Early changes of intracranial pressure, perfusion pressure, and blood flow after acute head injury. Part 1: An experimental study of the underlying pathophysiology

The present study examines intracranial pressure (ICP), cerebral perfusion pressure (CPP), and cerebral circulation immediately after experimental head injury in an animal model. The underlying systemic hemodynamic changes were also observed. To produce a standardized head injury, a fluid-percussion device was applied to the dura at the midline of 10 piglets. Seven other nontraumatized animals served as a control group. Hemodynamic parameters as well as ICP and CPP were recorded on-line, one value every 1.4 seconds. Cerebral blood flow (CBF) and cerebral vascular resistance (CVR) were measured three times using a microsphere technique. Immediately after head injury, the traumatized animals showed a sudden increase in ICP, with a maximum of 40 torr at 3 to 5 minutes, while there was a pronounced decrease in CPP from 85 to 40 torr. The CBF in the various brain areas fell from 55 to 22 ml/min/100 gm within 5 minutes after the impact, and CVR increased to 300% of control values within 90 minutes. The findings of this study demonstrated that cerebral circulation is critically jeopardized within a few minutes after trauma. This, in combination with a subsequent increase in CVR, makes the early development of ischemic brain damage very likely. In traumatized patients, treatment prior to hospital admission must therefore be directed at prevention of this fatal course.