Effects of hemorrhagic hypotension on the cerebral circulation. III. Neuropathology.

A neuropathological examination was made of 15 cats anesthetized with alpha-chloralose, subjected to a stepwise reduction in mean arterial pressure by graded hemorrhagic hypotension. Five animals were sacrificed by perfusion-fixation at a mean arterial pressure of 75 mm Hg, 5 at a mean pressure of 35 mm Hg and 5 at 25 mm Hg. Ischemic brain damage was seen in only 5 animals, one sacrificed at a mean arterial pressure of 35 mm Hg and 4 at a pressure of 25 mm Hg. It was maximal in the selectively vulnerable areas and included the boundary zones between the major arteries of the cerebral hemispheres, the Ammon's horn and the thalamus.