A method for treating a mammal suffering from a respiratory disease characterized by acute intermittent or chronic obstruction of the airways of the lungs, such as asthma, acute asthma, chronic obstructive pulmonary disease (COPD) and bronchiectasis comprising delivering to the lungs of the mammal a perfluorocarbon and a gas mixture comprising carbon dioxide (CO2), and pharmaceutical compositions of CO2 and perfluorocarbons are provided. The acute relief of airway obstruction provided by the said treatment provides an opportunity for concomitant or subsequent delivery of additional suitable active agent of conventional treatments.