Relative Ganglion-blocking Potencies of Cyclopropane, Halothane and Nitrous Oxide, and the Interaction of Nitrous Oxide with Halothane

The relative effects of halothane, cyclopropane, and nitrous oxide upon transmission in the stellate ganglion were examined in dogs previously given small doses of pentobarbital. The basis for estimating blockade was a comparison of the chronotropic responses to preganglionic and postganglionic nerve stimulation. We found that, while anesthetic actions varied widely in different preparations, there was a consistent relation among the responses to the various anesthetics when compared in the same preparation. Using this method halothane was found to be two to three times as potent in blocking ganglionic transmission as either cyclopropane or nitrous oxide when the agents were compared at equi-narcotic concentrations.