The relation of cerebral ischemia, hypoxia, and hypercarbia to the Cushing response

Abstract

A marked increase in intracranial pressure (ICP) produces a concomitant increase in systemic blood pressure (the Cushing response). A comparison is made between this response of systemic blood pressure to increased ICP and the blood pressure responses produced by ischemia, hypoxia and hypercarbia of the primate [rhesus monkey] brain. A carotid-to-carotid cross-perfusion system was used to produce a purely cerebral hypoxia and hypercarbia. Each stimulus, except hypercarbia, produced a hypertensive response that was qualitatively and quantitatively similar. These responses were characterized by a short latent period, a rapid development and an increase in mean arterial pressure of 60% of more. The similarity of the responses suggests that these stimuli act through a final common pathway independent of the purely mechanical effects of increased ICP upon the brain.