Effects of Variations in Intracranial Pressure

I. EFFECT OF RAISED INTRACRANIAL PRESSURE ON CONSCIOUSNESS The experiments here reported were begun with the intention of studying the effect of experimentally produced cerebral edema on consciousness in the dog. To do this, distilled water was perfused into the anatomic central end of the common carotid artery, and observations were made on whether or not this procedure would render the animal comatose. Kymographic records were simultaneously taken of the respiration, the general carotid blood pressure, the cerebrospinal fluid pressure in the cisterna magna and the pressure in the brain tissue (intracerebral pressure). It was at first assumed that the pressure in the lateral ventricles was being accurately recorded by measurement of the cisternal pressure. The fallacy of this assumption was later demonstrated by some chance measurements of the intraventricular pressure. In subsequent experiments the intraventricular pressure was simultaneously recorded with a mercury manometer. METHODS Ether was the anesthetic employed