Influence of positive end-expiratory pressure on intracranial pressure and cerebral perfusion pressure in patients with acute stroke

We undertook this study to evaluate the influence of positive end-expiratory pressure (PEEP) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in patients with acute stroke. A total of 20 ventilated patients of a neurological intensive care unit were examined under a protocol entailing variation of PEEP to 4, 8, 12, and 4 mm Hg; mean arterial blood pressure (MAP), ICP, heart rate, and mean velocity of the middle cerebral arteries (V(m) MCA) were recorded. CPP significantly changed depending on the various PEEP levels. No significant differences in remaining parameters were evident. Three distinct reaction patterns of the parameters monitored were observed: (1) All parameters remained stable through the various PEEP levels (15 patients, 40 examinations). (2) Increase in PEEP resulted in a significant decrease of MAP, while V(m) MCA remained unchanged, indicating an intact cerebral autoregulation. A slight (statistically insignificant) increase in ICP, which was significantly related to the MAP changes, was evident (7 patients, 16 examinations). (3) Increase in PEEP resulted in a decrease of MAP and V(m) MCA; ICP remained unchanged or demonstrated a slight decline (3 patients, 6 examinations). PEEP increase up to 12 mm Hg does not significantly influence ICP. The observed marked changes in CPP are mediated through the MAP. Thus, PEEP application should be safe, provided that MAP is maintained.