Goff et al. hypothesized that, because of its ability to increase sympathetic nervous system activity, desflurane might offer an alternative to halothane as a bronchodilating agent after intravenous induction of anesthesia. Fifty patients scheduled for elective surgery with use of general anesthesia were recruited for the study and randomized for administration of 2.3% sevoflurane in oxygen–air (n = 20), 7% desflurane in oxygen–air (n = 20), or 0.25 mg · kg−1· min−1thiopental infusion (n = 10). Each group of patients contained approximately the same percentage of smokers: 42, 55, and 50%, respectively. The research team recorded baseline airway flow and pressure after thiopental induction, after tracheal intubation, and at 2.5, 5, 7.5, and 10 min after beginning volatile anesthesia. Respiratory system resistance was determined using the isovolume technique.
Instead of decreasing respiratory resistance (Rrs), desflurane increased Rrs by 5%. Thiopental also increased Rrs, by approximately 10%, but sevoflurane decreased Rrs by 15%. In patients administered desflurane, the greatest increases in Rrs occurred in those who were smokers. The authors did not explore whether the effects of desflurane on Rrs are different at lower or higher inspired concentrations than those used in this study, or whether desflurane may necessitate more time to induce bronchodilation.