Effects of Varied Cerebrospinal Fluid Pressure on Cerebral Blood Flow in Dogs

Abstract

Abstract Effects of short‐term variations in cerebrospinal fluid pressure on cerebral blood flow in dogs were measured with the radioactive krypton clearance technique of Lassen et al . The cerebrospinal fluid pressure was increased stepwise by infusion of artificial cerohrospinal fluid, the pressure range from ‐15 to +150 mm Hg being investigated. The cerebral blood flow remained virtually stable, when the induced cerebrospinal pressure was lower than about 100 mm Hg. At higher values the cerebral blood flow began to fall. Thus, the existence of flow auto‐regulation was demonstrated also for the situation when perfusion pressure is reduced by a rise of the intracranial pressure. At very high cerebrospinal fluid pressures an additional reaction appeared in the form of a rise in the systemic arterial blood pressure. A discussion of the relative roles of these two regulating mechanisms is given.