Self-retaining brain retractor pressure during intracranial procedures.

One hundred and twenty recordings of the pressure beneath self-retaining brain retractors were obtained in 23 patients who were fully alert preoperatively. The brain retractor pressure (BRP) recordings showed a characteristic shape of the curves with an initial steep and later a more gradual slope. The BRP at the tip was higher than at the center of the retractor. The BRP recordings varied considerably as well in pressure (0-75 mmHg) as in time (4-40 minutes). Changes in systemic blood pressure and BRP in the 23 patients did not reduce the regional cerebral perfusion pressure (rCPP) below 10 mmHg for more than six to eight minutes, except in six cases. In five of the six patients an infarction demonstrated by CT scan developed beneath the area of application of the retractors. Only two patients later demonstrated clinical signs of cerebral infarction. Induced hypotension with sodium nitroprusside and the administration of mannitol did not influence the current pressure beneath the brain retractors.