The effect of intraventricular blood on cerebral blood flow in newborn dogs.

We investigated the effect of intraventricular blood on cerebral blood flow in the newborn puppy by infusing autologous blood into the lateral ventricle to produce and maintain an intraventricular pressure of approximately 15 mm Hg (mild insult), 30 mm Hg (moderate insult), or 50 mm Hg (severe insult) for 20 min. As the intraventricular pressure increased, flow decreased progressively to all areas of the brain directly proportional to the cerebral perfusion pressure. On return of the intraventricular pressure to baseline level, cerebral blood flow normalized despite the continued presence of a large amount of blood within the lateral ventricles. We suggest that blood within the ventricular system can result in a significant acute reduction of cerebral blood flow which appears to be mediated through the effect on cerebral perfusion pressure.