The risk of cerebral damage during graded brain retractor pressure in the rat.

A considerable reduction in regional cerebral blood flow has been demonstrated with brain retraction at a pressure of 30 mm Hg. The authors undertook a neuropathological study to assess the effect on brain tissue of brain retractors applied at varying pressures for 15 minutes. The following changes were found: after 20 mm Hg of brain retractor pressure (BRP) only one of six brains revealed infarction involving all cortical layers; after 30 mm Hg of BRP cortical infarction, partly hemorrhagic, was found in five of six brains; after 40 mm Hg of BRP all six animals showed cortical damage. There were no signs of cerebral damage outside the retractor application area or in deeper brain structures. It was concluded that only if BRP did not exceed 20 mm Hg for 15 minutes could damage be avoided in this model.