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Byline: G. Vajramuni, G. Umamaheswara Rao, S. Pillai
Background: Regional differences in vascular response to anesthetic agents in brain areas with and without tumors have not been investigated till now. The existence of such differences may influence the regional distribution of cerebral blood flow under anesthesia. Material and Methods: In 8 patients with frontotemporal gliomas, middle cerebral artery blood flow velocity (Vmca), pulsatality index (PI) and resistance index (RI) were determined in the normal and pathological cerebral hemispheres before and after stable nitrous oxide-halothane anesthesia. Results: During halothane anesthesia, there was an increase in Vmca both in the normal cerebral hemisphere (69 [+ or -] 11 to 100 [+ or -] 38 cm/s; P = 0.05) and the hemisphere with tumor (65 [+ or -] 17 to 83 [+ or -] 28 cm/s; P = 0.04). A significant decrease in the pulsatality index and the resistance index was also observed in both the hemispheres (P < 0.05). The percentage changes of Vmca,, PI and RI in both the hemispheres after anesthesia were not significantly different. Conclusions: In patients with cerebral tumors, nitrous oxide-halothane anesthesia causes comparable changes of cerebral blood flow velocities in the hemisphere with tumor and the normal hemisphere.
Inhalational anesthetics in current usage have varying levels of cerebral vasodilatory effect. Current literature does not clarify if there are any regional differences in the cerebral blood flow effects of inhalational anesthetics between normal areas and brain areas with tumor. If such differences exist, they may have major clinical implications similar to the steal and inverse steal phenomena caused by changes in arterial carbon dioxide pressure. If the cerebral vasodilatory response to inhalational anesthetics is totally or partially impaired in brain areas with tumor, administration of …