Systemic vascular responses to increased intracranial pressure. 3. Effects of individual balloon inflations on intracranial pressure and the systemic circulation.

The effects of discrete increases in the volume of an artificial space-occupying lesion on intracranial pressures and the systemic circulation were studied in six anaesthetised and artificially ventilated dogs. Each increase in volume, accompanied by an increase in supratentorial intracranial pressure, a decrease in supratentorial perfusion pressure, and an increase in transtentorial pressure gradient, induced alterations in the systemic circulation. There were a decrease in heart rate, marked alterations in the arrhythmia index, and increases in stroke volume and systemic vascular resistance. A period of transient systemic hypertension was noted to accompany each discrete increase in intracranial pressure.