The effects of 30% and 60% xenon inhalation on pial vessel diameter and intracranial pressure in rabbits

Xenon may increase cerebral blood flow and intracranial pressure (ICP). To evaluate the effects of xenon on brain circulation, we measured pial vessel diameter changes, CO2 reactivity, and TCP during xenon inhalation in rabbi ts. Minimum alveolar anesthetic concentration (MAC) for xenon was establish ed in rabbits (n = 6). By using a cranial window model, pial vessel diamete rs were measured at 30% and 60% xenon inhalation and in time control groups (n = 15). ICP, mean arterial blood pressure, and heart rate were recorded during 30% and 60% xenon inhalation (n = 5). Pial vessel diameters were mea sured during hypocapnia and hypercapnia conditions in 60% Xenon and Control groups (n = 14). MAC for xenon was 85%. Xenon (0.35 and 0.7 MAC) dilated t he arterioles (10% and 18%, respectively) and venules (2% and 4%, respectiv ely) (P < 0.05). Dilation of arterioles was more prominent than that of ven ules. ICP, mean arterial blood pressure, and heart rate did not change duri ng xenon inhalation. No difference in CO2 reactivity was observed between X enon and Control groups (P = 0.79). Sixty percent xenon (0.7 MAC) dilated b rain vessels, but venule changes were small. Xenon did not increase ICP and preserved CO2 reactivity of the brain vessels.