Local coupling of cerebral blood flow to cerebral glucose metabolism during inhalational anesthesia in rats - Desflurane versus isoflurane

Background: It is not known whether the effects of desflurane on local cere bral glucose utilization (LCGU) and local cerebral blood flow (LCBF) are di fferent from those of other volatile anesthetics. Methods: Using the autoradiographic iodoantipyrine and deoxyglucose methods , LCGU, LCBF, and their overall means were measured in 60 Sprague-Dawley ra ts (10 groups, n = 6 each) during desflurane and isoflurane anesthesia and in conscious controls. Results: During anesthesia, mean cerebral glucose utilization was decreased compared with conscious controls: 1 minimum alveolar concentration (MAC) d esflurane: -52%; 1 MAC isoflurane: -44%; 2 MAC desflurane: -62%; and 2 MAC isoflurane: -60%. Local analysis showed a reduction of LCGU in the majority of the 40 brain regions analyzed. Mean cerebral blood now was increased: 1 MAC desflurane: +40%; 1 MAC isoflurane: +43%; 2 MAC desflurane and 2 MAC i soflurane: +70%. LCBF was increased in all brain structures investigated ex cept in the auditory cortex. No significant differences (P < 0.05) could be observed between both anesthetics for mean values of cerebral glucose use and blood flow. Correlation coefficients obtained for the relation between LCGU and LCBF mere as follows: controls: 0.95; 1 MAC desflurane: 0.89; 2 MA C desflurane: 0.60; 1 MAC isoflurane: 0.87; and 2 MAC isoflurane: 0.68. Conclusion: Differences in the physicochemical properties of desflurane com pared with isoflurane are not associated with major differences in the effe cts of both volatile anesthetics on cerebral glucose utilization, blood flo w, and the coupling between LCBF and LCGU.