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

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Abstract

Objective

To determine the influence of positive end-expiratory pressure (PEEP) on intracranial pressure and cerebral perfusion pressure.

Design

Neurosurgical intensive care patients requiring intracranial pressure monitoring and mechanical ventilation were studied in a randomized, controlled study.

Setting

Tertiary care, neurosurgical intensive care unit.

Patients

Eighteen patients were enrolled in the study. Patients had posttraumatic head injuries (n = 9), subarachnoid hemorrhage (n = 7), obstructive hydrocephalus (n = 1), and intracerebral hemorrhage of unknown cause (n =1).

Interventions

Patients had PEEP levels of 5, 10, and 15 cm H2 O applied to their lungs.

Measurements and Main Results

Changes in intracranial pressure, mean arterial pressure, and cerebral perfusion pressure were measured. The results were analyzed separately for patients with normal and increased intracranial pressure (>15 mm Hg). PEEP at 5 cm H2 O had no effect on intracranial pressure in the group with normal intracranial pressure. However, PEEP at 10 and 15 cm H2 O produced a significant (p < .05) increase in intracranial pressure (1.9 and 1.5 mm Hg, respectively). In the group with increased intracranial pressure, no significant change in intracranial pressure occurred at any of the PEEP levels used. In both groups, cerebral perfusion pressure was unchanged throughout.

Conclusions

In patients with normal intracranial pressure, PEEP at 5 cm H sub 2 O did not significantly alter intracranial pressure. The clinical relevance of the intracranial pressure increase at PEEP levels of 10 and 15 cm H2 O is questionable because cerebral perfusion pressure did not change and remained >60 mm Hg. In patients with increased intracranial pressure, higher levels of PEEP did not significantly change intracranial pressure or cerebral perfusion pressure. (Crit Care Med 1997; 25:1059-1062)

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