Fig. 3. Response to a histamine challenge expressed as a change in airway area at baseline and after intravenous (i.v.) (top ) or inhalational (bottom ) administration of dexmedetomidine (Dex). Changes refer to the respective baseline (mean ± SD). The initial histamine challenge led to a decrease in airway area of 23.5 ± 20.5% (top ) or 29.1 ± 24.6% (bottom ). Intravenous dexmedetomidine significantly blocked this response, whereas dexmedetomidine as an aerosol did not (47.5 ± 17.8%; bottom ).