Intracranial hypertension and cerebral perfusion pressure: Influence on neurological deterioration and outcome in severe head injury

Object. Recently, a renewed emphasis has been placed on managing severe hea d injury by elevating cerebral perfusion pressure (CPP), which is defined a s the mean arterial pressure minus the intracranial pressure (ICP). Some au thors have suggested that CPP is more important in influencing outcome than is intracranial hypertension, a hypothesis that this study was designed to investigate. Methods. The authors examined the relative contribution of these two parame ters to outcome in a series of 427 patients prospectively studied in an int ernational, multicenter, randomized, double-blind trial of the N-methyl-D-a spartate antagonist Selfotel. Mortality rates rose from 9.6% in 292 patient s who had no clinically defined episodes of neurological deterioration to 5 6.4% in 117 patients who suffered one or more of these episodes; Is patient s were lost to follow up. Correspondingly, favorable outcome, defined as go od or moderate on the Glasgow Outcome Scale at 6 months, fell from 67.8% in patients without neurological deterioration to 29.1% in those with neurolo gical deterioration. In patients who had clinical evidence of neurological deterioration, the relative influence of ICP and CPP on outcome was assesse d. The most powerful predictor of neurological worsening was the presence o f intracranial hypertension (ICP greater than or equal to 20 mm Hg) either initially or during neurological deterioration. There was no correlation wi th the CPP as long as the CPP was greater than 60 mm Hg. Conclusions. Treatment protocols for the management of seven head injury sh ould emphasize the immediate reduction of raised ICP to less than 20 mm Hg if possible. A CPP greater than 60 mm Hg appears to have little influence o n the outcome of patients with severe head injury.