The Effects of Carbon Dioxide on Preganglionic Sympathetic Activity during Halothane, Methoxy-flurane, and Cyclopropane Anesthesia

The effects of 2.5 and 5.0 per cent inspired CO2 on cervical preganglionic sympathetic activity during exposure to equipotent concentrations of halothane, methoxyflurane, and cyclopropane have been compared with values during basal anesthesia with nitrous oxide-oxygen and gallamine in six cats. Although none of the three anesthetics changed the fractional increase in sympathetic nervous activity produced by CO2 from that observed during basal anesthesia, halothane and methoxyflurane depressed the absolute increase, while cyclopropane had no effect.