Effect of dexmedetomidine, a selective and potent alpha 2-agonist, on cerebral blood flow and oxygen consumption during halothane anesthesia in dogs.

The effect of the alpha 2-agonist dexmedetomidine on the cerebral blood flow (CBF) and the metabolic rate for oxygen was studied by a sagittal sinus outflow technique in dogs during halothane anesthesia. Dexmedetomidine was given in a dose (10 micrograms/kg) reported to reduce the anesthetic requirement of halothane by 90%. During 0.9% halothane anesthesia dexmedetomidine caused a significant reduction in CBF without influencing the metabolic rate for oxygen. Reducing the halothane concentration to 0.1% caused no further change in CBF, but increased the metabolic rate for oxygen 19%. The cerebral vasoconstrictive effect, combined with the 90% reduction in MAC for halothane, indicates that dexmedetomidine might be a useful adjunct to inhalation anesthetics during neurosurgery in situations where an increase in CBF should be avoided.