Intracranial pressure changes in brain-injured patients requiring positive end-expiratory pressure ventilation.

In 16 patients with severe head injury and 2 patients with subarachnoid hemorrhage, positive end-expiratory pressure (PEEP) ventilation was required to maintain adequate oxygenation. The effects of PEEP on intracranial pressure (ICP) were evaluated with respect to the volume-pressure response (VPR), an indicator of intracranial compliance, and the static lung compliance (CL). Based on these parameters: (a) All 11 patients with a normal VPR (less than 2 torr) had no significant change in ICP with PEEP therapy. (b) All 5 patients with abnormal VPR and a normal CL (greater than 30 ml/cm H2O) had significantly increased ICP or decreased cerebral perfusion pressure while on PEEP. (c) Two patients with both an abnormal VPR and a decreased CL had no significant change in their ICP with PEEP. (d) Significant elevations of ICP were also seen in 4 patients with abnormal VPRs concurrent with the rapid reduction or withdrawal of PEEP ventilation. Thus, the VPR is an accurate predictor of the effects of PEEP on the ICP. In addition, however, decreased lung compliance may buffer these effects in patients who have decreased intracranial compliance. We propose that ICP monitoring and intracranial compliance determination are necessary in the management of brain-injured patients requiring PEEP ventilation.