Effects of positive end-expiratory pressure on intracranial pressure and cerebral perfusion pressure.

The effect of positive end-expiratory pressure (PEEP) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) has been reported by several investigators, without any consensus being reached. Acute neurological and neurosurgical patients suffer intracranial hypertension and acute lung injury with hypoxemia. Since PEEP may improve hypoxemia but elevate ICP and decrease CPP, it is important to determine the influence of varying levels of PEEP on ICP and CPP. The aim of the study was to investigate the changes in ICP and CPP associated with different levels of PEEP. Twenty patients requiring ICP monitoring and mechanical ventilation were enrolled. Patients had severe head injury (n = 10), spontaneous intracerebral haemorrhage (n = 5), and subarachnoid haemorrhage (n = 5). PEEP was raised from 5 (basal) to 15 cm H2O in steps of 5 cm H2O. After at least 10 minutes of each new PEEP setting, ICP and CPP were measured. PEEP at 10 and 15 cm H2O produced a significant (p < 0.05) increase in intracranial pressure 11.6 +/- 5.6 and 14.6 +/- 6.28 mm Hg, respectively; no significant (p = 0.819) change occurred in CPP.