and AVDO 2 increased.Conclusions:When the brain is severely injured,there is cerebral hypoxia or ischemia during the first 24 hours,and cerebral hyperemia in the following secondfourth days. Severe elevation of ICP results in cerebral hypoxia and ischemia,but mild to moderate elevations of ICP do not.