A method of treating a disease involving surfactant deficiency or dysfunction in a patients lungs is disclosed comprising the steps of providing a liquid lung surfactant composition aerosolizing the lung surfactant composition with a vibrating aperture-type aerosol generator to form a surfactant aerosol and introducing the surfactant aerosol into the gas flow within a circuit of a pressure-assisted breathing system coupled to the patients respiratory system, whereby a therapeutically effective amount of said surfactant is delivered to the patients lungs. Apparatus is also disclosed that increases the efficiency of delivery of aerosolized medicaments such as aerosolized lung surfactant.
