Intravenous Dexmedetomidine Inhibits Cerebrovascular Dilation Induced by Isoflurane and Sevoflurane in Dogs

Authors:
  • HOHiroto Ohata
    Hiroto Ohata
  • HIHiroki Iida
    Hiroki Iida
  • SDShuji Dohi
    Shuji Dohi
  • YWYukinaga Watanabe
    Yukinaga Watanabe
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Abstract
O groups: the isoflurane group or the sevoflurane group (n = 24 each). Twenty-four dogs received saline (n = 6) or one of three different doses of dexmedetomidine (0.5, 1.0, or 2.0 [micro sign]g/kg) (n = 6 each) IV. Animals were then exposed to three different minimum alveolar anesthetic concentrations (MACs; 0.5, 1.0, and 1.5) of either isoflurane or sevoflurane. Cerebrovascular diameters were measured at each stage. Pretreatment with dexmedetomidine decreased pial vessel diameters. Both isoflurane and sevoflurane significantly dilated both arterioles and venules in a concentration-dependent manner. Isoflurane- and sevoflurane-induced dilation of cerebral arterioles was significantly attenuated in the presence of dexmedetomidine. The dexmedetomidine-induced attenuation of the vascular responses was not dependent on the dose of dexmedetomidine and was not different between isoflurane and sevoflurane. The vasodilation of cerebral pial vessels induced by isoflurane and sevoflurane could be attenuated by the systemic administration of dexmedetomidine, and this interaction between dexmedetomidine and volatile anesthetics showed no evidence of dose-dependency. Implications: The systemic administration of dexmedetomidine attenuates the dilation of cerebral vessels induced by isoflurane and sevoflurane in pentobarbital-anesthetized dogs. This interaction was not dependent on the clinical (0.5-2.0 [micro sign]g/kg) dose of dexmedetomidine and was not different between isoflurane and sevoflurane anesthesia. (Anesth Analg 1999;89:370-7)...

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