Brain tissue pressure: physiological observations in anesthetized cats.

This study of direct tissue pressure measurement from brain parenchyma in 25 anesthetized cats focuses on steady-state observations and responses to some common physiological manipulations. Tissue pressure recording by a needle system can be done accurately without significant alterations of the blood-brain barrier, brain water content, regional cerebral blood flow, and cerebrovascular reactivity to changes in PaCO2 and cerebral perfusion pressure. Methodological details, including in vitro and in vivo validation, are described.